/*
 ******************************************************************
 *           C++ Mathematical Expression Toolkit Library          *
 *                                                                *
 * Author: Arash Partow (1999-2024)                               *
 * URL: https://www.partow.net/programming/exprtk/index.html      *
 *                                                                *
 * Copyright notice:                                              *
 * Free use of the C++ Mathematical Expression Toolkit Library is *
 * permitted under the guidelines and in accordance with the most *
 * current version of the MIT License.                            *
 * https://www.opensource.org/licenses/MIT                        *
 * SPDX-License-Identifier: MIT                                   *
 *                                                                *
 * Example expressions:                                           *
 * (00) (y + x / y) * (x - y / x)                                 *
 * (01) (x^2 / sin(2 * pi / y)) - x / 2                           *
 * (02) sqrt(1 - (x^2))                                           *
 * (03) 1 - sin(2 * x) + cos(pi / y)                              *
 * (04) a * exp(2 * t) + c                                        *
 * (05) if(((x + 2) == 3) and ((y + 5) <= 9), 1 + w, 2 / z)       *
 * (06) (avg(x,y) <= x + y ? x - y : x * y) + 2 * pi / x          *
 * (07) z := x + sin(2 * pi / y)                                  *
 * (08) u := 2 * (pi * z) / (w := x + cos(y / pi))                *
 * (09) clamp(-1, sin(2 * pi * x) + cos(y / 2 * pi), +1)          *
 * (10) inrange(-2, m, +2) == if(({-2 <= m} and [m <= +2]), 1, 0) *
 * (11) (2sin(x)cos(2y)7 + 1) == (2 * sin(x) * cos(2*y) * 7 + 1)  *
 * (12) (x ilike 's*ri?g') and [y < (3 z^7 + w)]                  *
 *                                                                *
 ******************************************************************
*/


#ifndef INCLUDE_EXPRTK_HPP
#define INCLUDE_EXPRTK_HPP


#include <algorithm>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <functional>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>


namespace exprtk
{
   #ifdef exprtk_enable_debugging
     #define exprtk_debug(params) printf params
   #else
     #define exprtk_debug(params) (void)0
   #endif

   #define exprtk_error_location             \
   "exprtk.hpp:" + details::to_str(__LINE__) \

   #if __cplusplus >= 201103L
      #define exprtk_override override
      #define exprtk_final    final
      #define exprtk_delete   = delete
   #else
      #define exprtk_override
      #define exprtk_final
      #define exprtk_delete
   #endif

   #if __cplusplus >= 201603L
      #define exprtk_fallthrough [[fallthrough]];
   #elif __cplusplus >= 201103L
      #define exprtk_fallthrough [[gnu::fallthrough]];
   #else
      #ifndef _MSC_VER
      #define exprtk_fallthrough __attribute__ ((fallthrough));
      #else
      #define exprtk_fallthrough
      #endif
   #endif

   namespace details
   {
      typedef char                   char_t;
      typedef char_t*                char_ptr;
      typedef char_t const*          char_cptr;
      typedef unsigned char          uchar_t;
      typedef uchar_t*               uchar_ptr;
      typedef uchar_t const*         uchar_cptr;
      typedef unsigned long long int _uint64_t;
      typedef long long int          _int64_t;

      inline bool is_whitespace(const char_t c)
      {
         return (' '  == c) || ('\n' == c) ||
                ('\r' == c) || ('\t' == c) ||
                ('\b' == c) || ('\v' == c) ||
                ('\f' == c) ;
      }

      inline bool is_operator_char(const char_t c)
      {
         return ('+' == c) || ('-' == c) ||
                ('*' == c) || ('/' == c) ||
                ('^' == c) || ('<' == c) ||
                ('>' == c) || ('=' == c) ||
                (',' == c) || ('!' == c) ||
                ('(' == c) || (')' == c) ||
                ('[' == c) || (']' == c) ||
                ('{' == c) || ('}' == c) ||
                ('%' == c) || (':' == c) ||
                ('?' == c) || ('&' == c) ||
                ('|' == c) || (';' == c) ;
      }

      inline bool is_letter(const char_t c)
      {
         return (('a' <= c) && (c <= 'z')) ||
                (('A' <= c) && (c <= 'Z')) ;
      }

      inline bool is_digit(const char_t c)
      {
         return ('0' <= c) && (c <= '9');
      }

      inline bool is_letter_or_digit(const char_t c)
      {
         return is_letter(c) || is_digit(c);
      }

      inline bool is_left_bracket(const char_t c)
      {
         return ('(' == c) || ('[' == c) || ('{' == c);
      }

      inline bool is_right_bracket(const char_t c)
      {
         return (')' == c) || (']' == c) || ('}' == c);
      }

      inline bool is_bracket(const char_t c)
      {
         return is_left_bracket(c) || is_right_bracket(c);
      }

      inline bool is_sign(const char_t c)
      {
         return ('+' == c) || ('-' == c);
      }

      inline bool is_invalid(const char_t c)
      {
         return !is_whitespace   (c) &&
                !is_operator_char(c) &&
                !is_letter       (c) &&
                !is_digit        (c) &&
                ('.'  != c)          &&
                ('_'  != c)          &&
                ('$'  != c)          &&
                ('~'  != c)          &&
                ('\'' != c);
      }

      inline bool is_valid_string_char(const char_t c)
      {
         return std::isprint(static_cast<uchar_t>(c)) ||
                is_whitespace(c);
      }

      #ifndef exprtk_disable_caseinsensitivity
      inline void case_normalise(std::string& s)
      {
         for (std::size_t i = 0; i < s.size(); ++i)
         {
            s[i] = static_cast<std::string::value_type>(std::tolower(s[i]));
         }
      }

      inline bool imatch(const char_t c1, const char_t c2)
      {
         return std::tolower(c1) == std::tolower(c2);
      }

      inline bool imatch(const std::string& s1, const std::string& s2)
      {
         if (s1.size() == s2.size())
         {
            for (std::size_t i = 0; i < s1.size(); ++i)
            {
               if (std::tolower(s1[i]) != std::tolower(s2[i]))
               {
                  return false;
               }
            }

            return true;
         }

         return false;
      }

      struct ilesscompare
      {
         inline bool operator() (const std::string& s1, const std::string& s2) const
         {
            const std::size_t length = std::min(s1.size(),s2.size());

            for (std::size_t i = 0; i < length; ++i)
            {
               const char_t c1 = static_cast<char_t>(std::tolower(s1[i]));
               const char_t c2 = static_cast<char_t>(std::tolower(s2[i]));

               if (c1 < c2)
                  return true;
               else if (c2 < c1)
                  return false;
            }

            return s1.size() < s2.size();
         }
      };

      #else
      inline void case_normalise(std::string&)
      {}

      inline bool imatch(const char_t c1, const char_t c2)
      {
         return c1 == c2;
      }

      inline bool imatch(const std::string& s1, const std::string& s2)
      {
         return s1 == s2;
      }

      struct ilesscompare
      {
         inline bool operator() (const std::string& s1, const std::string& s2) const
         {
            return s1 < s2;
         }
      };
      #endif

      inline bool is_valid_sf_symbol(const std::string& symbol)
      {
         // Special function: $f12 or $F34
         return (4 == symbol.size())  &&
                ('$' == symbol[0])    &&
                imatch('f',symbol[1]) &&
                is_digit(symbol[2])   &&
                is_digit(symbol[3]);
      }

      inline const char_t& front(const std::string& s)
      {
         return s[0];
      }

      inline const char_t& back(const std::string& s)
      {
         return s[s.size() - 1];
      }

      inline std::string to_str(int i)
      {
         if (0 == i)
            return std::string("0");

         std::string result;

         const int sign = (i < 0) ? -1 : 1;

         for ( ; i; i /= 10)
         {
            result += '0' + static_cast<char_t>(sign * (i % 10));
         }

         if (sign < 0)
         {
            result += '-';
         }

         std::reverse(result.begin(), result.end());

         return result;
      }

      inline std::string to_str(std::size_t i)
      {
         return to_str(static_cast<int>(i));
      }

      inline bool is_hex_digit(const uchar_t digit)
      {
         return (('0' <= digit) && (digit <= '9')) ||
                (('A' <= digit) && (digit <= 'F')) ||
                (('a' <= digit) && (digit <= 'f')) ;
      }

      inline uchar_t hex_to_bin(uchar_t h)
      {
         if (('0' <= h) && (h <= '9'))
            return (h - '0');
         else
            return static_cast<uchar_t>(std::toupper(h) - 'A');
      }

      template <typename Iterator>
      inline bool parse_hex(Iterator& itr, Iterator end,
                            char_t& result)
      {
         if (
              (end ==  (itr    ))               ||
              (end ==  (itr + 1))               ||
              (end ==  (itr + 2))               ||
              (end ==  (itr + 3))               ||
              ('0' != *(itr    ))               ||
              ('X' != std::toupper(*(itr + 1))) ||
              (!is_hex_digit(*(itr + 2)))       ||
              (!is_hex_digit(*(itr + 3)))
            )
         {
            return false;
         }

         result = hex_to_bin(static_cast<uchar_t>(*(itr + 2))) << 4 |
                  hex_to_bin(static_cast<uchar_t>(*(itr + 3))) ;

         return true;
      }

      inline bool cleanup_escapes(std::string& s)
      {
         typedef std::string::iterator str_itr_t;

         str_itr_t itr1 = s.begin();
         str_itr_t itr2 = s.begin();
         str_itr_t end  = s.end  ();

         std::size_t removal_count  = 0;

         while (end != itr1)
         {
            if ('\\' == (*itr1))
            {
               if (end == ++itr1)
               {
                  return false;
               }
               else if (parse_hex(itr1, end, *itr2))
               {
                  itr1 += 4;
                  itr2 += 1;
                  removal_count += 4;
               }
               else if ('a' == (*itr1)) { (*itr2++) = '\a'; ++itr1; ++removal_count; }
               else if ('b' == (*itr1)) { (*itr2++) = '\b'; ++itr1; ++removal_count; }
               else if ('f' == (*itr1)) { (*itr2++) = '\f'; ++itr1; ++removal_count; }
               else if ('n' == (*itr1)) { (*itr2++) = '\n'; ++itr1; ++removal_count; }
               else if ('r' == (*itr1)) { (*itr2++) = '\r'; ++itr1; ++removal_count; }
               else if ('t' == (*itr1)) { (*itr2++) = '\t'; ++itr1; ++removal_count; }
               else if ('v' == (*itr1)) { (*itr2++) = '\v'; ++itr1; ++removal_count; }
               else if ('0' == (*itr1)) { (*itr2++) = '\0'; ++itr1; ++removal_count; }
               else
               {
                  (*itr2++) = (*itr1++);
                  ++removal_count;
               }

               continue;
            }
            else
               (*itr2++) = (*itr1++);
         }

         if ((removal_count > s.size()) || (0 == removal_count))
            return false;

         s.resize(s.size() - removal_count);

         return true;
      }

      class build_string
      {
      public:

         explicit build_string(const std::size_t& initial_size = 64)
         {
            data_.reserve(initial_size);
         }

         inline build_string& operator << (const std::string& s)
         {
            data_ += s;
            return (*this);
         }

         inline build_string& operator << (char_cptr s)
         {
            data_ += std::string(s);
            return (*this);
         }

         inline operator std::string () const
         {
            return data_;
         }

         inline std::string as_string() const
         {
            return data_;
         }

      private:

         std::string data_;
      };

      static const std::string reserved_words[] =
      {
         "assert",  "break", "case", "continue", "const",  "default",
         "false", "for", "if", "else", "ilike", "in", "like",  "and",
         "nand",  "nor",  "not",  "null",  "or",  "repeat", "return",
         "shl",  "shr",  "swap",  "switch",  "true",  "until", "var",
         "while", "xnor", "xor", "&", "|"
      };

      static const std::size_t reserved_words_size = sizeof(reserved_words) / sizeof(std::string);

      static const std::string reserved_symbols[] =
      {
         "abs", "acos",  "acosh", "and",  "asin", "asinh",  "assert",
         "atan", "atanh",  "atan2", "avg",  "break", "case",  "ceil",
         "clamp", "continue", "const",  "cos", "cosh", "cot",  "csc",
         "default",  "deg2grad", "deg2rad",  "equal", "erf",  "erfc",
         "exp", "expm1", "false", "floor", "for", "frac", "grad2deg",
         "hypot", "iclamp", "if",  "else", "ilike", "in",  "inrange",
         "like",  "log",  "log10", "log2",  "logn",  "log1p", "mand",
         "max", "min",  "mod", "mor",  "mul", "ncdf",  "nand", "nor",
         "not",   "not_equal",   "null",   "or",   "pow",  "rad2deg",
         "repeat", "return", "root", "round", "roundn", "sec", "sgn",
         "shl", "shr", "sin", "sinc", "sinh", "sqrt", "sum",  "swap",
         "switch", "tan",  "tanh", "true",  "trunc", "until",  "var",
         "while", "xnor", "xor", "&", "|"
      };

      static const std::size_t reserved_symbols_size = sizeof(reserved_symbols) / sizeof(std::string);

      static const std::string base_function_list[] =
      {
         "abs", "acos",  "acosh", "asin",  "asinh", "atan",  "atanh",
         "atan2",  "avg",  "ceil",  "clamp",  "cos",  "cosh",  "cot",
         "csc",  "equal",  "erf",  "erfc",  "exp",  "expm1", "floor",
         "frac", "hypot", "iclamp",  "like", "log", "log10",  "log2",
         "logn", "log1p", "mand", "max", "min", "mod", "mor",  "mul",
         "ncdf",  "pow",  "root",  "round",  "roundn",  "sec", "sgn",
         "sin", "sinc", "sinh", "sqrt", "sum", "swap", "tan", "tanh",
         "trunc",  "not_equal",  "inrange",  "deg2grad",   "deg2rad",
         "rad2deg", "grad2deg"
      };

      static const std::size_t base_function_list_size = sizeof(base_function_list) / sizeof(std::string);

      static const std::string logic_ops_list[] =
      {
         "and", "nand", "nor", "not", "or",  "xnor", "xor", "&", "|"
      };

      static const std::size_t logic_ops_list_size = sizeof(logic_ops_list) / sizeof(std::string);

      static const std::string cntrl_struct_list[] =
      {
         "if", "switch", "for", "while", "repeat", "return"
      };

      static const std::size_t cntrl_struct_list_size = sizeof(cntrl_struct_list) / sizeof(std::string);

      static const std::string arithmetic_ops_list[] =
      {
         "+", "-", "*", "/", "%", "^"
      };

      static const std::size_t arithmetic_ops_list_size = sizeof(arithmetic_ops_list) / sizeof(std::string);

      static const std::string assignment_ops_list[] =
      {
         ":=", "+=", "-=",
         "*=", "/=", "%="
      };

      static const std::size_t assignment_ops_list_size = sizeof(assignment_ops_list) / sizeof(std::string);

      static const std::string inequality_ops_list[] =
      {
         "<",  "<=", "==",
         "=",  "!=", "<>",
         ">=",  ">"
      };

      static const std::size_t inequality_ops_list_size = sizeof(inequality_ops_list) / sizeof(std::string);

      inline bool is_reserved_word(const std::string& symbol)
      {
         for (std::size_t i = 0; i < reserved_words_size; ++i)
         {
            if (imatch(symbol, reserved_words[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_reserved_symbol(const std::string& symbol)
      {
         for (std::size_t i = 0; i < reserved_symbols_size; ++i)
         {
            if (imatch(symbol, reserved_symbols[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_base_function(const std::string& function_name)
      {
         for (std::size_t i = 0; i < base_function_list_size; ++i)
         {
            if (imatch(function_name, base_function_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_control_struct(const std::string& cntrl_strct)
      {
         for (std::size_t i = 0; i < cntrl_struct_list_size; ++i)
         {
            if (imatch(cntrl_strct, cntrl_struct_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_logic_opr(const std::string& lgc_opr)
      {
         for (std::size_t i = 0; i < logic_ops_list_size; ++i)
         {
            if (imatch(lgc_opr, logic_ops_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      struct cs_match
      {
         static inline bool cmp(const char_t c0, const char_t c1)
         {
            return (c0 == c1);
         }
      };

      struct cis_match
      {
         static inline bool cmp(const char_t c0, const char_t c1)
         {
            return (std::tolower(c0) == std::tolower(c1));
         }
      };

      template <typename Iterator, typename Compare>
      inline bool match_impl(const Iterator pattern_begin,
                             const Iterator pattern_end  ,
                             const Iterator data_begin   ,
                             const Iterator data_end     ,
                             const typename std::iterator_traits<Iterator>::value_type& zero_or_more,
                             const typename std::iterator_traits<Iterator>::value_type& exactly_one )
      {
         typedef typename std::iterator_traits<Iterator>::value_type type;

         const Iterator null_itr(0);

         Iterator p_itr  = pattern_begin;
         Iterator d_itr  = data_begin;
         Iterator np_itr = null_itr;
         Iterator nd_itr = null_itr;

         for ( ; ; )
         {
            if (p_itr != pattern_end)
            {
               const type c = *(p_itr);

               if ((data_end != d_itr) && (Compare::cmp(c,*(d_itr)) || (exactly_one == c)))
               {
                  ++d_itr;
                  ++p_itr;
                  continue;
               }
               else if (zero_or_more == c)
               {
                  while ((pattern_end != p_itr) && (zero_or_more == *(p_itr)))
                  {
                     ++p_itr;
                  }

                  const type d = *(p_itr);

                  while ((data_end != d_itr) && !(Compare::cmp(d,*(d_itr)) || (exactly_one == d)))
                  {
                     ++d_itr;
                  }

                  // set backtrack iterators
                  np_itr = p_itr - 1;
                  nd_itr = d_itr + 1;

                  continue;
               }
            }
            else if (data_end == d_itr)
               break;

            if ((data_end == d_itr) || (null_itr == nd_itr))
                return false;

            p_itr = np_itr;
            d_itr = nd_itr;
         }

         return true;
      }

      inline bool wc_match(const std::string& wild_card,
                           const std::string& str)
      {
         return match_impl<char_cptr,cs_match>
                (
                   wild_card.data(),
                   wild_card.data() + wild_card.size(),
                   str.data(),
                   str.data() + str.size(),
                   '*', '?'
                );
      }

      inline bool wc_imatch(const std::string& wild_card,
                            const std::string& str)
      {
         return match_impl<char_cptr,cis_match>
                (
                   wild_card.data(),
                   wild_card.data() + wild_card.size(),
                   str.data(),
                   str.data() + str.size(),
                   '*', '?'
                );
      }

      inline bool sequence_match(const std::string& pattern,
                                 const std::string& str,
                                 std::size_t&       diff_index,
                                 char_t&            diff_value)
      {
         if (str.empty())
         {
            return ("Z" == pattern);
         }
         else if ('*' == pattern[0])
            return false;

         typedef std::string::const_iterator itr_t;

         itr_t p_itr = pattern.begin();
         itr_t s_itr = str    .begin();

         const itr_t p_end = pattern.end();
         const itr_t s_end = str    .end();

         while ((s_end != s_itr) && (p_end != p_itr))
         {
            if ('*' == (*p_itr))
            {
               const char_t target = static_cast<char_t>(std::toupper(*(p_itr - 1)));

               if ('*' == target)
               {
                  diff_index = static_cast<std::size_t>(std::distance(str.begin(),s_itr));
                  diff_value = static_cast<char_t>(std::toupper(*p_itr));

                  return false;
               }
               else
                  ++p_itr;

               while (s_itr != s_end)
               {
                  if (target != std::toupper(*s_itr))
                     break;
                  else
                     ++s_itr;
               }

               continue;
            }
            else if (
                      ('?' != *p_itr) &&
                      std::toupper(*p_itr) != std::toupper(*s_itr)
                    )
            {
               diff_index = static_cast<std::size_t>(std::distance(str.begin(),s_itr));
               diff_value = static_cast<char_t>(std::toupper(*p_itr));

               return false;
            }

            ++p_itr;
            ++s_itr;
         }

         return (
                  (s_end == s_itr) &&
                  (
                    (p_end ==  p_itr) ||
                    ('*'   == *p_itr)
                  )
                );
      }

      template<typename T>
      struct set_zero_value_impl
      {
         static inline void process(T* base_ptr, const std::size_t size)
         {
            const T zero = T(0);
            for (std::size_t i = 0; i < size; ++i)
            {
               base_ptr[i] = zero;
            }
         }
      };

      #define pod_set_zero_value(T)                                      \
      template <>                                                        \
      struct set_zero_value_impl<T>                                      \
      {                                                                  \
         static inline void process(T* base_ptr, const std::size_t size) \
         { std::memset(base_ptr, 0x00, size * sizeof(T)); }              \
      };                                                                 \

      pod_set_zero_value(float      )
      pod_set_zero_value(double     )
      pod_set_zero_value(long double)

      #ifdef pod_set_zero_value
      #undef pod_set_zero_value
      #endif

      template<typename T>
      inline void set_zero_value(T* data, const std::size_t size)
      {
         set_zero_value_impl<T>::process(data,size);
      }

      template<typename T>
      inline void set_zero_value(std::vector<T>& v)
      {
         set_zero_value(v.data(),v.size());
      }

      static const double pow10[] =
      {
         1.0,
         1.0E+001, 1.0E+002, 1.0E+003, 1.0E+004,
         1.0E+005, 1.0E+006, 1.0E+007, 1.0E+008,
         1.0E+009, 1.0E+010, 1.0E+011, 1.0E+012,
         1.0E+013, 1.0E+014, 1.0E+015, 1.0E+016
      };

      static const std::size_t pow10_size = sizeof(pow10) / sizeof(double);

      namespace numeric
      {
         namespace constant
         {
            static const double e       =  2.71828182845904523536028747135266249775724709369996;
            static const double pi      =  3.14159265358979323846264338327950288419716939937510;
            static const double pi_2    =  1.57079632679489661923132169163975144209858469968755;
            static const double pi_4    =  0.78539816339744830961566084581987572104929234984378;
            static const double pi_180  =  0.01745329251994329576923690768488612713442871888542;
            static const double _1_pi   =  0.31830988618379067153776752674502872406891929148091;
            static const double _2_pi   =  0.63661977236758134307553505349005744813783858296183;
            static const double _180_pi = 57.29577951308232087679815481410517033240547246656443;
            static const double log2    =  0.69314718055994530941723212145817656807550013436026;
            static const double sqrt2   =  1.41421356237309504880168872420969807856967187537695;
         }

         namespace details
         {
            struct unknown_type_tag { unknown_type_tag() {} };
            struct real_type_tag    { real_type_tag   () {} };
            struct int_type_tag     { int_type_tag    () {} };

            template <typename T>
            struct number_type
            {
               typedef unknown_type_tag type;
               number_type() {}
            };

            #define exprtk_register_real_type_tag(T)          \
            template <> struct number_type<T>                 \
            { typedef real_type_tag type; number_type() {} }; \

            #define exprtk_register_int_type_tag(T)           \
            template <> struct number_type<T>                 \
            { typedef int_type_tag type; number_type() {} };  \

            exprtk_register_real_type_tag(float      )
            exprtk_register_real_type_tag(double     )
            exprtk_register_real_type_tag(long double)

            exprtk_register_int_type_tag(short         )
            exprtk_register_int_type_tag(int           )
            exprtk_register_int_type_tag(_int64_t      )
            exprtk_register_int_type_tag(unsigned short)
            exprtk_register_int_type_tag(unsigned int  )
            exprtk_register_int_type_tag(_uint64_t     )

            #undef exprtk_register_real_type_tag
            #undef exprtk_register_int_type_tag

            template <typename T>
            struct epsilon_type {};

            #define exprtk_define_epsilon_type(Type, Epsilon)      \
            template <> struct epsilon_type<Type>                  \
            {                                                      \
               static inline Type value()                          \
               {                                                   \
                  const Type epsilon = static_cast<Type>(Epsilon); \
                  return epsilon;                                  \
               }                                                   \
            };                                                     \

            exprtk_define_epsilon_type(float      , 0.00000100000f)
            exprtk_define_epsilon_type(double     , 0.000000000100)
            exprtk_define_epsilon_type(long double, 0.000000000001)

            #undef exprtk_define_epsilon_type

            template <typename T>
            inline bool is_nan_impl(const T v, real_type_tag)
            {
               return std::not_equal_to<T>()(v,v);
            }

            template <typename T>
            inline int to_int32_impl(const T v, real_type_tag)
            {
               return static_cast<int>(v);
            }

            template <typename T>
            inline _int64_t to_int64_impl(const T v, real_type_tag)
            {
               return static_cast<_int64_t>(v);
            }

            template <typename T>
            inline _uint64_t to_uint64_impl(const T v, real_type_tag)
            {
               return static_cast<_uint64_t>(v);
            }

            template <typename T>
            inline bool is_true_impl(const T v)
            {
               return std::not_equal_to<T>()(T(0),v);
            }

            template <typename T>
            inline bool is_false_impl(const T v)
            {
               return std::equal_to<T>()(T(0),v);
            }

            template <typename T>
            inline T abs_impl(const T v, real_type_tag)
            {
               return ((v < T(0)) ? -v : v);
            }

            template <typename T>
            inline T min_impl(const T v0, const T v1, real_type_tag)
            {
               return std::min<T>(v0,v1);
            }

            template <typename T>
            inline T max_impl(const T v0, const T v1, real_type_tag)
            {
               return std::max<T>(v0,v1);
            }

            template <typename T>
            inline T equal_impl(const T v0, const T v1, real_type_tag)
            {
               const T epsilon = epsilon_type<T>::value();
               return (abs_impl(v0 - v1,real_type_tag()) <= (std::max(T(1),std::max(abs_impl(v0,real_type_tag()),abs_impl(v1,real_type_tag()))) * epsilon)) ? T(1) : T(0);
            }

            inline float equal_impl(const float v0, const float v1, real_type_tag)
            {
               const float epsilon = epsilon_type<float>::value();
               return (abs_impl(v0 - v1,real_type_tag()) <= (std::max(1.0f,std::max(abs_impl(v0,real_type_tag()),abs_impl(v1,real_type_tag()))) * epsilon)) ? 1.0f : 0.0f;
            }

            template <typename T>
            inline T equal_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 == v1) ? 1 : 0;
            }

            template <typename T>
            inline T expm1_impl(const T v, real_type_tag)
            {
               // return std::expm1<T>(v);
               if (abs_impl(v,real_type_tag()) < T(0.00001))
                  return v + (T(0.5) * v * v);
               else
                  return std::exp(v) - T(1);
            }

            template <typename T>
            inline T expm1_impl(const T v, int_type_tag)
            {
               return T(std::exp<double>(v)) - T(1);
            }

            template <typename T>
            inline T nequal_impl(const T v0, const T v1, real_type_tag)
            {
               typedef real_type_tag rtg;
               const T epsilon = epsilon_type<T>::value();
               return (abs_impl(v0 - v1,rtg()) > (std::max(T(1),std::max(abs_impl(v0,rtg()),abs_impl(v1,rtg()))) * epsilon)) ? T(1) : T(0);
            }

            inline float nequal_impl(const float v0, const float v1, real_type_tag)
            {
               typedef real_type_tag rtg;
               const float epsilon = epsilon_type<float>::value();
               return (abs_impl(v0 - v1,rtg()) > (std::max(1.0f,std::max(abs_impl(v0,rtg()),abs_impl(v1,rtg()))) * epsilon)) ? 1.0f : 0.0f;
            }

            template <typename T>
            inline T nequal_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 != v1) ? 1 : 0;
            }

            template <typename T>
            inline T modulus_impl(const T v0, const T v1, real_type_tag)
            {
               return std::fmod(v0,v1);
            }

            template <typename T>
            inline T modulus_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 % v1;
            }

            template <typename T>
            inline T pow_impl(const T v0, const T v1, real_type_tag)
            {
               return std::pow(v0,v1);
            }

            template <typename T>
            inline T pow_impl(const T v0, const T v1, int_type_tag)
            {
               return std::pow(static_cast<double>(v0),static_cast<double>(v1));
            }

            template <typename T>
            inline T logn_impl(const T v0, const T v1, real_type_tag)
            {
               return std::log(v0) / std::log(v1);
            }

            template <typename T>
            inline T logn_impl(const T v0, const T v1, int_type_tag)
            {
               return static_cast<T>(logn_impl<double>(static_cast<double>(v0),static_cast<double>(v1),real_type_tag()));
            }

            template <typename T>
            inline T log1p_impl(const T v, real_type_tag)
            {
               if (v > T(-1))
               {
                  if (abs_impl(v,real_type_tag()) > T(0.0001))
                  {
                     return std::log(T(1) + v);
                  }
                  else
                     return (T(-0.5) * v + T(1)) * v;
               }

               return std::numeric_limits<T>::quiet_NaN();
            }

            template <typename T>
            inline T log1p_impl(const T v, int_type_tag)
            {
               if (v > T(-1))
               {
                  return std::log(T(1) + v);
               }

               return std::numeric_limits<T>::quiet_NaN();
            }

            template <typename T>
            inline T root_impl(const T v0, const T v1, real_type_tag)
            {
               if (v1 < T(0))
                  return std::numeric_limits<T>::quiet_NaN();

               const std::size_t n = static_cast<std::size_t>(v1);

               if ((v0 < T(0)) && (0 == (n % 2)))
                  return std::numeric_limits<T>::quiet_NaN();

               return std::pow(v0, T(1) / n);
            }

            template <typename T>
            inline T root_impl(const T v0, const T v1, int_type_tag)
            {
               return root_impl<double>(static_cast<double>(v0),static_cast<double>(v1),real_type_tag());
            }

            template <typename T>
            inline T round_impl(const T v, real_type_tag)
            {
               return ((v < T(0)) ? std::ceil(v - T(0.5)) : std::floor(v + T(0.5)));
            }

            template <typename T>
            inline T roundn_impl(const T v0, const T v1, real_type_tag)
            {
               const int index = std::max<int>(0, std::min<int>(pow10_size - 1, static_cast<int>(std::floor(v1))));
               const T p10 = T(pow10[index]);

               if (v0 < T(0))
                  return T(std::ceil ((v0 * p10) - T(0.5)) / p10);
               else
                  return T(std::floor((v0 * p10) + T(0.5)) / p10);
            }

            template <typename T>
            inline T roundn_impl(const T v0, const T, int_type_tag)
            {
               return v0;
            }

            template <typename T>
            inline T hypot_impl(const T v0, const T v1, real_type_tag)
            {
               return std::sqrt((v0 * v0) + (v1 * v1));
            }

            template <typename T>
            inline T hypot_impl(const T v0, const T v1, int_type_tag)
            {
               return static_cast<T>(std::sqrt(static_cast<double>((v0 * v0) + (v1 * v1))));
            }

            template <typename T>
            inline T atan2_impl(const T v0, const T v1, real_type_tag)
            {
               return std::atan2(v0,v1);
            }

            template <typename T>
            inline T atan2_impl(const T, const T, int_type_tag)
            {
               return 0;
            }

            template <typename T>
            inline T shr_impl(const T v0, const T v1, real_type_tag)
            {
               return v0 * (T(1) / std::pow(T(2),static_cast<T>(static_cast<int>(v1))));
            }

            template <typename T>
            inline T shr_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 >> v1;
            }

            template <typename T>
            inline T shl_impl(const T v0, const T v1, real_type_tag)
            {
               return v0 * std::pow(T(2),static_cast<T>(static_cast<int>(v1)));
            }

            template <typename T>
            inline T shl_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 << v1;
            }

            template <typename T>
            inline T sgn_impl(const T v, real_type_tag)
            {
               if      (v > T(0)) return T(+1);
               else if (v < T(0)) return T(-1);
               else               return T( 0);
            }

            template <typename T>
            inline T sgn_impl(const T v, int_type_tag)
            {
               if      (v > T(0)) return T(+1);
               else if (v < T(0)) return T(-1);
               else               return T( 0);
            }

            template <typename T>
            inline T and_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_true_impl(v0) && is_true_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T and_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 && v1;
            }

            template <typename T>
            inline T nand_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) || is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T nand_impl(const T v0, const T v1, int_type_tag)
            {
               return !(v0 && v1);
            }

            template <typename T>
            inline T or_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_true_impl(v0) || is_true_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T or_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 || v1);
            }

            template <typename T>
            inline T nor_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) && is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T nor_impl(const T v0, const T v1, int_type_tag)
            {
               return !(v0 || v1);
            }

            template <typename T>
            inline T xor_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) != is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T xor_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 ^ v1;
            }

            template <typename T>
            inline T xnor_impl(const T v0, const T v1, real_type_tag)
            {
               const bool v0_true = is_true_impl(v0);
               const bool v1_true = is_true_impl(v1);

               if ((v0_true &&  v1_true) || (!v0_true && !v1_true))
                  return T(1);
               else
                  return T(0);
            }

            template <typename T>
            inline T xnor_impl(const T v0, const T v1, int_type_tag)
            {
               const bool v0_true = is_true_impl(v0);
               const bool v1_true = is_true_impl(v1);

               if ((v0_true &&  v1_true) || (!v0_true && !v1_true))
                  return T(1);
               else
                  return T(0);
            }

            #if (defined(_MSC_VER) && (_MSC_VER >= 1900)) || !defined(_MSC_VER)
            #define exprtk_define_erf(TT, impl)                \
            inline TT erf_impl(const TT v) { return impl(v); } \

            exprtk_define_erf(float      , ::erff)
            exprtk_define_erf(double     , ::erf )
            exprtk_define_erf(long double, ::erfl)
            #undef exprtk_define_erf
            #endif

            template <typename T>
            inline T erf_impl(const T v, real_type_tag)
            {
               #if defined(_MSC_VER) && (_MSC_VER < 1900)
               // Credits: Abramowitz & Stegun Equations 7.1.25-28
               static const T c[] =
               {
                  T( 1.26551223), T(1.00002368),
                  T( 0.37409196), T(0.09678418),
                  T(-0.18628806), T(0.27886807),
                  T(-1.13520398), T(1.48851587),
                  T(-0.82215223), T(0.17087277)
               };

               const T t = T(1) / (T(1) + T(0.5) * abs_impl(v,real_type_tag()));

               const T result = T(1) - t * std::exp((-v * v) -
                                            c[0] + t * (c[1] + t *
                                           (c[2] + t * (c[3] + t *
                                           (c[4] + t * (c[5] + t *
                                           (c[6] + t * (c[7] + t *
                                           (c[8] + t * (c[9]))))))))));

               return (v >= T(0)) ? result : -result;
               #else
               return erf_impl(v);
               #endif
            }

            template <typename T>
            inline T erf_impl(const T v, int_type_tag)
            {
               return erf_impl(static_cast<double>(v),real_type_tag());
            }

            #if (defined(_MSC_VER) && (_MSC_VER >= 1900)) || !defined(_MSC_VER)
            #define exprtk_define_erfc(TT, impl)                \
            inline TT erfc_impl(const TT v) { return impl(v); } \

            exprtk_define_erfc(float      ,::erfcf)
            exprtk_define_erfc(double     ,::erfc )
            exprtk_define_erfc(long double,::erfcl)
            #undef exprtk_define_erfc
            #endif

            template <typename T>
            inline T erfc_impl(const T v, real_type_tag)
            {
               #if defined(_MSC_VER) && (_MSC_VER < 1900)
               return T(1) - erf_impl(v,real_type_tag());
               #else
               return erfc_impl(v);
               #endif
            }

            template <typename T>
            inline T erfc_impl(const T v, int_type_tag)
            {
               return erfc_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T>
            inline T ncdf_impl(const T v, real_type_tag)
            {
               return T(0.5) * erfc_impl(-(v / T(numeric::constant::sqrt2)),real_type_tag());
            }

            template <typename T>
            inline T ncdf_impl(const T v, int_type_tag)
            {
               return ncdf_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T>
            inline T sinc_impl(const T v, real_type_tag)
            {
               if (std::abs(v) >= std::numeric_limits<T>::epsilon())
                   return(std::sin(v) / v);
               else
                  return T(1);
            }

            template <typename T>
            inline T sinc_impl(const T v, int_type_tag)
            {
               return sinc_impl(static_cast<double>(v),real_type_tag());
            }

            #if __cplusplus >= 201103L
            template <typename T>
            inline T acosh_impl(const T v, real_type_tag)
            {
               return std::acosh(v);
            }

            template <typename T>
            inline T asinh_impl(const T v, real_type_tag)
            {
               return std::asinh(v);
            }

            template <typename T>
            inline T atanh_impl(const T v, real_type_tag)
            {
               return std::atanh(v);
            }
            #else
            template <typename T>
            inline T acosh_impl(const T v, real_type_tag)
            {
               return std::log(v + std::sqrt((v * v) - T(1)));
            }

            template <typename T>
            inline T asinh_impl(const T v, real_type_tag)
            {
               return std::log(v + std::sqrt((v * v) + T(1)));
            }

            template <typename T>
            inline T atanh_impl(const T v, real_type_tag)
            {
               return (std::log(T(1) + v) - std::log(T(1) - v)) / T(2);
            }
            #endif

            template <typename T> inline T  acos_impl(const T v, real_type_tag) { return std::acos (v); }
            template <typename T> inline T  asin_impl(const T v, real_type_tag) { return std::asin (v); }
            template <typename T> inline T  atan_impl(const T v, real_type_tag) { return std::atan (v); }
            template <typename T> inline T  ceil_impl(const T v, real_type_tag) { return std::ceil (v); }
            template <typename T> inline T   cos_impl(const T v, real_type_tag) { return std::cos  (v); }
            template <typename T> inline T  cosh_impl(const T v, real_type_tag) { return std::cosh (v); }
            template <typename T> inline T   exp_impl(const T v, real_type_tag) { return std::exp  (v); }
            template <typename T> inline T floor_impl(const T v, real_type_tag) { return std::floor(v); }
            template <typename T> inline T   log_impl(const T v, real_type_tag) { return std::log  (v); }
            template <typename T> inline T log10_impl(const T v, real_type_tag) { return std::log10(v); }
            template <typename T> inline T  log2_impl(const T v, real_type_tag) { return std::log(v)/T(numeric::constant::log2); }
            template <typename T> inline T   neg_impl(const T v, real_type_tag) { return -v;            }
            template <typename T> inline T   pos_impl(const T v, real_type_tag) { return +v;            }
            template <typename T> inline T   sin_impl(const T v, real_type_tag) { return std::sin  (v); }
            template <typename T> inline T  sinh_impl(const T v, real_type_tag) { return std::sinh (v); }
            template <typename T> inline T  sqrt_impl(const T v, real_type_tag) { return std::sqrt (v); }
            template <typename T> inline T   tan_impl(const T v, real_type_tag) { return std::tan  (v); }
            template <typename T> inline T  tanh_impl(const T v, real_type_tag) { return std::tanh (v); }
            template <typename T> inline T   cot_impl(const T v, real_type_tag) { return T(1) / std::tan(v); }
            template <typename T> inline T   sec_impl(const T v, real_type_tag) { return T(1) / std::cos(v); }
            template <typename T> inline T   csc_impl(const T v, real_type_tag) { return T(1) / std::sin(v); }
            template <typename T> inline T   r2d_impl(const T v, real_type_tag) { return (v * T(numeric::constant::_180_pi)); }
            template <typename T> inline T   d2r_impl(const T v, real_type_tag) { return (v * T(numeric::constant::pi_180));  }
            template <typename T> inline T   d2g_impl(const T v, real_type_tag) { return (v * T(10.0/9.0)); }
            template <typename T> inline T   g2d_impl(const T v, real_type_tag) { return (v * T(9.0/10.0)); }
            template <typename T> inline T  notl_impl(const T v, real_type_tag) { return (std::not_equal_to<T>()(T(0),v) ? T(0) : T(1)); }
            template <typename T> inline T  frac_impl(const T v, real_type_tag) { return (v - static_cast<long long>(v)); }
            template <typename T> inline T trunc_impl(const T v, real_type_tag) { return T(static_cast<long long>(v));    }

            template <typename T> inline T   const_pi_impl(real_type_tag) { return T(numeric::constant::pi);            }
            template <typename T> inline T    const_e_impl(real_type_tag) { return T(numeric::constant::e);             }
            template <typename T> inline T const_qnan_impl(real_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }

            template <typename T> inline T   abs_impl(const T v, int_type_tag) { return ((v >= T(0)) ? v : -v); }
            template <typename T> inline T   exp_impl(const T v, int_type_tag) { return std::exp  (v); }
            template <typename T> inline T   log_impl(const T v, int_type_tag) { return std::log  (v); }
            template <typename T> inline T log10_impl(const T v, int_type_tag) { return std::log10(v); }
            template <typename T> inline T  log2_impl(const T v, int_type_tag) { return std::log(v)/T(numeric::constant::log2); }
            template <typename T> inline T   neg_impl(const T v, int_type_tag) { return -v;            }
            template <typename T> inline T   pos_impl(const T v, int_type_tag) { return +v;            }
            template <typename T> inline T  ceil_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T floor_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T round_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T  notl_impl(const T v, int_type_tag) { return !v;            }
            template <typename T> inline T  sqrt_impl(const T v, int_type_tag) { return std::sqrt (v); }
            template <typename T> inline T  frac_impl(const T  , int_type_tag) { return T(0);          }
            template <typename T> inline T trunc_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T  acos_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T acosh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  asin_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T asinh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  atan_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T atanh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   cos_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  cosh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   sin_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  sinh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   tan_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  tanh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   cot_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   sec_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   csc_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }

            template <typename T>
            inline bool is_integer_impl(const T& v, real_type_tag)
            {
               return std::equal_to<T>()(T(0),std::fmod(v,T(1)));
            }

            template <typename T>
            inline bool is_integer_impl(const T&, int_type_tag)
            {
               return true;
            }
         }

         template <typename Type>
         struct numeric_info { enum { length = 0, size = 32, bound_length = 0, min_exp = 0, max_exp = 0 }; };

         template <> struct numeric_info<int        > { enum { length = 10, size = 16, bound_length = 9 }; };
         template <> struct numeric_info<float      > { enum { min_exp =  -38, max_exp =  +38 }; };
         template <> struct numeric_info<double     > { enum { min_exp = -308, max_exp = +308 }; };
         template <> struct numeric_info<long double> { enum { min_exp = -308, max_exp = +308 }; };

         template <typename T>
         inline int to_int32(const T v)
         {
            const typename details::number_type<T>::type num_type;
            return to_int32_impl(v, num_type);
         }

         template <typename T>
         inline _int64_t to_int64(const T v)
         {
            const typename details::number_type<T>::type num_type;
            return to_int64_impl(v, num_type);
         }

         template <typename T>
         inline _uint64_t to_uint64(const T v)
         {
            const typename details::number_type<T>::type num_type;
            return to_uint64_impl(v, num_type);
         }

         template <typename T>
         inline bool is_nan(const T v)
         {
            const typename details::number_type<T>::type num_type;
            return is_nan_impl(v, num_type);
         }

         template <typename T>
         inline T min(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return min_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T max(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return max_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T equal(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return equal_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T nequal(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return nequal_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T modulus(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return modulus_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T pow(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return pow_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T logn(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return logn_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T root(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return root_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T roundn(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return roundn_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T hypot(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return hypot_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T atan2(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return atan2_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T shr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return shr_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T shl(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return shl_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T and_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return and_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T nand_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return nand_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T or_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return or_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T nor_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return nor_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T xor_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return xor_impl(v0, v1, num_type);
         }

         template <typename T>
         inline T xnor_opr(const T v0, const T v1)
         {
            const typename details::number_type<T>::type num_type;
            return xnor_impl(v0, v1, num_type);
         }

         template <typename T>
         inline bool is_integer(const T v)
         {
            const typename details::number_type<T>::type num_type;
            return is_integer_impl(v, num_type);
         }

         template <typename T, unsigned int N>
         struct fast_exp
         {
            static inline T result(T v)
            {
               unsigned int k = N;
               T l = T(1);

               while (k)
               {
                  if (1 == (k % 2))
                  {
                     l *= v;
                     --k;
                  }

                  v *= v;
                  k /= 2;
               }

               return l;
            }
         };

         template <typename T> struct fast_exp<T,10> { static inline T result(const T v) { T v_5 = fast_exp<T,5>::result(v); return v_5 * v_5; } };
         template <typename T> struct fast_exp<T, 9> { static inline T result(const T v) { return fast_exp<T,8>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 8> { static inline T result(const T v) { T v_4 = fast_exp<T,4>::result(v); return v_4 * v_4; } };
         template <typename T> struct fast_exp<T, 7> { static inline T result(const T v) { return fast_exp<T,6>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 6> { static inline T result(const T v) { T v_3 = fast_exp<T,3>::result(v); return v_3 * v_3; } };
         template <typename T> struct fast_exp<T, 5> { static inline T result(const T v) { return fast_exp<T,4>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 4> { static inline T result(const T v) { T v_2 = v * v; return v_2 * v_2; } };
         template <typename T> struct fast_exp<T, 3> { static inline T result(const T v) { return v * v * v; } };
         template <typename T> struct fast_exp<T, 2> { static inline T result(const T v) { return v * v;     } };
         template <typename T> struct fast_exp<T, 1> { static inline T result(const T v) { return v;         } };
         template <typename T> struct fast_exp<T, 0> { static inline T result(const T  ) { return T(1);      } };

         #define exprtk_define_unary_function(FunctionName)        \
         template <typename T>                                     \
         inline T FunctionName (const T v)                         \
         {                                                         \
            const typename details::number_type<T>::type num_type; \
            return  FunctionName##_impl(v,num_type);               \
         }                                                         \

         exprtk_define_unary_function(abs  )
         exprtk_define_unary_function(acos )
         exprtk_define_unary_function(acosh)
         exprtk_define_unary_function(asin )
         exprtk_define_unary_function(asinh)
         exprtk_define_unary_function(atan )
         exprtk_define_unary_function(atanh)
         exprtk_define_unary_function(ceil )
         exprtk_define_unary_function(cos  )
         exprtk_define_unary_function(cosh )
         exprtk_define_unary_function(exp  )
         exprtk_define_unary_function(expm1)
         exprtk_define_unary_function(floor)
         exprtk_define_unary_function(log  )
         exprtk_define_unary_function(log10)
         exprtk_define_unary_function(log2 )
         exprtk_define_unary_function(log1p)
         exprtk_define_unary_function(neg  )
         exprtk_define_unary_function(pos  )
         exprtk_define_unary_function(round)
         exprtk_define_unary_function(sin  )
         exprtk_define_unary_function(sinc )
         exprtk_define_unary_function(sinh )
         exprtk_define_unary_function(sqrt )
         exprtk_define_unary_function(tan  )
         exprtk_define_unary_function(tanh )
         exprtk_define_unary_function(cot  )
         exprtk_define_unary_function(sec  )
         exprtk_define_unary_function(csc  )
         exprtk_define_unary_function(r2d  )
         exprtk_define_unary_function(d2r  )
         exprtk_define_unary_function(d2g  )
         exprtk_define_unary_function(g2d  )
         exprtk_define_unary_function(notl )
         exprtk_define_unary_function(sgn  )
         exprtk_define_unary_function(erf  )
         exprtk_define_unary_function(erfc )
         exprtk_define_unary_function(ncdf )
         exprtk_define_unary_function(frac )
         exprtk_define_unary_function(trunc)
         #undef exprtk_define_unary_function
      }

      template <typename T>
      inline T compute_pow10(T d, const int exponent)
      {
         static const double fract10[] =
         {
            0.0,
            1.0E+001, 1.0E+002, 1.0E+003, 1.0E+004, 1.0E+005, 1.0E+006, 1.0E+007, 1.0E+008, 1.0E+009, 1.0E+010,
            1.0E+011, 1.0E+012, 1.0E+013, 1.0E+014, 1.0E+015, 1.0E+016, 1.0E+017, 1.0E+018, 1.0E+019, 1.0E+020,
            1.0E+021, 1.0E+022, 1.0E+023, 1.0E+024, 1.0E+025, 1.0E+026, 1.0E+027, 1.0E+028, 1.0E+029, 1.0E+030,
            1.0E+031, 1.0E+032, 1.0E+033, 1.0E+034, 1.0E+035, 1.0E+036, 1.0E+037, 1.0E+038, 1.0E+039, 1.0E+040,
            1.0E+041, 1.0E+042, 1.0E+043, 1.0E+044, 1.0E+045, 1.0E+046, 1.0E+047, 1.0E+048, 1.0E+049, 1.0E+050,
            1.0E+051, 1.0E+052, 1.0E+053, 1.0E+054, 1.0E+055, 1.0E+056, 1.0E+057, 1.0E+058, 1.0E+059, 1.0E+060,
            1.0E+061, 1.0E+062, 1.0E+063, 1.0E+064, 1.0E+065, 1.0E+066, 1.0E+067, 1.0E+068, 1.0E+069, 1.0E+070,
            1.0E+071, 1.0E+072, 1.0E+073, 1.0E+074, 1.0E+075, 1.0E+076, 1.0E+077, 1.0E+078, 1.0E+079, 1.0E+080,
            1.0E+081, 1.0E+082, 1.0E+083, 1.0E+084, 1.0E+085, 1.0E+086, 1.0E+087, 1.0E+088, 1.0E+089, 1.0E+090,
            1.0E+091, 1.0E+092, 1.0E+093, 1.0E+094, 1.0E+095, 1.0E+096, 1.0E+097, 1.0E+098, 1.0E+099, 1.0E+100,
            1.0E+101, 1.0E+102, 1.0E+103, 1.0E+104, 1.0E+105, 1.0E+106, 1.0E+107, 1.0E+108, 1.0E+109, 1.0E+110,
            1.0E+111, 1.0E+112, 1.0E+113, 1.0E+114, 1.0E+115, 1.0E+116, 1.0E+117, 1.0E+118, 1.0E+119, 1.0E+120,
            1.0E+121, 1.0E+122, 1.0E+123, 1.0E+124, 1.0E+125, 1.0E+126, 1.0E+127, 1.0E+128, 1.0E+129, 1.0E+130,
            1.0E+131, 1.0E+132, 1.0E+133, 1.0E+134, 1.0E+135, 1.0E+136, 1.0E+137, 1.0E+138, 1.0E+139, 1.0E+140,
            1.0E+141, 1.0E+142, 1.0E+143, 1.0E+144, 1.0E+145, 1.0E+146, 1.0E+147, 1.0E+148, 1.0E+149, 1.0E+150,
            1.0E+151, 1.0E+152, 1.0E+153, 1.0E+154, 1.0E+155, 1.0E+156, 1.0E+157, 1.0E+158, 1.0E+159, 1.0E+160,
            1.0E+161, 1.0E+162, 1.0E+163, 1.0E+164, 1.0E+165, 1.0E+166, 1.0E+167, 1.0E+168, 1.0E+169, 1.0E+170,
            1.0E+171, 1.0E+172, 1.0E+173, 1.0E+174, 1.0E+175, 1.0E+176, 1.0E+177, 1.0E+178, 1.0E+179, 1.0E+180,
            1.0E+181, 1.0E+182, 1.0E+183, 1.0E+184, 1.0E+185, 1.0E+186, 1.0E+187, 1.0E+188, 1.0E+189, 1.0E+190,
            1.0E+191, 1.0E+192, 1.0E+193, 1.0E+194, 1.0E+195, 1.0E+196, 1.0E+197, 1.0E+198, 1.0E+199, 1.0E+200,
            1.0E+201, 1.0E+202, 1.0E+203, 1.0E+204, 1.0E+205, 1.0E+206, 1.0E+207, 1.0E+208, 1.0E+209, 1.0E+210,
            1.0E+211, 1.0E+212, 1.0E+213, 1.0E+214, 1.0E+215, 1.0E+216, 1.0E+217, 1.0E+218, 1.0E+219, 1.0E+220,
            1.0E+221, 1.0E+222, 1.0E+223, 1.0E+224, 1.0E+225, 1.0E+226, 1.0E+227, 1.0E+228, 1.0E+229, 1.0E+230,
            1.0E+231, 1.0E+232, 1.0E+233, 1.0E+234, 1.0E+235, 1.0E+236, 1.0E+237, 1.0E+238, 1.0E+239, 1.0E+240,
            1.0E+241, 1.0E+242, 1.0E+243, 1.0E+244, 1.0E+245, 1.0E+246, 1.0E+247, 1.0E+248, 1.0E+249, 1.0E+250,
            1.0E+251, 1.0E+252, 1.0E+253, 1.0E+254, 1.0E+255, 1.0E+256, 1.0E+257, 1.0E+258, 1.0E+259, 1.0E+260,
            1.0E+261, 1.0E+262, 1.0E+263, 1.0E+264, 1.0E+265, 1.0E+266, 1.0E+267, 1.0E+268, 1.0E+269, 1.0E+270,
            1.0E+271, 1.0E+272, 1.0E+273, 1.0E+274, 1.0E+275, 1.0E+276, 1.0E+277, 1.0E+278, 1.0E+279, 1.0E+280,
            1.0E+281, 1.0E+282, 1.0E+283, 1.0E+284, 1.0E+285, 1.0E+286, 1.0E+287, 1.0E+288, 1.0E+289, 1.0E+290,
            1.0E+291, 1.0E+292, 1.0E+293, 1.0E+294, 1.0E+295, 1.0E+296, 1.0E+297, 1.0E+298, 1.0E+299, 1.0E+300,
            1.0E+301, 1.0E+302, 1.0E+303, 1.0E+304, 1.0E+305, 1.0E+306, 1.0E+307, 1.0E+308
         };

         static const int fract10_size = static_cast<int>(sizeof(fract10) / sizeof(double));

         const int e = std::abs(exponent);

         if (exponent >= std::numeric_limits<T>::min_exponent10)
         {
            if (e < fract10_size)
            {
               if (exponent > 0)
                  return T(d * fract10[e]);
               else
                  return T(d / fract10[e]);
            }
            else
               return T(d * std::pow(10.0, 10.0 * exponent));
         }
         else
         {
                     d /= T(fract10[           -std::numeric_limits<T>::min_exponent10]);
            return T(d /    fract10[-exponent + std::numeric_limits<T>::min_exponent10]);
         }
      }

      template <typename Iterator, typename T>
      inline bool string_to_type_converter_impl_ref(Iterator& itr, const Iterator end, T& result)
      {
         if (itr == end)
            return false;

         const bool negative = ('-' == (*itr));

         if (negative || ('+' == (*itr)))
         {
            if (end == ++itr)
               return false;
         }

         static const uchar_t zero = static_cast<uchar_t>('0');

         while ((end != itr) && (zero == (*itr))) ++itr;

         bool return_result = true;
         unsigned int digit = 0;
         const std::size_t length = static_cast<std::size_t>(std::distance(itr,end));

         if (length <= 4)
         {
            switch (length)
            {
               #ifdef exprtk_use_lut

               #define exprtk_process_digit                          \
               if ((digit = details::digit_table[(int)*itr++]) < 10) \
                  result = result * 10 + (digit);                    \
               else                                                  \
               {                                                     \
                  return_result = false;                             \
                  break;                                             \
               }                                                     \
               exprtk_fallthrough                                    \

               #else

               #define exprtk_process_digit        \
               if ((digit = (*itr++ - zero)) < 10) \
                  result = result * T(10) + digit; \
               else                                \
               {                                   \
                  return_result = false;           \
                  break;                           \
               }                                   \
               exprtk_fallthrough                  \

               #endif

               case 4 : exprtk_process_digit
               case 3 : exprtk_process_digit
               case 2 : exprtk_process_digit
               case 1 : if ((digit = (*itr - zero))>= 10)
                        {
                           digit = 0;
                           return_result = false;
                        }

               #undef exprtk_process_digit
            }
         }
         else
            return_result = false;

         if (length && return_result)
         {
            result = result * 10 + static_cast<T>(digit);
            ++itr;
         }

         result = negative ? -result : result;
         return return_result;
      }

      template <typename Iterator, typename T>
      static inline bool parse_nan(Iterator& itr, const Iterator end, T& t)
      {
         typedef typename std::iterator_traits<Iterator>::value_type type;

         static const std::size_t nan_length = 3;

         if (std::distance(itr,end) != static_cast<int>(nan_length))
            return false;

         if (static_cast<type>('n') == (*itr))
         {
            if (
                 (static_cast<type>('a') != *(itr + 1)) ||
                 (static_cast<type>('n') != *(itr + 2))
               )
            {
               return false;
            }
         }
         else if (
                   (static_cast<type>('A') != *(itr + 1)) ||
                   (static_cast<type>('N') != *(itr + 2))
                 )
         {
            return false;
         }

         t = std::numeric_limits<T>::quiet_NaN();

         return true;
      }

      template <typename Iterator, typename T>
      static inline bool parse_inf(Iterator& itr, const Iterator end, T& t, const bool negative)
      {
         static const char_t inf_uc[] = "INFINITY";
         static const char_t inf_lc[] = "infinity";
         static const std::size_t inf_length = 8;

         const std::size_t length = static_cast<std::size_t>(std::distance(itr,end));

         if ((3 != length) && (inf_length != length))
            return false;

         char_cptr inf_itr = ('i' == (*itr)) ? inf_lc : inf_uc;

         while (end != itr)
         {
            if (*inf_itr == static_cast<char_t>(*itr))
            {
               ++itr;
               ++inf_itr;
               continue;
            }
            else
               return false;
         }

         if (negative)
            t = -std::numeric_limits<T>::infinity();
         else
            t =  std::numeric_limits<T>::infinity();

         return true;
      }

      template <typename T>
      inline bool valid_exponent(const int exponent, numeric::details::real_type_tag)
      {
         using namespace details::numeric;
         return (numeric_info<T>::min_exp <= exponent) && (exponent <= numeric_info<T>::max_exp);
      }

      template <typename Iterator, typename T>
      inline bool string_to_real(Iterator& itr_external, const Iterator end, T& t, numeric::details::real_type_tag)
      {
         if (end == itr_external) return false;

         Iterator itr = itr_external;

         T d = T(0);

         const bool negative = ('-' == (*itr));

         if (negative || '+' == (*itr))
         {
            if (end == ++itr)
               return false;
         }

         bool instate = false;

         static const char_t zero = static_cast<uchar_t>('0');

         #define parse_digit_1(d)          \
         if ((digit = (*itr - zero)) < 10) \
            { d = d * T(10) + digit; }     \
         else                              \
            { break; }                     \
         if (end == ++itr) break;          \

         #define parse_digit_2(d)          \
         if ((digit = (*itr - zero)) < 10) \
            { d = d * T(10) + digit; }     \
         else                              \
            { break; }                     \
            ++itr;                         \

         if ('.' != (*itr))
         {
            const Iterator curr = itr;

            while ((end != itr) && (zero == (*itr))) ++itr;

            while (end != itr)
            {
               unsigned int digit;
               parse_digit_1(d)
               parse_digit_1(d)
               parse_digit_2(d)
            }

            if (curr != itr) instate = true;
         }

         int exponent = 0;

         if (end != itr)
         {
            if ('.' == (*itr))
            {
               const Iterator curr = ++itr;
               T tmp_d = T(0);

               while (end != itr)
               {
                  unsigned int digit;
                  parse_digit_1(tmp_d)
                  parse_digit_1(tmp_d)
                  parse_digit_2(tmp_d)
               }

               if (curr != itr)
               {
                  instate = true;

                  const int frac_exponent = static_cast<int>(-std::distance(curr, itr));

                  if (!valid_exponent<T>(frac_exponent, numeric::details::real_type_tag()))
                     return false;

                  d += compute_pow10(tmp_d, frac_exponent);
               }

               #undef parse_digit_1
               #undef parse_digit_2
            }

            if (end != itr)
            {
               typename std::iterator_traits<Iterator>::value_type c = (*itr);

               if (('e' == c) || ('E' == c))
               {
                  int exp = 0;

                  if (!details::string_to_type_converter_impl_ref(++itr, end, exp))
                  {
                     if (end == itr)
                        return false;
                     else
                        c = (*itr);
                  }

                  exponent += exp;
               }

               if (end != itr)
               {
                  if (('f' == c) || ('F' == c) || ('l' == c) || ('L' == c))
                     ++itr;
                  else if ('#' == c)
                  {
                     if (end == ++itr)
                        return false;
                     else if (('I' <= (*itr)) && ((*itr) <= 'n'))
                     {
                        if (('i' == (*itr)) || ('I' == (*itr)))
                        {
                           return parse_inf(itr, end, t, negative);
                        }
                        else if (('n' == (*itr)) || ('N' == (*itr)))
                        {
                           return parse_nan(itr, end, t);
                        }
                        else
                           return false;
                     }
                     else
                        return false;
                  }
                  else if (('I' <= (*itr)) && ((*itr) <= 'n'))
                  {
                     if (('i' == (*itr)) || ('I' == (*itr)))
                     {
                        return parse_inf(itr, end, t, negative);
                     }
                     else if (('n' == (*itr)) || ('N' == (*itr)))
                     {
                        return parse_nan(itr, end, t);
                     }
                     else
                        return false;
                  }
                  else
                     return false;
               }
            }
         }

         if ((end != itr) || (!instate))
            return false;
         else if (!valid_exponent<T>(exponent, numeric::details::real_type_tag()))
            return false;
         else if (exponent)
            d = compute_pow10(d,exponent);

         t = static_cast<T>((negative) ? -d : d);
         return true;
      }

      template <typename T>
      inline bool string_to_real(const std::string& s, T& t)
      {
         const typename numeric::details::number_type<T>::type num_type;

         char_cptr begin = s.data();
         char_cptr end   = s.data() + s.size();

         return string_to_real(begin, end, t, num_type);
      }

      template <typename T>
      struct functor_t
      {
         /*
            Note: The following definitions for Type, may require tweaking
                  based on the compiler and target architecture. The benchmark
                  should provide enough information to make the right choice.
         */
         //typedef T Type;
         //typedef const T Type;
         typedef const T& Type;
         typedef       T& RefType;
         typedef T (*qfunc_t)(Type t0, Type t1, Type t2, Type t3);
         typedef T (*tfunc_t)(Type t0, Type t1, Type t2);
         typedef T (*bfunc_t)(Type t0, Type t1);
         typedef T (*ufunc_t)(Type t0);
      };

   } // namespace details

   struct loop_runtime_check
   {
      enum loop_types
      {
         e_invalid           = 0,
         e_for_loop          = 1,
         e_while_loop        = 2,
         e_repeat_until_loop = 4,
         e_all_loops         = 7
      };

      enum violation_type
      {
          e_unknown         = 0,
          e_iteration_count = 1,
          e_timeout         = 2
      };

      loop_types loop_set;

      loop_runtime_check()
      : loop_set(e_invalid)
      , max_loop_iterations(0)
      {}

      details::_uint64_t max_loop_iterations;

      struct violation_context
      {
         loop_types loop;
         violation_type violation;
         details::_uint64_t iteration_count;
      };

      virtual bool check()
      {
         return true;
      }

      virtual void handle_runtime_violation(const violation_context&)
      {
         throw std::runtime_error("ExprTk Loop runtime violation.");
      }

      virtual ~loop_runtime_check()
      {}
   };

   typedef loop_runtime_check* loop_runtime_check_ptr;

   struct vector_access_runtime_check
   {
      struct violation_context
      {
         void* base_ptr;
         void* end_ptr;
         void* access_ptr;
         std::size_t type_size;
      };

      virtual ~vector_access_runtime_check()
      {}

      virtual bool handle_runtime_violation(violation_context& /*context*/)
      {
         throw std::runtime_error("ExprTk runtime vector access violation.");
         #if !defined(_MSC_VER) && !defined(__NVCOMPILER)
         return false;
         #endif
      }
   };

   typedef vector_access_runtime_check* vector_access_runtime_check_ptr;

   struct assert_check
   {
      struct assert_context
      {
         std::string condition;
         std::string message;
         std::string id;
         std::size_t offet;
      };

      virtual ~assert_check()
      {}

      virtual void handle_assert(const assert_context& /*context*/)
      {
      }
   };

   typedef assert_check* assert_check_ptr;

   struct compilation_check
   {
      struct compilation_context
      {
         std::string error_message;
      };

      virtual bool continue_compilation(compilation_context& /*context*/) = 0;

      virtual ~compilation_check()
      {}
   };

   typedef compilation_check* compilation_check_ptr;

   namespace lexer
   {
      struct token
      {
         enum token_type
         {
            e_none        =   0, e_error       =   1, e_err_symbol  =   2,
            e_err_number  =   3, e_err_string  =   4, e_err_sfunc   =   5,
            e_eof         =   6, e_number      =   7, e_symbol      =   8,
            e_string      =   9, e_assign      =  10, e_addass      =  11,
            e_subass      =  12, e_mulass      =  13, e_divass      =  14,
            e_modass      =  15, e_shr         =  16, e_shl         =  17,
            e_lte         =  18, e_ne          =  19, e_gte         =  20,
            e_swap        =  21, e_lt          = '<', e_gt          = '>',
            e_eq          = '=', e_rbracket    = ')', e_lbracket    = '(',
            e_rsqrbracket = ']', e_lsqrbracket = '[', e_rcrlbracket = '}',
            e_lcrlbracket = '{', e_comma       = ',', e_add         = '+',
            e_sub         = '-', e_div         = '/', e_mul         = '*',
            e_mod         = '%', e_pow         = '^', e_colon       = ':',
            e_ternary     = '?'
         };

         token()
         : type(e_none)
         , value("")
         , position(std::numeric_limits<std::size_t>::max())
         {}

         void clear()
         {
            type     = e_none;
            value    = "";
            position = std::numeric_limits<std::size_t>::max();
         }

         template <typename Iterator>
         inline token& set_operator(const token_type tt,
                                    const Iterator begin, const Iterator end,
                                    const Iterator base_begin = Iterator(0))
         {
            type = tt;
            value.assign(begin,end);
            if (base_begin)
               position = static_cast<std::size_t>(std::distance(base_begin,begin));
            return (*this);
         }

         template <typename Iterator>
         inline token& set_symbol(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_symbol;
            value.assign(begin,end);
            if (base_begin)
               position = static_cast<std::size_t>(std::distance(base_begin,begin));
            return (*this);
         }

         template <typename Iterator>
         inline token& set_numeric(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_number;
            value.assign(begin,end);
            if (base_begin)
               position = static_cast<std::size_t>(std::distance(base_begin,begin));
            return (*this);
         }

         template <typename Iterator>
         inline token& set_string(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_string;
            value.assign(begin,end);
            if (base_begin)
               position = static_cast<std::size_t>(std::distance(base_begin,begin));
            return (*this);
         }

         inline token& set_string(const std::string& s, const std::size_t p)
         {
            type     = e_string;
            value    = s;
            position = p;
            return (*this);
         }

         template <typename Iterator>
         inline token& set_error(const token_type et,
                                 const Iterator begin, const Iterator end,
                                 const Iterator base_begin = Iterator(0))
         {
            if (
                 (e_error      == et) ||
                 (e_err_symbol == et) ||
                 (e_err_number == et) ||
                 (e_err_string == et) ||
                 (e_err_sfunc  == et)
               )
            {
               type = et;
            }
            else
               type = e_error;

            value.assign(begin,end);

            if (base_begin)
               position = static_cast<std::size_t>(std::distance(base_begin,begin));

            return (*this);
         }

         static inline std::string to_str(token_type t)
         {
            switch (t)
            {
               case e_none        : return "NONE";
               case e_error       : return "ERROR";
               case e_err_symbol  : return "ERROR_SYMBOL";
               case e_err_number  : return "ERROR_NUMBER";
               case e_err_string  : return "ERROR_STRING";
               case e_eof         : return "EOF";
               case e_number      : return "NUMBER";
               case e_symbol      : return "SYMBOL";
               case e_string      : return "STRING";
               case e_assign      : return ":=";
               case e_addass      : return "+=";
               case e_subass      : return "-=";
               case e_mulass      : return "*=";
               case e_divass      : return "/=";
               case e_modass      : return "%=";
               case e_shr         : return ">>";
               case e_shl         : return "<<";
               case e_lte         : return "<=";
               case e_ne          : return "!=";
               case e_gte         : return ">=";
               case e_lt          : return "<";
               case e_gt          : return ">";
               case e_eq          : return "=";
               case e_rbracket    : return ")";
               case e_lbracket    : return "(";
               case e_rsqrbracket : return "]";
               case e_lsqrbracket : return "[";
               case e_rcrlbracket : return "}";
               case e_lcrlbracket : return "{";
               case e_comma       : return ",";
               case e_add         : return "+";
               case e_sub         : return "-";
               case e_div         : return "/";
               case e_mul         : return "*";
               case e_mod         : return "%";
               case e_pow         : return "^";
               case e_colon       : return ":";
               case e_ternary     : return "?";
               case e_swap        : return "<=>";
               default            : return "UNKNOWN";
            }
         }

         inline bool is_error() const
         {
            return (
                     (e_error      == type) ||
                     (e_err_symbol == type) ||
                     (e_err_number == type) ||
                     (e_err_string == type) ||
                     (e_err_sfunc  == type)
                   );
         }

         token_type type;
         std::string value;
         std::size_t position;
      };

      class generator
      {
      public:

         typedef token token_t;
         typedef std::vector<token_t> token_list_t;
         typedef token_list_t::iterator token_list_itr_t;
         typedef details::char_t char_t;

         generator()
         : base_itr_(0)
         , s_itr_   (0)
         , s_end_   (0)
         {
            clear();
         }

         inline void clear()
         {
            base_itr_ = 0;
            s_itr_    = 0;
            s_end_    = 0;
            token_list_.clear();
            token_itr_ = token_list_.end();
            store_token_itr_ = token_list_.end();
         }

         inline bool process(const std::string& str)
         {
            base_itr_ = str.data();
            s_itr_    = str.data();
            s_end_    = str.data() + str.size();

            eof_token_.set_operator(token_t::e_eof, s_end_, s_end_, base_itr_);
            token_list_.clear();

            while (!is_end(s_itr_))
            {
               scan_token();

               if (!token_list_.empty() && token_list_.back().is_error())
                  return false;
            }

            return true;
         }

         inline bool empty() const
         {
            return token_list_.empty();
         }

         inline std::size_t size() const
         {
            return token_list_.size();
         }

         inline void begin()
         {
            token_itr_ = token_list_.begin();
            store_token_itr_ = token_list_.begin();
         }

         inline void store()
         {
            store_token_itr_ = token_itr_;
         }

         inline void restore()
         {
            token_itr_ = store_token_itr_;
         }

         inline token_t& next_token()
         {
            if (token_list_.end() != token_itr_)
            {
               return *token_itr_++;
            }
            else
               return eof_token_;
         }

         inline token_t& peek_next_token()
         {
            if (token_list_.end() != token_itr_)
            {
               return *token_itr_;
            }
            else
               return eof_token_;
         }

         inline token_t& operator[](const std::size_t& index)
         {
            if (index < token_list_.size())
            {
               return token_list_[index];
            }
            else
               return eof_token_;
         }

         inline token_t operator[](const std::size_t& index) const
         {
            if (index < token_list_.size())
            {
               return token_list_[index];
            }
            else
               return eof_token_;
         }

         inline bool finished() const
         {
            return (token_list_.end() == token_itr_);
         }

         inline void insert_front(token_t::token_type tk_type)
         {
            if (
                 !token_list_.empty() &&
                 (token_list_.end() != token_itr_)
               )
            {
               token_t t = *token_itr_;

               t.type     = tk_type;
               token_itr_ = token_list_.insert(token_itr_,t);
            }
         }

         inline std::string substr(const std::size_t& begin, const std::size_t& end) const
         {
            const details::char_cptr begin_itr = ((base_itr_ + begin) < s_end_) ? (base_itr_ + begin) : s_end_;
            const details::char_cptr end_itr   = ((base_itr_ + end  ) < s_end_) ? (base_itr_ + end  ) : s_end_;

            return std::string(begin_itr,end_itr);
         }

         inline std::string remaining() const
         {
            if (finished())
               return "";
            else if (token_list_.begin() != token_itr_)
               return std::string(base_itr_ + (token_itr_ - 1)->position, s_end_);
            else
               return std::string(base_itr_ + token_itr_->position, s_end_);
         }

      private:

         inline bool is_end(details::char_cptr itr) const
         {
            return (s_end_ == itr);
         }

         #ifndef exprtk_disable_comments
         inline bool is_comment_start(details::char_cptr itr) const
         {
            const char_t c0 = *(itr + 0);
            const char_t c1 = *(itr + 1);

            if ('#' == c0)
               return true;
            else if (!is_end(itr + 1))
            {
               if (('/' == c0) && ('/' == c1)) return true;
               if (('/' == c0) && ('*' == c1)) return true;
            }
            return false;
         }
         #else
         inline bool is_comment_start(details::char_cptr) const
         {
            return false;
         }
         #endif

         inline void skip_whitespace()
         {
            while (!is_end(s_itr_) && details::is_whitespace(*s_itr_))
            {
               ++s_itr_;
            }
         }

         inline void skip_comments()
         {
            #ifndef exprtk_disable_comments
            // The following comment styles are supported:
            // 1. // .... \n
            // 2. #  .... \n
            // 3. /* .... */
            struct test
            {
               static inline bool comment_start(const char_t c0, const char_t c1, int& mode, int& incr)
               {
                  mode = 0;
                  if      ('#' == c0)    { mode = 1; incr = 1; }
                  else if ('/' == c0)
                  {
                     if      ('/' == c1) { mode = 1; incr = 2; }
                     else if ('*' == c1) { mode = 2; incr = 2; }
                  }
                  return (0 != mode);
               }

               static inline bool comment_end(const char_t c0, const char_t c1, int& mode)
               {
                  if (
                       ((1 == mode) && ('\n' == c0)) ||
                       ((2 == mode) && ( '*' == c0) && ('/' == c1))
                     )
                  {
                     mode = 0;
                     return true;
                  }
                  else
                     return false;
               }
            };

            int mode      = 0;
            int increment = 0;

            if (is_end(s_itr_))
               return;
            else if (!test::comment_start(*s_itr_, *(s_itr_ + 1), mode, increment))
               return;

            details::char_cptr cmt_start = s_itr_;

            s_itr_ += increment;

            while (!is_end(s_itr_))
            {
               if ((1 == mode) && test::comment_end(*s_itr_, 0, mode))
               {
                  ++s_itr_;
                  return;
               }

               if ((2 == mode))
               {
                  if (!is_end((s_itr_ + 1)) && test::comment_end(*s_itr_, *(s_itr_ + 1), mode))
                  {
                     s_itr_ += 2;
                     return;
                  }
               }

               ++s_itr_;
            }

            if (2 == mode)
            {
               token_t t;
               t.set_error(token::e_error, cmt_start, cmt_start + mode, base_itr_);
               token_list_.push_back(t);
            }
            #endif
         }

         inline bool next_is_digit(const details::char_cptr itr) const
         {
            return ((itr + 1) != s_end_) &&
                   details::is_digit(*(itr + 1));
         }

         inline void scan_token()
         {
            const char_t c = *s_itr_;

            if (details::is_whitespace(c))
            {
               skip_whitespace();
               return;
            }
            else if (is_comment_start(s_itr_))
            {
               skip_comments();
               return;
            }
            else if (details::is_operator_char(c))
            {
               scan_operator();
               return;
            }
            else if (details::is_letter(c))
            {
               scan_symbol();
               return;
            }
            else if (('.' == c) && !next_is_digit(s_itr_))
            {
               scan_operator();
               return;
            }
            else if (details::is_digit(c) || ('.' == c))
            {
               scan_number();
               return;
            }
            else if ('$' == c)
            {
               scan_special_function();
               return;
            }
            #ifndef exprtk_disable_string_capabilities
            else if ('\'' == c)
            {
               scan_string();
               return;
            }
            #endif
            else if ('~' == c)
            {
               token_t t;
               t.set_symbol(s_itr_, s_itr_ + 1, base_itr_);
               token_list_.push_back(t);
               ++s_itr_;
               return;
            }
            else
            {
               token_t t;
               t.set_error(token::e_error, s_itr_, s_itr_ + 2, base_itr_);
               token_list_.push_back(t);
               ++s_itr_;
            }
         }

         inline void scan_operator()
         {
            token_t t;

            const char_t c0 = s_itr_[0];

            if (!is_end(s_itr_ + 1))
            {
               const char_t c1 = s_itr_[1];

               if (!is_end(s_itr_ + 2))
               {
                  const char_t c2 = s_itr_[2];

                  if ((c0 == '<') && (c1 == '=') && (c2 == '>'))
                  {
                     t.set_operator(token_t::e_swap, s_itr_, s_itr_ + 3, base_itr_);
                     token_list_.push_back(t);
                     s_itr_ += 3;
                     return;
                  }
               }

               token_t::token_type ttype = token_t::e_none;

               if      ((c0 == '<') && (c1 == '=')) ttype = token_t::e_lte;
               else if ((c0 == '>') && (c1 == '=')) ttype = token_t::e_gte;
               else if ((c0 == '<') && (c1 == '>')) ttype = token_t::e_ne;
               else if ((c0 == '!') && (c1 == '=')) ttype = token_t::e_ne;
               else if ((c0 == '=') && (c1 == '=')) ttype = token_t::e_eq;
               else if ((c0 == ':') && (c1 == '=')) ttype = token_t::e_assign;
               else if ((c0 == '<') && (c1 == '<')) ttype = token_t::e_shl;
               else if ((c0 == '>') && (c1 == '>')) ttype = token_t::e_shr;
               else if ((c0 == '+') && (c1 == '=')) ttype = token_t::e_addass;
               else if ((c0 == '-') && (c1 == '=')) ttype = token_t::e_subass;
               else if ((c0 == '*') && (c1 == '=')) ttype = token_t::e_mulass;
               else if ((c0 == '/') && (c1 == '=')) ttype = token_t::e_divass;
               else if ((c0 == '%') && (c1 == '=')) ttype = token_t::e_modass;

               if (token_t::e_none != ttype)
               {
                  t.set_operator(ttype, s_itr_, s_itr_ + 2, base_itr_);
                  token_list_.push_back(t);
                  s_itr_ += 2;
                  return;
               }
            }

            if ('<' == c0)
               t.set_operator(token_t::e_lt , s_itr_, s_itr_ + 1, base_itr_);
            else if ('>' == c0)
               t.set_operator(token_t::e_gt , s_itr_, s_itr_ + 1, base_itr_);
            else if (';' == c0)
               t.set_operator(token_t::e_eof, s_itr_, s_itr_ + 1, base_itr_);
            else if ('&' == c0)
               t.set_symbol(s_itr_, s_itr_ + 1, base_itr_);
            else if ('|' == c0)
               t.set_symbol(s_itr_, s_itr_ + 1, base_itr_);
            else
               t.set_operator(token_t::token_type(c0), s_itr_, s_itr_ + 1, base_itr_);

            token_list_.push_back(t);
            ++s_itr_;
         }

         inline void scan_symbol()
         {
            details::char_cptr initial_itr = s_itr_;

            while (!is_end(s_itr_))
            {
               if (!details::is_letter_or_digit(*s_itr_) && ('_' != (*s_itr_)))
               {
                  if ('.' != (*s_itr_))
                     break;
                  /*
                     Permit symbols that contain a 'dot'
                     Allowed   : abc.xyz, a123.xyz, abc.123, abc_.xyz a123_.xyz abc._123
                     Disallowed: .abc, abc.<white-space>, abc.<eof>, abc.<operator +,-,*,/...>
                  */
                  if (
                       (s_itr_ != initial_itr)                     &&
                       !is_end(s_itr_ + 1)                         &&
                       !details::is_letter_or_digit(*(s_itr_ + 1)) &&
                       ('_' != (*(s_itr_ + 1)))
                     )
                     break;
               }

               ++s_itr_;
            }

            token_t t;
            t.set_symbol(initial_itr, s_itr_, base_itr_);
            token_list_.push_back(t);
         }

         inline void scan_number()
         {
            /*
               Attempt to match a valid numeric value in one of the following formats:
               (01) 123456
               (02) 123456.
               (03) 123.456
               (04) 123.456e3
               (05) 123.456E3
               (06) 123.456e+3
               (07) 123.456E+3
               (08) 123.456e-3
               (09) 123.456E-3
               (00) .1234
               (11) .1234e3
               (12) .1234E+3
               (13) .1234e+3
               (14) .1234E-3
               (15) .1234e-3
            */

            details::char_cptr initial_itr = s_itr_;
            bool dot_found                 = false;
            bool e_found                   = false;
            bool post_e_sign_found         = false;
            bool post_e_digit_found        = false;
            token_t t;

            while (!is_end(s_itr_))
            {
               if ('.' == (*s_itr_))
               {
                  if (dot_found)
                  {
                     t.set_error(token::e_err_number, initial_itr, s_itr_, base_itr_);
                     token_list_.push_back(t);

                     return;
                  }

                  dot_found = true;
                  ++s_itr_;

                  continue;
               }
               else if ('e' == std::tolower(*s_itr_))
               {
                  const char_t& c = *(s_itr_ + 1);

                  if (is_end(s_itr_ + 1))
                  {
                     t.set_error(token::e_err_number, initial_itr, s_itr_, base_itr_);
                     token_list_.push_back(t);

                     return;
                  }
                  else if (
                            ('+' != c) &&
                            ('-' != c) &&
                            !details::is_digit(c)
                          )
                  {
                     t.set_error(token::e_err_number, initial_itr, s_itr_, base_itr_);
                     token_list_.push_back(t);

                     return;
                  }

                  e_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (e_found && details::is_sign(*s_itr_) && !post_e_digit_found)
               {
                  if (post_e_sign_found)
                  {
                     t.set_error(token::e_err_number, initial_itr, s_itr_, base_itr_);
                     token_list_.push_back(t);

                     return;
                  }

                  post_e_sign_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (e_found && details::is_digit(*s_itr_))
               {
                  post_e_digit_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (('.' != (*s_itr_)) && !details::is_digit(*s_itr_))
                  break;
               else
                  ++s_itr_;
            }

            t.set_numeric(initial_itr, s_itr_, base_itr_);
            token_list_.push_back(t);

            return;
         }

         inline void scan_special_function()
         {
            details::char_cptr initial_itr = s_itr_;
            token_t t;

            // $fdd(x,x,x) = at least 11 chars
            if (std::distance(s_itr_,s_end_) < 11)
            {
               t.set_error(
                  token::e_err_sfunc,
                  initial_itr, std::min(initial_itr + 11, s_end_),
                  base_itr_);
               token_list_.push_back(t);

               return;
            }

            if (
                 !(('$' == *s_itr_)                       &&
                   (details::imatch  ('f',*(s_itr_ + 1))) &&
                   (details::is_digit(*(s_itr_ + 2)))     &&
                   (details::is_digit(*(s_itr_ + 3))))
               )
            {
               t.set_error(
                  token::e_err_sfunc,
                  initial_itr, std::min(initial_itr + 4, s_end_),
                  base_itr_);
               token_list_.push_back(t);

               return;
            }

            s_itr_ += 4; // $fdd = 4chars

            t.set_symbol(initial_itr, s_itr_, base_itr_);
            token_list_.push_back(t);

            return;
         }

         #ifndef exprtk_disable_string_capabilities
         inline void scan_string()
         {
            details::char_cptr initial_itr = s_itr_ + 1;
            token_t t;

            if (std::distance(s_itr_,s_end_) < 2)
            {
               t.set_error(token::e_err_string, s_itr_, s_end_, base_itr_);
               token_list_.push_back(t);

               return;
            }

            ++s_itr_;

            bool escaped_found = false;
            bool escaped = false;

            while (!is_end(s_itr_))
            {
               if (!details::is_valid_string_char(*s_itr_))
               {
                  t.set_error(token::e_err_string, initial_itr, s_itr_, base_itr_);
                  token_list_.push_back(t);

                  return;
               }
               else if (!escaped && ('\\' == *s_itr_))
               {
                  escaped_found = true;
                  escaped = true;
                  ++s_itr_;

                  continue;
               }
               else if (!escaped)
               {
                  if ('\'' == *s_itr_)
                     break;
               }
               else if (escaped)
               {
                  if (
                       !is_end(s_itr_) && ('0' == *(s_itr_)) &&
                       ((s_itr_ + 4) <= s_end_)
                     )
                  {
                     const bool x_separator = ('X' == std::toupper(*(s_itr_ + 1)));

                     const bool both_digits = details::is_hex_digit(*(s_itr_ + 2)) &&
                                              details::is_hex_digit(*(s_itr_ + 3)) ;

                     if (!(x_separator && both_digits))
                     {
                        t.set_error(token::e_err_string, initial_itr, s_itr_, base_itr_);
                        token_list_.push_back(t);

                        return;
                     }
                     else
                        s_itr_ += 3;
                  }

                  escaped = false;
               }

               ++s_itr_;
            }

            if (is_end(s_itr_))
            {
               t.set_error(token::e_err_string, initial_itr, s_itr_, base_itr_);
               token_list_.push_back(t);

               return;
            }

            if (!escaped_found)
               t.set_string(initial_itr, s_itr_, base_itr_);
            else
            {
               std::string parsed_string(initial_itr,s_itr_);

               if (!details::cleanup_escapes(parsed_string))
               {
                  t.set_error(token::e_err_string, initial_itr, s_itr_, base_itr_);
                  token_list_.push_back(t);

                  return;
               }

               t.set_string(
                  parsed_string,
                  static_cast<std::size_t>(std::distance(base_itr_,initial_itr)));
            }

            token_list_.push_back(t);
            ++s_itr_;

            return;
         }
         #endif

      private:

         token_list_t       token_list_;
         token_list_itr_t   token_itr_;
         token_list_itr_t   store_token_itr_;
         token_t            eof_token_;
         details::char_cptr base_itr_;
         details::char_cptr s_itr_;
         details::char_cptr s_end_;

         friend class token_scanner;
         friend class token_modifier;
         friend class token_inserter;
         friend class token_joiner;
      }; // class generator

      class helper_interface
      {
      public:

         virtual void init()                     {              }
         virtual void reset()                    {              }
         virtual bool result()                   { return true; }
         virtual std::size_t process(generator&) { return 0;    }
         virtual ~helper_interface()             {              }
      };

      class token_scanner : public helper_interface
      {
      public:

         virtual ~token_scanner()
         {}

         explicit token_scanner(const std::size_t& stride)
         : stride_(stride)
         {
            if (stride > 4)
            {
               throw std::invalid_argument("token_scanner() - Invalid stride value");
            }
         }

         inline std::size_t process(generator& g) exprtk_override
         {
            if (g.token_list_.size() >= stride_)
            {
               for (std::size_t i = 0; i < (g.token_list_.size() - stride_ + 1); ++i)
               {
                  token t;

                  switch (stride_)
                  {
                     case 1 :
                              {
                                 const token& t0 = g.token_list_[i];

                                 if (!operator()(t0))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 2 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];

                                 if (!operator()(t0, t1))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 3 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];
                                 const token& t2 = g.token_list_[i + 2];

                                 if (!operator()(t0, t1, t2))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 4 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];
                                 const token& t2 = g.token_list_[i + 2];
                                 const token& t3 = g.token_list_[i + 3];

                                 if (!operator()(t0, t1, t2, t3))
                                 {
                                    return i;
                                 }
                              }
                              break;
                  }
               }
            }

            return (g.token_list_.size() - stride_ + 1);
         }

         virtual bool operator() (const token&)
         {
            return false;
         }

         virtual bool operator() (const token&, const token&)
         {
            return false;
         }

         virtual bool operator() (const token&, const token&, const token&)
         {
            return false;
         }

         virtual bool operator() (const token&, const token&, const token&, const token&)
         {
            return false;
         }

      private:

         const std::size_t stride_;
      }; // class token_scanner

      class token_modifier : public helper_interface
      {
      public:

         inline std::size_t process(generator& g) exprtk_override
         {
            std::size_t changes = 0;

            for (std::size_t i = 0; i < g.token_list_.size(); ++i)
            {
               if (modify(g.token_list_[i])) changes++;
            }

            return changes;
         }

         virtual bool modify(token& t) = 0;
      };

      class token_inserter : public helper_interface
      {
      public:

         explicit token_inserter(const std::size_t& stride)
         : stride_(stride)
         {
            if (stride > 5)
            {
               throw std::invalid_argument("token_inserter() - Invalid stride value");
            }
         }

         inline std::size_t process(generator& g) exprtk_override
         {
            if (g.token_list_.empty())
               return 0;
            else if (g.token_list_.size() < stride_)
               return 0;

            std::size_t changes = 0;

            typedef std::pair<std::size_t, token> insert_t;
            std::vector<insert_t> insert_list;
            insert_list.reserve(10000);

            for (std::size_t i = 0; i < (g.token_list_.size() - stride_ + 1); ++i)
            {
               int insert_index = -1;
               token t;

               switch (stride_)
               {
                  case 1 : insert_index = insert(g.token_list_[i],t);
                           break;

                  case 2 : insert_index = insert(g.token_list_[i], g.token_list_[i + 1], t);
                           break;

                  case 3 : insert_index = insert(g.token_list_[i], g.token_list_[i + 1], g.token_list_[i + 2], t);
                           break;

                  case 4 : insert_index = insert(g.token_list_[i], g.token_list_[i + 1], g.token_list_[i + 2], g.token_list_[i + 3], t);
                           break;

                  case 5 : insert_index = insert(g.token_list_[i], g.token_list_[i + 1], g.token_list_[i + 2], g.token_list_[i + 3], g.token_list_[i + 4], t);
                           break;
               }

               if ((insert_index >= 0) && (insert_index <= (static_cast<int>(stride_) + 1)))
               {
                  insert_list.push_back(insert_t(i, t));
                  changes++;
               }
            }

            if (!insert_list.empty())
            {
               generator::token_list_t token_list;

               std::size_t insert_index = 0;

               for (std::size_t i = 0; i < g.token_list_.size(); ++i)
               {
                  token_list.push_back(g.token_list_[i]);

                  if (
                       (insert_index < insert_list.size()) &&
                       (insert_list[insert_index].first == i)
                     )
                  {
                     token_list.push_back(insert_list[insert_index].second);
                     insert_index++;
                  }
               }

               std::swap(g.token_list_,token_list);
            }

            return changes;
         }

         #define token_inserter_empty_body \
         {                                 \
            return -1;                     \
         }                                 \

         inline virtual int insert(const token&, token&)
         token_inserter_empty_body

         inline virtual int insert(const token&, const token&, token&)
         token_inserter_empty_body

         inline virtual int insert(const token&, const token&, const token&, token&)
         token_inserter_empty_body

         inline virtual int insert(const token&, const token&, const token&, const token&, token&)
         token_inserter_empty_body

         inline virtual int insert(const token&, const token&, const token&, const token&, const token&, token&)
         token_inserter_empty_body

         #undef token_inserter_empty_body

      private:

         const std::size_t stride_;
      };

      class token_joiner : public helper_interface
      {
      public:

         explicit token_joiner(const std::size_t& stride)
         : stride_(stride)
         {}

         inline std::size_t process(generator& g) exprtk_override
         {
            if (g.token_list_.empty())
               return 0;

            switch (stride_)
            {
               case 2  : return process_stride_2(g);
               case 3  : return process_stride_3(g);
               default : return 0;
            }
         }

         virtual bool join(const token&, const token&, token&)               { return false; }
         virtual bool join(const token&, const token&, const token&, token&) { return false; }

      private:

         inline std::size_t process_stride_2(generator& g)
         {
            if (g.token_list_.size() < 2)
               return 0;

            std::size_t changes = 0;

            generator::token_list_t token_list;
            token_list.reserve(10000);

            for (int i = 0; i < static_cast<int>(g.token_list_.size() - 1); ++i)
            {
               token t;

               for ( ; ; )
               {
                  if (!join(g[i], g[i + 1], t))
                  {
                     token_list.push_back(g[i]);
                     break;
                  }

                  token_list.push_back(t);

                  ++changes;

                  i += 2;

                  if (static_cast<std::size_t>(i) >= (g.token_list_.size() - 1))
                     break;
               }
            }

            token_list.push_back(g.token_list_.back());

            assert(token_list.size() <= g.token_list_.size());

            std::swap(token_list, g.token_list_);

            return changes;
         }

         inline std::size_t process_stride_3(generator& g)
         {
            if (g.token_list_.size() < 3)
               return 0;

            std::size_t changes = 0;

            generator::token_list_t token_list;
            token_list.reserve(10000);

            for (int i = 0; i < static_cast<int>(g.token_list_.size() - 2); ++i)
            {
               token t;

               for ( ; ; )
               {
                  if (!join(g[i], g[i + 1], g[i + 2], t))
                  {
                     token_list.push_back(g[i]);
                     break;
                  }

                  token_list.push_back(t);

                  ++changes;

                  i += 3;

                  if (static_cast<std::size_t>(i) >= (g.token_list_.size() - 2))
                     break;
               }
            }

            token_list.push_back(*(g.token_list_.begin() + g.token_list_.size() - 2));
            token_list.push_back(*(g.token_list_.begin() + g.token_list_.size() - 1));

            assert(token_list.size() <= g.token_list_.size());

            std::swap(token_list, g.token_list_);

            return changes;
         }

         const std::size_t stride_;
      };

      namespace helper
      {

         inline void dump(const lexer::generator& generator)
         {
            for (std::size_t i = 0; i < generator.size(); ++i)
            {
               const lexer::token& t = generator[i];
               printf("Token[%02d] @ %03d  %6s  -->  '%s'\n",
                      static_cast<int>(i),
                      static_cast<int>(t.position),
                      t.to_str(t.type).c_str(),
                      t.value.c_str());
            }
         }

         class commutative_inserter : public lexer::token_inserter
         {
         public:

            using lexer::token_inserter::insert;

            commutative_inserter()
            : lexer::token_inserter(2)
            {}

            inline void ignore_symbol(const std::string& symbol)
            {
               ignore_set_.insert(symbol);
            }

            inline int insert(const lexer::token& t0, const lexer::token& t1, lexer::token& new_token) exprtk_override
            {
               bool match         = false;
               new_token.type     = lexer::token::e_mul;
               new_token.value    = "*";
               new_token.position = t1.position;

               if (t0.type == lexer::token::e_symbol)
               {
                  if (ignore_set_.end() != ignore_set_.find(t0.value))
                  {
                     return -1;
                  }
                  else if (!t0.value.empty() && ('$' == t0.value[0]))
                  {
                     return -1;
                  }
               }

               if (t1.type == lexer::token::e_symbol)
               {
                  if (ignore_set_.end() != ignore_set_.find(t1.value))
                  {
                     return -1;
                  }
               }
               if      ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lbracket   )) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lcrlbracket)) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lsqrbracket)) match = true;
               else if ((t0.type == lexer::token::e_symbol     ) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rbracket   ) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rcrlbracket) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rsqrbracket) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rbracket   ) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_rcrlbracket) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_rsqrbracket) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_symbol     ) && (t1.type == lexer::token::e_symbol     )) match = true;

               return (match) ? 1 : -1;
            }

         private:

            std::set<std::string,details::ilesscompare> ignore_set_;
         };

         class operator_joiner exprtk_final : public token_joiner
         {
         public:

            explicit operator_joiner(const std::size_t& stride)
            : token_joiner(stride)
            {}

            inline bool join(const lexer::token& t0, const lexer::token& t1, lexer::token& t) exprtk_override
            {
               // ': =' --> ':='
               if ((t0.type == lexer::token::e_colon) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_assign;
                  t.value    = ":=";
                  t.position = t0.position;

                  return true;
               }
               // '+ =' --> '+='
               else if ((t0.type == lexer::token::e_add) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_addass;
                  t.value    = "+=";
                  t.position = t0.position;

                  return true;
               }
               // '- =' --> '-='
               else if ((t0.type == lexer::token::e_sub) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_subass;
                  t.value    = "-=";
                  t.position = t0.position;

                  return true;
               }
               // '* =' --> '*='
               else if ((t0.type == lexer::token::e_mul) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_mulass;
                  t.value    = "*=";
                  t.position = t0.position;

                  return true;
               }
               // '/ =' --> '/='
               else if ((t0.type == lexer::token::e_div) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_divass;
                  t.value    = "/=";
                  t.position = t0.position;

                  return true;
               }
               // '% =' --> '%='
               else if ((t0.type == lexer::token::e_mod) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_modass;
                  t.value    = "%=";
                  t.position = t0.position;

                  return true;
               }
               // '> =' --> '>='
               else if ((t0.type == lexer::token::e_gt) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_gte;
                  t.value    = ">=";
                  t.position = t0.position;

                  return true;
               }
               // '< =' --> '<='
               else if ((t0.type == lexer::token::e_lt) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_lte;
                  t.value    = "<=";
                  t.position = t0.position;

                  return true;
               }
               // '= =' --> '=='
               else if ((t0.type == lexer::token::e_eq) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_eq;
                  t.value    = "==";
                  t.position = t0.position;

                  return true;
               }
               // '! =' --> '!='
               else if ((static_cast<details::char_t>(t0.type) == '!') && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_ne;
                  t.value    = "!=";
                  t.position = t0.position;

                  return true;
               }
               // '< >' --> '<>'
               else if ((t0.type == lexer::token::e_lt) && (t1.type == lexer::token::e_gt))
               {
                  t.type     = lexer::token::e_ne;
                  t.value    = "<>";
                  t.position = t0.position;

                  return true;
               }
               // '<= >' --> '<=>'
               else if ((t0.type == lexer::token::e_lte) && (t1.type == lexer::token::e_gt))
               {
                  t.type     = lexer::token::e_swap;
                  t.value    = "<=>";
                  t.position = t0.position;

                  return true;
               }
               // '+ -' --> '-'
               else if ((t0.type == lexer::token::e_add) && (t1.type == lexer::token::e_sub))
               {
                  t.type     = lexer::token::e_sub;
                  t.value    = "-";
                  t.position = t0.position;

                  return true;
               }
               // '- +' --> '-'
               else if ((t0.type == lexer::token::e_sub) && (t1.type == lexer::token::e_add))
               {
                  t.type     = lexer::token::e_sub;
                  t.value    = "-";
                  t.position = t0.position;

                  return true;
               }
               // '- -' --> '+'
               else if ((t0.type == lexer::token::e_sub) && (t1.type == lexer::token::e_sub))
               {
                  /*
                     Note: May need to reconsider this when wanting to implement
                     pre/postfix decrement operator
                  */
                  t.type     = lexer::token::e_add;
                  t.value    = "+";
                  t.position = t0.position;

                  return true;
               }
               else
                  return false;
            }

            inline bool join(const lexer::token& t0,
                             const lexer::token& t1,
                             const lexer::token& t2,
                             lexer::token& t) exprtk_override
            {
               // '[ * ]' --> '[*]'
               if (
                    (t0.type == lexer::token::e_lsqrbracket) &&
                    (t1.type == lexer::token::e_mul        ) &&
                    (t2.type == lexer::token::e_rsqrbracket)
                  )
               {
                  t.type     = lexer::token::e_symbol;
                  t.value    = "[*]";
                  t.position = t0.position;

                  return true;
               }
               else
                  return false;
            }
         };

         class bracket_checker exprtk_final : public lexer::token_scanner
         {
         public:

            using lexer::token_scanner::operator();

            bracket_checker()
            : token_scanner(1)
            , state_(true)
            {}

            bool result() exprtk_override
            {
               if (!stack_.empty())
               {
                  lexer::token t;
                  t.value      = stack_.top().first;
                  t.position   = stack_.top().second;
                  error_token_ = t;
                  state_       = false;

                  return false;
               }
               else
                  return state_;
            }

            lexer::token error_token()
            {
               return error_token_;
            }

            void reset() exprtk_override
            {
               // Why? because msvc doesn't support swap properly.
               stack_ = std::stack<std::pair<char,std::size_t> >();
               state_ = true;
               error_token_.clear();
            }

            bool operator() (const lexer::token& t) exprtk_override
            {
               if (
                    !t.value.empty()                       &&
                    (lexer::token::e_string != t.type)     &&
                    (lexer::token::e_symbol != t.type)     &&
                    exprtk::details::is_bracket(t.value[0])
                  )
               {
                  details::char_t c = t.value[0];

                  if      (t.type == lexer::token::e_lbracket   ) stack_.push(std::make_pair(')',t.position));
                  else if (t.type == lexer::token::e_lcrlbracket) stack_.push(std::make_pair('}',t.position));
                  else if (t.type == lexer::token::e_lsqrbracket) stack_.push(std::make_pair(']',t.position));
                  else if (exprtk::details::is_right_bracket(c))
                  {
                     if (stack_.empty())
                     {
                        state_       = false;
                        error_token_ = t;

                        return false;
                     }
                     else if (c != stack_.top().first)
                     {
                        state_       = false;
                        error_token_ = t;

                        return false;
                     }
                     else
                        stack_.pop();
                  }
               }

               return true;
            }

         private:

            bool state_;
            std::stack<std::pair<char,std::size_t> > stack_;
            lexer::token error_token_;
         };

         template <typename T>
         class numeric_checker exprtk_final : public lexer::token_scanner
         {
         public:

            using lexer::token_scanner::operator();

            numeric_checker()
            : token_scanner (1)
            , current_index_(0)
            {}

            bool result() exprtk_override
            {
               return error_list_.empty();
            }

            void reset() exprtk_override
            {
               error_list_.clear();
               current_index_ = 0;
            }

            bool operator() (const lexer::token& t) exprtk_override
            {
               if (token::e_number == t.type)
               {
                  T v;

                  if (!exprtk::details::string_to_real(t.value,v))
                  {
                     error_list_.push_back(current_index_);
                  }
               }

               ++current_index_;

               return true;
            }

            std::size_t error_count() const
            {
               return error_list_.size();
            }

            std::size_t error_index(const std::size_t& i)
            {
               if (i < error_list_.size())
                  return error_list_[i];
               else
                  return std::numeric_limits<std::size_t>::max();
            }

            void clear_errors()
            {
               error_list_.clear();
            }

         private:

            std::size_t current_index_;
            std::vector<std::size_t> error_list_;
         };

         class symbol_replacer exprtk_final : public lexer::token_modifier
         {
         private:

            typedef std::map<std::string,std::pair<std::string,token::token_type>,details::ilesscompare> replace_map_t;

         public:

            bool remove(const std::string& target_symbol)
            {
               const replace_map_t::iterator itr = replace_map_.find(target_symbol);

               if (replace_map_.end() == itr)
                  return false;

               replace_map_.erase(itr);

               return true;
            }

            bool add_replace(const std::string& target_symbol,
                             const std::string& replace_symbol,
                             const lexer::token::token_type token_type = lexer::token::e_symbol)
            {
               const replace_map_t::iterator itr = replace_map_.find(target_symbol);

               if (replace_map_.end() != itr)
               {
                  return false;
               }

               replace_map_[target_symbol] = std::make_pair(replace_symbol,token_type);

               return true;
            }

            void clear()
            {
               replace_map_.clear();
            }

         private:

            bool modify(lexer::token& t) exprtk_override
            {
               if (lexer::token::e_symbol == t.type)
               {
                  if (replace_map_.empty())
                     return false;

                  const replace_map_t::iterator itr = replace_map_.find(t.value);

                  if (replace_map_.end() != itr)
                  {
                     t.value = itr->second.first;
                     t.type  = itr->second.second;

                     return true;
                  }
               }

               return false;
            }

            replace_map_t replace_map_;
         };

         class sequence_validator exprtk_final : public lexer::token_scanner
         {
         private:

            typedef std::pair<lexer::token::token_type,lexer::token::token_type> token_pair_t;
            typedef std::set<token_pair_t> set_t;

         public:

            using lexer::token_scanner::operator();

            sequence_validator()
            : lexer::token_scanner(2)
            {
               add_invalid(lexer::token::e_number, lexer::token::e_number);
               add_invalid(lexer::token::e_string, lexer::token::e_string);
               add_invalid(lexer::token::e_number, lexer::token::e_string);
               add_invalid(lexer::token::e_string, lexer::token::e_number);

               add_invalid_set1(lexer::token::e_assign );
               add_invalid_set1(lexer::token::e_shr    );
               add_invalid_set1(lexer::token::e_shl    );
               add_invalid_set1(lexer::token::e_lte    );
               add_invalid_set1(lexer::token::e_ne     );
               add_invalid_set1(lexer::token::e_gte    );
               add_invalid_set1(lexer::token::e_lt     );
               add_invalid_set1(lexer::token::e_gt     );
               add_invalid_set1(lexer::token::e_eq     );
               add_invalid_set1(lexer::token::e_comma  );
               add_invalid_set1(lexer::token::e_add    );
               add_invalid_set1(lexer::token::e_sub    );
               add_invalid_set1(lexer::token::e_div    );
               add_invalid_set1(lexer::token::e_mul    );
               add_invalid_set1(lexer::token::e_mod    );
               add_invalid_set1(lexer::token::e_pow    );
               add_invalid_set1(lexer::token::e_colon  );
               add_invalid_set1(lexer::token::e_ternary);
            }

            bool result() exprtk_override
            {
               return error_list_.empty();
            }

            bool operator() (const lexer::token& t0, const lexer::token& t1) exprtk_override
            {
               const set_t::value_type p = std::make_pair(t0.type,t1.type);

               if (invalid_bracket_check(t0.type,t1.type))
               {
                  error_list_.push_back(std::make_pair(t0,t1));
               }
               else if (invalid_comb_.find(p) != invalid_comb_.end())
               {
                  error_list_.push_back(std::make_pair(t0,t1));
               }

               return true;
            }

            std::size_t error_count() const
            {
               return error_list_.size();
            }

            std::pair<lexer::token,lexer::token> error(const std::size_t index)
            {
               if (index < error_list_.size())
               {
                  return error_list_[index];
               }
               else
               {
                  static const lexer::token error_token;
                  return std::make_pair(error_token,error_token);
               }
            }

            void clear_errors()
            {
               error_list_.clear();
            }

         private:

            void add_invalid(const lexer::token::token_type base, const lexer::token::token_type t)
            {
               invalid_comb_.insert(std::make_pair(base,t));
            }

            void add_invalid_set1(const lexer::token::token_type t)
            {
               add_invalid(t, lexer::token::e_assign);
               add_invalid(t, lexer::token::e_shr   );
               add_invalid(t, lexer::token::e_shl   );
               add_invalid(t, lexer::token::e_lte   );
               add_invalid(t, lexer::token::e_ne    );
               add_invalid(t, lexer::token::e_gte   );
               add_invalid(t, lexer::token::e_lt    );
               add_invalid(t, lexer::token::e_gt    );
               add_invalid(t, lexer::token::e_eq    );
               add_invalid(t, lexer::token::e_comma );
               add_invalid(t, lexer::token::e_div   );
               add_invalid(t, lexer::token::e_mul   );
               add_invalid(t, lexer::token::e_mod   );
               add_invalid(t, lexer::token::e_pow   );
               add_invalid(t, lexer::token::e_colon );
            }

            bool invalid_bracket_check(const lexer::token::token_type base, const lexer::token::token_type t)
            {
               if (details::is_right_bracket(static_cast<details::char_t>(base)))
               {
                  switch (t)
                  {
                     case lexer::token::e_assign : return (']' != base);
                     case lexer::token::e_string : return (')' != base);
                     default                     : return false;
                  }
               }
               else if (details::is_left_bracket(static_cast<details::char_t>(base)))
               {
                  if (details::is_right_bracket(static_cast<details::char_t>(t)))
                     return false;
                  else if (details::is_left_bracket(static_cast<details::char_t>(t)))
                     return false;
                  else
                  {
                     switch (t)
                     {
                        case lexer::token::e_number  : return false;
                        case lexer::token::e_symbol  : return false;
                        case lexer::token::e_string  : return false;
                        case lexer::token::e_add     : return false;
                        case lexer::token::e_sub     : return false;
                        case lexer::token::e_colon   : return false;
                        case lexer::token::e_ternary : return false;
                        default                      : return true ;
                     }
                  }
               }
               else if (details::is_right_bracket(static_cast<details::char_t>(t)))
               {
                  switch (base)
                  {
                     case lexer::token::e_number  : return false;
                     case lexer::token::e_symbol  : return false;
                     case lexer::token::e_string  : return false;
                     case lexer::token::e_eof     : return false;
                     case lexer::token::e_colon   : return false;
                     case lexer::token::e_ternary : return false;
                     default                      : return true ;
                  }
               }
               else if (details::is_left_bracket(static_cast<details::char_t>(t)))
               {
                  switch (base)
                  {
                     case lexer::token::e_rbracket    : return true;
                     case lexer::token::e_rsqrbracket : return true;
                     case lexer::token::e_rcrlbracket : return true;
                     default                          : return false;
                  }
               }

               return false;
            }

            set_t invalid_comb_;
            std::vector<std::pair<lexer::token,lexer::token> > error_list_;
         };

         class sequence_validator_3tokens exprtk_final : public lexer::token_scanner
         {
         private:

            typedef lexer::token::token_type token_t;
            typedef std::pair<token_t,std::pair<token_t,token_t> > token_triplet_t;
            typedef std::set<token_triplet_t> set_t;

         public:

            using lexer::token_scanner::operator();

            sequence_validator_3tokens()
            : lexer::token_scanner(3)
            {
               add_invalid(lexer::token::e_number , lexer::token::e_number , lexer::token::e_number);
               add_invalid(lexer::token::e_string , lexer::token::e_string , lexer::token::e_string);
               add_invalid(lexer::token::e_comma  , lexer::token::e_comma  , lexer::token::e_comma );

               add_invalid(lexer::token::e_add    , lexer::token::e_add    , lexer::token::e_add   );
               add_invalid(lexer::token::e_sub    , lexer::token::e_sub    , lexer::token::e_sub   );
               add_invalid(lexer::token::e_div    , lexer::token::e_div    , lexer::token::e_div   );
               add_invalid(lexer::token::e_mul    , lexer::token::e_mul    , lexer::token::e_mul   );
               add_invalid(lexer::token::e_mod    , lexer::token::e_mod    , lexer::token::e_mod   );
               add_invalid(lexer::token::e_pow    , lexer::token::e_pow    , lexer::token::e_pow   );

               add_invalid(lexer::token::e_add    , lexer::token::e_sub    , lexer::token::e_add   );
               add_invalid(lexer::token::e_sub    , lexer::token::e_add    , lexer::token::e_sub   );
               add_invalid(lexer::token::e_div    , lexer::token::e_mul    , lexer::token::e_div   );
               add_invalid(lexer::token::e_mul    , lexer::token::e_div    , lexer::token::e_mul   );
               add_invalid(lexer::token::e_mod    , lexer::token::e_pow    , lexer::token::e_mod   );
               add_invalid(lexer::token::e_pow    , lexer::token::e_mod    , lexer::token::e_pow   );
            }

            bool result() exprtk_override
            {
               return error_list_.empty();
            }

            bool operator() (const lexer::token& t0, const lexer::token& t1, const lexer::token& t2) exprtk_override
            {
               const set_t::value_type p = std::make_pair(t0.type,std::make_pair(t1.type,t2.type));

               if (invalid_comb_.find(p) != invalid_comb_.end())
               {
                  error_list_.push_back(std::make_pair(t0,t1));
               }

               return true;
            }

            std::size_t error_count() const
            {
               return error_list_.size();
            }

            std::pair<lexer::token,lexer::token> error(const std::size_t index)
            {
               if (index < error_list_.size())
               {
                  return error_list_[index];
               }
               else
               {
                  static const lexer::token error_token;
                  return std::make_pair(error_token,error_token);
               }
            }

            void clear_errors()
            {
               error_list_.clear();
            }

         private:

            void add_invalid(const token_t t0, const token_t t1, const token_t t2)
            {
               invalid_comb_.insert(std::make_pair(t0,std::make_pair(t1,t2)));
            }

            set_t invalid_comb_;
            std::vector<std::pair<lexer::token,lexer::token> > error_list_;
         };

         struct helper_assembly
         {
            inline bool register_scanner(lexer::token_scanner* scanner)
            {
               if (token_scanner_list.end() != std::find(token_scanner_list.begin(),
                                                         token_scanner_list.end  (),
                                                         scanner))
               {
                  return false;
               }

               token_scanner_list.push_back(scanner);

               return true;
            }

            inline bool register_modifier(lexer::token_modifier* modifier)
            {
               if (token_modifier_list.end() != std::find(token_modifier_list.begin(),
                                                          token_modifier_list.end  (),
                                                          modifier))
               {
                  return false;
               }

               token_modifier_list.push_back(modifier);

               return true;
            }

            inline bool register_joiner(lexer::token_joiner* joiner)
            {
               if (token_joiner_list.end() != std::find(token_joiner_list.begin(),
                                                        token_joiner_list.end  (),
                                                        joiner))
               {
                  return false;
               }

               token_joiner_list.push_back(joiner);

               return true;
            }

            inline bool register_inserter(lexer::token_inserter* inserter)
            {
               if (token_inserter_list.end() != std::find(token_inserter_list.begin(),
                                                          token_inserter_list.end  (),
                                                          inserter))
               {
                  return false;
               }

               token_inserter_list.push_back(inserter);

               return true;
            }

            inline bool run_modifiers(lexer::generator& g)
            {
               error_token_modifier = reinterpret_cast<lexer::token_modifier*>(0);

               for (std::size_t i = 0; i < token_modifier_list.size(); ++i)
               {
                  lexer::token_modifier& modifier = (*token_modifier_list[i]);

                  modifier.reset();
                  modifier.process(g);

                  if (!modifier.result())
                  {
                     error_token_modifier = token_modifier_list[i];

                     return false;
                  }
               }

               return true;
            }

            inline bool run_joiners(lexer::generator& g)
            {
               error_token_joiner = reinterpret_cast<lexer::token_joiner*>(0);

               for (std::size_t i = 0; i < token_joiner_list.size(); ++i)
               {
                  lexer::token_joiner& joiner = (*token_joiner_list[i]);

                  joiner.reset();
                  joiner.process(g);

                  if (!joiner.result())
                  {
                     error_token_joiner = token_joiner_list[i];

                     return false;
                  }
               }

               return true;
            }

            inline bool run_inserters(lexer::generator& g)
            {
               error_token_inserter = reinterpret_cast<lexer::token_inserter*>(0);

               for (std::size_t i = 0; i < token_inserter_list.size(); ++i)
               {
                  lexer::token_inserter& inserter = (*token_inserter_list[i]);

                  inserter.reset();
                  inserter.process(g);

                  if (!inserter.result())
                  {
                     error_token_inserter = token_inserter_list[i];

                     return false;
                  }
               }

               return true;
            }

            inline bool run_scanners(lexer::generator& g)
            {
               error_token_scanner = reinterpret_cast<lexer::token_scanner*>(0);

               for (std::size_t i = 0; i < token_scanner_list.size(); ++i)
               {
                  lexer::token_scanner& scanner = (*token_scanner_list[i]);

                  scanner.reset();
                  scanner.process(g);

                  if (!scanner.result())
                  {
                     error_token_scanner = token_scanner_list[i];

                     return false;
                  }
               }

               return true;
            }

            std::vector<lexer::token_scanner*>  token_scanner_list;
            std::vector<lexer::token_modifier*> token_modifier_list;
            std::vector<lexer::token_joiner*>   token_joiner_list;
            std::vector<lexer::token_inserter*> token_inserter_list;

            lexer::token_scanner*  error_token_scanner;
            lexer::token_modifier* error_token_modifier;
            lexer::token_joiner*   error_token_joiner;
            lexer::token_inserter* error_token_inserter;
         };
      }

      class parser_helper
      {
      public:

         typedef token     token_t;
         typedef generator generator_t;

         inline bool init(const std::string& str)
         {
            if (!lexer_.process(str))
            {
               return false;
            }

            lexer_.begin();

            next_token();

            return true;
         }

         inline generator_t& lexer()
         {
            return lexer_;
         }

         inline const generator_t& lexer() const
         {
            return lexer_;
         }

         inline void store_token()
         {
            lexer_.store();
            store_current_token_ = current_token_;
         }

         inline void restore_token()
         {
            lexer_.restore();
            current_token_ = store_current_token_;
         }

         inline void next_token()
         {
            current_token_ = lexer_.next_token();
         }

         inline const token_t& current_token() const
         {
            return current_token_;
         }

         inline const token_t& peek_next_token()
         {
            return lexer_.peek_next_token();
         }

         enum token_advance_mode
         {
            e_hold    = 0,
            e_advance = 1
         };

         inline void advance_token(const token_advance_mode mode)
         {
            if (e_advance == mode)
            {
               next_token();
            }
         }

         inline bool token_is(const token_t::token_type& ttype, const token_advance_mode mode = e_advance)
         {
            if (current_token().type != ttype)
            {
               return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is(const token_t::token_type& ttype,
                              const std::string& value,
                              const token_advance_mode mode = e_advance)
         {
            if (
                 (current_token().type != ttype) ||
                 !exprtk::details::imatch(value,current_token().value)
               )
            {
               return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is(const std::string& value,
                              const token_advance_mode mode = e_advance)
         {
            if (!exprtk::details::imatch(value,current_token().value))
            {
               return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is_arithmetic_opr(const token_advance_mode mode = e_advance)
         {
            switch (current_token().type)
            {
               case token_t::e_add :
               case token_t::e_sub :
               case token_t::e_div :
               case token_t::e_mul :
               case token_t::e_mod :
               case token_t::e_pow : break;
               default             : return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is_ineq_opr(const token_advance_mode mode = e_advance)
         {
            switch (current_token().type)
            {
               case token_t::e_eq  :
               case token_t::e_lte :
               case token_t::e_ne  :
               case token_t::e_gte :
               case token_t::e_lt  :
               case token_t::e_gt  : break;
               default             : return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is_left_bracket(const token_advance_mode mode = e_advance)
         {
            switch (current_token().type)
            {
               case token_t::e_lbracket    :
               case token_t::e_lcrlbracket :
               case token_t::e_lsqrbracket : break;
               default                     : return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is_right_bracket(const token_advance_mode mode = e_advance)
         {
            switch (current_token().type)
            {
               case token_t::e_rbracket    :
               case token_t::e_rcrlbracket :
               case token_t::e_rsqrbracket : break;
               default                     : return false;
            }

            advance_token(mode);

            return true;
         }

         inline bool token_is_loop(const token_advance_mode mode = e_advance)
         {
            return token_is("for"   , mode) ||
                   token_is("while" , mode) ||
                   token_is("repeat", mode) ;
         }

         inline bool peek_token_is(const token_t::token_type& ttype)
         {
            return (lexer_.peek_next_token().type == ttype);
         }

         inline bool peek_token_is(const std::string& s)
         {
            return (exprtk::details::imatch(lexer_.peek_next_token().value,s));
         }

      private:

         generator_t lexer_;
         token_t     current_token_;
         token_t     store_current_token_;
      };
   }

   template <typename T>
   class vector_view
   {
   public:

      typedef T* data_ptr_t;

      vector_view(data_ptr_t data, const std::size_t& size)
      : base_size_(size)
      , size_(size)
      , data_(data)
      , data_ref_(0)
      {
         assert(size_ > 0);
      }

      vector_view(const vector_view<T>& vv)
      : base_size_(vv.base_size_)
      , size_(vv.size_)
      , data_(vv.data_)
      , data_ref_(0)
      {
         assert(size_ > 0);
      }

      inline void rebase(data_ptr_t data)
      {
         data_ = data;

         if (!data_ref_.empty())
         {
            for (std::size_t i = 0; i < data_ref_.size(); ++i)
            {
               (*data_ref_[i]) = data;
            }
         }
      }

      inline data_ptr_t data() const
      {
         return data_;
      }

      inline std::size_t base_size() const
      {
         return base_size_;
      }

      inline std::size_t size() const
      {
         return size_;
      }

      inline const T& operator[](const std::size_t index) const
      {
         assert(index < size_);
         return data_[index];
      }

      inline T& operator[](const std::size_t index)
      {
         assert(index < size_);
         return data_[index];
      }

      void set_ref(data_ptr_t* data_ref)
      {
         data_ref_.push_back(data_ref);
         exprtk_debug(("vector_view::set_ref() - data_ref: %p data_ref_.size(): %d\n",
                       reinterpret_cast<void*>(data_ref),
                       static_cast<int>(data_ref_.size())));
      }

      void remove_ref(data_ptr_t* data_ref)
      {
         data_ref_.erase(
            std::remove(data_ref_.begin(), data_ref_.end(), data_ref),
            data_ref_.end());
         exprtk_debug(("vector_view::remove_ref() - data_ref: %p data_ref_.size(): %d\n",
                       reinterpret_cast<void*>(data_ref),
                       static_cast<int>(data_ref_.size())));
      }

      bool set_size(const std::size_t new_size)
      {
         if ((new_size > 0) && (new_size <= base_size_))
         {
            size_ = new_size;
            exprtk_debug(("vector_view::set_size() - data_: %p size: %lu\n",
                          reinterpret_cast<void*>(data_),
                          size_));
            return true;
         }

         exprtk_debug(("vector_view::set_size() - error invalid new_size: %lu  base_size: %lu\n",
                       new_size,
                       base_size_));
         return false;
      }

   private:

      const std::size_t base_size_;
      std::size_t size_;
      data_ptr_t  data_;
      std::vector<data_ptr_t*> data_ref_;
   };

   template <typename T>
   inline vector_view<T> make_vector_view(T* data,
                                          const std::size_t size, const std::size_t offset = 0)
   {
      return vector_view<T>(data + offset, size);
   }

   template <typename T>
   inline vector_view<T> make_vector_view(std::vector<T>& v,
                                          const std::size_t size, const std::size_t offset = 0)
   {
      return vector_view<T>(v.data() + offset, size);
   }

   template <typename T> class results_context;

   template <typename T>
   struct type_store
   {
      enum store_type
      {
         e_unknown,
         e_scalar ,
         e_vector ,
         e_string
      };

      type_store()
      : data(0)
      , size(0)
      , type(e_unknown)
      {}

      union
      {
         void* data;
         T*    vec_data;
      };

      std::size_t size;
      store_type  type;

      class parameter_list
      {
      public:

         explicit parameter_list(std::vector<type_store>& pl)
         : parameter_list_(pl)
         {}

         inline bool empty() const
         {
            return parameter_list_.empty();
         }

         inline std::size_t size() const
         {
            return parameter_list_.size();
         }

         inline type_store& operator[](const std::size_t& index)
         {
            return parameter_list_[index];
         }

         inline const type_store& operator[](const std::size_t& index) const
         {
            return parameter_list_[index];
         }

         inline type_store& front()
         {
            return parameter_list_[0];
         }

         inline const type_store& front() const
         {
            return parameter_list_[0];
         }

         inline type_store& back()
         {
            return parameter_list_.back();
         }

         inline const type_store& back() const
         {
            return parameter_list_.back();
         }

      private:

         std::vector<type_store>& parameter_list_;

         friend class results_context<T>;
      };

      template <typename ViewType>
      struct type_view
      {
         typedef type_store<T> type_store_t;
         typedef ViewType      value_t;

         explicit type_view(type_store_t& ts)
         : ts_(ts)
         , data_(reinterpret_cast<value_t*>(ts_.data))
         {}

         explicit type_view(const type_store_t& ts)
         : ts_(const_cast<type_store_t&>(ts))
         , data_(reinterpret_cast<value_t*>(ts_.data))
         {}

         inline std::size_t size() const
         {
            return ts_.size;
         }

         inline value_t& operator[](const std::size_t& i)
         {
            return data_[i];
         }

         inline const value_t& operator[](const std::size_t& i) const
         {
            return data_[i];
         }

         inline const value_t* begin() const { return data_; }
         inline       value_t* begin()       { return data_; }

         inline const value_t* end() const
         {
            return static_cast<value_t*>(data_ + ts_.size);
         }

         inline value_t* end()
         {
            return static_cast<value_t*>(data_ + ts_.size);
         }

         type_store_t& ts_;
         value_t* data_;
      };

      typedef type_view<T>    vector_view;
      typedef type_view<char> string_view;

      struct scalar_view
      {
         typedef type_store<T> type_store_t;
         typedef T value_t;

         explicit scalar_view(type_store_t& ts)
         : v_(*reinterpret_cast<value_t*>(ts.data))
         {}

         explicit scalar_view(const type_store_t& ts)
         : v_(*reinterpret_cast<value_t*>(const_cast<type_store_t&>(ts).data))
         {}

         inline value_t& operator() ()
         {
            return v_;
         }

         inline const value_t& operator() () const
         {
            return v_;
         }

         inline operator value_t() const
         {
            return v_;
         }

         inline operator value_t()
         {
            return v_;
         }

         template <typename IntType>
         inline bool to_int(IntType& i) const
         {
            if (!exprtk::details::numeric::is_integer(v_))
               return false;

            i = static_cast<IntType>(v_);

            return true;
         }

         template <typename UIntType>
         inline bool to_uint(UIntType& u) const
         {
            if (v_ < T(0))
               return false;
            else if (!exprtk::details::numeric::is_integer(v_))
               return false;

            u = static_cast<UIntType>(v_);

            return true;
         }

         T& v_;
      };
   };

   template <typename StringView>
   inline std::string to_str(const StringView& view)
   {
      return std::string(view.begin(),view.size());
   }

   #ifndef exprtk_disable_return_statement
   namespace details
   {
      template <typename T> class return_node;
      template <typename T> class return_envelope_node;
   }
   #endif

   template <typename T>
   class results_context
   {
   public:

      typedef type_store<T> type_store_t;
      typedef typename type_store_t::scalar_view scalar_t;
      typedef typename type_store_t::vector_view vector_t;
      typedef typename type_store_t::string_view string_t;

      results_context()
      : results_available_(false)
      {}

      inline std::size_t count() const
      {
         if (results_available_)
            return parameter_list_.size();
         else
            return 0;
      }

      inline type_store_t& operator[](const std::size_t& index)
      {
         return parameter_list_[index];
      }

      inline const type_store_t& operator[](const std::size_t& index) const
      {
         return parameter_list_[index];
      }

      inline bool get_scalar(const std::size_t& index, T& out) const
      {
         if (
              (index < parameter_list_.size()) &&
              (parameter_list_[index].type == type_store_t::e_scalar)
            )
         {
            const scalar_t scalar(parameter_list_[index]);
            out = scalar();
            return true;
         }

         return false;
      }

      template <typename OutputIterator>
      inline bool get_vector(const std::size_t& index, OutputIterator out_itr) const
      {
         if (
              (index < parameter_list_.size()) &&
              (parameter_list_[index].type == type_store_t::e_vector)
            )
         {
            const vector_t vector(parameter_list_[index]);
            for (std::size_t i = 0; i < vector.size(); ++i)
            {
               *(out_itr++) = vector[i];
            }

            return true;
         }

         return false;
      }

      inline bool get_vector(const std::size_t& index, std::vector<T>& out) const
      {
         return get_vector(index,std::back_inserter(out));
      }

      inline bool get_string(const std::size_t& index, std::string& out) const
      {
         if (
              (index < parameter_list_.size()) &&
              (parameter_list_[index].type == type_store_t::e_string)
            )
         {
            const string_t str(parameter_list_[index]);
            out.assign(str.begin(),str.size());
            return true;
         }

         return false;
      }

   private:

      inline void clear()
      {
         results_available_ = false;
      }

      typedef std::vector<type_store_t> ts_list_t;
      typedef typename type_store_t::parameter_list parameter_list_t;

      inline void assign(const parameter_list_t& pl)
      {
         parameter_list_    = pl.parameter_list_;
         results_available_ = true;
      }

      bool results_available_;
      ts_list_t parameter_list_;

      #ifndef exprtk_disable_return_statement
      friend class details::return_node<T>;
      friend class details::return_envelope_node<T>;
      #endif
   };

   namespace details
   {
      enum operator_type
      {
         e_default , e_null    , e_add     , e_sub     ,
         e_mul     , e_div     , e_mod     , e_pow     ,
         e_atan2   , e_min     , e_max     , e_avg     ,
         e_sum     , e_prod    , e_lt      , e_lte     ,
         e_eq      , e_equal   , e_ne      , e_nequal  ,
         e_gte     , e_gt      , e_and     , e_nand    ,
         e_or      , e_nor     , e_xor     , e_xnor    ,
         e_mand    , e_mor     , e_scand   , e_scor    ,
         e_shr     , e_shl     , e_abs     , e_acos    ,
         e_acosh   , e_asin    , e_asinh   , e_atan    ,
         e_atanh   , e_ceil    , e_cos     , e_cosh    ,
         e_exp     , e_expm1   , e_floor   , e_log     ,
         e_log10   , e_log2    , e_log1p   , e_logn    ,
         e_neg     , e_pos     , e_round   , e_roundn  ,
         e_root    , e_sqrt    , e_sin     , e_sinc    ,
         e_sinh    , e_sec     , e_csc     , e_tan     ,
         e_tanh    , e_cot     , e_clamp   , e_iclamp  ,
         e_inrange , e_sgn     , e_r2d     , e_d2r     ,
         e_d2g     , e_g2d     , e_hypot   , e_notl    ,
         e_erf     , e_erfc    , e_ncdf    , e_frac    ,
         e_trunc   , e_assign  , e_addass  , e_subass  ,
         e_mulass  , e_divass  , e_modass  , e_in      ,
         e_like    , e_ilike   , e_multi   , e_smulti  ,
         e_swap    ,

         // Do not add new functions/operators after this point.
         e_sf00 = 1000, e_sf01 = 1001, e_sf02 = 1002, e_sf03 = 1003,
         e_sf04 = 1004, e_sf05 = 1005, e_sf06 = 1006, e_sf07 = 1007,
         e_sf08 = 1008, e_sf09 = 1009, e_sf10 = 1010, e_sf11 = 1011,
         e_sf12 = 1012, e_sf13 = 1013, e_sf14 = 1014, e_sf15 = 1015,
         e_sf16 = 1016, e_sf17 = 1017, e_sf18 = 1018, e_sf19 = 1019,
         e_sf20 = 1020, e_sf21 = 1021, e_sf22 = 1022, e_sf23 = 1023,
         e_sf24 = 1024, e_sf25 = 1025, e_sf26 = 1026, e_sf27 = 1027,
         e_sf28 = 1028, e_sf29 = 1029, e_sf30 = 1030, e_sf31 = 1031,
         e_sf32 = 1032, e_sf33 = 1033, e_sf34 = 1034, e_sf35 = 1035,
         e_sf36 = 1036, e_sf37 = 1037, e_sf38 = 1038, e_sf39 = 1039,
         e_sf40 = 1040, e_sf41 = 1041, e_sf42 = 1042, e_sf43 = 1043,
         e_sf44 = 1044, e_sf45 = 1045, e_sf46 = 1046, e_sf47 = 1047,
         e_sf48 = 1048, e_sf49 = 1049, e_sf50 = 1050, e_sf51 = 1051,
         e_sf52 = 1052, e_sf53 = 1053, e_sf54 = 1054, e_sf55 = 1055,
         e_sf56 = 1056, e_sf57 = 1057, e_sf58 = 1058, e_sf59 = 1059,
         e_sf60 = 1060, e_sf61 = 1061, e_sf62 = 1062, e_sf63 = 1063,
         e_sf64 = 1064, e_sf65 = 1065, e_sf66 = 1066, e_sf67 = 1067,
         e_sf68 = 1068, e_sf69 = 1069, e_sf70 = 1070, e_sf71 = 1071,
         e_sf72 = 1072, e_sf73 = 1073, e_sf74 = 1074, e_sf75 = 1075,
         e_sf76 = 1076, e_sf77 = 1077, e_sf78 = 1078, e_sf79 = 1079,
         e_sf80 = 1080, e_sf81 = 1081, e_sf82 = 1082, e_sf83 = 1083,
         e_sf84 = 1084, e_sf85 = 1085, e_sf86 = 1086, e_sf87 = 1087,
         e_sf88 = 1088, e_sf89 = 1089, e_sf90 = 1090, e_sf91 = 1091,
         e_sf92 = 1092, e_sf93 = 1093, e_sf94 = 1094, e_sf95 = 1095,
         e_sf96 = 1096, e_sf97 = 1097, e_sf98 = 1098, e_sf99 = 1099,
         e_sffinal  = 1100,
         e_sf4ext00 = 2000, e_sf4ext01 = 2001, e_sf4ext02 = 2002, e_sf4ext03 = 2003,
         e_sf4ext04 = 2004, e_sf4ext05 = 2005, e_sf4ext06 = 2006, e_sf4ext07 = 2007,
         e_sf4ext08 = 2008, e_sf4ext09 = 2009, e_sf4ext10 = 2010, e_sf4ext11 = 2011,
         e_sf4ext12 = 2012, e_sf4ext13 = 2013, e_sf4ext14 = 2014, e_sf4ext15 = 2015,
         e_sf4ext16 = 2016, e_sf4ext17 = 2017, e_sf4ext18 = 2018, e_sf4ext19 = 2019,
         e_sf4ext20 = 2020, e_sf4ext21 = 2021, e_sf4ext22 = 2022, e_sf4ext23 = 2023,
         e_sf4ext24 = 2024, e_sf4ext25 = 2025, e_sf4ext26 = 2026, e_sf4ext27 = 2027,
         e_sf4ext28 = 2028, e_sf4ext29 = 2029, e_sf4ext30 = 2030, e_sf4ext31 = 2031,
         e_sf4ext32 = 2032, e_sf4ext33 = 2033, e_sf4ext34 = 2034, e_sf4ext35 = 2035,
         e_sf4ext36 = 2036, e_sf4ext37 = 2037, e_sf4ext38 = 2038, e_sf4ext39 = 2039,
         e_sf4ext40 = 2040, e_sf4ext41 = 2041, e_sf4ext42 = 2042, e_sf4ext43 = 2043,
         e_sf4ext44 = 2044, e_sf4ext45 = 2045, e_sf4ext46 = 2046, e_sf4ext47 = 2047,
         e_sf4ext48 = 2048, e_sf4ext49 = 2049, e_sf4ext50 = 2050, e_sf4ext51 = 2051,
         e_sf4ext52 = 2052, e_sf4ext53 = 2053, e_sf4ext54 = 2054, e_sf4ext55 = 2055,
         e_sf4ext56 = 2056, e_sf4ext57 = 2057, e_sf4ext58 = 2058, e_sf4ext59 = 2059,
         e_sf4ext60 = 2060, e_sf4ext61 = 2061
      };

      inline std::string to_str(const operator_type opr)
      {
         switch (opr)
         {
            case e_add    : return  "+"  ;
            case e_sub    : return  "-"  ;
            case e_mul    : return  "*"  ;
            case e_div    : return  "/"  ;
            case e_mod    : return  "%"  ;
            case e_pow    : return  "^"  ;
            case e_assign : return ":="  ;
            case e_addass : return "+="  ;
            case e_subass : return "-="  ;
            case e_mulass : return "*="  ;
            case e_divass : return "/="  ;
            case e_modass : return "%="  ;
            case e_lt     : return  "<"  ;
            case e_lte    : return "<="  ;
            case e_eq     : return "=="  ;
            case e_equal  : return  "="  ;
            case e_ne     : return "!="  ;
            case e_nequal : return "<>"  ;
            case e_gte    : return ">="  ;
            case e_gt     : return  ">"  ;
            case e_and    : return "and" ;
            case e_or     : return "or"  ;
            case e_xor    : return "xor" ;
            case e_nand   : return "nand";
            case e_nor    : return "nor" ;
            case e_xnor   : return "xnor";
            default       : return "N/A" ;
         }
      }

      struct base_operation_t
      {
         base_operation_t(const operator_type t, const unsigned int& np)
         : type(t)
         , num_params(np)
         {}

         operator_type type;
         unsigned int num_params;
      };

      namespace loop_unroll
      {
         const unsigned int global_loop_batch_size =
         #ifndef exprtk_disable_superscalar_unroll
         16;
         #else
          4;
         #endif

         struct details
         {
            explicit details(const std::size_t& vsize,
                             const unsigned int loop_batch_size = global_loop_batch_size)
            : batch_size(loop_batch_size   )
            , remainder (vsize % batch_size)
            , upper_bound(static_cast<int>(vsize - (remainder ? loop_batch_size : 0)))
            {}

            unsigned int batch_size;
            int remainder;
            int upper_bound;
         };
      }

      #ifdef exprtk_enable_debugging
      inline void dump_ptr(const std::string& s, const void* ptr, const std::size_t size = 0)
      {
         if (size)
            exprtk_debug(("%s - addr: %p size: %d\n",
                          s.c_str(),
                          ptr,
                          static_cast<unsigned int>(size)));
         else
            exprtk_debug(("%s - addr: %p\n", s.c_str(), ptr));
      }

      template <typename T>
      inline void dump_vector(const std::string& vec_name, const T* data, const std::size_t size)
      {
         printf("----- %s (%p) -----\n",
                vec_name.c_str(),
                static_cast<const void*>(data));
         printf("[ ");
         for (std::size_t i = 0; i <  size; ++i)
         {
            printf("%8.3f\t", data[i]);
         }
         printf(" ]\n");
         printf("---------------------\n");
      }
      #else
      inline void dump_ptr(const std::string&, const void*) {}
      inline void dump_ptr(const std::string&, const void*, const std::size_t) {}
      template <typename T>
      inline void dump_vector(const std::string&, const T*, const std::size_t) {}
      #endif

      template <typename T>
      class vec_data_store
      {
      public:

         typedef vec_data_store<T> type;
         typedef T* data_t;

      private:

         struct control_block
         {
            control_block()
            : ref_count(1)
            , size     (0)
            , data     (0)
            , destruct (true)
            {}

            explicit control_block(const std::size_t& dsize)
            : ref_count(1    )
            , size     (dsize)
            , data     (0    )
            , destruct (true )
            { create_data(); }

            control_block(const std::size_t& dsize, data_t dptr, bool dstrct = false)
            : ref_count(1     )
            , size     (dsize )
            , data     (dptr  )
            , destruct (dstrct)
            {}

           ~control_block()
            {
               if (data && destruct && (0 == ref_count))
               {
                  dump_ptr("~vec_data_store::control_block() data",data);
                  delete[] data;
                  data = reinterpret_cast<data_t>(0);
               }
            }

            static inline control_block* create(const std::size_t& dsize, data_t data_ptr = data_t(0), bool dstrct = false)
            {
               if (dsize)
               {
                  if (0 == data_ptr)
                     return (new control_block(dsize));
                  else
                     return (new control_block(dsize, data_ptr, dstrct));
               }
               else
                  return (new control_block);
            }

            static inline void destroy(control_block*& cntrl_blck)
            {
               if (cntrl_blck)
               {
                  if (
                       (0 !=   cntrl_blck->ref_count) &&
                       (0 == --cntrl_blck->ref_count)
                     )
                  {
                     delete cntrl_blck;
                  }

                  cntrl_blck = 0;
               }
            }

            std::size_t ref_count;
            std::size_t size;
            data_t      data;
            bool        destruct;

         private:

            control_block(const control_block&) exprtk_delete;
            control_block& operator=(const control_block&) exprtk_delete;

            inline void create_data()
            {
               destruct = true;
               data     = new T[size];
               std::fill_n(data, size, T(0));
               dump_ptr("control_block::create_data() - data", data, size);
            }
         };

      public:

         vec_data_store()
         : control_block_(control_block::create(0))
         {}

         explicit vec_data_store(const std::size_t& size)
         : control_block_(control_block::create(size,reinterpret_cast<data_t>(0),true))
         {}

         vec_data_store(const std::size_t& size, data_t data, bool dstrct = false)
         : control_block_(control_block::create(size, data, dstrct))
         {}

         vec_data_store(const type& vds)
         {
            control_block_ = vds.control_block_;
            control_block_->ref_count++;
         }

        ~vec_data_store()
         {
            control_block::destroy(control_block_);
         }

         type& operator=(const type& vds)
         {
            if (this != &vds)
            {
               const std::size_t final_size = min_size(control_block_, vds.control_block_);

               vds.control_block_->size = final_size;
                   control_block_->size = final_size;

               if (control_block_->destruct || (0 == control_block_->data))
               {
                  control_block::destroy(control_block_);

                  control_block_ = vds.control_block_;
                  control_block_->ref_count++;
               }
            }

            return (*this);
         }

         inline data_t data()
         {
            return control_block_->data;
         }

         inline data_t data() const
         {
            return control_block_->data;
         }

         inline std::size_t size() const
         {
            return control_block_->size;
         }

         inline data_t& ref()
         {
            return control_block_->data;
         }

         inline void dump() const
         {
            #ifdef exprtk_enable_debugging
            exprtk_debug(("size: %d\taddress:%p\tdestruct:%c\n",
                          size(),
                          data(),
                          (control_block_->destruct ? 'T' : 'F')));

            for (std::size_t i = 0; i < size(); ++i)
            {
               if (5 == i)
                  exprtk_debug(("\n"));

               exprtk_debug(("%15.10f ", data()[i]));
            }
            exprtk_debug(("\n"));
            #endif
         }

         static inline void match_sizes(type& vds0, type& vds1)
         {
            const std::size_t size = min_size(vds0.control_block_,vds1.control_block_);
            vds0.control_block_->size = size;
            vds1.control_block_->size = size;
         }

      private:

         static inline std::size_t min_size(const control_block* cb0, const control_block* cb1)
         {
            const std::size_t size0 = cb0->size;
            const std::size_t size1 = cb1->size;

            if (size0 && size1)
               return std::min(size0,size1);
            else
               return (size0) ? size0 : size1;
         }

         control_block* control_block_;
      };

      namespace numeric
      {
         namespace details
         {
            template <typename T>
            inline T process_impl(const operator_type operation, const T arg)
            {
               switch (operation)
               {
                  case e_abs   : return numeric::abs  (arg);
                  case e_acos  : return numeric::acos (arg);
                  case e_acosh : return numeric::acosh(arg);
                  case e_asin  : return numeric::asin (arg);
                  case e_asinh : return numeric::asinh(arg);
                  case e_atan  : return numeric::atan (arg);
                  case e_atanh : return numeric::atanh(arg);
                  case e_ceil  : return numeric::ceil (arg);
                  case e_cos   : return numeric::cos  (arg);
                  case e_cosh  : return numeric::cosh (arg);
                  case e_exp   : return numeric::exp  (arg);
                  case e_expm1 : return numeric::expm1(arg);
                  case e_floor : return numeric::floor(arg);
                  case e_log   : return numeric::log  (arg);
                  case e_log10 : return numeric::log10(arg);
                  case e_log2  : return numeric::log2 (arg);
                  case e_log1p : return numeric::log1p(arg);
                  case e_neg   : return numeric::neg  (arg);
                  case e_pos   : return numeric::pos  (arg);
                  case e_round : return numeric::round(arg);
                  case e_sin   : return numeric::sin  (arg);
                  case e_sinc  : return numeric::sinc (arg);
                  case e_sinh  : return numeric::sinh (arg);
                  case e_sqrt  : return numeric::sqrt (arg);
                  case e_tan   : return numeric::tan  (arg);
                  case e_tanh  : return numeric::tanh (arg);
                  case e_cot   : return numeric::cot  (arg);
                  case e_sec   : return numeric::sec  (arg);
                  case e_csc   : return numeric::csc  (arg);
                  case e_r2d   : return numeric::r2d  (arg);
                  case e_d2r   : return numeric::d2r  (arg);
                  case e_d2g   : return numeric::d2g  (arg);
                  case e_g2d   : return numeric::g2d  (arg);
                  case e_notl  : return numeric::notl (arg);
                  case e_sgn   : return numeric::sgn  (arg);
                  case e_erf   : return numeric::erf  (arg);
                  case e_erfc  : return numeric::erfc (arg);
                  case e_ncdf  : return numeric::ncdf (arg);
                  case e_frac  : return numeric::frac (arg);
                  case e_trunc : return numeric::trunc(arg);

                  default      : exprtk_debug(("numeric::details::process_impl<T> - Invalid unary operation.\n"));
                                 return std::numeric_limits<T>::quiet_NaN();
               }
            }

            template <typename T>
            inline T process_impl(const operator_type operation, const T arg0, const T arg1)
            {
               switch (operation)
               {
                  case e_add    : return (arg0 + arg1);
                  case e_sub    : return (arg0 - arg1);
                  case e_mul    : return (arg0 * arg1);
                  case e_div    : return (arg0 / arg1);
                  case e_mod    : return modulus<T>(arg0,arg1);
                  case e_pow    : return pow<T>(arg0,arg1);
                  case e_atan2  : return atan2<T>(arg0,arg1);
                  case e_min    : return std::min<T>(arg0,arg1);
                  case e_max    : return std::max<T>(arg0,arg1);
                  case e_logn   : return logn<T>(arg0,arg1);
                  case e_lt     : return (arg0 <  arg1) ? T(1) : T(0);
                  case e_lte    : return (arg0 <= arg1) ? T(1) : T(0);
                  case e_eq     : return std::equal_to<T>()(arg0,arg1) ? T(1) : T(0);
                  case e_ne     : return std::not_equal_to<T>()(arg0,arg1) ? T(1) : T(0);
                  case e_gte    : return (arg0 >= arg1) ? T(1) : T(0);
                  case e_gt     : return (arg0 >  arg1) ? T(1) : T(0);
                  case e_and    : return and_opr <T>(arg0,arg1);
                  case e_nand   : return nand_opr<T>(arg0,arg1);
                  case e_or     : return or_opr  <T>(arg0,arg1);
                  case e_nor    : return nor_opr <T>(arg0,arg1);
                  case e_xor    : return xor_opr <T>(arg0,arg1);
                  case e_xnor   : return xnor_opr<T>(arg0,arg1);
                  case e_root   : return root    <T>(arg0,arg1);
                  case e_roundn : return roundn  <T>(arg0,arg1);
                  case e_equal  : return equal   <T>(arg0,arg1);
                  case e_nequal : return nequal  <T>(arg0,arg1);
                  case e_hypot  : return hypot   <T>(arg0,arg1);
                  case e_shr    : return shr     <T>(arg0,arg1);
                  case e_shl    : return shl     <T>(arg0,arg1);

                  default       : exprtk_debug(("numeric::details::process_impl<T> - Invalid binary operation.\n"));
                                  return std::numeric_limits<T>::quiet_NaN();
               }
            }

            template <typename T>
            inline T process_impl(const operator_type operation, const T arg0, const T arg1, int_type_tag)
            {
               switch (operation)
               {
                  case e_add    : return (arg0 + arg1);
                  case e_sub    : return (arg0 - arg1);
                  case e_mul    : return (arg0 * arg1);
                  case e_div    : return (arg0 / arg1);
                  case e_mod    : return arg0 % arg1;
                  case e_pow    : return pow<T>(arg0,arg1);
                  case e_min    : return std::min<T>(arg0,arg1);
                  case e_max    : return std::max<T>(arg0,arg1);
                  case e_logn   : return logn<T>(arg0,arg1);
                  case e_lt     : return (arg0 <  arg1) ? T(1) : T(0);
                  case e_lte    : return (arg0 <= arg1) ? T(1) : T(0);
                  case e_eq     : return (arg0 == arg1) ? T(1) : T(0);
                  case e_ne     : return (arg0 != arg1) ? T(1) : T(0);
                  case e_gte    : return (arg0 >= arg1) ? T(1) : T(0);
                  case e_gt     : return (arg0 >  arg1) ? T(1) : T(0);
                  case e_and    : return ((arg0 != T(0)) && (arg1 != T(0))) ? T(1) : T(0);
                  case e_nand   : return ((arg0 != T(0)) && (arg1 != T(0))) ? T(0) : T(1);
                  case e_or     : return ((arg0 != T(0)) || (arg1 != T(0))) ? T(1) : T(0);
                  case e_nor    : return ((arg0 != T(0)) || (arg1 != T(0))) ? T(0) : T(1);
                  case e_xor    : return arg0 ^ arg1;
                  case e_xnor   : return !(arg0 ^ arg1);
                  case e_root   : return root<T>(arg0,arg1);
                  case e_equal  : return arg0 == arg1;
                  case e_nequal : return arg0 != arg1;
                  case e_hypot  : return hypot<T>(arg0,arg1);
                  case e_shr    : return arg0 >> arg1;
                  case e_shl    : return arg0 << arg1;

                  default       : exprtk_debug(("numeric::details::process_impl<IntType> - Invalid binary operation.\n"));
                                  return std::numeric_limits<T>::quiet_NaN();
               }
            }
         }

         template <typename T>
         inline T process(const operator_type operation, const T arg)
         {
            return exprtk::details::numeric::details::process_impl(operation,arg);
         }

         template <typename T>
         inline T process(const operator_type operation, const T arg0, const T arg1)
         {
            return exprtk::details::numeric::details::process_impl(operation, arg0, arg1);
         }
      }

      template <typename Node>
      struct node_collector_interface
      {
         typedef Node* node_ptr_t;
         typedef Node** node_pp_t;
         typedef std::vector<node_pp_t> noderef_list_t;

         virtual ~node_collector_interface()
         {}

         virtual void collect_nodes(noderef_list_t&)
         {}
      };

      template <typename Node>
      struct node_depth_base;

      template <typename T>
      class expression_node : public node_collector_interface<expression_node<T> >
                            , public node_depth_base<expression_node<T> >
      {
      public:

         enum node_type
         {
            e_none          , e_null          , e_constant    , e_unary        ,
            e_binary        , e_binary_ext    , e_trinary     , e_quaternary   ,
            e_vararg        , e_conditional   , e_while       , e_repeat       ,
            e_for           , e_switch        , e_mswitch     , e_return       ,
            e_retenv        , e_variable      , e_stringvar   , e_stringconst  ,
            e_stringvarrng  , e_cstringvarrng , e_strgenrange , e_strconcat    ,
            e_stringvarsize , e_strswap       , e_stringsize  , e_stringvararg ,
            e_function      , e_vafunction    , e_genfunction , e_strfunction  ,
            e_strcondition  , e_strccondition , e_add         , e_sub          ,
            e_mul           , e_div           , e_mod         , e_pow          ,
            e_lt            , e_lte           , e_gt          , e_gte          ,
            e_eq            , e_ne            , e_and         , e_nand         ,
            e_or            , e_nor           , e_xor         , e_xnor         ,
            e_in            , e_like          , e_ilike       , e_inranges     ,
            e_ipow          , e_ipowinv       , e_abs         , e_acos         ,
            e_acosh         , e_asin          , e_asinh       , e_atan         ,
            e_atanh         , e_ceil          , e_cos         , e_cosh         ,
            e_exp           , e_expm1         , e_floor       , e_log          ,
            e_log10         , e_log2          , e_log1p       , e_neg          ,
            e_pos           , e_round         , e_sin         , e_sinc         ,
            e_sinh          , e_sqrt          , e_tan         , e_tanh         ,
            e_cot           , e_sec           , e_csc         , e_r2d          ,
            e_d2r           , e_d2g           , e_g2d         , e_notl         ,
            e_sgn           , e_erf           , e_erfc        , e_ncdf         ,
            e_frac          , e_trunc         , e_uvouv       , e_vov          ,
            e_cov           , e_voc           , e_vob         , e_bov          ,
            e_cob           , e_boc           , e_vovov       , e_vovoc        ,
            e_vocov         , e_covov         , e_covoc       , e_vovovov      ,
            e_vovovoc       , e_vovocov       , e_vocovov     , e_covovov      ,
            e_covocov       , e_vocovoc       , e_covovoc     , e_vococov      ,
            e_sf3ext        , e_sf4ext        , e_nulleq      , e_strass       ,
            e_vector        , e_vecsize       , e_vecelem     , e_veccelem     ,
            e_vecelemrtc    , e_veccelemrtc   , e_rbvecelem   , e_rbvecelemrtc ,
            e_rbveccelem    , e_rbveccelemrtc , e_vecinit     , e_vecvalass    ,
            e_vecvecass     , e_vecopvalass   , e_vecopvecass , e_vecfunc      ,
            e_vecvecswap    , e_vecvecineq    , e_vecvalineq  , e_valvecineq   ,
            e_vecvecarith   , e_vecvalarith   , e_valvecarith , e_vecunaryop   ,
            e_vecondition   , e_break         , e_continue    , e_swap         ,
            e_assert
         };

         typedef T value_type;
         typedef expression_node<T>* expression_ptr;
         typedef node_collector_interface<expression_node<T> > nci_t;
         typedef typename nci_t::noderef_list_t noderef_list_t;
         typedef node_depth_base<expression_node<T> > ndb_t;

         virtual ~expression_node()
         {}

         inline virtual T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline virtual expression_node<T>* branch(const std::size_t& index = 0) const
         {
            return reinterpret_cast<expression_ptr>(index * 0);
         }

         inline virtual node_type type() const
         {
            return e_none;
         }

         inline virtual bool valid() const
         {
            return true;
         }
      }; // class expression_node

      template <typename T>
      inline bool is_generally_string_node(const expression_node<T>* node);

      inline bool is_true(const double v)
      {
         return std::not_equal_to<double>()(0.0,v);
      }

      inline bool is_true(const long double v)
      {
         return std::not_equal_to<long double>()(0.0L,v);
      }

      inline bool is_true(const float v)
      {
         return std::not_equal_to<float>()(0.0f,v);
      }

      template <typename T>
      inline bool is_true(const expression_node<T>* node)
      {
         return std::not_equal_to<T>()(T(0),node->value());
      }

      template <typename T>
      inline bool is_true(const std::pair<expression_node<T>*,bool>& node)
      {
         return std::not_equal_to<T>()(T(0),node.first->value());
      }

      template <typename T>
      inline bool is_false(const expression_node<T>* node)
      {
         return std::equal_to<T>()(T(0),node->value());
      }

      template <typename T>
      inline bool is_false(const std::pair<expression_node<T>*,bool>& node)
      {
         return std::equal_to<T>()(T(0),node.first->value());
      }

      template <typename T>
      inline bool is_literal_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_constant == node->type());
      }

      template <typename T>
      inline bool is_unary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_unary == node->type());
      }

      template <typename T>
      inline bool is_neg_unary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_neg == node->type());
      }

      template <typename T>
      inline bool is_binary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_binary == node->type());
      }

      template <typename T>
      inline bool is_variable_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_variable == node->type());
      }

      template <typename T>
      inline bool is_ivariable_node(const expression_node<T>* node)
      {
         return node &&
                (
                  details::expression_node<T>::e_variable      == node->type() ||
                  details::expression_node<T>::e_vecelem       == node->type() ||
                  details::expression_node<T>::e_veccelem      == node->type() ||
                  details::expression_node<T>::e_vecelemrtc    == node->type() ||
                  details::expression_node<T>::e_veccelemrtc   == node->type() ||
                  details::expression_node<T>::e_rbvecelem     == node->type() ||
                  details::expression_node<T>::e_rbveccelem    == node->type() ||
                  details::expression_node<T>::e_rbvecelemrtc  == node->type() ||
                  details::expression_node<T>::e_rbveccelemrtc == node->type()
                );
      }

      template <typename T>
      inline bool is_vector_elem_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vecelem == node->type());
      }

      template <typename T>
      inline bool is_vector_celem_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_veccelem == node->type());
      }

      template <typename T>
      inline bool is_vector_elem_rtc_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vecelemrtc == node->type());
      }

      template <typename T>
      inline bool is_vector_celem_rtc_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_veccelemrtc == node->type());
      }

      template <typename T>
      inline bool is_rebasevector_elem_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_rbvecelem == node->type());
      }

      template <typename T>
      inline bool is_rebasevector_elem_rtc_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_rbvecelemrtc == node->type());
      }

      template <typename T>
      inline bool is_rebasevector_celem_rtc_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_rbveccelemrtc == node->type());
      }

      template <typename T>
      inline bool is_rebasevector_celem_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_rbveccelem == node->type());
      }

      template <typename T>
      inline bool is_vector_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vector == node->type());
      }

      template <typename T>
      inline bool is_ivector_node(const expression_node<T>* node)
      {
         if (node)
         {
            switch (node->type())
            {
               case details::expression_node<T>::e_vector      :
               case details::expression_node<T>::e_vecvalass   :
               case details::expression_node<T>::e_vecvecass   :
               case details::expression_node<T>::e_vecopvalass :
               case details::expression_node<T>::e_vecopvecass :
               case details::expression_node<T>::e_vecvecswap  :
               case details::expression_node<T>::e_vecvecarith :
               case details::expression_node<T>::e_vecvalarith :
               case details::expression_node<T>::e_valvecarith :
               case details::expression_node<T>::e_vecunaryop  :
               case details::expression_node<T>::e_vecondition : return true;
               default                                         : return false;
            }
         }
         else
            return false;
      }

      template <typename T>
      inline bool is_constant_node(const expression_node<T>* node)
      {
         return node &&
         (
           details::expression_node<T>::e_constant    == node->type() ||
           details::expression_node<T>::e_stringconst == node->type()
         );
      }

      template <typename T>
      inline bool is_null_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_null == node->type());
      }

      template <typename T>
      inline bool is_break_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_break == node->type());
      }

      template <typename T>
      inline bool is_continue_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_continue == node->type());
      }

      template <typename T>
      inline bool is_swap_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_swap == node->type());
      }

      template <typename T>
      inline bool is_function(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_function == node->type());
      }

      template <typename T>
      inline bool is_vararg_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vararg == node->type());
      }

      template <typename T>
      inline bool is_return_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_return == node->type());
      }

      template <typename T> class unary_node;

      template <typename T>
      inline bool is_negate_node(const expression_node<T>* node)
      {
         if (node && is_unary_node(node))
         {
            return (details::e_neg == static_cast<const unary_node<T>*>(node)->operation());
         }
         else
            return false;
      }

      template <typename T>
      inline bool is_assert_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_assert == node->type());
      }

      template <typename T>
      inline bool branch_deletable(const expression_node<T>* node)
      {
         return (0 != node)             &&
                !is_variable_node(node) &&
                !is_string_node  (node) ;
      }

      template <std::size_t N, typename T>
      inline bool all_nodes_valid(expression_node<T>* const (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            if (0 == b[i]) return false;
         }

         return true;
      }

      template <typename T,
                typename Allocator,
                template <typename, typename> class Sequence>
      inline bool all_nodes_valid(const Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            if (0 == b[i]) return false;
         }

         return true;
      }

      template <std::size_t N, typename T>
      inline bool all_nodes_variables(expression_node<T>* const (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            if (0 == b[i])
               return false;
            else if (!is_variable_node(b[i]))
               return false;
         }

         return true;
      }

      template <typename T,
                typename Allocator,
                template <typename, typename> class Sequence>
      inline bool all_nodes_variables(const Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            if (0 == b[i])
               return false;
            else if (!is_variable_node(b[i]))
               return false;
         }

         return true;
      }

      template <typename Node>
      class node_collection_destructor
      {
      public:

         typedef node_collector_interface<Node> nci_t;

         typedef typename nci_t::node_ptr_t     node_ptr_t;
         typedef typename nci_t::node_pp_t      node_pp_t;
         typedef typename nci_t::noderef_list_t noderef_list_t;

         static void delete_nodes(node_ptr_t& root)
         {
            std::vector<node_pp_t> node_delete_list;
            node_delete_list.reserve(1000);

            collect_nodes(root, node_delete_list);

            for (std::size_t i = 0; i < node_delete_list.size(); ++i)
            {
               node_ptr_t& node = *node_delete_list[i];
               exprtk_debug(("ncd::delete_nodes() - deleting: %p\n", reinterpret_cast<void*>(node)));
               delete node;
               node = reinterpret_cast<node_ptr_t>(0);
            }
         }

      private:

         static void collect_nodes(node_ptr_t& root, noderef_list_t& node_delete_list)
         {
            std::deque<node_ptr_t> node_list;
            node_list.push_back(root);
            node_delete_list.push_back(&root);

            noderef_list_t child_node_delete_list;
            child_node_delete_list.reserve(1000);

            while (!node_list.empty())
            {
               node_list.front()->collect_nodes(child_node_delete_list);

               if (!child_node_delete_list.empty())
               {
                  for (std::size_t i = 0; i < child_node_delete_list.size(); ++i)
                  {
                     node_pp_t& node = child_node_delete_list[i];

                     if (0 == (*node))
                     {
                        exprtk_debug(("ncd::collect_nodes() - null node encountered.\n"));
                     }

                     node_list.push_back(*node);
                  }

                  node_delete_list.insert(
                     node_delete_list.end(),
                     child_node_delete_list.begin(), child_node_delete_list.end());

                  child_node_delete_list.clear();
               }

               node_list.pop_front();
            }

            std::reverse(node_delete_list.begin(), node_delete_list.end());
         }
      };

      template <typename NodeAllocator, typename T, std::size_t N>
      inline void free_all_nodes(NodeAllocator& node_allocator, expression_node<T>* (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            free_node(node_allocator,b[i]);
         }
      }

      template <typename NodeAllocator,
                typename T,
                typename Allocator,
                template <typename, typename> class Sequence>
      inline void free_all_nodes(NodeAllocator& node_allocator, Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            free_node(node_allocator,b[i]);
         }

         b.clear();
      }

      template <typename NodeAllocator, typename T>
      inline void free_node(NodeAllocator&, expression_node<T>*& node)
      {
         if ((0 == node) || is_variable_node(node) || is_string_node(node))
         {
            return;
         }

         node_collection_destructor<expression_node<T> >
            ::delete_nodes(node);
      }

      template <typename T>
      inline void destroy_node(expression_node<T>*& node)
      {
         if (0 != node)
         {
            node_collection_destructor<expression_node<T> >
               ::delete_nodes(node);
         }
      }

      template <typename Node>
      struct node_depth_base
      {
         typedef Node* node_ptr_t;
         typedef std::pair<node_ptr_t,bool> nb_pair_t;

         node_depth_base()
         : depth_set(false)
         , depth(0)
         {}

         virtual ~node_depth_base()
         {}

         virtual std::size_t node_depth() const { return 1; }

         std::size_t compute_node_depth(const Node* const& node) const
         {
            if (!depth_set)
            {
               depth = 1 + (node ? node->node_depth() : 0);
               depth_set = true;
            }

            return depth;
         }

         std::size_t compute_node_depth(const nb_pair_t& branch) const
         {
            if (!depth_set)
            {
               depth = 1 + (branch.first ? branch.first->node_depth() : 0);
               depth_set = true;
            }

            return depth;
         }

         template <std::size_t N>
         std::size_t compute_node_depth(const nb_pair_t (&branch)[N]) const
         {
            if (!depth_set)
            {
               depth = 0;

               for (std::size_t i = 0; i < N; ++i)
               {
                  if (branch[i].first)
                  {
                     depth = std::max(depth,branch[i].first->node_depth());
                  }
               }

               depth += 1;
               depth_set = true;
            }

            return depth;
         }

         template <typename BranchType>
         std::size_t max_node_depth(const BranchType& n0, const BranchType& n1) const
         {
            return std::max(compute_node_depth(n0), compute_node_depth(n1));
         }

         template <typename BranchType>
         std::size_t max_node_depth(const BranchType& n0, const BranchType& n1, const BranchType& n2) const
         {
            return std::max(compute_node_depth(n0),
                   std::max(compute_node_depth(n1), compute_node_depth(n2)));
         }

         template <typename BranchType>
         std::size_t max_node_depth(const BranchType& n0, const BranchType& n1,
                                    const BranchType& n2, const BranchType& n3) const
         {
            return std::max(
                     std::max(compute_node_depth(n0), compute_node_depth(n1)),
                     std::max(compute_node_depth(n2), compute_node_depth(n3)));
         }

         template <typename BranchType>
         std::size_t compute_node_depth(const BranchType& n0, const BranchType& n1) const
         {
            if (!depth_set)
            {
               depth = 1 + max_node_depth(n0, n1);
               depth_set = true;
            }

            return depth;
         }

         template <typename BranchType>
         std::size_t compute_node_depth(const BranchType& n0, const BranchType& n1,
                                        const BranchType& n2) const
         {
            if (!depth_set)
            {
               depth = 1 + max_node_depth(n0, n1, n2);
               depth_set = true;
            }

            return depth;
         }

         template <typename BranchType>
         std::size_t compute_node_depth(const BranchType& n0, const BranchType& n1,
                                        const BranchType& n2, const BranchType& n3) const
         {
            if (!depth_set)
            {
               depth = 1 + max_node_depth(n0, n1, n2, n3);
               depth_set = true;
            }

            return depth;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         std::size_t compute_node_depth(const Sequence<node_ptr_t, Allocator>& branch_list) const
         {
            if (!depth_set)
            {
               for (std::size_t i = 0; i < branch_list.size(); ++i)
               {
                  if (branch_list[i])
                  {
                     depth = std::max(depth, compute_node_depth(branch_list[i]));
                  }
               }

               depth_set = true;
            }

            return depth;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         std::size_t compute_node_depth(const Sequence<nb_pair_t,Allocator>& branch_list) const
         {
            if (!depth_set)
            {
               for (std::size_t i = 0; i < branch_list.size(); ++i)
               {
                  if (branch_list[i].first)
                  {
                     depth = std::max(depth, compute_node_depth(branch_list[i].first));
                  }
               }

               depth_set = true;
            }

            return depth;
         }

         mutable bool depth_set;
         mutable std::size_t depth;

         template <typename NodeSequence>
         void collect(node_ptr_t const& node,
                      const bool deletable,
                      NodeSequence& delete_node_list) const
         {
            if ((0 != node) && deletable)
            {
               delete_node_list.push_back(const_cast<node_ptr_t*>(&node));
            }
         }

         template <typename NodeSequence>
         void collect(const nb_pair_t& branch,
                      NodeSequence& delete_node_list) const
         {
            collect(branch.first, branch.second, delete_node_list);
         }

         template <typename NodeSequence>
         void collect(Node*& node,
                      NodeSequence& delete_node_list) const
         {
            collect(node, branch_deletable(node), delete_node_list);
         }

         template <std::size_t N, typename NodeSequence>
         void collect(const nb_pair_t(&branch)[N],
                      NodeSequence& delete_node_list) const
         {
            for (std::size_t i = 0; i < N; ++i)
            {
               collect(branch[i].first, branch[i].second, delete_node_list);
            }
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence,
                   typename NodeSequence>
         void collect(const Sequence<nb_pair_t, Allocator>& branch,
                      NodeSequence& delete_node_list) const
         {
            for (std::size_t i = 0; i < branch.size(); ++i)
            {
               collect(branch[i].first, branch[i].second, delete_node_list);
            }
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence,
                   typename NodeSequence>
         void collect(const Sequence<node_ptr_t, Allocator>& branch_list,
                      NodeSequence& delete_node_list) const
         {
            for (std::size_t i = 0; i < branch_list.size(); ++i)
            {
               collect(branch_list[i], branch_deletable(branch_list[i]), delete_node_list);
            }
         }

         template <typename Boolean,
                   typename AllocatorT,
                   typename AllocatorB,
                   template <typename, typename> class Sequence,
                   typename NodeSequence>
         void collect(const Sequence<node_ptr_t, AllocatorT>& branch_list,
                      const Sequence<Boolean, AllocatorB>& branch_deletable_list,
                      NodeSequence& delete_node_list) const
         {
            for (std::size_t i = 0; i < branch_list.size(); ++i)
            {
               collect(branch_list[i], branch_deletable_list[i], delete_node_list);
            }
         }
      };

      template <typename Type>
      class vector_holder
      {
      private:

         typedef Type value_type;
         typedef value_type* value_ptr;
         typedef const value_ptr const_value_ptr;
         typedef vector_holder<Type> vector_holder_t;

         class vector_holder_base
         {
         public:

            virtual ~vector_holder_base()
            {}

            inline value_ptr operator[](const std::size_t& index) const
            {
               return value_at(index);
            }

            inline std::size_t size() const
            {
               return vector_size();
            }

            inline std::size_t base_size() const
            {
               return vector_base_size();
            }

            inline value_ptr data() const
            {
               return value_at(0);
            }

            virtual inline bool rebaseable() const
            {
               return false;
            }

            virtual void set_ref(value_ptr*)
            {}

            virtual void remove_ref(value_ptr*)
            {}

            virtual vector_view<Type>* rebaseable_instance()
            {
               return reinterpret_cast<vector_view<Type>*>(0);
            }

         protected:

            virtual value_ptr value_at(const std::size_t&) const = 0;
            virtual std::size_t vector_size()              const = 0;
            virtual std::size_t vector_base_size()         const = 0;
         };

         class array_vector_impl exprtk_final : public vector_holder_base
         {
         public:

            array_vector_impl(const Type* vec, const std::size_t& vec_size)
            : vec_(vec)
            , size_(vec_size)
            {}

         protected:

            value_ptr value_at(const std::size_t& index) const exprtk_override
            {
               assert(index < size_);
               return const_cast<const_value_ptr>(vec_ + index);
            }

            std::size_t vector_size() const exprtk_override
            {
               return size_;
            }

            std::size_t vector_base_size() const exprtk_override
            {
               return vector_size();
            }

         private:

            array_vector_impl(const array_vector_impl&) exprtk_delete;
            array_vector_impl& operator=(const array_vector_impl&) exprtk_delete;

            const Type* vec_;
            const std::size_t size_;
         };

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         class sequence_vector_impl exprtk_final : public vector_holder_base
         {
         public:

            typedef Sequence<Type,Allocator> sequence_t;

            explicit sequence_vector_impl(sequence_t& seq)
            : sequence_(seq)
            {}

         protected:

            value_ptr value_at(const std::size_t& index) const exprtk_override
            {
               assert(index < sequence_.size());
               return (&sequence_[index]);
            }

            std::size_t vector_size() const exprtk_override
            {
               return sequence_.size();
            }

            std::size_t vector_base_size() const exprtk_override
            {
               return vector_size();
            }

         private:

            sequence_vector_impl(const sequence_vector_impl&) exprtk_delete;
            sequence_vector_impl& operator=(const sequence_vector_impl&) exprtk_delete;

            sequence_t& sequence_;
         };

         class vector_view_impl exprtk_final : public vector_holder_base
         {
         public:

            typedef exprtk::vector_view<Type> vector_view_t;

            vector_view_impl(vector_view_t& vec_view)
            : vec_view_(vec_view)
            {
               assert(vec_view_.size() > 0);
            }

            void set_ref(value_ptr* ref) exprtk_override
            {
               vec_view_.set_ref(ref);
            }

            void remove_ref(value_ptr* ref) exprtk_override
            {
               vec_view_.remove_ref(ref);
            }

            bool rebaseable() const exprtk_override
            {
               return true;
            }

            vector_view<Type>* rebaseable_instance() exprtk_override
            {
               return &vec_view_;
            }

         protected:

            value_ptr value_at(const std::size_t& index) const exprtk_override
            {
               assert(index < vec_view_.size());
               return (&vec_view_[index]);
            }

            std::size_t vector_size() const exprtk_override
            {
               return vec_view_.size();
            }

            std::size_t vector_base_size() const exprtk_override
            {
               return vec_view_.base_size();
            }

         private:

            vector_view_impl(const vector_view_impl&) exprtk_delete;
            vector_view_impl& operator=(const vector_view_impl&) exprtk_delete;

            vector_view_t& vec_view_;
         };

         class resizable_vector_impl exprtk_final : public vector_holder_base
         {
         public:

            resizable_vector_impl(vector_holder& vec_view_holder,
                                  const Type* vec,
                                  const std::size_t& vec_size)
            : vec_(vec)
            , size_(vec_size)
            , vec_view_holder_(*vec_view_holder.rebaseable_instance())
            {
               assert(vec_view_holder.rebaseable_instance());
               assert(size_ <= vector_base_size());
            }

            virtual ~resizable_vector_impl()
            {}

         protected:

            value_ptr value_at(const std::size_t& index) const exprtk_override
            {
               assert(index < vector_size());
               return const_cast<const_value_ptr>(vec_ + index);
            }

            std::size_t vector_size() const exprtk_override
            {
               return vec_view_holder_.size();
            }

            std::size_t vector_base_size() const exprtk_override
            {
               return vec_view_holder_.base_size();
            }

            bool rebaseable() const exprtk_override
            {
               return true;
            }

            virtual vector_view<Type>* rebaseable_instance() exprtk_override
            {
               return &vec_view_holder_;
            }

         private:

            resizable_vector_impl(const resizable_vector_impl&) exprtk_delete;
            resizable_vector_impl& operator=(const resizable_vector_impl&) exprtk_delete;

            const Type* vec_;
            const std::size_t size_;
            vector_view<Type>& vec_view_holder_;
         };

      public:

         typedef typename details::vec_data_store<Type> vds_t;

         vector_holder(Type* vec, const std::size_t& vec_size)
         : vector_holder_base_(new(buffer)array_vector_impl(vec,vec_size))
         {}

         explicit vector_holder(const vds_t& vds)
         : vector_holder_base_(new(buffer)array_vector_impl(vds.data(),vds.size()))
         {}

         template <typename Allocator>
         explicit vector_holder(std::vector<Type,Allocator>& vec)
         : vector_holder_base_(new(buffer)sequence_vector_impl<Allocator,std::vector>(vec))
         {}

         explicit vector_holder(exprtk::vector_view<Type>& vec)
         : vector_holder_base_(new(buffer)vector_view_impl(vec))
         {}

         explicit vector_holder(vector_holder_t& vec_holder, const vds_t& vds)
         : vector_holder_base_(new(buffer)resizable_vector_impl(vec_holder, vds.data(), vds.size()))
         {}

         inline value_ptr operator[](const std::size_t& index) const
         {
            return (*vector_holder_base_)[index];
         }

         inline std::size_t size() const
         {
            return vector_holder_base_->size();
         }

         inline std::size_t base_size() const
         {
            return vector_holder_base_->base_size();
         }

         inline value_ptr data() const
         {
            return vector_holder_base_->data();
         }

         void set_ref(value_ptr* ref)
         {
            if (rebaseable())
            {
               vector_holder_base_->set_ref(ref);
            }
         }

         void remove_ref(value_ptr* ref)
         {
            if (rebaseable())
            {
               vector_holder_base_->remove_ref(ref);
            }
         }

         bool rebaseable() const
         {
            return vector_holder_base_->rebaseable();
         }

         vector_view<Type>* rebaseable_instance()
         {
            return vector_holder_base_->rebaseable_instance();
         }

      private:

         vector_holder(const vector_holder<Type>&) exprtk_delete;
         vector_holder<Type>& operator=(const vector_holder<Type>&) exprtk_delete;

         mutable vector_holder_base* vector_holder_base_;
         uchar_t buffer[64];
      };

      template <typename T>
      class null_node exprtk_final : public expression_node<T>
      {
      public:

         inline T value() const exprtk_override
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_null;
         }
      };

      template <typename T, std::size_t N>
      inline void construct_branch_pair(std::pair<expression_node<T>*,bool> (&branch)[N],
                                        expression_node<T>* b,
                                        const std::size_t& index)
      {
         if (b && (index < N))
         {
            branch[index] = std::make_pair(b,branch_deletable(b));
         }
      }

      template <typename T>
      inline void construct_branch_pair(std::pair<expression_node<T>*,bool>& branch, expression_node<T>* b)
      {
         if (b)
         {
            branch = std::make_pair(b,branch_deletable(b));
         }
      }

      template <std::size_t N, typename T>
      inline void init_branches(std::pair<expression_node<T>*,bool> (&branch)[N],
                                expression_node<T>* b0,
                                expression_node<T>* b1 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b2 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b3 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b4 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b5 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b6 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b7 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b8 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b9 = reinterpret_cast<expression_node<T>*>(0))
      {
         construct_branch_pair(branch, b0, 0);
         construct_branch_pair(branch, b1, 1);
         construct_branch_pair(branch, b2, 2);
         construct_branch_pair(branch, b3, 3);
         construct_branch_pair(branch, b4, 4);
         construct_branch_pair(branch, b5, 5);
         construct_branch_pair(branch, b6, 6);
         construct_branch_pair(branch, b7, 7);
         construct_branch_pair(branch, b8, 8);
         construct_branch_pair(branch, b9, 9);
      }

      template <typename T>
      class null_eq_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         explicit null_eq_node(expression_ptr branch, const bool equality = true)
         : equality_(equality)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const T v = branch_.first->value();
            const bool result = details::numeric::is_nan(v);

            if (result)
               return equality_ ? T(1) : T(0);
            else
               return equality_ ? T(0) : T(1);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_nulleq;
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         bool equality_;
         branch_t branch_;
      };

      template <typename T>
      class literal_node exprtk_final : public expression_node<T>
      {
      public:

         explicit literal_node(const T& v)
         : value_(v)
         {}

         inline T value() const exprtk_override
         {
            return value_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_constant;
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return reinterpret_cast<expression_node<T>*>(0);
         }

      private:

         literal_node(const literal_node<T>&) exprtk_delete;
         literal_node<T>& operator=(const literal_node<T>&) exprtk_delete;

         const T value_;
      };

      template <typename T>
      struct range_pack;

      template <typename T>
      struct range_data_type;

      template <typename T>
      class range_interface
      {
      public:

         typedef range_pack<T> range_t;

         virtual ~range_interface()
         {}

         virtual range_t& range_ref() = 0;

         virtual const range_t& range_ref() const = 0;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T>
      class string_base_node
      {
      public:

         typedef range_data_type<T> range_data_type_t;

         virtual ~string_base_node()
         {}

         virtual std::string str () const = 0;

         virtual char_cptr   base() const = 0;

         virtual std::size_t size() const = 0;
      };

      template <typename T>
      class string_literal_node exprtk_final
                                : public expression_node <T>
                                , public string_base_node<T>
                                , public range_interface <T>
      {
      public:

         typedef range_pack<T> range_t;

         explicit string_literal_node(const std::string& v)
         : value_(v)
         {
            rp_.n0_c = std::make_pair<bool,std::size_t>(true, 0);
            rp_.n1_c = std::make_pair<bool,std::size_t>(true, v.size());
            rp_.cache.first  = rp_.n0_c.second;
            rp_.cache.second = rp_.n1_c.second;
         }

         inline T value() const exprtk_override
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringconst;
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return reinterpret_cast<expression_node<T>*>(0);
         }

         std::string str() const exprtk_override
         {
            return value_;
         }

         char_cptr base() const exprtk_override
         {
            return value_.data();
         }

         std::size_t size() const exprtk_override
         {
            return value_.size();
         }

         range_t& range_ref() exprtk_override
         {
            return rp_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return rp_;
         }

      private:

         string_literal_node(const string_literal_node<T>&) exprtk_delete;
         string_literal_node<T>& operator=(const string_literal_node<T>&) exprtk_delete;

         const std::string value_;
         range_t rp_;
      };
      #endif

      template <typename T>
      class unary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         unary_node(const operator_type& opr, expression_ptr branch)
         : operation_(opr)
         {
            construct_branch_pair(branch_,branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return numeric::process<T>
                     (operation_,branch_.first->value());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_unary;
         }

         inline operator_type operation()
         {
            return operation_;
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline void release()
         {
            branch_.second = false;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_final
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         operator_type operation_;
         branch_t branch_;
      };

      template <typename T>
      class binary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         binary_node(const operator_type& opr,
                     expression_ptr branch0,
                     expression_ptr branch1)
         : operation_(opr)
         {
            init_branches<2>(branch_, branch0, branch1);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return numeric::process<T>
                   (
                      operation_,
                      branch_[0].first->value(),
                      branch_[1].first->value()
                   );
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_binary;
         }

         inline operator_type operation()
         {
            return operation_;
         }

         inline expression_node<T>* branch(const std::size_t& index = 0) const exprtk_override
         {
            assert(index < 2);
            return branch_[index].first;
         }

         inline bool valid() const exprtk_override
         {
            return
               branch_[0].first && branch_[0].first->valid() &&
               branch_[1].first && branch_[1].first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_final
         {
            return expression_node<T>::ndb_t::template compute_node_depth<2>(branch_);
         }

      private:

         operator_type operation_;
         branch_t branch_[2];
      };

      template <typename T, typename Operation>
      class binary_ext_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         binary_ext_node(expression_ptr branch0, expression_ptr branch1)
         {
            init_branches<2>(branch_, branch0, branch1);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const T arg0 = branch_[0].first->value();
            const T arg1 = branch_[1].first->value();
            return Operation::process(arg0,arg1);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_binary_ext;
         }

         inline operator_type operation()
         {
            return Operation::operation();
         }

         inline expression_node<T>* branch(const std::size_t& index = 0) const exprtk_override
         {
            assert(index < 2);
            return branch_[index].first;
         }

         inline bool valid() const exprtk_override
         {
            return
               branch_[0].first && branch_[0].first->valid() &&
               branch_[1].first && branch_[1].first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::template compute_node_depth<2>(branch_);
         }

      protected:

         branch_t branch_[2];
      };

      template <typename T>
      class trinary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         trinary_node(const operator_type& opr,
                      expression_ptr branch0,
                      expression_ptr branch1,
                      expression_ptr branch2)
         : operation_(opr)
         {
            init_branches<3>(branch_, branch0, branch1, branch2);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const T arg0 = branch_[0].first->value();
            const T arg1 = branch_[1].first->value();
            const T arg2 = branch_[2].first->value();

            switch (operation_)
            {
               case e_inrange : return (arg1 < arg0) ? T(0) : ((arg1 > arg2) ? T(0) : T(1));

               case e_clamp   : return (arg1 < arg0) ? arg0 : (arg1 > arg2 ? arg2 : arg1);

               case e_iclamp  : if ((arg1 <= arg0) || (arg1 >= arg2))
                                   return arg1;
                                else
                                   return ((T(2) * arg1  <= (arg2 + arg0)) ? arg0 : arg2);

               default        : exprtk_debug(("trinary_node::value() - Error: Invalid operation\n"));
                                return std::numeric_limits<T>::quiet_NaN();
            }
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_trinary;
         }

         inline bool valid() const exprtk_override
         {
            return
               branch_[0].first && branch_[0].first->valid() &&
               branch_[1].first && branch_[1].first->valid() &&
               branch_[2].first && branch_[2].first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override exprtk_final
         {
            return expression_node<T>::ndb_t::template compute_node_depth<3>(branch_);
         }

      protected:

         operator_type operation_;
         branch_t branch_[3];
      };

      template <typename T>
      class quaternary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         quaternary_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1,
                         expression_ptr branch2,
                         expression_ptr branch3)
         : operation_(opr)
         {
            init_branches<4>(branch_, branch0, branch1, branch2, branch3);
         }

         inline T value() const exprtk_override
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_quaternary;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override exprtk_final
         {
            return expression_node<T>::ndb_t::template compute_node_depth<4>(branch_);
         }

         inline bool valid() const exprtk_override
         {
            return
               branch_[0].first && branch_[0].first->valid() &&
               branch_[1].first && branch_[1].first->valid() &&
               branch_[2].first && branch_[2].first->valid() &&
               branch_[3].first && branch_[3].first->valid() ;
         }

      protected:

         operator_type operation_;
         branch_t branch_[4];
      };

      template <typename T>
      class conditional_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         conditional_node(expression_ptr condition,
                          expression_ptr consequent,
                          expression_ptr alternative)
         {
            construct_branch_pair(condition_  , condition  );
            construct_branch_pair(consequent_ , consequent );
            construct_branch_pair(alternative_, alternative);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (is_true(condition_))
               return consequent_.first->value();
            else
               return alternative_.first->value();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_conditional;
         }

         inline bool valid() const exprtk_override
         {
            return
               condition_  .first && condition_  .first->valid() &&
               consequent_ .first && consequent_ .first->valid() &&
               alternative_.first && alternative_.first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(condition_   , node_delete_list);
            expression_node<T>::ndb_t::collect(consequent_  , node_delete_list);
            expression_node<T>::ndb_t::collect(alternative_ , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (condition_, consequent_, alternative_);
         }

      private:

         branch_t condition_;
         branch_t consequent_;
         branch_t alternative_;
      };

      template <typename T>
      class cons_conditional_node exprtk_final : public expression_node<T>
      {
      public:

         // Consequent only conditional statement node
         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         cons_conditional_node(expression_ptr condition,
                               expression_ptr consequent)
         {
            construct_branch_pair(condition_ , condition );
            construct_branch_pair(consequent_, consequent);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (is_true(condition_))
               return consequent_.first->value();
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_conditional;
         }

         inline bool valid() const exprtk_override
         {
            return
               condition_ .first && condition_ .first->valid() &&
               consequent_.first && consequent_.first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(condition_  , node_delete_list);
            expression_node<T>::ndb_t::collect(consequent_ , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::
               compute_node_depth(condition_, consequent_);
         }

      private:

         branch_t condition_;
         branch_t consequent_;
      };

      #ifndef exprtk_disable_break_continue
      template <typename T>
      class break_exception
      {
      public:

         explicit break_exception(const T& v)
         : value(v)
         {}

         T value;
      };

      class continue_exception {};

      template <typename T>
      class break_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         explicit break_node(expression_ptr ret = expression_ptr(0))
         {
            construct_branch_pair(return_, ret);
         }

         inline T value() const exprtk_override
         {
            const T result = return_.first ?
                             return_.first->value() :
                             std::numeric_limits<T>::quiet_NaN();

            throw break_exception<T>(result);

            #if !defined(_MSC_VER) && !defined(__NVCOMPILER)
            return std::numeric_limits<T>::quiet_NaN();
            #endif
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_break;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(return_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(return_);
         }

      private:

         branch_t return_;
      };

      template <typename T>
      class continue_node exprtk_final : public expression_node<T>
      {
      public:

         inline T value() const exprtk_override
         {
            throw continue_exception();
            #if !defined(_MSC_VER) && !defined(__NVCOMPILER)
            return std::numeric_limits<T>::quiet_NaN();
            #endif
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_break;
         }
      };
      #endif

      struct loop_runtime_checker
      {
         loop_runtime_checker(loop_runtime_check_ptr loop_runtime_check,
                              loop_runtime_check::loop_types lp_typ = loop_runtime_check::e_invalid)
         : iteration_count_(0)
         , loop_runtime_check_(loop_runtime_check)
         , max_loop_iterations_(loop_runtime_check_->max_loop_iterations)
         , loop_type_(lp_typ)
         {
            assert(loop_runtime_check_);
         }

         inline void reset(const _uint64_t initial_value = 0) const
         {
            iteration_count_ = initial_value;
         }

         inline bool check() const
         {
            assert(loop_runtime_check_);

            if (
                 (++iteration_count_ <= max_loop_iterations_) &&
                 loop_runtime_check_->check()
               )
            {
               return true;
            }

            loop_runtime_check::violation_context ctxt;
            ctxt.loop      = loop_type_;
            ctxt.violation = loop_runtime_check::e_iteration_count;

            loop_runtime_check_->handle_runtime_violation(ctxt);

            return false;
         }

         bool valid() const
         {
            return 0 != loop_runtime_check_;
         }

         mutable _uint64_t iteration_count_;
         mutable loop_runtime_check_ptr loop_runtime_check_;
         const details::_uint64_t& max_loop_iterations_;
         loop_runtime_check::loop_types loop_type_;
      };

      template <typename T>
      class while_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         while_loop_node(expression_ptr condition,
                         expression_ptr loop_body)
         {
            construct_branch_pair(condition_, condition);
            construct_branch_pair(loop_body_, loop_body);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            while (is_true(condition_))
            {
               result = loop_body_.first->value();
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_while;
         }

         inline bool valid() const exprtk_override
         {
            return
               condition_.first && condition_.first->valid() &&
               loop_body_.first && loop_body_.first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(condition_ , node_delete_list);
            expression_node<T>::ndb_t::collect(loop_body_ , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(condition_, loop_body_);
         }

      protected:

         branch_t condition_;
         branch_t loop_body_;
      };

      template <typename T>
      class while_loop_rtc_node exprtk_final
                                : public while_loop_node<T>
                                , public loop_runtime_checker
      {
      public:

         typedef while_loop_node<T>  parent_t;
         typedef expression_node<T>* expression_ptr;

         while_loop_rtc_node(expression_ptr condition,
                             expression_ptr loop_body,
                             loop_runtime_check_ptr loop_rt_chk)
         : parent_t(condition, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_while_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {

            T result = T(0);

            loop_runtime_checker::reset();

            while (is_true(parent_t::condition_) && loop_runtime_checker::check())
            {
               result = parent_t::loop_body_.first->value();
            }

            return result;
         }

         using parent_t::valid;

         bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };

      template <typename T>
      class repeat_until_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         repeat_until_loop_node(expression_ptr condition,
                                expression_ptr loop_body)
         {
            construct_branch_pair(condition_, condition);
            construct_branch_pair(loop_body_, loop_body);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            do
            {
               result = loop_body_.first->value();
            }
            while (is_false(condition_.first));

            return result;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_repeat;
         }

         inline bool valid() const exprtk_override
         {
            return
               condition_.first && condition_.first->valid() &&
               loop_body_.first && loop_body_.first->valid() ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(condition_ , node_delete_list);
            expression_node<T>::ndb_t::collect(loop_body_ , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(condition_, loop_body_);
         }

      protected:

         branch_t condition_;
         branch_t loop_body_;
      };

      template <typename T>
      class repeat_until_loop_rtc_node exprtk_final
                                       : public repeat_until_loop_node<T>
                                       , public loop_runtime_checker
      {
      public:

         typedef repeat_until_loop_node<T> parent_t;
         typedef expression_node<T>*       expression_ptr;

         repeat_until_loop_rtc_node(expression_ptr condition,
                                    expression_ptr loop_body,
                                    loop_runtime_check_ptr loop_rt_chk)
         : parent_t(condition, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_repeat_until_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            loop_runtime_checker::reset(1);

            do
            {
               result = parent_t::loop_body_.first->value();
            }
            while (is_false(parent_t::condition_.first) && loop_runtime_checker::check());

            return result;
         }

         using parent_t::valid;

         inline bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };

      template <typename T>
      class for_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         for_loop_node(expression_ptr initialiser,
                       expression_ptr condition,
                       expression_ptr incrementor,
                       expression_ptr loop_body)
         {
            construct_branch_pair(initialiser_, initialiser);
            construct_branch_pair(condition_  , condition  );
            construct_branch_pair(incrementor_, incrementor);
            construct_branch_pair(loop_body_  , loop_body  );
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            if (initialiser_.first)
               initialiser_.first->value();

            if (incrementor_.first)
            {
               while (is_true(condition_))
               {
                  result = loop_body_.first->value();
                  incrementor_.first->value();
               }
            }
            else
            {
               while (is_true(condition_))
               {
                  result = loop_body_.first->value();
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_for;
         }

         inline bool valid() const exprtk_override
         {
            return condition_.first && loop_body_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_ , node_delete_list);
            expression_node<T>::ndb_t::collect(condition_   , node_delete_list);
            expression_node<T>::ndb_t::collect(incrementor_ , node_delete_list);
            expression_node<T>::ndb_t::collect(loop_body_   , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (initialiser_, condition_, incrementor_, loop_body_);
         }

      protected:

         branch_t initialiser_;
         branch_t condition_  ;
         branch_t incrementor_;
         branch_t loop_body_  ;
      };

      template <typename T>
      class for_loop_rtc_node exprtk_final
                              : public for_loop_node<T>
                              , public loop_runtime_checker
      {
      public:

         typedef for_loop_node<T>    parent_t;
         typedef expression_node<T>* expression_ptr;

         for_loop_rtc_node(expression_ptr initialiser,
                           expression_ptr condition,
                           expression_ptr incrementor,
                           expression_ptr loop_body,
                           loop_runtime_check_ptr loop_rt_chk)
         : parent_t(initialiser, condition, incrementor, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_for_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            loop_runtime_checker::reset();

            if (parent_t::initialiser_.first)
               parent_t::initialiser_.first->value();

            if (parent_t::incrementor_.first)
            {
               while (is_true(parent_t::condition_) && loop_runtime_checker::check())
               {
                  result = parent_t::loop_body_.first->value();
                  parent_t::incrementor_.first->value();
               }
            }
            else
            {
               while (is_true(parent_t::condition_) && loop_runtime_checker::check())
               {
                  result = parent_t::loop_body_.first->value();
               }
            }

            return result;
         }

         using parent_t::valid;

         inline bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };

      #ifndef exprtk_disable_break_continue
      template <typename T>
      class while_loop_bc_node : public while_loop_node<T>
      {
      public:

         typedef while_loop_node<T>  parent_t;
         typedef expression_node<T>* expression_ptr;

         while_loop_bc_node(expression_ptr condition,
                            expression_ptr loop_body)
         : parent_t(condition, loop_body)
         {
            assert(parent_t::valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            while (is_true(parent_t::condition_))
            {
               try
               {
                  result = parent_t::loop_body_.first->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }

            return result;
         }
      };

      template <typename T>
      class while_loop_bc_rtc_node exprtk_final
                                   : public while_loop_bc_node<T>
                                   , public loop_runtime_checker
      {
      public:

         typedef while_loop_bc_node<T> parent_t;
         typedef expression_node<T>*   expression_ptr;

         while_loop_bc_rtc_node(expression_ptr condition,
                                expression_ptr loop_body,
                                loop_runtime_check_ptr loop_rt_chk)
         : parent_t(condition, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_while_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            loop_runtime_checker::reset();

            while (is_true(parent_t::condition_) && loop_runtime_checker::check())
            {
               try
               {
                  result = parent_t::loop_body_.first->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }

            return result;
         }

         using parent_t::valid;

         inline bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };

      template <typename T>
      class repeat_until_loop_bc_node : public repeat_until_loop_node<T>
      {
      public:

         typedef repeat_until_loop_node<T> parent_t;
         typedef expression_node<T>*       expression_ptr;

         repeat_until_loop_bc_node(expression_ptr condition,
                                   expression_ptr loop_body)
         : parent_t(condition, loop_body)
         {
            assert(parent_t::valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            do
            {
               try
               {
                  result = parent_t::loop_body_.first->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }
            while (is_false(parent_t::condition_.first));

            return result;
         }
      };

      template <typename T>
      class repeat_until_loop_bc_rtc_node exprtk_final
                                          : public repeat_until_loop_bc_node<T>
                                          , public loop_runtime_checker
      {
      public:

         typedef repeat_until_loop_bc_node<T> parent_t;
         typedef expression_node<T>*          expression_ptr;

         repeat_until_loop_bc_rtc_node(expression_ptr condition,
                                       expression_ptr loop_body,
                                       loop_runtime_check_ptr loop_rt_chk)
         : parent_t(condition, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_repeat_until_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            loop_runtime_checker::reset();

            do
            {
               try
               {
                  result = parent_t::loop_body_.first->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }
            while (is_false(parent_t::condition_.first) && loop_runtime_checker::check());

            return result;
         }

         using parent_t::valid;

         inline bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };

      template <typename T>
      class for_loop_bc_node : public for_loop_node<T>
      {
      public:

         typedef for_loop_node<T>    parent_t;
         typedef expression_node<T>* expression_ptr;

         for_loop_bc_node(expression_ptr initialiser,
                          expression_ptr condition,
                          expression_ptr incrementor,
                          expression_ptr loop_body)
         : parent_t(initialiser, condition, incrementor, loop_body)
         {
            assert(parent_t::valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            if (parent_t::initialiser_.first)
               parent_t::initialiser_.first->value();

            if (parent_t::incrementor_.first)
            {
               while (is_true(parent_t::condition_))
               {
                  try
                  {
                     result = parent_t::loop_body_.first->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}

                  parent_t::incrementor_.first->value();
               }
            }
            else
            {
               while (is_true(parent_t::condition_))
               {
                  try
                  {
                     result = parent_t::loop_body_.first->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}
               }
            }

            return result;
         }
      };

      template <typename T>
      class for_loop_bc_rtc_node exprtk_final
                                 : public for_loop_bc_node<T>
                                 , public loop_runtime_checker
      {
      public:

         typedef for_loop_bc_node<T> parent_t;
         typedef expression_node<T>* expression_ptr;

         for_loop_bc_rtc_node(expression_ptr initialiser,
                              expression_ptr condition,
                              expression_ptr incrementor,
                              expression_ptr loop_body,
                              loop_runtime_check_ptr loop_rt_chk)
         : parent_t(initialiser, condition, incrementor, loop_body)
         , loop_runtime_checker(loop_rt_chk, loop_runtime_check::e_for_loop)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T result = T(0);

            loop_runtime_checker::reset();

            if (parent_t::initialiser_.first)
               parent_t::initialiser_.first->value();

            if (parent_t::incrementor_.first)
            {
               while (is_true(parent_t::condition_) && loop_runtime_checker::check())
               {
                  try
                  {
                     result = parent_t::loop_body_.first->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}

                  parent_t::incrementor_.first->value();
               }
            }
            else
            {
               while (is_true(parent_t::condition_) && loop_runtime_checker::check())
               {
                  try
                  {
                     result = parent_t::loop_body_.first->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}
               }
            }

            return result;
         }

         using parent_t::valid;

         inline bool valid() const exprtk_override exprtk_final
         {
            return parent_t::valid() &&
                   loop_runtime_checker::valid();
         }
      };
      #endif

      template <typename T>
      class switch_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit switch_node(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            if (1 != (arg_list.size() & 1))
               return;

            arg_list_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i] && arg_list[i]->valid())
               {
                  construct_branch_pair(arg_list_[i], arg_list[i]);
               }
               else
               {
                  arg_list_.clear();
                  return;
               }
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const std::size_t upper_bound = (arg_list_.size() - 1);

            for (std::size_t i = 0; i < upper_bound; i += 2)
            {
               expression_ptr condition  = arg_list_[i    ].first;
               expression_ptr consequent = arg_list_[i + 1].first;

               if (is_true(condition))
               {
                  return consequent->value();
               }
            }

            return arg_list_[upper_bound].first->value();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override exprtk_final
         {
            return expression_node<T>::e_switch;
         }

         inline bool valid() const exprtk_override
         {
            return !arg_list_.empty();
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(arg_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override exprtk_final
         {
            return expression_node<T>::ndb_t::compute_node_depth(arg_list_);
         }

      protected:

         std::vector<branch_t> arg_list_;
      };

      template <typename T, typename Switch_N>
      class switch_n_node exprtk_final : public switch_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit switch_n_node(const Sequence<expression_ptr,Allocator>& arg_list)
         : switch_node<T>(arg_list)
         {}

         inline T value() const exprtk_override
         {
            return Switch_N::process(switch_node<T>::arg_list_);
         }
      };

      template <typename T>
      class multi_switch_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit multi_switch_node(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            if (0 != (arg_list.size() & 1))
               return;

            arg_list_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i] && arg_list[i]->valid())
               {
                  construct_branch_pair(arg_list_[i], arg_list[i]);
               }
               else
               {
                  arg_list_.clear();
                  return;
               }
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const std::size_t upper_bound = (arg_list_.size() - 1);

            T result = T(0);

            for (std::size_t i = 0; i < upper_bound; i += 2)
            {
               expression_ptr condition  = arg_list_[i    ].first;
               expression_ptr consequent = arg_list_[i + 1].first;

               if (is_true(condition))
               {
                  result = consequent->value();
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_mswitch;
         }

         inline bool valid() const exprtk_override
         {
            return !arg_list_.empty() && (0 == (arg_list_.size() % 2));
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(arg_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override exprtk_final
         {
            return expression_node<T>::ndb_t::compute_node_depth(arg_list_);
         }

      private:

         std::vector<branch_t> arg_list_;
      };

      template <typename T>
      class ivariable
      {
      public:

         virtual ~ivariable()
         {}

         virtual T& ref() = 0;
         virtual const T& ref() const = 0;
      };

      template <typename T>
      class variable_node exprtk_final
                          : public expression_node<T>
                          , public ivariable      <T>
      {
      public:

         static T null_value;

         explicit variable_node()
         : value_(&null_value)
         {}

         explicit variable_node(T& v)
         : value_(&v)
         {}

         inline bool operator <(const variable_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const exprtk_override
         {
            return (*value_);
         }

         inline T& ref() exprtk_override
         {
            return (*value_);
         }

         inline const T& ref() const exprtk_override
         {
            return (*value_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_variable;
         }

      private:

         T* value_;
      };

      template <typename T>
      T variable_node<T>::null_value = T(std::numeric_limits<T>::quiet_NaN());

      template <typename T>
      struct range_pack
      {
         typedef expression_node<T>*           expression_node_ptr;
         typedef std::pair<std::size_t,std::size_t> cached_range_t;

         range_pack()
         : n0_e (std::make_pair(false,expression_node_ptr(0)))
         , n1_e (std::make_pair(false,expression_node_ptr(0)))
         , n0_c (std::make_pair(false,0))
         , n1_c (std::make_pair(false,0))
         , cache(std::make_pair(0,0))
         {}

         void clear()
         {
            n0_e  = std::make_pair(false,expression_node_ptr(0));
            n1_e  = std::make_pair(false,expression_node_ptr(0));
            n0_c  = std::make_pair(false,0);
            n1_c  = std::make_pair(false,0);
            cache = std::make_pair(0,0);
         }

         void free()
         {
            if (n0_e.first && n0_e.second)
            {
               n0_e.first = false;

               if (
                    !is_variable_node(n0_e.second) &&
                    !is_string_node  (n0_e.second)
                  )
               {
                  destroy_node(n0_e.second);
               }
            }

            if (n1_e.first && n1_e.second)
            {
               n1_e.first = false;

               if (
                    !is_variable_node(n1_e.second) &&
                    !is_string_node  (n1_e.second)
                  )
               {
                  destroy_node(n1_e.second);
               }
            }
         }

         bool const_range() const
         {
           return ( n0_c.first &&  n1_c.first) &&
                  (!n0_e.first && !n1_e.first);
         }

         bool var_range() const
         {
           return ( n0_e.first &&  n1_e.first) &&
                  (!n0_c.first && !n1_c.first);
         }

         bool operator() (std::size_t& r0, std::size_t& r1,
                          const std::size_t& size = std::numeric_limits<std::size_t>::max()) const
         {
            if (n0_c.first)
               r0 = n0_c.second;
            else if (n0_e.first)
            {
               r0 = static_cast<std::size_t>(details::numeric::to_int64(n0_e.second->value()));
            }
            else
               return false;

            if (n1_c.first)
               r1 = n1_c.second;
            else if (n1_e.first)
            {
               r1 = static_cast<std::size_t>(details::numeric::to_int64(n1_e.second->value()));
            }
            else
               return false;

            if (
                 (std::numeric_limits<std::size_t>::max() != size) &&
                 (std::numeric_limits<std::size_t>::max() == r1  )
               )
            {
               r1 = size;
            }

            cache.first  = r0;
            cache.second = r1;

            #ifndef exprtk_enable_range_runtime_checks
            return (r0 <= r1);
            #else
            return range_runtime_check(r0, r1, size);
            #endif
         }

         inline std::size_t const_size() const
         {
            return (n1_c.second - n0_c.second);
         }

         inline std::size_t cache_size() const
         {
            return (cache.second - cache.first);
         }

         std::pair<bool,expression_node_ptr> n0_e;
         std::pair<bool,expression_node_ptr> n1_e;
         std::pair<bool,std::size_t        > n0_c;
         std::pair<bool,std::size_t        > n1_c;
         mutable cached_range_t             cache;

         #ifdef exprtk_enable_range_runtime_checks
         bool range_runtime_check(const std::size_t r0,
                                  const std::size_t r1,
                                  const std::size_t size) const
         {
            if (r0 > size)
            {
               throw std::runtime_error("range error: (r0 < 0) || (r0 > size)");
               #if !defined(_MSC_VER) && !defined(__NVCOMPILER)
               return false;
               #endif
            }

            if (r1 > size)
            {
               throw std::runtime_error("range error: (r1 < 0) || (r1 > size)");
               #if !defined(_MSC_VER) && !defined(__NVCOMPILER)
               return false;
               #endif
            }

            return (r0 <= r1);
         }
         #endif
      };

      template <typename T>
      class string_base_node;

      template <typename T>
      struct range_data_type
      {
         typedef range_pack<T> range_t;
         typedef string_base_node<T>* strbase_ptr_t;

         range_data_type()
         : range(0)
         , data (0)
         , size (0)
         , type_size(0)
         , str_node (0)
         {}

         range_t*      range;
         void*         data;
         std::size_t   size;
         std::size_t   type_size;
         strbase_ptr_t str_node;
      };

      template <typename T> class vector_node;

      template <typename T>
      class vector_interface
      {
      public:

         typedef vector_node<T>*   vector_node_ptr;
         typedef vec_data_store<T> vds_t;

         virtual ~vector_interface()
         {}

         virtual std::size_t size     () const = 0;

         virtual std::size_t base_size() const = 0;

         virtual vector_node_ptr vec  () const = 0;

         virtual vector_node_ptr vec  ()       = 0;

         virtual       vds_t& vds     ()       = 0;

         virtual const vds_t& vds     () const = 0;

         virtual bool side_effect     () const { return false; }
      };

      template <typename T>
      class vector_node exprtk_final
                        : public expression_node <T>
                        , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vec_data_store<T>   vds_t;

         explicit vector_node(vector_holder_t* vh)
         : vector_holder_(vh)
         , vds_((*vector_holder_).size(),(*vector_holder_)[0])
         {
            vector_holder_->set_ref(&vds_.ref());
         }

         vector_node(const vds_t& vds, vector_holder_t* vh)
         : vector_holder_(vh)
         , vds_(vds)
         {}

        ~vector_node()
         {
            assert(valid());
            vector_holder_->remove_ref(&vds_.ref());
         }

         inline T value() const exprtk_override
         {
            return vds().data()[0];
         }

         vector_node_ptr vec() const exprtk_override
         {
            return const_cast<vector_node_ptr>(this);
         }

         vector_node_ptr vec() exprtk_override
         {
            return this;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vector;
         }

         inline bool valid() const exprtk_override
         {
            return vector_holder_;
         }

         std::size_t size() const exprtk_override
         {
            return vec_holder().size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         inline vector_holder_t& vec_holder() const
         {
            return (*vector_holder_);
         }

      private:

         vector_holder_t* vector_holder_;
         vds_t                      vds_;
      };

      template <typename T>
      class vector_size_node exprtk_final
                        : public expression_node <T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_holder<T>    vector_holder_t;

         explicit vector_size_node(vector_holder_t* vh)
         : vector_holder_(vh)
         {}

        ~vector_size_node()
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            assert(vector_holder_);
            return static_cast<T>(vector_holder_->size());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecsize;
         }

         inline bool valid() const exprtk_override
         {
            return vector_holder_ && vector_holder_->size();
         }

         inline vector_holder_t* vec_holder()
         {
            return vector_holder_;
         }

      private:

         vector_holder_t* vector_holder_;
      };

      template <typename T>
      class vector_elem_node exprtk_final
                             : public expression_node<T>
                             , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         vector_elem_node(expression_ptr vec_node,
                          expression_ptr index,
                          vector_holder_ptr vec_holder)
         : vector_holder_(vec_holder)
         , vector_base_((*vec_holder)[0])
         {
            construct_branch_pair(vector_node_, vec_node);
            construct_branch_pair(index_      , index   );
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecelem;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_        &&
               index_.first          &&
               vector_node_.first    &&
               index_.first->valid() &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
            expression_node<T>::ndb_t::collect(index_      , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (vector_node_, index_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();
            return (vector_base_ + details::numeric::to_uint64(index_.first->value()));
         }

         vector_holder_ptr vector_holder_;
         T* vector_base_;
         branch_t vector_node_;
         branch_t index_;
      };

      template <typename T>
      class vector_celem_node exprtk_final
                              : public expression_node<T>
                              , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         vector_celem_node(expression_ptr vec_node,
                           const std::size_t index,
                           vector_holder_ptr vec_holder)
         : index_(index)
         , vector_holder_(vec_holder)
         , vector_base_((*vec_holder)[0])
         {
            construct_branch_pair(vector_node_, vec_node);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_veccelem;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_     &&
               vector_node_.first &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(vector_node_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();
            return (vector_base_ + index_);
         }

         const std::size_t index_;
         vector_holder_ptr vector_holder_;
         T* vector_base_;
         branch_t vector_node_;
      };

      template <typename T>
      class vector_elem_rtc_node exprtk_final
                                 : public expression_node<T>
                                 , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         vector_elem_rtc_node(expression_ptr vec_node,
                              expression_ptr index,
                              vector_holder_ptr vec_holder,
                              vector_access_runtime_check_ptr vec_rt_chk)
         : vector_holder_(vec_holder)
         , vector_base_((*vec_holder)[0])
         , vec_rt_chk_(vec_rt_chk)
         , max_vector_index_(vector_holder_->size() - 1)
         {
            construct_branch_pair(vector_node_, vec_node);
            construct_branch_pair(index_      , index   );
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecelemrtc;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_        &&
               index_.first          &&
               vector_node_.first    &&
               index_.first->valid() &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
            expression_node<T>::ndb_t::collect(index_,       node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (vector_node_, index_);
         }

      private:

         inline T* access_vector() const
         {
            const _uint64_t index = details::numeric::to_uint64(index_.first->value());
            vector_node_.first->value();

            if (index <= max_vector_index_)
            {
               return (vector_holder_->data() + index);
            }

            assert(vec_rt_chk_);

            vector_access_runtime_check::violation_context context;
            context.base_ptr   = reinterpret_cast<void*>(vector_base_);
            context.end_ptr    = reinterpret_cast<void*>(vector_base_ + vector_holder_->size());
            context.access_ptr = reinterpret_cast<void*>(vector_base_ + index);
            context.type_size  = sizeof(T);

            return vec_rt_chk_->handle_runtime_violation(context) ?
               reinterpret_cast<T*>(context.access_ptr) :
               vector_base_ ;
         }

         vector_holder_ptr vector_holder_;
         T*                vector_base_;
         branch_t          vector_node_;
         branch_t          index_;
         vector_access_runtime_check_ptr vec_rt_chk_;
         const std::size_t max_vector_index_;
      };

      template <typename T>
      class vector_celem_rtc_node exprtk_final
                                 : public expression_node<T>
                                 , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         vector_celem_rtc_node(expression_ptr vec_node,
                               const std::size_t index,
                               vector_holder_ptr vec_holder,
                               vector_access_runtime_check_ptr vec_rt_chk)
         : index_(index)
         , max_vector_index_(vec_holder->size() - 1)
         , vector_holder_(vec_holder)
         , vector_base_((*vec_holder)[0])
         , vec_rt_chk_(vec_rt_chk)
         {
            construct_branch_pair(vector_node_, vec_node);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_veccelemrtc;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_     &&
               vector_node_.first &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(vector_node_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();

            if (index_ <= max_vector_index_)
            {
               return (vector_holder_->data() + index_);
            }

            assert(vec_rt_chk_);

            vector_access_runtime_check::violation_context context;
            context.base_ptr   = reinterpret_cast<void*>(vector_base_);
            context.end_ptr    = reinterpret_cast<void*>(vector_base_ + vector_holder_->size());
            context.access_ptr = reinterpret_cast<void*>(vector_base_ + index_);
            context.type_size  = sizeof(T);

            return vec_rt_chk_->handle_runtime_violation(context) ?
               reinterpret_cast<T*>(context.access_ptr) :
               vector_base_ ;
         }

         const std::size_t index_;
         const std::size_t max_vector_index_;
         vector_holder_ptr vector_holder_;
         T*                vector_base_;
         branch_t          vector_node_;
         vector_access_runtime_check_ptr vec_rt_chk_;
      };

      template <typename T>
      class rebasevector_elem_node exprtk_final
                                   : public expression_node<T>
                                   , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef vec_data_store<T>              vds_t;
         typedef std::pair<expression_ptr,bool> branch_t;

         rebasevector_elem_node(expression_ptr vec_node,
                                expression_ptr index,
                                vector_holder_ptr vec_holder)
         : vector_holder_(vec_holder)
         {
            construct_branch_pair(vector_node_, vec_node);
            construct_branch_pair(index_      , index   );
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_rbvecelem;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_        &&
               index_.first          &&
               vector_node_.first    &&
               index_.first->valid() &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
            expression_node<T>::ndb_t::collect(index_,       node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (vector_node_, index_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();
            return (vector_holder_->data() + details::numeric::to_uint64(index_.first->value()));
         }

         vector_holder_ptr vector_holder_;
         branch_t          vector_node_;
         branch_t          index_;
      };

      template <typename T>
      class rebasevector_celem_node exprtk_final
                                    : public expression_node<T>
                                    , public ivariable      <T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_holder_t*    vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         rebasevector_celem_node(expression_ptr vec_node,
                                 const std::size_t index,
                                 vector_holder_ptr vec_holder)
         : index_(index)
         , vector_holder_(vec_holder)
         {
            construct_branch_pair(vector_node_, vec_node);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            vector_node_.first->value();
            return ref();;
         }

         inline T& ref() exprtk_override
         {
            return *(vector_holder_->data() + index_);
         }

         inline const T& ref() const exprtk_override
         {
            return *(vector_holder_->data() + index_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_rbveccelem;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_     &&
               vector_node_.first &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(vector_node_);
         }

      private:

         const std::size_t index_;
         vector_holder_ptr vector_holder_;
         branch_t          vector_node_;
      };

      template <typename T>
      class rebasevector_elem_rtc_node exprtk_final
                                       : public expression_node<T>
                                       , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         rebasevector_elem_rtc_node(expression_ptr vec_node,
                                    expression_ptr index,
                                    vector_holder_ptr vec_holder,
                                    vector_access_runtime_check_ptr vec_rt_chk)
         : vector_holder_(vec_holder)
         , vec_rt_chk_(vec_rt_chk)
         {
            construct_branch_pair(vector_node_, vec_node);
            construct_branch_pair(index_      , index   );
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_rbvecelemrtc;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_        &&
               index_.first          &&
               vector_node_.first    &&
               index_.first->valid() &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
            expression_node<T>::ndb_t::collect(index_      , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (vector_node_, index_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();
            const _uint64_t index = details::numeric::to_uint64(index_.first->value());

            if (index <= (vector_holder_->size() - 1))
            {
               return (vector_holder_->data() + index);
            }

            assert(vec_rt_chk_);

            vector_access_runtime_check::violation_context context;
            context.base_ptr   = reinterpret_cast<void*>(vector_holder_->data());
            context.end_ptr    = reinterpret_cast<void*>(vector_holder_->data() + vector_holder_->size());
            context.access_ptr = reinterpret_cast<void*>(vector_holder_->data() + index);
            context.type_size  = sizeof(T);

            return vec_rt_chk_->handle_runtime_violation(context) ?
                   reinterpret_cast<T*>(context.access_ptr) :
                   vector_holder_->data() ;
         }

         vector_holder_ptr vector_holder_;
         branch_t          vector_node_;
         branch_t          index_;
         vector_access_runtime_check_ptr vec_rt_chk_;
      };

      template <typename T>
      class rebasevector_celem_rtc_node exprtk_final
                                    : public expression_node<T>
                                    , public ivariable      <T>
      {
      public:

         typedef expression_node<T>*            expression_ptr;
         typedef vector_holder<T>               vector_holder_t;
         typedef vector_holder_t*               vector_holder_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         rebasevector_celem_rtc_node(expression_ptr vec_node,
                                     const std::size_t index,
                                     vector_holder_ptr vec_holder,
                                     vector_access_runtime_check_ptr vec_rt_chk)
         : index_(index)
         , vector_holder_(vec_holder)
         , vector_base_((*vec_holder)[0])
         , vec_rt_chk_(vec_rt_chk)
         {
            construct_branch_pair(vector_node_, vec_node);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return *access_vector();
         }

         inline T& ref() exprtk_override
         {
            return *access_vector();
         }

         inline const T& ref() const exprtk_override
         {
            return *access_vector();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_rbveccelemrtc;
         }

         inline bool valid() const exprtk_override
         {
            return
               vector_holder_     &&
               vector_node_.first &&
               vector_node_.first->valid();
         }

         inline vector_holder_t& vec_holder()
         {
            return (*vector_holder_);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(vector_node_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(vector_node_);
         }

      private:

         inline T* access_vector() const
         {
            vector_node_.first->value();

            if (index_ <= vector_holder_->size() - 1)
            {
               return (vector_holder_->data() + index_);
            }

            assert(vec_rt_chk_);

            vector_access_runtime_check::violation_context context;
            context.base_ptr   = reinterpret_cast<void*>(vector_base_);
            context.end_ptr    = reinterpret_cast<void*>(vector_base_ + vector_holder_->size());
            context.access_ptr = reinterpret_cast<void*>(vector_base_ + index_);
            context.type_size  = sizeof(T);

            return vec_rt_chk_->handle_runtime_violation(context) ?
               reinterpret_cast<T*>(context.access_ptr) :
               vector_base_ ;
         }

         const std::size_t index_;
         vector_holder_ptr vector_holder_;
         T*                vector_base_;
         branch_t          vector_node_;
         vector_access_runtime_check_ptr vec_rt_chk_;
      };

      template <typename T>
      class vector_initialisation_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_initialisation_node(T* vector_base,
                                    const std::size_t& size,
                                    const std::vector<expression_ptr>& initialiser_list,
                                    const bool single_value_initialse)
         : vector_base_(vector_base)
         , initialiser_list_(initialiser_list)
         , size_(size)
         , single_value_initialse_(single_value_initialse)
         , zero_value_initialse_(false)
         , const_nonzero_literal_value_initialse_(false)
         , single_initialiser_value_(T(0))
         {
            if (single_value_initialse_)
            {
               if (initialiser_list_.empty())
                  zero_value_initialse_ = true;
               else if (
                         (initialiser_list_.size() == 1) &&
                         details::is_constant_node(initialiser_list_[0]) &&
                         (T(0) == initialiser_list_[0]->value())
                       )
               {
                  zero_value_initialse_ = true;
               }
               else
               {
                  assert(initialiser_list_.size() == 1);

                  if (details::is_constant_node(initialiser_list_[0]))
                  {
                     const_nonzero_literal_value_initialse_ = true;
                     single_initialiser_value_ = initialiser_list_[0]->value();
                     assert(T(0) != single_initialiser_value_);
                  }
               }
            }
         }

         inline T value() const exprtk_override
         {
            if (single_value_initialse_)
            {
               if (zero_value_initialse_)
               {
                  details::set_zero_value(vector_base_, size_);
               }
               else if (const_nonzero_literal_value_initialse_)
               {
                  for (std::size_t i = 0; i < size_; ++i)
                  {
                     *(vector_base_ + i) = single_initialiser_value_;
                  }
               }
               else
               {
                  for (std::size_t i = 0; i < size_; ++i)
                  {
                     *(vector_base_ + i) = initialiser_list_[0]->value();
                  }
               }
            }
            else
            {
               const std::size_t initialiser_list_size = initialiser_list_.size();

               for (std::size_t i = 0; i < initialiser_list_size; ++i)
               {
                  *(vector_base_ + i) = initialiser_list_[i]->value();
               }

               if (initialiser_list_size < size_)
               {
                  details::set_zero_value(
                     vector_base_ + initialiser_list_size,
                     (size_ - initialiser_list_size));
               }
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_initialisation_node(const vector_initialisation_node<T>&) exprtk_delete;
         vector_initialisation_node<T>& operator=(const vector_initialisation_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         std::vector<expression_ptr> initialiser_list_;
         const std::size_t size_;
         const bool single_value_initialse_;
         bool zero_value_initialse_;
         bool const_nonzero_literal_value_initialse_;
         T single_initialiser_value_;
      };

      template <typename T>
      class vector_init_zero_value_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_zero_value_node(T* vector_base,
                                     const std::size_t& size,
                                     const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {}

         inline T value() const exprtk_override
         {
            details::set_zero_value(vector_base_, size_);
            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_zero_value_node(const vector_init_zero_value_node<T>&) exprtk_delete;
         vector_init_zero_value_node<T>& operator=(const vector_init_zero_value_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
      };

      template <typename T>
      class vector_init_single_constvalue_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_single_constvalue_node(T* vector_base,
                                            const std::size_t& size,
                                            const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            single_initialiser_value_ = initialiser_list_[0]->value();
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            for (std::size_t i = 0; i < size_; ++i)
            {
               *(vector_base_ + i) = single_initialiser_value_;
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                   (initialiser_list_.size() == 1) &&
                   (details::is_constant_node(initialiser_list_[0])) &&
                   (single_initialiser_value_ != T(0));
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_single_constvalue_node(const vector_init_single_constvalue_node<T>&) exprtk_delete;
         vector_init_single_constvalue_node<T>& operator=(const vector_init_single_constvalue_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
         T single_initialiser_value_;
      };

      template <typename T>
      class vector_init_single_value_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_single_value_node(T* vector_base,
                                       const std::size_t& size,
                                       const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            expression_node<T>& node = *initialiser_list_[0];

            for (std::size_t i = 0; i < size_; ++i)
            {
               *(vector_base_ + i) = node.value();
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                   (initialiser_list_.size() == 1) &&
                   !details::is_constant_node(initialiser_list_[0]);
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_single_value_node(const vector_init_single_value_node<T>&) exprtk_delete;
         vector_init_single_value_node<T>& operator=(const vector_init_single_value_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
      };

      template <typename T>
      class vector_init_iota_constconst_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_iota_constconst_node(T* vector_base,
                                          const std::size_t& size,
                                          const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            base_value_      = initialiser_list_[0]->value();
            increment_value_ = initialiser_list_[1]->value();

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T value = base_value_;

            for (std::size_t i = 0; i < size_; ++i, value += increment_value_)
            {
               *(vector_base_ + i) = value;
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                   (initialiser_list_.size() == 2) &&
                   (details::is_constant_node(initialiser_list_[0])) &&
                   (details::is_constant_node(initialiser_list_[1])) ;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_iota_constconst_node(const vector_init_iota_constconst_node<T>&) exprtk_delete;
         vector_init_iota_constconst_node<T>& operator=(const vector_init_iota_constconst_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
         T base_value_;
         T increment_value_;
      };

      template <typename T>
      class vector_init_iota_constnconst_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_iota_constnconst_node(T* vector_base,
                                           const std::size_t& size,
                                           const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            assert(valid());
            base_value_ = initialiser_list_[0]->value();
         }

         inline T value() const exprtk_override
         {
            T value = base_value_;
            expression_node<T>& increment = *initialiser_list_[1];

            for (std::size_t i = 0; i < size_; ++i, value += increment.value())
            {
               *(vector_base_ + i) = value;
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                  (initialiser_list_.size() == 2) &&
                  ( details::is_constant_node(initialiser_list_[0])) &&
                  (!details::is_constant_node(initialiser_list_[1]));
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_iota_constnconst_node(const vector_init_iota_constnconst_node<T>&) exprtk_delete;
         vector_init_iota_constnconst_node<T>& operator=(const vector_init_iota_constnconst_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
         T base_value_;
      };

      template <typename T>
      class vector_init_iota_nconstconst_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_iota_nconstconst_node(T* vector_base,
                                           const std::size_t& size,
                                           const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T value = initialiser_list_[0]->value();
            const T increment = initialiser_list_[1]->value();

            for (std::size_t i = 0; i < size_; ++i, value += increment)
            {
               *(vector_base_ + i) = value;
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                   (initialiser_list_.size() == 2) &&
                   (!details::is_constant_node(initialiser_list_[0])) &&
                   (details::is_constant_node(initialiser_list_[1]));
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_iota_nconstconst_node(const vector_init_iota_nconstconst_node<T>&) exprtk_delete;
         vector_init_iota_nconstconst_node<T>& operator=(const vector_init_iota_nconstconst_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
      };

      template <typename T>
      class vector_init_iota_nconstnconst_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_init_iota_nconstnconst_node(T* vector_base,
                                            const std::size_t& size,
                                            const std::vector<expression_ptr>& initialiser_list)
         : vector_base_(vector_base)
         , size_(size)
         , initialiser_list_(initialiser_list)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T value = initialiser_list_[0]->value();
            expression_node<T>& increment = *initialiser_list_[1];

            for (std::size_t i = 0; i < size_; ++i, value += increment.value())
            {
               *(vector_base_ + i) = value;
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecinit;
         }

         inline bool valid() const exprtk_override
         {
            return vector_base_ &&
                   (initialiser_list_.size() == 2) &&
                   (!details::is_constant_node(initialiser_list_[0])) &&
                   (!details::is_constant_node(initialiser_list_[1]));
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(initialiser_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(initialiser_list_);
         }

      private:

         vector_init_iota_nconstnconst_node(const vector_init_iota_nconstnconst_node<T>&) exprtk_delete;
         vector_init_iota_nconstnconst_node<T>& operator=(const vector_init_iota_nconstnconst_node<T>&) exprtk_delete;

         mutable T* vector_base_;
         const std::size_t size_;
         std::vector<expression_ptr> initialiser_list_;
      };

      template <typename T>
      class swap_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef variable_node<T>*   variable_node_ptr;

         swap_node(variable_node_ptr var0, variable_node_ptr var1)
         : var0_(var0)
         , var1_(var1)
         {}

         inline T value() const exprtk_override
         {
            std::swap(var0_->ref(),var1_->ref());
            return var1_->ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_swap;
         }

      private:

         variable_node_ptr var0_;
         variable_node_ptr var1_;
      };

      template <typename T>
      class swap_generic_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef ivariable<T>*       ivariable_ptr;

         swap_generic_node(expression_ptr var0, expression_ptr var1)
         : binary_node<T>(details::e_swap, var0, var1)
         , var0_(dynamic_cast<ivariable_ptr>(var0))
         , var1_(dynamic_cast<ivariable_ptr>(var1))
         {}

         inline T value() const exprtk_override
         {
            std::swap(var0_->ref(),var1_->ref());
            return var1_->ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_swap;
         }

      private:

         ivariable_ptr var0_;
         ivariable_ptr var1_;
      };

      template <typename T>
      class swap_vecvec_node exprtk_final
                             : public binary_node     <T>
                             , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node    <T>* vector_node_ptr;
         typedef vec_data_store <T>  vds_t;

         using binary_node<T>::branch;

         swap_vecvec_node(expression_ptr branch0,
                          expression_ptr branch1)
         : binary_node<T>(details::e_swap, branch0, branch1)
         , vec0_node_ptr_(0)
         , vec1_node_ptr_(0)
         , initialised_  (false)
         {
            if (is_ivector_node(branch(0)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(0))))
               {
                  vec0_node_ptr_ = vi->vec();
                  vds()          = vi->vds();
               }
            }

            if (is_ivector_node(branch(1)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(1))))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               initialised_ = size() <= base_size();
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            binary_node<T>::branch(0)->value();
            binary_node<T>::branch(1)->value();

            T* vec0 = vec0_node_ptr_->vds().data();
            T* vec1 = vec1_node_ptr_->vds().data();

            assert(size() <= base_size());
            const std::size_t n = size();

            for (std::size_t i = 0; i < n; ++i)
            {
               std::swap(vec0[i],vec1[i]);
            }

            return vec1_node_ptr_->value();
         }

         vector_node_ptr vec() const exprtk_override
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvecswap;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

         std::size_t size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().size(),
               vec1_node_ptr_->vec_holder().size());
         }

         std::size_t base_size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().base_size(),
               vec1_node_ptr_->vec_holder().base_size());
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         bool            initialised_;
         vds_t           vds_;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T>
      class stringvar_node exprtk_final
                           : public expression_node <T>
                           , public string_base_node<T>
                           , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;

         static std::string null_value;

         explicit stringvar_node()
         : value_(&null_value)
         {}

         explicit stringvar_node(std::string& v)
         : value_(&v)
         {
            rp_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            rp_.n1_c = std::make_pair<bool,std::size_t>(true,v.size());
            rp_.cache.first  = rp_.n0_c.second;
            rp_.cache.second = rp_.n1_c.second;
         }

         inline bool operator <(const stringvar_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const exprtk_override
         {
            rp_.n1_c.second  = (*value_).size();
            rp_.cache.second = rp_.n1_c.second;

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return ref();
         }

         char_cptr base() const exprtk_override
         {
            return &(*value_)[0];
         }

         std::size_t size() const exprtk_override
         {
            return ref().size();
         }

         std::string& ref()
         {
            return (*value_);
         }

         const std::string& ref() const
         {
            return (*value_);
         }

         range_t& range_ref() exprtk_override
         {
            return rp_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringvar;
         }

         void rebase(std::string& s)
         {
            value_ = &s;
            rp_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            rp_.n1_c = std::make_pair<bool,std::size_t>(true,value_->size() - 1);
            rp_.cache.first  = rp_.n0_c.second;
            rp_.cache.second = rp_.n1_c.second;
         }

      private:

         std::string* value_;
         mutable range_t rp_;
      };

      template <typename T>
      std::string stringvar_node<T>::null_value = std::string("");

      template <typename T>
      class string_range_node exprtk_final
                              : public expression_node <T>
                              , public string_base_node<T>
                              , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;

         static std::string null_value;

         explicit string_range_node(std::string& v, const range_t& rp)
         : value_(&v)
         , rp_(rp)
         {}

         virtual ~string_range_node()
         {
            rp_.free();
         }

         inline bool operator <(const string_range_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const exprtk_override
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline std::string str() const exprtk_override
         {
            return (*value_);
         }

         char_cptr base() const exprtk_override
         {
            return &(*value_)[0];
         }

         std::size_t size() const exprtk_override
         {
            return ref().size();
         }

         inline range_t range() const
         {
            return rp_;
         }

         inline virtual std::string& ref()
         {
            return (*value_);
         }

         inline virtual const std::string& ref() const
         {
            return (*value_);
         }

         inline range_t& range_ref() exprtk_override
         {
            return rp_;
         }

         inline const range_t& range_ref() const exprtk_override
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringvarrng;
         }

      private:

         std::string* value_;
         range_t      rp_;
      };

      template <typename T>
      std::string string_range_node<T>::null_value = std::string("");

      template <typename T>
      class const_string_range_node exprtk_final
                                    : public expression_node <T>
                                    , public string_base_node<T>
                                    , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;

         explicit const_string_range_node(const std::string& v, const range_t& rp)
         : value_(v)
         , rp_(rp)
         {}

        ~const_string_range_node()
         {
            rp_.free();
         }

         inline T value() const exprtk_override
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return value_;
         }

         char_cptr base() const exprtk_override
         {
            return value_.data();
         }

         std::size_t size() const exprtk_override
         {
            return value_.size();
         }

         range_t range() const
         {
            return rp_;
         }

         range_t& range_ref() exprtk_override
         {
            return rp_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_cstringvarrng;
         }

      private:

         const_string_range_node(const const_string_range_node<T>&) exprtk_delete;
         const_string_range_node<T>& operator=(const const_string_range_node<T>&) exprtk_delete;

         const std::string value_;
         range_t rp_;
      };

      template <typename T>
      class generic_string_range_node exprtk_final
                                      : public expression_node <T>
                                      , public string_base_node<T>
                                      , public range_interface <T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>* str_base_ptr;
         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface<T>   irange_t;
         typedef irange_t*            irange_ptr;
         typedef std::pair<expression_ptr,bool>  branch_t;

         generic_string_range_node(expression_ptr str_branch, const range_t& brange)
         : initialised_(false)
         , str_base_ptr_ (0)
         , str_range_ptr_(0)
         , base_range_(brange)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);
            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            construct_branch_pair(branch_, str_branch);

            if (is_generally_string_node(branch_.first))
            {
               str_base_ptr_ = dynamic_cast<str_base_ptr>(branch_.first);

               if (0 == str_base_ptr_)
                  return;

               str_range_ptr_ = dynamic_cast<irange_ptr>(branch_.first);

               if (0 == str_range_ptr_)
                  return;
            }

            initialised_ = (str_base_ptr_ && str_range_ptr_);
            assert(valid());
         }

        ~generic_string_range_node()
         {
            base_range_.free();
         }

         inline T value() const exprtk_override
         {
            branch_.first->value();

            std::size_t str_r0 = 0;
            std::size_t str_r1 = 0;

            std::size_t r0 = 0;
            std::size_t r1 = 0;

            const range_t& range = str_range_ptr_->range_ref();

            const std::size_t base_str_size = str_base_ptr_->size();

            if (
                  range      (str_r0, str_r1, base_str_size         ) &&
                  base_range_(r0    , r1    , base_str_size - str_r0)
               )
            {
               const std::size_t size = r1 - r0;

               range_.n1_c.second  = size;
               range_.cache.second = range_.n1_c.second;

               value_.assign(str_base_ptr_->base() + str_r0 + r0, size);
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return value_;
         }

         char_cptr base() const exprtk_override
         {
            return &value_[0];
         }

         std::size_t size() const exprtk_override
         {
            return value_.size();
         }

         range_t& range_ref() exprtk_override
         {
            return range_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strgenrange;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         bool                initialised_;
         branch_t            branch_;
         str_base_ptr        str_base_ptr_;
         irange_ptr          str_range_ptr_;
         mutable range_t     base_range_;
         mutable range_t     range_;
         mutable std::string value_;
      };

      template <typename T>
      class string_concat_node exprtk_final
                               : public binary_node     <T>
                               , public string_base_node<T>
                               , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_interface<T>   irange_t;
         typedef irange_t*            irange_ptr;
         typedef range_t*             range_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;

         using binary_node<T>::branch;

         string_concat_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , initialised_(false)
         , str0_base_ptr_ (0)
         , str1_base_ptr_ (0)
         , str0_range_ptr_(0)
         , str1_range_ptr_(0)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(branch(0)))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(branch(0));

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(branch(0));

               if (0 == str0_range_ptr_)
                  return;
            }

            if (is_generally_string_node(branch(1)))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(branch(1));

               if (0 == str1_base_ptr_)
                  return;

               str1_range_ptr_ = dynamic_cast<irange_ptr>(branch(1));

               if (0 == str1_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            std::size_t str0_r0 = 0;
            std::size_t str0_r1 = 0;

            std::size_t str1_r0 = 0;
            std::size_t str1_r1 = 0;

            const range_t& range0 = str0_range_ptr_->range_ref();
            const range_t& range1 = str1_range_ptr_->range_ref();

            if (
                  range0(str0_r0, str0_r1, str0_base_ptr_->size()) &&
                  range1(str1_r0, str1_r1, str1_base_ptr_->size())
               )
            {
               const std::size_t size0 = (str0_r1 - str0_r0);
               const std::size_t size1 = (str1_r1 - str1_r0);

               value_.assign(str0_base_ptr_->base() + str0_r0, size0);
               value_.append(str1_base_ptr_->base() + str1_r0, size1);

               range_.n1_c.second  = value_.size();
               range_.cache.second = range_.n1_c.second;
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return value_;
         }

         char_cptr base() const exprtk_override
         {
            return &value_[0];
         }

         std::size_t size() const exprtk_override
         {
            return value_.size();
         }

         range_t& range_ref() exprtk_override
         {
            return range_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strconcat;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

      private:

         bool                initialised_;
         str_base_ptr        str0_base_ptr_;
         str_base_ptr        str1_base_ptr_;
         irange_ptr          str0_range_ptr_;
         irange_ptr          str1_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;
      };

      template <typename T>
      class swap_string_node exprtk_final
                             : public binary_node     <T>
                             , public string_base_node<T>
                             , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface<T>   irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>* str_base_ptr;

         using binary_node<T>::branch;

         swap_string_node(expression_ptr branch0, expression_ptr branch1)
         : binary_node<T>(details::e_swap, branch0, branch1)
         , initialised_(false)
         , str0_node_ptr_(0)
         , str1_node_ptr_(0)
         {
            if (is_string_node(branch(0)))
            {
               str0_node_ptr_ = static_cast<strvar_node_ptr>(branch(0));
            }

            if (is_string_node(branch(1)))
            {
               str1_node_ptr_ = static_cast<strvar_node_ptr>(branch(1));
            }

            initialised_ = (str0_node_ptr_ && str1_node_ptr_);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            std::swap(str0_node_ptr_->ref(), str1_node_ptr_->ref());

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return str0_node_ptr_->str();
         }

         char_cptr base() const exprtk_override
         {
           return str0_node_ptr_->base();
         }

         std::size_t size() const exprtk_override
         {
            return str0_node_ptr_->size();
         }

         range_t& range_ref() exprtk_override
         {
            return str0_node_ptr_->range_ref();
         }

         const range_t& range_ref() const exprtk_override
         {
            return str0_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strswap;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

      private:

         bool initialised_;
         strvar_node_ptr str0_node_ptr_;
         strvar_node_ptr str1_node_ptr_;
      };

      template <typename T>
      class swap_genstrings_node exprtk_final : public binary_node<T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface<T>   irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;

         using binary_node<T>::branch;

         swap_genstrings_node(expression_ptr branch0,
                              expression_ptr branch1)
         : binary_node<T>(details::e_default, branch0, branch1)
         , str0_base_ptr_ (0)
         , str1_base_ptr_ (0)
         , str0_range_ptr_(0)
         , str1_range_ptr_(0)
         , initialised_(false)
         {
            if (is_generally_string_node(branch(0)))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(branch(0));

               if (0 == str0_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(0));

               if (0 == range)
                  return;

               str0_range_ptr_ = &(range->range_ref());
            }

            if (is_generally_string_node(branch(1)))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(branch(1));

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(1));

               if (0 == range)
                  return;

               str1_range_ptr_ = &(range->range_ref());
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            std::size_t str0_r0 = 0;
            std::size_t str0_r1 = 0;

            std::size_t str1_r0 = 0;
            std::size_t str1_r1 = 0;

            const range_t& range0 = (*str0_range_ptr_);
            const range_t& range1 = (*str1_range_ptr_);

            if (
                  range0(str0_r0, str0_r1, str0_base_ptr_->size()) &&
                  range1(str1_r0, str1_r1, str1_base_ptr_->size())
               )
            {
               const std::size_t size0    = range0.cache_size();
               const std::size_t size1    = range1.cache_size();
               const std::size_t max_size = std::min(size0,size1);

               char_ptr s0 = const_cast<char_ptr>(str0_base_ptr_->base() + str0_r0);
               char_ptr s1 = const_cast<char_ptr>(str1_base_ptr_->base() + str1_r0);

               loop_unroll::details lud(max_size);
               char_cptr upper_bound = s0 + lud.upper_bound;

               while (s0 < upper_bound)
               {
                  #define exprtk_loop(N)   \
                  std::swap(s0[N], s1[N]); \

                  exprtk_loop( 0) exprtk_loop( 1)
                  exprtk_loop( 2) exprtk_loop( 3)
                  #ifndef exprtk_disable_superscalar_unroll
                  exprtk_loop( 4) exprtk_loop( 5)
                  exprtk_loop( 6) exprtk_loop( 7)
                  exprtk_loop( 8) exprtk_loop( 9)
                  exprtk_loop(10) exprtk_loop(11)
                  exprtk_loop(12) exprtk_loop(13)
                  exprtk_loop(14) exprtk_loop(15)
                  #endif

                  s0 += lud.batch_size;
                  s1 += lud.batch_size;
               }

               int i = 0;

               switch (lud.remainder)
               {
                  #define case_stmt(N)                       \
                  case N : { std::swap(s0[i], s1[i]); ++i; } \
                  exprtk_fallthrough                         \

                  #ifndef exprtk_disable_superscalar_unroll
                  case_stmt(15) case_stmt(14)
                  case_stmt(13) case_stmt(12)
                  case_stmt(11) case_stmt(10)
                  case_stmt( 9) case_stmt( 8)
                  case_stmt( 7) case_stmt( 6)
                  case_stmt( 5) case_stmt( 4)
                  #endif
                  case_stmt( 3) case_stmt( 2)
                  case_stmt( 1)
                  default: break;
               }

               #undef exprtk_loop
               #undef case_stmt
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strswap;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

      private:

         swap_genstrings_node(const swap_genstrings_node<T>&) exprtk_delete;
         swap_genstrings_node<T>& operator=(const swap_genstrings_node<T>&) exprtk_delete;

         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         range_ptr    str0_range_ptr_;
         range_ptr    str1_range_ptr_;
         bool         initialised_;
      };

      template <typename T>
      class stringvar_size_node exprtk_final : public expression_node<T>
      {
      public:

         static const std::string null_value;

         explicit stringvar_size_node()
         : value_(&null_value)
         {}

         explicit stringvar_size_node(std::string& v)
         : value_(&v)
         {}

         inline T value() const exprtk_override
         {
            return T((*value_).size());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringvarsize;
         }

      private:

         const std::string* value_;
      };

      template <typename T>
      const std::string stringvar_size_node<T>::null_value = std::string("");

      template <typename T>
      class string_size_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;
         typedef std::pair<expression_ptr,bool>  branch_t;

         explicit string_size_node(expression_ptr branch)
         : str_base_ptr_(0)
         {
            construct_branch_pair(branch_, branch);

            if (is_generally_string_node(branch_.first))
            {
               str_base_ptr_ = dynamic_cast<str_base_ptr>(branch_.first);
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch_.first->value();
            return T(str_base_ptr_->size());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringsize;
         }

         inline bool valid() const exprtk_override
         {
            return str_base_ptr_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         branch_t     branch_;
         str_base_ptr str_base_ptr_;
      };

      struct asn_assignment
      {
         static inline void execute(std::string& s, char_cptr data, const std::size_t size)
         { s.assign(data,size); }
      };

      struct asn_addassignment
      {
         static inline void execute(std::string& s, char_cptr data, const std::size_t size)
         { s.append(data,size); }
      };

      template <typename T, typename AssignmentProcess = asn_assignment>
      class assignment_string_node exprtk_final
                                   : public binary_node     <T>
                                   , public string_base_node<T>
                                   , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface <T>  irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>* str_base_ptr;

         using binary_node<T>::branch;

         assignment_string_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , initialised_(false)
         , str0_base_ptr_ (0)
         , str1_base_ptr_ (0)
         , str0_node_ptr_ (0)
         , str1_range_ptr_(0)
         {
            if (is_string_node(branch(0)))
            {
               str0_node_ptr_ = static_cast<strvar_node_ptr>(branch(0));
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(branch(0));
            }

            if (is_generally_string_node(branch(1)))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(branch(1));

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(1));

               if (0 == range)
                  return;

               str1_range_ptr_ = &(range->range_ref());
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_node_ptr_  &&
                           str1_range_ptr_ ;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(1)->value();

            std::size_t r0 = 0;
            std::size_t r1 = 0;

            const range_t& range = (*str1_range_ptr_);

            if (range(r0, r1, str1_base_ptr_->size()))
            {
               AssignmentProcess::execute(
                  str0_node_ptr_->ref(),
                  str1_base_ptr_->base() + r0, (r1 - r0));

               branch(0)->value();
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return str0_node_ptr_->str();
         }

         char_cptr base() const exprtk_override
         {
           return str0_node_ptr_->base();
         }

         std::size_t size() const exprtk_override
         {
            return str0_node_ptr_->size();
         }

         range_t& range_ref() exprtk_override
         {
            return str0_node_ptr_->range_ref();
         }

         const range_t& range_ref() const exprtk_override
         {
            return str0_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strass;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

      private:

         bool            initialised_;
         str_base_ptr    str0_base_ptr_;
         str_base_ptr    str1_base_ptr_;
         strvar_node_ptr str0_node_ptr_;
         range_ptr       str1_range_ptr_;
      };

      template <typename T, typename AssignmentProcess = asn_assignment>
      class assignment_string_range_node exprtk_final
                                         : public binary_node     <T>
                                         , public string_base_node<T>
                                         , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*              range_ptr;
         typedef range_interface  <T>  irange_t;
         typedef irange_t*             irange_ptr;
         typedef expression_node  <T>* expression_ptr;
         typedef stringvar_node   <T>* strvar_node_ptr;
         typedef string_range_node<T>* str_rng_node_ptr;
         typedef string_base_node <T>* str_base_ptr;

         using binary_node<T>::branch;

         assignment_string_range_node(const operator_type& opr,
                                      expression_ptr branch0,
                                      expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , initialised_(false)
         , str0_base_ptr_    (0)
         , str1_base_ptr_    (0)
         , str0_rng_node_ptr_(0)
         , str0_range_ptr_   (0)
         , str1_range_ptr_   (0)
         {
            if (is_string_range_node(branch(0)))
            {
               str0_rng_node_ptr_ = static_cast<str_rng_node_ptr>(branch(0));
               str0_base_ptr_     = dynamic_cast<str_base_ptr>(branch(0));
               irange_ptr range   = dynamic_cast<irange_ptr>(branch(0));

               if (0 == range)
                  return;

               str0_range_ptr_ = &(range->range_ref());
            }

            if (is_generally_string_node(branch(1)))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(branch(1));

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(1));

               if (0 == range)
                  return;

               str1_range_ptr_ = &(range->range_ref());
            }

            initialised_ = str0_base_ptr_     &&
                           str1_base_ptr_     &&
                           str0_rng_node_ptr_ &&
                           str0_range_ptr_    &&
                           str1_range_ptr_    ;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            std::size_t s0_r0 = 0;
            std::size_t s0_r1 = 0;

            std::size_t s1_r0 = 0;
            std::size_t s1_r1 = 0;

            const range_t& range0 = (*str0_range_ptr_);
            const range_t& range1 = (*str1_range_ptr_);

            if (
                  range0(s0_r0, s0_r1, str0_base_ptr_->size()) &&
                  range1(s1_r0, s1_r1, str1_base_ptr_->size())
               )
            {
               const std::size_t size = std::min((s0_r1 - s0_r0), (s1_r1 - s1_r0));

               std::copy(
                  str1_base_ptr_->base() + s1_r0,
                  str1_base_ptr_->base() + s1_r0 + size,
                  const_cast<char_ptr>(base() + s0_r0));
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return str0_base_ptr_->str();
         }

         char_cptr base() const exprtk_override
         {
            return str0_base_ptr_->base();
         }

         std::size_t size() const exprtk_override
         {
            return str0_base_ptr_->size();
         }

         range_t& range_ref() exprtk_override
         {
            return str0_rng_node_ptr_->range_ref();
         }

         const range_t& range_ref() const exprtk_override
         {
            return str0_rng_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strass;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_ && binary_node<T>::valid();
         }

      private:

         bool             initialised_;
         str_base_ptr     str0_base_ptr_;
         str_base_ptr     str1_base_ptr_;
         str_rng_node_ptr str0_rng_node_ptr_;
         range_ptr        str0_range_ptr_;
         range_ptr        str1_range_ptr_;
      };

      template <typename T>
      class conditional_string_node exprtk_final
                                    : public trinary_node    <T>
                                    , public string_base_node<T>
                                    , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface <T>  irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;

         conditional_string_node(expression_ptr condition,
                                 expression_ptr consequent,
                                 expression_ptr alternative)
         : trinary_node<T>(details::e_default, consequent, alternative, condition)
         , initialised_(false)
         , str0_base_ptr_ (0)
         , str1_base_ptr_ (0)
         , str0_range_ptr_(0)
         , str1_range_ptr_(0)
         , condition_  (condition  )
         , consequent_ (consequent )
         , alternative_(alternative)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(trinary_node<T>::branch_[0].first))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(trinary_node<T>::branch_[0].first);

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(trinary_node<T>::branch_[0].first);

               if (0 == str0_range_ptr_)
                  return;
            }

            if (is_generally_string_node(trinary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(trinary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               str1_range_ptr_ = dynamic_cast<irange_ptr>(trinary_node<T>::branch_[1].first);

               if (0 == str1_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            if (is_true(condition_))
            {
               consequent_->value();

               const range_t& range = str0_range_ptr_->range_ref();

               if (range(r0, r1, str0_base_ptr_->size()))
               {
                  const std::size_t size = (r1 - r0);

                  value_.assign(str0_base_ptr_->base() + r0, size);

                  range_.n1_c.second  = value_.size();
                  range_.cache.second = range_.n1_c.second;

                  return T(1);
               }
            }
            else
            {
               alternative_->value();

               const range_t& range = str1_range_ptr_->range_ref();

               if (range(r0, r1, str1_base_ptr_->size()))
               {
                  const std::size_t size = (r1 - r0);

                  value_.assign(str1_base_ptr_->base() + r0, size);

                  range_.n1_c.second  = value_.size();
                  range_.cache.second = range_.n1_c.second;

                  return T(0);
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return value_;
         }

         char_cptr base() const exprtk_override
         {
            return &value_[0];
         }

         std::size_t size() const exprtk_override
         {
            return value_.size();
         }

         range_t& range_ref() exprtk_override
         {
            return range_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strcondition;
         }

         inline bool valid() const exprtk_override
         {
            return
               initialised_                         &&
               condition_  && condition_  ->valid() &&
               consequent_ && consequent_ ->valid() &&
               alternative_&& alternative_->valid() ;
         }

      private:

         bool initialised_;
         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         irange_ptr   str0_range_ptr_;
         irange_ptr   str1_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;

         expression_ptr condition_;
         expression_ptr consequent_;
         expression_ptr alternative_;
      };

      template <typename T>
      class cons_conditional_str_node exprtk_final
                                      : public binary_node     <T>
                                      , public string_base_node<T>
                                      , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface <T>  irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;

         using binary_node<T>::branch;

         cons_conditional_str_node(expression_ptr condition,
                                   expression_ptr consequent)
         : binary_node<T>(details::e_default, consequent, condition)
         , initialised_(false)
         , str0_base_ptr_ (0)
         , str0_range_ptr_(0)
         , condition_ (condition )
         , consequent_(consequent)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(branch(0)))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(branch(0));

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(branch(0));

               if (0 == str0_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_ && str0_range_ptr_ ;
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (is_true(condition_))
            {
               consequent_->value();

               const range_t& range = str0_range_ptr_->range_ref();

               std::size_t r0 = 0;
               std::size_t r1 = 0;

               if (range(r0, r1, str0_base_ptr_->size()))
               {
                  const std::size_t size = (r1 - r0);

                  value_.assign(str0_base_ptr_->base() + r0, size);

                  range_.n1_c.second  = value_.size();
                  range_.cache.second = range_.n1_c.second;

                  return T(1);
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         char_cptr base() const
         {
            return &value_[0];
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strccondition;
         }

         inline bool valid() const exprtk_override
         {
            return
               initialised_                         &&
               condition_  && condition_  ->valid() &&
               consequent_ && consequent_ ->valid() ;
         }

      private:

         bool initialised_;
         str_base_ptr str0_base_ptr_;
         irange_ptr   str0_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;

         expression_ptr condition_;
         expression_ptr consequent_;
      };

      template <typename T, typename VarArgFunction>
      class str_vararg_node exprtk_final
                            : public expression_node <T>
                            , public string_base_node<T>
                            , public range_interface <T>
      {
      public:

         typedef typename range_interface<T>::range_t range_t;
         typedef range_t*             range_ptr;
         typedef range_interface <T>  irange_t;
         typedef irange_t*            irange_ptr;
         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit str_vararg_node(const Sequence<expression_ptr,Allocator>& arg_list)
         : initialised_(false)
         , str_base_ptr_ (0)
         , str_range_ptr_(0)
         {
            construct_branch_pair(final_node_, const_cast<expression_ptr>(arg_list.back()));

            if (0 == final_node_.first)
               return;
            else if (!is_generally_string_node(final_node_.first))
               return;

            str_base_ptr_ = dynamic_cast<str_base_ptr>(final_node_.first);

            if (0 == str_base_ptr_)
               return;

            str_range_ptr_ = dynamic_cast<irange_ptr>(final_node_.first);

            if (0 == str_range_ptr_)
               return;

            if (arg_list.size() > 1)
            {
               const std::size_t arg_list_size = arg_list.size() - 1;

               arg_list_.resize(arg_list_size);

               for (std::size_t i = 0; i < arg_list_size; ++i)
               {
                  if (arg_list[i] && arg_list[i]->valid())
                  {
                     construct_branch_pair(arg_list_[i], arg_list[i]);
                  }
                  else
                  {
                     arg_list_.clear();
                     return;
                  }
               }

               initialised_ = true;
            }

            initialised_ &= str_base_ptr_ && str_range_ptr_;
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (!arg_list_.empty())
            {
               VarArgFunction::process(arg_list_);
            }

            final_node_.first->value();

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const exprtk_override
         {
            return str_base_ptr_->str();
         }

         char_cptr base() const exprtk_override
         {
            return str_base_ptr_->base();
         }

         std::size_t size() const exprtk_override
         {
            return str_base_ptr_->size();
         }

         range_t& range_ref() exprtk_override
         {
            return str_range_ptr_->range_ref();
         }

         const range_t& range_ref() const exprtk_override
         {
            return str_range_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_stringvararg;
         }

         inline bool valid() const exprtk_override
         {
            return
               initialised_ &&
               final_node_.first && final_node_.first->valid();
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(final_node_ , node_delete_list);
            expression_node<T>::ndb_t::collect(arg_list_   , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return std::max(
               expression_node<T>::ndb_t::compute_node_depth(final_node_),
               expression_node<T>::ndb_t::compute_node_depth(arg_list_  ));
         }

      private:

         bool                  initialised_;
         branch_t              final_node_;
         str_base_ptr          str_base_ptr_;
         irange_ptr            str_range_ptr_;
         std::vector<branch_t> arg_list_;
      };
      #endif

      template <typename T>
      class assert_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef string_base_node<T>* str_base_ptr;
         typedef assert_check::assert_context assert_context_t;

         assert_node(expression_ptr   assert_condition_node,
                     expression_ptr   assert_message_node,
                     assert_check_ptr assert_check,
                     assert_context_t context)
         : assert_message_str_base_(0)
         , assert_check_(assert_check)
         , context_(context)
         {
            construct_branch_pair(assert_condition_node_, assert_condition_node);
            construct_branch_pair(assert_message_node_  , assert_message_node  );

            #ifndef exprtk_disable_string_capabilities
            if (
                  assert_message_node_.first &&
                  details::is_generally_string_node(assert_message_node_.first)
               )
            {
               assert_message_str_base_ = dynamic_cast<str_base_ptr>(assert_message_node_.first);
            }
            #endif

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (details::is_true(assert_condition_node_.first->value()))
            {
               return T(1);
            }

            #ifndef exprtk_disable_string_capabilities
            if (assert_message_node_.first)
            {
               assert_message_node_.first->value();
               assert(assert_message_str_base_);
               context_.message = assert_message_str_base_->str();
            }
            #endif

            assert_check_->handle_assert(context_);
            return T(0);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_assert;
         }

         inline bool valid() const exprtk_override
         {
            return (
                     assert_check_ &&
                     assert_condition_node_.first &&
                     assert_condition_node_.first->valid()
                   ) &&
                   (
                     (0 == assert_message_node_.first) ||
                     (
                       assert_message_node_.first &&
                       assert_message_str_base_   &&
                       assert_message_node_.first->valid() &&
                       details::is_generally_string_node(assert_message_node_.first)
                     )
                   );
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(assert_condition_node_, node_delete_list);
            expression_node<T>::ndb_t::collect(assert_message_node_  , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (assert_condition_node_, assert_message_node_);
         }

      private:

         branch_t         assert_condition_node_;
         branch_t         assert_message_node_;
         str_base_ptr     assert_message_str_base_;
         assert_check_ptr assert_check_;
         mutable assert_context_t context_;
      };

      template <typename T, std::size_t N>
      inline T axn(const T a, const T x)
      {
         // a*x^n
         return a * exprtk::details::numeric::fast_exp<T,N>::result(x);
      }

      template <typename T, std::size_t N>
      inline T axnb(const T a, const T x, const T b)
      {
         // a*x^n+b
         return a * exprtk::details::numeric::fast_exp<T,N>::result(x) + b;
      }

      template <typename T>
      struct sf_base
      {
         typedef typename details::functor_t<T>::Type Type;
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t quaternary_functor_t;
         typedef typename functor_t::tfunc_t trinary_functor_t;
         typedef typename functor_t::bfunc_t binary_functor_t;
         typedef typename functor_t::ufunc_t unary_functor_t;
      };

      #define define_sfop3(NN, OP0, OP1)                 \
      template <typename T>                              \
      struct sf##NN##_op : public sf_base<T>             \
      {                                                  \
         typedef typename sf_base<T>::Type const Type;   \
         static inline T process(Type x, Type y, Type z) \
         {                                               \
            return (OP0);                                \
         }                                               \
         static inline std::string id()                  \
         {                                               \
            return (OP1);                                \
         }                                               \
      };                                                 \

      define_sfop3(00,(x + y) / z       ,"(t+t)/t")
      define_sfop3(01,(x + y) * z       ,"(t+t)*t")
      define_sfop3(02,(x + y) - z       ,"(t+t)-t")
      define_sfop3(03,(x + y) + z       ,"(t+t)+t")
      define_sfop3(04,(x - y) + z       ,"(t-t)+t")
      define_sfop3(05,(x - y) / z       ,"(t-t)/t")
      define_sfop3(06,(x - y) * z       ,"(t-t)*t")
      define_sfop3(07,(x * y) + z       ,"(t*t)+t")
      define_sfop3(08,(x * y) - z       ,"(t*t)-t")
      define_sfop3(09,(x * y) / z       ,"(t*t)/t")
      define_sfop3(10,(x * y) * z       ,"(t*t)*t")
      define_sfop3(11,(x / y) + z       ,"(t/t)+t")
      define_sfop3(12,(x / y) - z       ,"(t/t)-t")
      define_sfop3(13,(x / y) / z       ,"(t/t)/t")
      define_sfop3(14,(x / y) * z       ,"(t/t)*t")
      define_sfop3(15,x / (y + z)       ,"t/(t+t)")
      define_sfop3(16,x / (y - z)       ,"t/(t-t)")
      define_sfop3(17,x / (y * z)       ,"t/(t*t)")
      define_sfop3(18,x / (y / z)       ,"t/(t/t)")
      define_sfop3(19,x * (y + z)       ,"t*(t+t)")
      define_sfop3(20,x * (y - z)       ,"t*(t-t)")
      define_sfop3(21,x * (y * z)       ,"t*(t*t)")
      define_sfop3(22,x * (y / z)       ,"t*(t/t)")
      define_sfop3(23,x - (y + z)       ,"t-(t+t)")
      define_sfop3(24,x - (y - z)       ,"t-(t-t)")
      define_sfop3(25,x - (y / z)       ,"t-(t/t)")
      define_sfop3(26,x - (y * z)       ,"t-(t*t)")
      define_sfop3(27,x + (y * z)       ,"t+(t*t)")
      define_sfop3(28,x + (y / z)       ,"t+(t/t)")
      define_sfop3(29,x + (y + z)       ,"t+(t+t)")
      define_sfop3(30,x + (y - z)       ,"t+(t-t)")
      define_sfop3(31,(axnb<T,2>(x,y,z)),"       ")
      define_sfop3(32,(axnb<T,3>(x,y,z)),"       ")
      define_sfop3(33,(axnb<T,4>(x,y,z)),"       ")
      define_sfop3(34,(axnb<T,5>(x,y,z)),"       ")
      define_sfop3(35,(axnb<T,6>(x,y,z)),"       ")
      define_sfop3(36,(axnb<T,7>(x,y,z)),"       ")
      define_sfop3(37,(axnb<T,8>(x,y,z)),"       ")
      define_sfop3(38,(axnb<T,9>(x,y,z)),"       ")
      define_sfop3(39,x * numeric::log(y)   + z,"")
      define_sfop3(40,x * numeric::log(y)   - z,"")
      define_sfop3(41,x * numeric::log10(y) + z,"")
      define_sfop3(42,x * numeric::log10(y) - z,"")
      define_sfop3(43,x * numeric::sin(y) + z  ,"")
      define_sfop3(44,x * numeric::sin(y) - z  ,"")
      define_sfop3(45,x * numeric::cos(y) + z  ,"")
      define_sfop3(46,x * numeric::cos(y) - z  ,"")
      define_sfop3(47,details::is_true(x) ? y : z,"")

      #define define_sfop4(NN, OP0, OP1)                         \
      template <typename T>                                      \
      struct sf##NN##_op : public sf_base<T>                     \
      {                                                          \
         typedef typename sf_base<T>::Type const Type;           \
         static inline T process(Type x, Type y, Type z, Type w) \
         {                                                       \
            return (OP0);                                        \
         }                                                       \
         static inline std::string id()                          \
         {                                                       \
            return (OP1);                                        \
         }                                                       \
      };                                                         \

      define_sfop4(48,(x + ((y + z) / w)),"t+((t+t)/t)")
      define_sfop4(49,(x + ((y + z) * w)),"t+((t+t)*t)")
      define_sfop4(50,(x + ((y - z) / w)),"t+((t-t)/t)")
      define_sfop4(51,(x + ((y - z) * w)),"t+((t-t)*t)")
      define_sfop4(52,(x + ((y * z) / w)),"t+((t*t)/t)")
      define_sfop4(53,(x + ((y * z) * w)),"t+((t*t)*t)")
      define_sfop4(54,(x + ((y / z) + w)),"t+((t/t)+t)")
      define_sfop4(55,(x + ((y / z) / w)),"t+((t/t)/t)")
      define_sfop4(56,(x + ((y / z) * w)),"t+((t/t)*t)")
      define_sfop4(57,(x - ((y + z) / w)),"t-((t+t)/t)")
      define_sfop4(58,(x - ((y + z) * w)),"t-((t+t)*t)")
      define_sfop4(59,(x - ((y - z) / w)),"t-((t-t)/t)")
      define_sfop4(60,(x - ((y - z) * w)),"t-((t-t)*t)")
      define_sfop4(61,(x - ((y * z) / w)),"t-((t*t)/t)")
      define_sfop4(62,(x - ((y * z) * w)),"t-((t*t)*t)")
      define_sfop4(63,(x - ((y / z) / w)),"t-((t/t)/t)")
      define_sfop4(64,(x - ((y / z) * w)),"t-((t/t)*t)")
      define_sfop4(65,(((x + y) * z) - w),"((t+t)*t)-t")
      define_sfop4(66,(((x - y) * z) - w),"((t-t)*t)-t")
      define_sfop4(67,(((x * y) * z) - w),"((t*t)*t)-t")
      define_sfop4(68,(((x / y) * z) - w),"((t/t)*t)-t")
      define_sfop4(69,(((x + y) / z) - w),"((t+t)/t)-t")
      define_sfop4(70,(((x - y) / z) - w),"((t-t)/t)-t")
      define_sfop4(71,(((x * y) / z) - w),"((t*t)/t)-t")
      define_sfop4(72,(((x / y) / z) - w),"((t/t)/t)-t")
      define_sfop4(73,((x * y) + (z * w)),"(t*t)+(t*t)")
      define_sfop4(74,((x * y) - (z * w)),"(t*t)-(t*t)")
      define_sfop4(75,((x * y) + (z / w)),"(t*t)+(t/t)")
      define_sfop4(76,((x * y) - (z / w)),"(t*t)-(t/t)")
      define_sfop4(77,((x / y) + (z / w)),"(t/t)+(t/t)")
      define_sfop4(78,((x / y) - (z / w)),"(t/t)-(t/t)")
      define_sfop4(79,((x / y) - (z * w)),"(t/t)-(t*t)")
      define_sfop4(80,(x / (y + (z * w))),"t/(t+(t*t))")
      define_sfop4(81,(x / (y - (z * w))),"t/(t-(t*t))")
      define_sfop4(82,(x * (y + (z * w))),"t*(t+(t*t))")
      define_sfop4(83,(x * (y - (z * w))),"t*(t-(t*t))")

      define_sfop4(84,(axn<T,2>(x,y) + axn<T,2>(z,w)),"")
      define_sfop4(85,(axn<T,3>(x,y) + axn<T,3>(z,w)),"")
      define_sfop4(86,(axn<T,4>(x,y) + axn<T,4>(z,w)),"")
      define_sfop4(87,(axn<T,5>(x,y) + axn<T,5>(z,w)),"")
      define_sfop4(88,(axn<T,6>(x,y) + axn<T,6>(z,w)),"")
      define_sfop4(89,(axn<T,7>(x,y) + axn<T,7>(z,w)),"")
      define_sfop4(90,(axn<T,8>(x,y) + axn<T,8>(z,w)),"")
      define_sfop4(91,(axn<T,9>(x,y) + axn<T,9>(z,w)),"")
      define_sfop4(92,((details::is_true(x) && details::is_true(y)) ? z : w),"")
      define_sfop4(93,((details::is_true(x) || details::is_true(y)) ? z : w),"")
      define_sfop4(94,((x <  y) ? z : w),"")
      define_sfop4(95,((x <= y) ? z : w),"")
      define_sfop4(96,((x >  y) ? z : w),"")
      define_sfop4(97,((x >= y) ? z : w),"")
      define_sfop4(98,(details::is_true(numeric::equal(x,y)) ? z : w),"")
      define_sfop4(99,(x * numeric::sin(y) + z * numeric::cos(w)),"")

      define_sfop4(ext00,((x + y) - (z * w)),"(t+t)-(t*t)")
      define_sfop4(ext01,((x + y) - (z / w)),"(t+t)-(t/t)")
      define_sfop4(ext02,((x + y) + (z * w)),"(t+t)+(t*t)")
      define_sfop4(ext03,((x + y) + (z / w)),"(t+t)+(t/t)")
      define_sfop4(ext04,((x - y) + (z * w)),"(t-t)+(t*t)")
      define_sfop4(ext05,((x - y) + (z / w)),"(t-t)+(t/t)")
      define_sfop4(ext06,((x - y) - (z * w)),"(t-t)-(t*t)")
      define_sfop4(ext07,((x - y) - (z / w)),"(t-t)-(t/t)")
      define_sfop4(ext08,((x + y) - (z - w)),"(t+t)-(t-t)")
      define_sfop4(ext09,((x + y) + (z - w)),"(t+t)+(t-t)")
      define_sfop4(ext10,((x + y) + (z + w)),"(t+t)+(t+t)")
      define_sfop4(ext11,((x + y) * (z - w)),"(t+t)*(t-t)")
      define_sfop4(ext12,((x + y) / (z - w)),"(t+t)/(t-t)")
      define_sfop4(ext13,((x - y) - (z + w)),"(t-t)-(t+t)")
      define_sfop4(ext14,((x - y) + (z + w)),"(t-t)+(t+t)")
      define_sfop4(ext15,((x - y) * (z + w)),"(t-t)*(t+t)")
      define_sfop4(ext16,((x - y) / (z + w)),"(t-t)/(t+t)")
      define_sfop4(ext17,((x * y) - (z + w)),"(t*t)-(t+t)")
      define_sfop4(ext18,((x / y) - (z + w)),"(t/t)-(t+t)")
      define_sfop4(ext19,((x * y) + (z + w)),"(t*t)+(t+t)")
      define_sfop4(ext20,((x / y) + (z + w)),"(t/t)+(t+t)")
      define_sfop4(ext21,((x * y) + (z - w)),"(t*t)+(t-t)")
      define_sfop4(ext22,((x / y) + (z - w)),"(t/t)+(t-t)")
      define_sfop4(ext23,((x * y) - (z - w)),"(t*t)-(t-t)")
      define_sfop4(ext24,((x / y) - (z - w)),"(t/t)-(t-t)")
      define_sfop4(ext25,((x + y) * (z * w)),"(t+t)*(t*t)")
      define_sfop4(ext26,((x + y) * (z / w)),"(t+t)*(t/t)")
      define_sfop4(ext27,((x + y) / (z * w)),"(t+t)/(t*t)")
      define_sfop4(ext28,((x + y) / (z / w)),"(t+t)/(t/t)")
      define_sfop4(ext29,((x - y) / (z * w)),"(t-t)/(t*t)")
      define_sfop4(ext30,((x - y) / (z / w)),"(t-t)/(t/t)")
      define_sfop4(ext31,((x - y) * (z * w)),"(t-t)*(t*t)")
      define_sfop4(ext32,((x - y) * (z / w)),"(t-t)*(t/t)")
      define_sfop4(ext33,((x * y) * (z + w)),"(t*t)*(t+t)")
      define_sfop4(ext34,((x / y) * (z + w)),"(t/t)*(t+t)")
      define_sfop4(ext35,((x * y) / (z + w)),"(t*t)/(t+t)")
      define_sfop4(ext36,((x / y) / (z + w)),"(t/t)/(t+t)")
      define_sfop4(ext37,((x * y) / (z - w)),"(t*t)/(t-t)")
      define_sfop4(ext38,((x / y) / (z - w)),"(t/t)/(t-t)")
      define_sfop4(ext39,((x * y) * (z - w)),"(t*t)*(t-t)")
      define_sfop4(ext40,((x * y) / (z * w)),"(t*t)/(t*t)")
      define_sfop4(ext41,((x / y) * (z / w)),"(t/t)*(t/t)")
      define_sfop4(ext42,((x / y) * (z - w)),"(t/t)*(t-t)")
      define_sfop4(ext43,((x * y) * (z * w)),"(t*t)*(t*t)")
      define_sfop4(ext44,(x + (y * (z / w))),"t+(t*(t/t))")
      define_sfop4(ext45,(x - (y * (z / w))),"t-(t*(t/t))")
      define_sfop4(ext46,(x + (y / (z * w))),"t+(t/(t*t))")
      define_sfop4(ext47,(x - (y / (z * w))),"t-(t/(t*t))")
      define_sfop4(ext48,(((x - y) - z) * w),"((t-t)-t)*t")
      define_sfop4(ext49,(((x - y) - z) / w),"((t-t)-t)/t")
      define_sfop4(ext50,(((x - y) + z) * w),"((t-t)+t)*t")
      define_sfop4(ext51,(((x - y) + z) / w),"((t-t)+t)/t")
      define_sfop4(ext52,((x + (y - z)) * w),"(t+(t-t))*t")
      define_sfop4(ext53,((x + (y - z)) / w),"(t+(t-t))/t")
      define_sfop4(ext54,((x + y) / (z + w)),"(t+t)/(t+t)")
      define_sfop4(ext55,((x - y) / (z - w)),"(t-t)/(t-t)")
      define_sfop4(ext56,((x + y) * (z + w)),"(t+t)*(t+t)")
      define_sfop4(ext57,((x - y) * (z - w)),"(t-t)*(t-t)")
      define_sfop4(ext58,((x - y) + (z - w)),"(t-t)+(t-t)")
      define_sfop4(ext59,((x - y) - (z - w)),"(t-t)-(t-t)")
      define_sfop4(ext60,((x / y) + (z * w)),"(t/t)+(t*t)")
      define_sfop4(ext61,(((x * y) * z) / w),"((t*t)*t)/t")

      #undef define_sfop3
      #undef define_sfop4

      template <typename T, typename SpecialFunction>
      class sf3_node exprtk_final : public trinary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf3_node(const operator_type& opr,
                  expression_ptr branch0,
                  expression_ptr branch1,
                  expression_ptr branch2)
         : trinary_node<T>(opr, branch0, branch1, branch2)
         {}

         inline T value() const exprtk_override
         {
            const T x = trinary_node<T>::branch_[0].first->value();
            const T y = trinary_node<T>::branch_[1].first->value();
            const T z = trinary_node<T>::branch_[2].first->value();

            return SpecialFunction::process(x, y, z);
         }
      };

      template <typename T, typename SpecialFunction>
      class sf4_node exprtk_final : public quaternary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf4_node(const operator_type& opr,
                  expression_ptr branch0,
                  expression_ptr branch1,
                  expression_ptr branch2,
                  expression_ptr branch3)
         : quaternary_node<T>(opr, branch0, branch1, branch2, branch3)
         {}

         inline T value() const exprtk_override
         {
            const T x = quaternary_node<T>::branch_[0].first->value();
            const T y = quaternary_node<T>::branch_[1].first->value();
            const T z = quaternary_node<T>::branch_[2].first->value();
            const T w = quaternary_node<T>::branch_[3].first->value();

            return SpecialFunction::process(x, y, z, w);
         }
      };

      template <typename T, typename SpecialFunction>
      class sf3_var_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf3_var_node(const T& v0, const T& v1, const T& v2)
         : v0_(v0)
         , v1_(v1)
         , v2_(v2)
         {}

         inline T value() const exprtk_override
         {
            return SpecialFunction::process(v0_, v1_, v2_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_trinary;
         }

      private:

         sf3_var_node(const sf3_var_node<T,SpecialFunction>&) exprtk_delete;
         sf3_var_node<T,SpecialFunction>& operator=(const sf3_var_node<T,SpecialFunction>&) exprtk_delete;

         const T& v0_;
         const T& v1_;
         const T& v2_;
      };

      template <typename T, typename SpecialFunction>
      class sf4_var_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf4_var_node(const T& v0, const T& v1, const T& v2, const T& v3)
         : v0_(v0)
         , v1_(v1)
         , v2_(v2)
         , v3_(v3)
         {}

         inline T value() const exprtk_override
         {
            return SpecialFunction::process(v0_, v1_, v2_, v3_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_trinary;
         }

      private:

         sf4_var_node(const sf4_var_node<T,SpecialFunction>&) exprtk_delete;
         sf4_var_node<T,SpecialFunction>& operator=(const sf4_var_node<T,SpecialFunction>&) exprtk_delete;

         const T& v0_;
         const T& v1_;
         const T& v2_;
         const T& v3_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit vararg_node(const Sequence<expression_ptr,Allocator>& arg_list)
         : initialised_(false)
         {
            arg_list_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i] && arg_list[i]->valid())
               {
                  construct_branch_pair(arg_list_[i],arg_list[i]);
               }
               else
               {
                  arg_list_.clear();
                  return;
               }
            }

            initialised_ = (arg_list_.size() == arg_list.size());
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return VarArgFunction::process(arg_list_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vararg;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(arg_list_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(arg_list_);
         }

         std::size_t size() const
         {
            return arg_list_.size();
         }

         expression_ptr operator[](const std::size_t& index) const
         {
            return arg_list_[index].first;
         }

      private:

         std::vector<branch_t> arg_list_;
         bool initialised_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_varnode exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         explicit vararg_varnode(const Sequence<expression_ptr,Allocator>& arg_list)
         : initialised_(false)
         {
            arg_list_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i] && arg_list[i]->valid() && is_variable_node(arg_list[i]))
               {
                  variable_node<T>* var_node_ptr = static_cast<variable_node<T>*>(arg_list[i]);
                  arg_list_[i] = (&var_node_ptr->ref());
               }
               else
               {
                  arg_list_.clear();
                  return;
               }
            }

            initialised_ = (arg_list.size() == arg_list_.size());
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return VarArgFunction::process(arg_list_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vararg;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

      private:

         std::vector<const T*> arg_list_;
         bool initialised_;
      };

      template <typename T, typename VecFunction>
      class vectorize_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         explicit vectorize_node(const expression_ptr v)
         : ivec_ptr_(0)
         {
            construct_branch_pair(v_, v);

            if (is_ivector_node(v_.first))
            {
               ivec_ptr_ = dynamic_cast<vector_interface<T>*>(v_.first);
            }
         }

         inline T value() const exprtk_override
         {
            v_.first->value();
            return VecFunction::process(ivec_ptr_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecfunc;
         }

         inline bool valid() const exprtk_override
         {
            return ivec_ptr_ && v_.first && v_.first->valid();
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(v_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(v_);
         }

      private:

         vector_interface<T>* ivec_ptr_;
         branch_t                    v_;
      };

      template <typename T>
      class assignment_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , var_node_ptr_(0)
         {
            if (is_variable_node(branch(0)))
            {
               var_node_ptr_ = static_cast<variable_node<T>*>(branch(0));
            }
         }

         inline T value() const exprtk_override
         {
            T& result = var_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return var_node_ptr_ && binary_node<T>::valid();
         }

      private:

         variable_node<T>* var_node_ptr_;
      };

      template <typename T>
      class assignment_vec_elem_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_vec_elem_node(const operator_type& opr,
                                  expression_ptr branch0,
                                  expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_elem_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_elem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& result = vec_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return vec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         vector_elem_node<T>* vec_node_ptr_;
      };

      template <typename T>
      class assignment_vec_elem_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_vec_elem_rtc_node(const operator_type& opr,
                                      expression_ptr branch0,
                                      expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_elem_rtc_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_elem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& result = vec_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return vec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         vector_elem_rtc_node<T>* vec_node_ptr_;
      };

      template <typename T>
      class assignment_rebasevec_elem_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using expression_node<T>::branch;

         assignment_rebasevec_elem_node(const operator_type& opr,
                                        expression_ptr branch0,
                                        expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_elem_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_elem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& result = rbvec_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_elem_node<T>* rbvec_node_ptr_;
      };

      template <typename T>
      class assignment_rebasevec_elem_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using expression_node<T>::branch;

         assignment_rebasevec_elem_rtc_node(const operator_type& opr,
                                            expression_ptr branch0,
                                            expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_elem_rtc_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_elem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& result = rbvec_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_elem_rtc_node<T>* rbvec_node_ptr_;
      };

      template <typename T>
      class assignment_rebasevec_celem_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_rebasevec_celem_node(const operator_type& opr,
                                         expression_ptr branch0,
                                         expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_celem_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_celem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& result = rbvec_node_ptr_->ref();
               result = branch(1)->value();

            return result;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_celem_node<T>* rbvec_node_ptr_;
      };

      template <typename T>
      class assignment_vec_node exprtk_final
                                : public binary_node     <T>
                                , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vec_data_store<T>   vds_t;

         using binary_node<T>::branch;

         assignment_vec_node(const operator_type& opr,
                             expression_ptr branch0,
                             expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_node<T>*>(branch(0));
               vds()         = vec_node_ptr_->vds();
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const T v = branch(1)->value();

            T* vec = vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec + lud.upper_bound;

            while (vec < upper_bound)
            {
               #define exprtk_loop(N) \
               vec[N] = v;            \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec += lud.batch_size;
            }

            switch (lud.remainder)
            {
               #define case_stmt(N) \
               case N : *vec++ = v; \
               exprtk_fallthrough   \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15) case_stmt(14)
               case_stmt(13) case_stmt(12)
               case_stmt(11) case_stmt(10)
               case_stmt( 9) case_stmt( 8)
               case_stmt( 7) case_stmt( 6)
               case_stmt( 5) case_stmt( 4)
               #endif
               case_stmt( 3) case_stmt( 2)
               case 1 : *vec++ = v;
            }

            #undef exprtk_loop
            #undef case_stmt

            return vec_node_ptr_->value();
         }

         vector_node_ptr vec() const exprtk_override
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvalass;
         }

         inline bool valid() const exprtk_override
         {
            return
               vec_node_ptr_ &&
               (vds().size() <= vec_node_ptr_->vec_holder().base_size()) &&
               binary_node<T>::valid();
         }

         std::size_t size() const exprtk_override
         {
            return vec_node_ptr_->vec_holder().size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec_node_ptr_->vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         vds_t           vds_;
      };

      template <typename T>
      class assignment_vecvec_node exprtk_final
                                   : public binary_node     <T>
                                   , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vec_data_store<T>   vds_t;

         using binary_node<T>::branch;

         assignment_vecvec_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec0_node_ptr_(0)
         , vec1_node_ptr_(0)
         , initialised_(false)
         , src_is_ivec_(false)
         {
            if (is_vector_node(branch(0)))
            {
               vec0_node_ptr_ = static_cast<vector_node<T>*>(branch(0));
               vds()          = vec0_node_ptr_->vds();
            }

            if (is_vector_node(branch(1)))
            {
               vec1_node_ptr_ = static_cast<vector_node<T>*>(branch(1));
               vds_t::match_sizes(vds(),vec1_node_ptr_->vds());
            }
            else if (is_ivector_node(branch(1)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(1))))
               {
                  vec1_node_ptr_ = vi->vec();

                  if (!vi->side_effect())
                  {
                     vi->vds()    = vds();
                     src_is_ivec_ = true;
                  }
                  else
                     vds_t::match_sizes(vds(),vi->vds());
               }
            }

            initialised_ =
               vec0_node_ptr_               &&
               vec1_node_ptr_               &&
               (size() <= base_size())      &&
               (vds_.size() <= base_size()) &&
               binary_node<T>::valid();

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(1)->value();

            if (src_is_ivec_)
               return vec0_node_ptr_->value();

            T* vec0 = vec0_node_ptr_->vds().data();
            T* vec1 = vec1_node_ptr_->vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec0 + lud.upper_bound;

            while (vec0 < upper_bound)
            {
               #define exprtk_loop(N) \
               vec0[N] = vec1[N];     \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
            }

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through) \
               case N : *vec0++ = *vec1++;       \
               fall_through                      \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return vec0_node_ptr_->value();
         }

         vector_node_ptr vec() exprtk_override
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec() const exprtk_override
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvecass;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

         std::size_t size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().size(),
               vec1_node_ptr_->vec_holder().size());
         }

         std::size_t base_size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().base_size(),
               vec1_node_ptr_->vec_holder().base_size());
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         bool            initialised_;
         bool            src_is_ivec_;
         vds_t           vds_;
      };

      template <typename T, typename Operation>
      class assignment_op_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_op_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , var_node_ptr_(0)
         {
            if (is_variable_node(branch(0)))
            {
               var_node_ptr_ = static_cast<variable_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = var_node_ptr_->ref();
            v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return var_node_ptr_ && binary_node<T>::valid();
         }

      private:

         variable_node<T>* var_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_elem_op_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_vec_elem_op_node(const operator_type& opr,
                                     expression_ptr branch0,
                                     expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_elem_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_elem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = vec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return vec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         vector_elem_node<T>* vec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_elem_op_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_vec_elem_op_rtc_node(const operator_type& opr,
                                         expression_ptr branch0,
                                         expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_elem_rtc_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_elem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = vec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return vec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         vector_elem_rtc_node<T>* vec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_celem_op_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_vec_celem_op_rtc_node(const operator_type& opr,
                                          expression_ptr branch0,
                                          expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_celem_rtc_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_celem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = vec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return vec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         vector_celem_rtc_node<T>* vec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_rebasevec_elem_op_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_rebasevec_elem_op_node(const operator_type& opr,
                                           expression_ptr branch0,
                                           expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_elem_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_elem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = rbvec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_elem_node<T>* rbvec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_rebasevec_celem_op_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_rebasevec_celem_op_node(const operator_type& opr,
                                            expression_ptr branch0,
                                            expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_celem_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_celem_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = rbvec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_celem_node<T>* rbvec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_rebasevec_elem_op_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_rebasevec_elem_op_rtc_node(const operator_type& opr,
                                               expression_ptr branch0,
                                               expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_elem_rtc_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_elem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = rbvec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_elem_rtc_node<T>* rbvec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_rebasevec_celem_op_rtc_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         assignment_rebasevec_celem_op_rtc_node(const operator_type& opr,
                                                expression_ptr branch0,
                                                expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , rbvec_node_ptr_(0)
         {
            if (is_rebasevector_celem_rtc_node(branch(0)))
            {
               rbvec_node_ptr_ = static_cast<rebasevector_celem_rtc_node<T>*>(branch(0));
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            T& v = rbvec_node_ptr_->ref();
               v = Operation::process(v,branch(1)->value());

            return v;
         }

         inline bool valid() const exprtk_override
         {
            return rbvec_node_ptr_ && binary_node<T>::valid();
         }

      private:

         rebasevector_celem_rtc_node<T>* rbvec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_op_node exprtk_final
                                   : public binary_node     <T>
                                   , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vec_data_store<T>   vds_t;

         using binary_node<T>::branch;

         assignment_vec_op_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec_node_ptr_(0)
         {
            if (is_vector_node(branch(0)))
            {
               vec_node_ptr_ = static_cast<vector_node<T>*>(branch(0));
               vds()         = vec_node_ptr_->vds();
            }

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            const T v = branch(1)->value();

            T* vec = vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec + lud.upper_bound;

            while (vec < upper_bound)
            {
               #define exprtk_loop(N)       \
               Operation::assign(vec[N],v); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec += lud.batch_size;
            }

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through)     \
               case N : Operation::assign(*vec++,v); \
               fall_through                          \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return vec_node_ptr_->value();
         }

         vector_node_ptr vec() const exprtk_override
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecopvalass;
         }

         inline bool valid() const exprtk_override
         {
            return
               vec_node_ptr_           &&
               (size() <= base_size()) &&
               binary_node<T>::valid() ;
         }

         std::size_t size() const exprtk_override
         {
            return vec_node_ptr_->vec_holder().size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec_node_ptr_->vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

         bool side_effect() const exprtk_override
         {
            return true;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         vds_t           vds_;
      };

      template <typename T, typename Operation>
      class assignment_vecvec_op_node exprtk_final
                                      : public binary_node     <T>
                                      , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vec_data_store<T>   vds_t;

         using binary_node<T>::branch;

         assignment_vecvec_op_node(const operator_type& opr,
                                   expression_ptr branch0,
                                   expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec0_node_ptr_(0)
         , vec1_node_ptr_(0)
         , initialised_(false)
         {
            if (is_vector_node(branch(0)))
            {
               vec0_node_ptr_ = static_cast<vector_node<T>*>(branch(0));
               vds()          = vec0_node_ptr_->vds();
            }

            if (is_vector_node(branch(1)))
            {
               vec1_node_ptr_ = static_cast<vector_node<T>*>(branch(1));
               vec1_node_ptr_->vds() = vds();
            }
            else if (is_ivector_node(branch(1)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(1))))
               {
                  vec1_node_ptr_ = vi->vec();
                  vec1_node_ptr_->vds() = vi->vds();
               }
               else
                  vds_t::match_sizes(vds(),vec1_node_ptr_->vds());
            }

            initialised_ =
               vec0_node_ptr_          &&
               vec1_node_ptr_          &&
               (size() <= base_size()) &&
               binary_node<T>::valid();

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

                  T* vec0 = vec0_node_ptr_->vds().data();
            const T* vec1 = vec1_node_ptr_->vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec0 + lud.upper_bound;

            while (vec0 < upper_bound)
            {
               #define exprtk_loop(N)                          \
               vec0[N] = Operation::process(vec0[N], vec1[N]); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through)                                 \
               case N : { vec0[i] = Operation::process(vec0[i], vec1[i]); ++i; } \
               fall_through                                                      \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return vec0_node_ptr_->value();
         }

         vector_node_ptr vec() const exprtk_override
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecopvecass;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

         std::size_t size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().size(),
               vec1_node_ptr_->vec_holder().size());
         }

         std::size_t base_size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().base_size(),
               vec1_node_ptr_->vec_holder().base_size());
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

         bool side_effect() const exprtk_override
         {
            return true;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         bool            initialised_;
         vds_t           vds_;
      };

      template <typename T>
      struct memory_context_t
      {
         typedef vector_node<T>*  vector_node_ptr;
         typedef vector_holder<T> vector_holder_t;
         typedef vector_holder_t* vector_holder_ptr;

         memory_context_t()
         : temp_(0)
         , temp_vec_node_(0)
         {}

         void clear()
         {
            delete temp_vec_node_;
            delete temp_;
         }

         vector_holder_ptr temp_;
         vector_node_ptr   temp_vec_node_;
      };

      template <typename T>
      inline memory_context_t<T> make_memory_context(vector_holder<T>& vec_holder,
                                                     vec_data_store<T>& vds)
      {
         memory_context_t<T> result_ctxt;
         result_ctxt.temp_  = (vec_holder.rebaseable()) ?
                              new vector_holder<T>(vec_holder,vds) :
                              new vector_holder<T>(vds) ;
         result_ctxt.temp_vec_node_ = new vector_node  <T>(vds,result_ctxt.temp_);
         return result_ctxt;
      }

      template <typename T>
      inline memory_context_t<T> make_memory_context(vector_holder<T>& vec_holder0,
                                                     vector_holder<T>& vec_holder1,
                                                     vec_data_store<T>& vds)
      {
         memory_context_t<T> result_ctxt;

         if (!vec_holder0.rebaseable() && !vec_holder1.rebaseable())
            result_ctxt.temp_ = new vector_holder<T>(vds);
         else if (vec_holder0.rebaseable() && !vec_holder1.rebaseable())
            result_ctxt.temp_ = new vector_holder<T>(vec_holder0,vds);
         else if (!vec_holder0.rebaseable() && vec_holder1.rebaseable())
            result_ctxt.temp_ = new vector_holder<T>(vec_holder1,vds);
         else
         {
            result_ctxt.temp_ = (vec_holder0.base_size() >= vec_holder1.base_size()) ?
                                new vector_holder<T>(vec_holder0, vds) :
                                new vector_holder<T>(vec_holder1, vds) ;
         }

         result_ctxt.temp_vec_node_ = new vector_node <T>(vds,result_ctxt.temp_);
         return result_ctxt;
      }

      template <typename T, typename Operation>
      class vec_binop_vecvec_node exprtk_final
                                  : public binary_node     <T>
                                  , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_holder_t*    vector_holder_ptr;
         typedef vec_data_store<T>   vds_t;
         typedef memory_context_t<T> memory_context;

         using binary_node<T>::branch;

         vec_binop_vecvec_node(const operator_type& opr,
                               expression_ptr branch0,
                               expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec0_node_ptr_(0)
         , vec1_node_ptr_(0)
         , initialised_(false)
         {
            bool v0_is_ivec = false;
            bool v1_is_ivec = false;

            if (is_vector_node(branch(0)))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(branch(0));
            }
            else if (is_ivector_node(branch(0)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(0))))
               {
                  vec0_node_ptr_ = vi->vec();
                  v0_is_ivec     = true;
               }
            }

            if (is_vector_node(branch(1)))
            {
               vec1_node_ptr_ = static_cast<vector_node_ptr>(branch(1));
            }
            else if (is_ivector_node(branch(1)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(1))))
               {
                  vec1_node_ptr_ = vi->vec();
                  v1_is_ivec     = true;
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->vec_holder();
               vector_holder<T>& vec1 = vec1_node_ptr_->vec_holder();

               if (v0_is_ivec && (vec0.base_size() <= vec1.base_size()))
               {
                  vds_ = vds_t(vec0_node_ptr_->vds());
               }
               else if (v1_is_ivec && (vec1.base_size() <= vec0.base_size()))
               {
                  vds_ = vds_t(vec1_node_ptr_->vds());
               }
               else
               {
                  vds_ = vds_t(std::min(vec0.base_size(),vec1.base_size()));
               }

               memory_context_ = make_memory_context(vec0, vec1, vds());

               initialised_ =
                  (size() <= base_size()) &&
                  binary_node<T>::valid();
            }

            assert(valid());
         }

        ~vec_binop_vecvec_node()
         {
            memory_context_.clear();
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            const T* vec0 = vec0_node_ptr_->vds().data();
            const T* vec1 = vec1_node_ptr_->vds().data();
                  T* vec2 = vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec2 + lud.upper_bound;

            while (vec2 < upper_bound)
            {
               #define exprtk_loop(N)                          \
               vec2[N] = Operation::process(vec0[N], vec1[N]); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
               vec2 += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N)                                              \
               case N : { vec2[i] = Operation::process(vec0[i], vec1[i]); ++i; } \
               exprtk_fallthrough                                                \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15) case_stmt(14)
               case_stmt(13) case_stmt(12)
               case_stmt(11) case_stmt(10)
               case_stmt( 9) case_stmt( 8)
               case_stmt( 7) case_stmt( 6)
               case_stmt( 5) case_stmt( 4)
               #endif
               case_stmt( 3) case_stmt( 2)
               case_stmt( 1)
               default: break;
            }

            #undef exprtk_loop
            #undef case_stmt

            return (vds().data())[0];
         }

         vector_node_ptr vec() const exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvecarith;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

         std::size_t size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().size(),
               vec1_node_ptr_->vec_holder().size());
         }

         std::size_t base_size() const exprtk_override
         {
            return std::min(
               vec0_node_ptr_->vec_holder().base_size(),
               vec1_node_ptr_->vec_holder().base_size());
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node_ptr vec0_node_ptr_;
         vector_node_ptr vec1_node_ptr_;
         bool            initialised_;
         vds_t           vds_;
         memory_context  memory_context_;
      };

      template <typename T, typename Operation>
      class vec_binop_vecval_node exprtk_final
                                  : public binary_node     <T>
                                  , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_holder_t*    vector_holder_ptr;
         typedef vec_data_store<T>   vds_t;
         typedef memory_context_t<T> memory_context;

         using binary_node<T>::branch;

         vec_binop_vecval_node(const operator_type& opr,
                               expression_ptr branch0,
                               expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec0_node_ptr_(0)
         {
            bool v0_is_ivec = false;

            if (is_vector_node(branch(0)))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(branch(0));
            }
            else if (is_ivector_node(branch(0)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(0))))
               {
                  vec0_node_ptr_ = vi->vec();
                  v0_is_ivec     = true;
               }
            }

            if (vec0_node_ptr_)
            {
               if (v0_is_ivec)
                  vds() = vec0_node_ptr_->vds();
               else
                  vds() = vds_t(vec0_node_ptr_->base_size());

               memory_context_ = make_memory_context(vec0_node_ptr_->vec_holder(), vds());
            }

            assert(valid());
         }

        ~vec_binop_vecval_node()
         {
            memory_context_.clear();
         }

         inline T value() const exprtk_override
         {
                        branch(0)->value();
            const T v = branch(1)->value();

            const T* vec0 = vec0_node_ptr_->vds().data();
                  T* vec1 = vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec0 + lud.upper_bound;

            while (vec0 < upper_bound)
            {
               #define exprtk_loop(N)                    \
               vec1[N] = Operation::process(vec0[N], v); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through)                           \
               case N : { vec1[i] = Operation::process(vec0[i], v); ++i; } \
               fall_through                                                \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return (vds().data())[0];
         }

         vector_node_ptr vec() const exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvalarith;
         }

         inline bool valid() const exprtk_override
         {
            return
               vec0_node_ptr_          &&
               (size() <= base_size()) &&
               binary_node<T>::valid();
         }

         std::size_t size() const exprtk_override
         {
            return vec0_node_ptr_->size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec0_node_ptr_->vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node_ptr   vec0_node_ptr_;
         vds_t             vds_;
         memory_context    memory_context_;
      };

      template <typename T, typename Operation>
      class vec_binop_valvec_node exprtk_final
                                  : public binary_node     <T>
                                  , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_holder_t*    vector_holder_ptr;
         typedef vec_data_store<T>   vds_t;
         typedef memory_context_t<T> memory_context;

         using binary_node<T>::branch;

         vec_binop_valvec_node(const operator_type& opr,
                               expression_ptr branch0,
                               expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , vec1_node_ptr_(0)
         {
            bool v1_is_ivec = false;

            if (is_vector_node(branch(1)))
            {
               vec1_node_ptr_ = static_cast<vector_node_ptr>(branch(1));
            }
            else if (is_ivector_node(branch(1)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(1))))
               {
                  vec1_node_ptr_ = vi->vec();
                  v1_is_ivec     = true;
               }
            }

            if (vec1_node_ptr_)
            {
               if (v1_is_ivec)
                  vds() = vec1_node_ptr_->vds();
               else
                  vds() = vds_t(vec1_node_ptr_->base_size());

               memory_context_ = make_memory_context(vec1_node_ptr_->vec_holder(), vds());
            }

            assert(valid());
         }

        ~vec_binop_valvec_node()
         {
            memory_context_.clear();
         }

         inline T value() const exprtk_override
         {
            const T v = branch(0)->value();
                        branch(1)->value();

                  T* vec0 = vds().data();
            const T* vec1 = vec1_node_ptr_->vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec0 + lud.upper_bound;

            while (vec0 < upper_bound)
            {
               #define exprtk_loop(N)                    \
               vec0[N] = Operation::process(v, vec1[N]); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through)                           \
               case N : { vec0[i] = Operation::process(v, vec1[i]); ++i; } \
               fall_through                                                \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return (vds().data())[0];
         }

         vector_node_ptr vec() const exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecvalarith;
         }

         inline bool valid() const exprtk_override
         {
            return
               vec1_node_ptr_               &&
               (size() <= base_size())      &&
               (vds_.size() <= base_size()) &&
               binary_node<T>::valid();
         }

         std::size_t size() const exprtk_override
         {
            return vec1_node_ptr_->vec_holder().size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec1_node_ptr_->vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node_ptr   vec1_node_ptr_;
         vds_t             vds_;
         memory_context    memory_context_;
      };

      template <typename T, typename Operation>
      class unary_vector_node exprtk_final
                              : public unary_node      <T>
                              , public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_holder_t*    vector_holder_ptr;
         typedef vec_data_store<T>   vds_t;
         typedef memory_context_t<T> memory_context;

         using expression_node<T>::branch;

         unary_vector_node(const operator_type& opr, expression_ptr branch0)
         : unary_node<T>(opr, branch0)
         , vec0_node_ptr_(0)
         {
            bool vec0_is_ivec = false;

            if (is_vector_node(branch(0)))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(branch(0));
            }
            else if (is_ivector_node(branch(0)))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if (0 != (vi = dynamic_cast<vector_interface<T>*>(branch(0))))
               {
                  vec0_node_ptr_ = vi->vec();
                  vec0_is_ivec   = true;
               }
            }

            if (vec0_node_ptr_)
            {
               if (vec0_is_ivec)
                  vds_ = vec0_node_ptr_->vds();
               else
                  vds_ = vds_t(vec0_node_ptr_->base_size());

               memory_context_ = make_memory_context(vec0_node_ptr_->vec_holder(), vds());
            }

            assert(valid());
         }

        ~unary_vector_node()
         {
            memory_context_.clear();
         }

         inline T value() const exprtk_override
         {
            branch()->value();

            const T* vec0 = vec0_node_ptr_->vds().data();
                  T* vec1 = vds().data();

            loop_unroll::details lud(size());
            const T* upper_bound = vec0 + lud.upper_bound;

            while (vec0 < upper_bound)
            {
               #define exprtk_loop(N)                 \
               vec1[N] = Operation::process(vec0[N]); \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec0 += lud.batch_size;
               vec1 += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N)                                     \
               case N : { vec1[i] = Operation::process(vec0[i]); ++i; } \
               exprtk_fallthrough                                       \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15) case_stmt(14)
               case_stmt(13) case_stmt(12)
               case_stmt(11) case_stmt(10)
               case_stmt( 9) case_stmt( 8)
               case_stmt( 7) case_stmt( 6)
               case_stmt( 5) case_stmt( 4)
               #endif
               case_stmt( 3) case_stmt( 2)
               case_stmt( 1)
               default: break;
            }

            #undef exprtk_loop
            #undef case_stmt

            return (vds().data())[0];
         }

         vector_node_ptr vec() const exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecunaryop;
         }

         inline bool valid() const exprtk_override
         {
            return vec0_node_ptr_ && unary_node<T>::valid();
         }

         std::size_t size() const exprtk_override
         {
            return vec0_node_ptr_->vec_holder().size();
         }

         std::size_t base_size() const exprtk_override
         {
            return vec0_node_ptr_->vec_holder().base_size();
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

      private:

         vector_node_ptr vec0_node_ptr_;
         vds_t           vds_;
         memory_context  memory_context_;
      };

      template <typename T>
      class conditional_vector_node exprtk_final
                                    : public expression_node <T>
                                    , public vector_interface<T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef vector_interface<T>* vec_interface_ptr;
         typedef vector_node     <T>* vector_node_ptr;
         typedef vector_holder   <T>  vector_holder_t;
         typedef vector_holder_t*     vector_holder_ptr;
         typedef vec_data_store  <T>  vds_t;
         typedef memory_context_t<T> memory_context;
         typedef std::pair<expression_ptr,bool> branch_t;

         conditional_vector_node(expression_ptr condition,
                                 expression_ptr consequent,
                                 expression_ptr alternative)
         : consequent_node_ptr_ (0)
         , alternative_node_ptr_(0)
         , temp_vec_node_       (0)
         , temp_                (0)
         , result_vec_size_     (0)
         , initialised_         (false)
         {
            construct_branch_pair(condition_  , condition  );
            construct_branch_pair(consequent_ , consequent );
            construct_branch_pair(alternative_, alternative);

            if (details::is_ivector_node(consequent_.first))
            {
               vec_interface_ptr ivec_ptr = dynamic_cast<vec_interface_ptr>(consequent_.first);

               if (0 != ivec_ptr)
               {
                  consequent_node_ptr_ = ivec_ptr->vec();
               }
            }

            if (details::is_ivector_node(alternative_.first))
            {
               vec_interface_ptr ivec_ptr = dynamic_cast<vec_interface_ptr>(alternative_.first);

               if (0 != ivec_ptr)
               {
                  alternative_node_ptr_ = ivec_ptr->vec();
               }
            }

            if (consequent_node_ptr_ && alternative_node_ptr_)
            {
               const std::size_t vec_size =
                  std::max(consequent_node_ptr_ ->vec_holder().base_size(),
                           alternative_node_ptr_->vec_holder().base_size());

               vds_            = vds_t(vec_size);
               memory_context_ = make_memory_context(
                  consequent_node_ptr_ ->vec_holder(),
                  alternative_node_ptr_->vec_holder(),
                  vds());

               initialised_ = (vec_size > 0);
            }

            assert(initialised_);
         }

        ~conditional_vector_node()
         {
            memory_context_.clear();
         }

         inline T value() const exprtk_override
         {
            T result = T(0);
            T* source_vector = 0;
            T* result_vector = vds().data();

            if (is_true(condition_))
            {
               result           = consequent_.first->value();
               source_vector    = consequent_node_ptr_->vds().data();
               result_vec_size_ = consequent_node_ptr_->size();
            }
            else
            {
               result           = alternative_.first->value();
               source_vector    = alternative_node_ptr_->vds().data();
               result_vec_size_ = alternative_node_ptr_->size();
            }

            for (std::size_t i = 0; i < result_vec_size_; ++i)
            {
               result_vector[i] = source_vector[i];
            }

            return result;
         }

         vector_node_ptr vec() const exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         vector_node_ptr vec() exprtk_override
         {
            return memory_context_.temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vecondition;
         }

         inline bool valid() const exprtk_override
         {
            return
               initialised_                                      &&
               condition_  .first && condition_  .first->valid() &&
               consequent_ .first && consequent_ .first->valid() &&
               alternative_.first && alternative_.first->valid() &&
               size() <= base_size();
         }

         std::size_t size() const exprtk_override
         {
            return result_vec_size_;
         }

         std::size_t base_size() const exprtk_override
         {
            return std::min(
               consequent_node_ptr_ ->vec_holder().base_size(),
               alternative_node_ptr_->vec_holder().base_size());
         }

         vds_t& vds() exprtk_override
         {
            return vds_;
         }

         const vds_t& vds() const exprtk_override
         {
            return vds_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(condition_   , node_delete_list);
            expression_node<T>::ndb_t::collect(consequent_  , node_delete_list);
            expression_node<T>::ndb_t::collect(alternative_ , node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth
               (condition_, consequent_, alternative_);
         }

      private:

         branch_t            condition_;
         branch_t            consequent_;
         branch_t            alternative_;
         vector_node_ptr     consequent_node_ptr_;
         vector_node_ptr     alternative_node_ptr_;
         vector_node_ptr     temp_vec_node_;
         vector_holder_ptr   temp_;
         vds_t               vds_;
         mutable std::size_t result_vec_size_;
         bool                initialised_;
         memory_context      memory_context_;
      };

      template <typename T>
      class scand_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         scand_node(const operator_type& opr,
                    expression_ptr branch0,
                    expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         {
            assert(binary_node<T>::valid());
         }

         inline T value() const exprtk_override
         {
            return (
                     std::not_equal_to<T>()
                        (T(0),branch(0)->value()) &&
                     std::not_equal_to<T>()
                        (T(0),branch(1)->value())
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      class scor_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         using binary_node<T>::branch;

         scor_node(const operator_type& opr,
                   expression_ptr branch0,
                   expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         {
            assert(binary_node<T>::valid());
         }

         inline T value() const exprtk_override
         {
            return (
                     std::not_equal_to<T>()
                        (T(0),branch(0)->value()) ||
                     std::not_equal_to<T>()
                        (T(0),branch(1)->value())
                   ) ? T(1) : T(0);
         }
      };

      template <typename T, typename IFunction, std::size_t N>
      class function_N_node exprtk_final : public expression_node<T>
      {
      public:

         // Function of N parameters.
         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef IFunction ifunction;

         explicit function_N_node(ifunction* func)
         : function_((N == func->param_count) ? func : reinterpret_cast<ifunction*>(0))
         , parameter_count_(func->param_count)
         , initialised_(false)
         {}

         template <std::size_t NumBranches>
         bool init_branches(expression_ptr (&b)[NumBranches])
         {
            // Needed for incompetent and broken msvc compiler versions
            #ifdef _MSC_VER
             #pragma warning(push)
             #pragma warning(disable: 4127)
            #endif

            if (N != NumBranches)
            {
               return false;
            }

            for (std::size_t i = 0; i < NumBranches; ++i)
            {
               if (b[i] && b[i]->valid())
                  branch_[i] = std::make_pair(b[i],branch_deletable(b[i]));
               else
                  return false;
            }

            initialised_ = function_;
            assert(valid());
            return initialised_;

            #ifdef _MSC_VER
             #pragma warning(pop)
            #endif
         }

         inline bool operator <(const function_N_node<T,IFunction,N>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const exprtk_override
         {
            // Needed for incompetent and broken msvc compiler versions
            #ifdef _MSC_VER
             #pragma warning(push)
             #pragma warning(disable: 4127)
            #endif

            T v[N];
            evaluate_branches<T,N>::execute(v,branch_);
            return invoke<T,N>::execute(*function_,v);

            #ifdef _MSC_VER
             #pragma warning(pop)
            #endif
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_function;
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::template compute_node_depth<N>(branch_);
         }

         template <typename T_, std::size_t BranchCount>
         struct evaluate_branches
         {
            static inline void execute(T_ (&v)[BranchCount], const branch_t (&b)[BranchCount])
            {
               for (std::size_t i = 0; i < BranchCount; ++i)
               {
                  v[i] = b[i].first->value();
               }
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,6>
         {
            static inline void execute(T_ (&v)[6], const branch_t (&b)[6])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
               v[3] = b[3].first->value();
               v[4] = b[4].first->value();
               v[5] = b[5].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,5>
         {
            static inline void execute(T_ (&v)[5], const branch_t (&b)[5])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
               v[3] = b[3].first->value();
               v[4] = b[4].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,4>
         {
            static inline void execute(T_ (&v)[4], const branch_t (&b)[4])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
               v[3] = b[3].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,3>
         {
            static inline void execute(T_ (&v)[3], const branch_t (&b)[3])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,2>
         {
            static inline void execute(T_ (&v)[2], const branch_t (&b)[2])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,1>
         {
            static inline void execute(T_ (&v)[1], const branch_t (&b)[1])
            {
               v[0] = b[0].first->value();
            }
         };

         template <typename T_, std::size_t ParamCount>
         struct invoke { static inline T execute(ifunction&, branch_t (&)[ParamCount]) { return std::numeric_limits<T_>::quiet_NaN(); } };

         template <typename T_>
         struct invoke<T_,20>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[20])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16],v[17],v[18],v[19]); }
         };

         template <typename T_>
         struct invoke<T_,19>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[19])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16],v[17],v[18]); }
         };

         template <typename T_>
         struct invoke<T_,18>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[18])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12], v[13], v[14], v[15], v[16], v[17]); }
         };

         template <typename T_>
         struct invoke<T_,17>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[17])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12], v[13], v[14], v[15], v[16]); }
         };

         template <typename T_>
         struct invoke<T_,16>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[16])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12], v[13], v[14], v[15]); }
         };

         template <typename T_>
         struct invoke<T_,15>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[15])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12], v[13], v[14]); }
         };

         template <typename T_>
         struct invoke<T_,14>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[14])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12], v[13]); }
         };

         template <typename T_>
         struct invoke<T_,13>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[13])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11], v[12]); }
         };

         template <typename T_>
         struct invoke<T_,12>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[12])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10], v[11]); }
         };

         template <typename T_>
         struct invoke<T_,11>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[11])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9], v[10]); }
         };

         template <typename T_>
         struct invoke<T_,10>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[10])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8], v[9]); }
         };

         template <typename T_>
         struct invoke<T_,9>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[9])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7], v[8]); }
         };

         template <typename T_>
         struct invoke<T_,8>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[8])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7]); }
         };

         template <typename T_>
         struct invoke<T_,7>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[7])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5], v[6]); }
         };

         template <typename T_>
         struct invoke<T_,6>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[6])
            { return f(v[0], v[1], v[2], v[3], v[4], v[5]); }
         };

         template <typename T_>
         struct invoke<T_,5>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[5])
            { return f(v[0], v[1], v[2], v[3], v[4]); }
         };

         template <typename T_>
         struct invoke<T_,4>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[4])
            { return f(v[0], v[1], v[2], v[3]); }
         };

         template <typename T_>
         struct invoke<T_,3>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[3])
            { return f(v[0], v[1], v[2]); }
         };

         template <typename T_>
         struct invoke<T_,2>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[2])
            { return f(v[0], v[1]); }
         };

         template <typename T_>
         struct invoke<T_,1>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[1])
            { return f(v[0]); }
         };

      private:

         ifunction*  function_;
         std::size_t parameter_count_;
         branch_t    branch_[N];
         bool        initialised_;
      };

      template <typename T, typename IFunction>
      class function_N_node<T,IFunction,0> exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef IFunction ifunction;

         explicit function_N_node(ifunction* func)
         : function_((0 == func->param_count) ? func : reinterpret_cast<ifunction*>(0))
         {
            assert(valid());
         }

         inline bool operator <(const function_N_node<T,IFunction,0>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const exprtk_override
         {
            return (*function_)();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_function;
         }

         inline bool valid() const exprtk_override
         {
            return function_;
         }

      private:

         ifunction* function_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_function_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vararg_function_node(VarArgFunction*  func,
                              const std::vector<expression_ptr>& arg_list)
         : function_(func)
         , arg_list_(arg_list)
         {
            value_list_.resize(arg_list.size(),std::numeric_limits<T>::quiet_NaN());
            assert(valid());
         }

         inline bool operator <(const vararg_function_node<T,VarArgFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const exprtk_override
         {
            populate_value_list();
            return (*function_)(value_list_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_vafunction;
         }

         inline bool valid() const exprtk_override
         {
            return function_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               if (arg_list_[i] && !details::is_variable_node(arg_list_[i]))
               {
                  node_delete_list.push_back(&arg_list_[i]);
               }
            }
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(arg_list_);
         }

      private:

         inline void populate_value_list() const
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               value_list_[i] = arg_list_[i]->value();
            }
         }

         VarArgFunction* function_;
         std::vector<expression_ptr> arg_list_;
         mutable std::vector<T> value_list_;
      };

      template <typename T, typename GenericFunction>
      class generic_function_node : public expression_node<T>
      {
      public:

         typedef type_store<T>       type_store_t;
         typedef expression_node<T>* expression_ptr;
         typedef variable_node<T>    variable_node_t;
         typedef vector_node<T>      vector_node_t;
         typedef variable_node_t*    variable_node_ptr_t;
         typedef vector_node_t*      vector_node_ptr_t;
         typedef range_interface<T>  range_interface_t;
         typedef range_data_type<T>  range_data_type_t;
         typedef typename range_interface<T>::range_t range_t;

         typedef std::pair<expression_ptr,bool> branch_t;
         typedef vector_holder<T>* vh_t;
         typedef vector_view<T>*   vecview_t;

         typedef std::vector<T>                 tmp_vs_t;
         typedef std::vector<type_store_t>      typestore_list_t;
         typedef std::vector<range_data_type_t> range_list_t;

         explicit generic_function_node(const std::vector<expression_ptr>& arg_list,
                                        GenericFunction* func = reinterpret_cast<GenericFunction*>(0))
         : function_(func)
         , arg_list_(arg_list)
         {}

         virtual ~generic_function_node()
         {
            for (std::size_t i = 0; i < vv_list_.size(); ++i)
            {
               vecview_t& vv = vv_list_[i];
               if (vv && typestore_list_[i].vec_data)
               {
                  vv->remove_ref(&typestore_list_[i].vec_data);
                  typestore_list_[i].vec_data = 0;
               }
            }
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override exprtk_final
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

         virtual bool init_branches()
         {
            expr_as_vec1_store_.resize(arg_list_.size(), T(0)               );
            typestore_list_    .resize(arg_list_.size(), type_store_t()     );
            range_list_        .resize(arg_list_.size(), range_data_type_t());
            branch_            .resize(arg_list_.size(), branch_t(reinterpret_cast<expression_ptr>(0),false));
            vv_list_           .resize(arg_list_.size(), vecview_t(0));

            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               type_store_t& ts = typestore_list_[i];

               if (0 == arg_list_[i])
                  return false;
               else if (is_ivector_node(arg_list_[i]))
               {
                  vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

                  if (0 == (vi = dynamic_cast<vector_interface<T>*>(arg_list_[i])))
                     return false;

                  ts.size = vi->size();
                  ts.data = vi->vds().data();
                  ts.type = type_store_t::e_vector;

                  if (
                       vi->vec()->vec_holder().rebaseable() &&
                       vi->vec()->vec_holder().rebaseable_instance()
                     )
                  {
                     vv_list_[i] = vi->vec()->vec_holder().rebaseable_instance();
                     vv_list_[i]->set_ref(&ts.vec_data);
                  }
               }
               #ifndef exprtk_disable_string_capabilities
               else if (is_generally_string_node(arg_list_[i]))
               {
                  string_base_node<T>* sbn = reinterpret_cast<string_base_node<T>*>(0);

                  if (0 == (sbn = dynamic_cast<string_base_node<T>*>(arg_list_[i])))
                     return false;

                  ts.size = sbn->size();
                  ts.data = reinterpret_cast<void*>(const_cast<char_ptr>(sbn->base()));
                  ts.type = type_store_t::e_string;

                  range_list_[i].data      = ts.data;
                  range_list_[i].size      = ts.size;
                  range_list_[i].type_size = sizeof(char);
                  range_list_[i].str_node  = sbn;

                  range_interface_t* ri = reinterpret_cast<range_interface_t*>(0);

                  if (0 == (ri = dynamic_cast<range_interface_t*>(arg_list_[i])))
                     return false;

                  const range_t& rp = ri->range_ref();

                  if (
                       rp.const_range() &&
                       is_const_string_range_node(arg_list_[i])
                     )
                  {
                     ts.size = rp.const_size();
                     ts.data = static_cast<char_ptr>(ts.data) + rp.n0_c.second;
                     range_list_[i].range = reinterpret_cast<range_t*>(0);
                  }
                  else
                  {
                     range_list_[i].range = &(ri->range_ref());
                     range_param_list_.push_back(i);
                  }
               }
               #endif
               else if (is_variable_node(arg_list_[i]))
               {
                  variable_node_ptr_t var = variable_node_ptr_t(0);

                  if (0 == (var = dynamic_cast<variable_node_ptr_t>(arg_list_[i])))
                     return false;

                  ts.size = 1;
                  ts.data = &var->ref();
                  ts.type = type_store_t::e_scalar;
               }
               else
               {
                  ts.size = 1;
                  ts.data = reinterpret_cast<void*>(&expr_as_vec1_store_[i]);
                  ts.type = type_store_t::e_scalar;
               }

               branch_[i] = std::make_pair(arg_list_[i],branch_deletable(arg_list_[i]));
            }

            return true;
         }

         inline bool operator <(const generic_function_node<T,GenericFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const exprtk_override
         {
            if (populate_value_list())
            {
               typedef typename GenericFunction::parameter_list_t parameter_list_t;

               return (*function_)(parameter_list_t(typestore_list_));
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_genfunction;
         }

         inline bool valid() const exprtk_override
         {
            return function_;
         }

      protected:

         inline virtual bool populate_value_list() const
         {
            for (std::size_t i = 0; i < branch_.size(); ++i)
            {
               expr_as_vec1_store_[i] = branch_[i].first->value();
            }

            if (!range_param_list_.empty())
            {
               assert(range_param_list_.size() <= branch_.size());

               for (std::size_t i = 0; i < range_param_list_.size(); ++i)
               {
                  const std::size_t  index = range_param_list_[i];
                  range_data_type_t& rdt   = range_list_[index];

                  const range_t& rp = (*rdt.range);
                  std::size_t r0    = 0;
                  std::size_t r1    = 0;

                  const std::size_t data_size =
                  #ifndef exprtk_disable_string_capabilities
                     rdt.str_node ? rdt.str_node->size() : rdt.size;
                  #else
                     rdt.size;
                  #endif

                  if (!rp(r0, r1, data_size))
                  {
                     return false;
                  }

                  type_store_t& ts = typestore_list_[index];

                  ts.size = rp.cache_size();
                  #ifndef exprtk_disable_string_capabilities
                  if (ts.type == type_store_t::e_string)
                     ts.data = const_cast<char_ptr>(rdt.str_node->base()) + rp.cache.first;
                  else
                  #endif
                     ts.data = static_cast<char_ptr>(rdt.data) + (rp.cache.first * rdt.type_size);
               }
            }

            return true;
         }

         GenericFunction* function_;
         mutable typestore_list_t typestore_list_;

      private:

         std::vector<expression_ptr> arg_list_;
         std::vector<branch_t>       branch_;
         std::vector<vecview_t>      vv_list_;
         mutable tmp_vs_t            expr_as_vec1_store_;
         mutable range_list_t        range_list_;
         std::vector<std::size_t>    range_param_list_;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T, typename StringFunction>
      class string_function_node : public generic_function_node<T,StringFunction>
                                 , public string_base_node<T>
                                 , public range_interface <T>
      {
      public:

         typedef generic_function_node<T,StringFunction> gen_function_t;
         typedef typename range_interface<T>::range_t range_t;

         string_function_node(StringFunction* func,
                              const std::vector<typename gen_function_t::expression_ptr>& arg_list)
         : gen_function_t(arg_list,func)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);
            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;
            assert(valid());
         }

         inline bool operator <(const string_function_node<T,StringFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const exprtk_override
         {
            if (gen_function_t::populate_value_list())
            {
               typedef typename StringFunction::parameter_list_t parameter_list_t;

               const T result =
                  (*gen_function_t::function_)
                  (
                     ret_string_,
                     parameter_list_t(gen_function_t::typestore_list_)
                  );

               range_.n1_c.second  = ret_string_.size();
               range_.cache.second = range_.n1_c.second;

               return result;
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strfunction;
         }

         inline bool valid() const exprtk_override
         {
            return gen_function_t::function_;
         }

         std::string str() const exprtk_override
         {
            return ret_string_;
         }

         char_cptr base() const exprtk_override
         {
           return &ret_string_[0];
         }

         std::size_t size() const exprtk_override
         {
            return ret_string_.size();
         }

         range_t& range_ref() exprtk_override
         {
            return range_;
         }

         const range_t& range_ref() const exprtk_override
         {
            return range_;
         }

      protected:

         mutable range_t     range_;
         mutable std::string ret_string_;
      };
      #endif

      template <typename T, typename GenericFunction>
      class multimode_genfunction_node : public generic_function_node<T,GenericFunction>
      {
      public:

         typedef generic_function_node<T,GenericFunction> gen_function_t;
         typedef typename gen_function_t::range_t         range_t;

         multimode_genfunction_node(GenericFunction* func,
                                    const std::size_t& param_seq_index,
                                    const std::vector<typename gen_function_t::expression_ptr>& arg_list)
         : gen_function_t(arg_list,func)
         , param_seq_index_(param_seq_index)
         {}

         inline T value() const exprtk_override
         {
            assert(gen_function_t::valid());

            if (gen_function_t::populate_value_list())
            {
               typedef typename GenericFunction::parameter_list_t parameter_list_t;

               return
                  (*gen_function_t::function_)
                  (
                     param_seq_index_,
                     parameter_list_t(gen_function_t::typestore_list_)
                  );
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override exprtk_final
         {
            return expression_node<T>::e_genfunction;
         }

      private:

         std::size_t param_seq_index_;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T, typename StringFunction>
      class multimode_strfunction_node exprtk_final : public string_function_node<T,StringFunction>
      {
      public:

         typedef string_function_node<T,StringFunction> str_function_t;
         typedef typename str_function_t::range_t range_t;

         multimode_strfunction_node(StringFunction* func,
                                    const std::size_t& param_seq_index,
                                    const std::vector<typename str_function_t::expression_ptr>& arg_list)
         : str_function_t(func,arg_list)
         , param_seq_index_(param_seq_index)
         {}

         inline T value() const exprtk_override
         {
            if (str_function_t::populate_value_list())
            {
               typedef typename StringFunction::parameter_list_t parameter_list_t;

               const T result =
                  (*str_function_t::function_)
                  (
                     param_seq_index_,
                     str_function_t::ret_string_,
                     parameter_list_t(str_function_t::typestore_list_)
                  );

               str_function_t::range_.n1_c.second  = str_function_t::ret_string_.size();
               str_function_t::range_.cache.second = str_function_t::range_.n1_c.second;

               return result;
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_strfunction;
         }

      private:

         const std::size_t param_seq_index_;
      };
      #endif

      class return_exception {};

      template <typename T>
      class null_igenfunc
      {
      public:

         virtual ~null_igenfunc()
         {}

         typedef type_store<T> generic_type;
         typedef typename generic_type::parameter_list parameter_list_t;

         inline virtual T operator() (parameter_list_t)
         {
            return std::numeric_limits<T>::quiet_NaN();
         }
      };

      #ifndef exprtk_disable_return_statement
      template <typename T>
      class return_node exprtk_final : public generic_function_node<T,null_igenfunc<T> >
      {
      public:

         typedef results_context<T>   results_context_t;
         typedef null_igenfunc<T>     igeneric_function_t;
         typedef igeneric_function_t* igeneric_function_ptr;
         typedef generic_function_node<T,igeneric_function_t> gen_function_t;

         return_node(const std::vector<typename gen_function_t::expression_ptr>& arg_list,
                     results_context_t& rc)
         : gen_function_t  (arg_list)
         , results_context_(&rc)
         {
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            if (gen_function_t::populate_value_list())
            {
               typedef typename type_store<T>::parameter_list parameter_list_t;

               results_context_->
                  assign(parameter_list_t(gen_function_t::typestore_list_));

               throw return_exception();
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_return;
         }

         inline bool valid() const exprtk_override
         {
            return results_context_;
         }

      private:

         results_context_t* results_context_;
      };

      template <typename T>
      class return_envelope_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef results_context<T>  results_context_t;
         typedef std::pair<expression_ptr,bool> branch_t;

         return_envelope_node(expression_ptr body, results_context_t& rc)
         : results_context_(&rc  )
         , return_invoked_ (false)
         {
            construct_branch_pair(body_, body);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            try
            {
               return_invoked_ = false;
               results_context_->clear();

               return body_.first->value();
            }
            catch(const return_exception&)
            {
               return_invoked_ = true;

               return std::numeric_limits<T>::quiet_NaN();
            }
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_retenv;
         }

         inline bool valid() const exprtk_override
         {
            return results_context_ && body_.first;
         }

         inline bool* retinvk_ptr()
         {
            return &return_invoked_;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(body_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(body_);
         }

      private:

         results_context_t* results_context_;
         mutable bool        return_invoked_;
         branch_t                      body_;
      };
      #endif

      #define exprtk_define_unary_op(OpName)                    \
      template <typename T>                                     \
      struct OpName##_op                                        \
      {                                                         \
         typedef typename functor_t<T>::Type Type;              \
         typedef typename expression_node<T>::node_type node_t; \
                                                                \
         static inline T process(Type v)                        \
         {                                                      \
            return numeric:: OpName (v);                        \
         }                                                      \
                                                                \
         static inline node_t type()                            \
         {                                                      \
            return expression_node<T>::e_##OpName;              \
         }                                                      \
                                                                \
         static inline details::operator_type operation()       \
         {                                                      \
            return details::e_##OpName;                         \
         }                                                      \
      };                                                        \

      exprtk_define_unary_op(abs  )
      exprtk_define_unary_op(acos )
      exprtk_define_unary_op(acosh)
      exprtk_define_unary_op(asin )
      exprtk_define_unary_op(asinh)
      exprtk_define_unary_op(atan )
      exprtk_define_unary_op(atanh)
      exprtk_define_unary_op(ceil )
      exprtk_define_unary_op(cos  )
      exprtk_define_unary_op(cosh )
      exprtk_define_unary_op(cot  )
      exprtk_define_unary_op(csc  )
      exprtk_define_unary_op(d2g  )
      exprtk_define_unary_op(d2r  )
      exprtk_define_unary_op(erf  )
      exprtk_define_unary_op(erfc )
      exprtk_define_unary_op(exp  )
      exprtk_define_unary_op(expm1)
      exprtk_define_unary_op(floor)
      exprtk_define_unary_op(frac )
      exprtk_define_unary_op(g2d  )
      exprtk_define_unary_op(log  )
      exprtk_define_unary_op(log10)
      exprtk_define_unary_op(log2 )
      exprtk_define_unary_op(log1p)
      exprtk_define_unary_op(ncdf )
      exprtk_define_unary_op(neg  )
      exprtk_define_unary_op(notl )
      exprtk_define_unary_op(pos  )
      exprtk_define_unary_op(r2d  )
      exprtk_define_unary_op(round)
      exprtk_define_unary_op(sec  )
      exprtk_define_unary_op(sgn  )
      exprtk_define_unary_op(sin  )
      exprtk_define_unary_op(sinc )
      exprtk_define_unary_op(sinh )
      exprtk_define_unary_op(sqrt )
      exprtk_define_unary_op(tan  )
      exprtk_define_unary_op(tanh )
      exprtk_define_unary_op(trunc)
      #undef exprtk_define_unary_op

      template <typename T>
      struct opr_base
      {
         typedef typename details::functor_t<T>::Type    Type;
         typedef typename details::functor_t<T>::RefType RefType;
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t    quaternary_functor_t;
         typedef typename functor_t::tfunc_t    trinary_functor_t;
         typedef typename functor_t::bfunc_t    binary_functor_t;
         typedef typename functor_t::ufunc_t    unary_functor_t;
      };

      template <typename T>
      struct add_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return t1 + t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 + t2 + t3; }
         static inline void assign(RefType t1, Type t2) { t1 += t2; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_add; }
         static inline details::operator_type operation() { return details::e_add; }
      };

      template <typename T>
      struct mul_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return t1 * t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 * t2 * t3; }
         static inline void assign(RefType t1, Type t2) { t1 *= t2; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_mul; }
         static inline details::operator_type operation() { return details::e_mul; }
      };

      template <typename T>
      struct sub_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return t1 - t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 - t2 - t3; }
         static inline void assign(RefType t1, Type t2) { t1 -= t2; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_sub; }
         static inline details::operator_type operation() { return details::e_sub; }
      };

      template <typename T>
      struct div_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return t1 / t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 / t2 / t3; }
         static inline void assign(RefType t1, Type t2) { t1 /= t2; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_div; }
         static inline details::operator_type operation() { return details::e_div; }
      };

      template <typename T>
      struct mod_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return numeric::modulus<T>(t1,t2); }
         static inline void assign(RefType t1, Type t2) { t1 = numeric::modulus<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_mod; }
         static inline details::operator_type operation() { return details::e_mod; }
      };

      template <typename T>
      struct pow_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type    Type;
         typedef typename opr_base<T>::RefType RefType;

         static inline T process(Type t1, Type t2) { return numeric::pow<T>(t1,t2); }
         static inline void assign(RefType t1, Type t2) { t1 = numeric::pow<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_pow; }
         static inline details::operator_type operation() { return details::e_pow; }
      };

      template <typename T>
      struct lt_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return ((t1 < t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 < t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_lt; }
         static inline details::operator_type operation() { return details::e_lt; }
      };

      template <typename T>
      struct lte_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return ((t1 <= t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 <= t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_lte; }
         static inline details::operator_type operation() { return details::e_lte; }
      };

      template <typename T>
      struct gt_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return ((t1 > t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 > t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_gt; }
         static inline details::operator_type operation() { return details::e_gt; }
      };

      template <typename T>
      struct gte_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return ((t1 >= t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 >= t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_gte; }
         static inline details::operator_type operation() { return details::e_gte; }
      };

      template <typename T>
      struct eq_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (std::equal_to<T>()(t1,t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 == t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_eq; }
         static inline details::operator_type operation() { return details::e_eq; }
      };

      template <typename T>
      struct equal_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return numeric::equal(t1,t2); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 == t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_eq; }
         static inline details::operator_type operation() { return details::e_equal; }
      };

      template <typename T>
      struct ne_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return (std::not_equal_to<T>()(t1,t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 != t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_ne; }
         static inline details::operator_type operation() { return details::e_ne; }
      };

      template <typename T>
      struct and_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return (details::is_true(t1) && details::is_true(t2)) ? T(1) : T(0); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_and; }
         static inline details::operator_type operation() { return details::e_and; }
      };

      template <typename T>
      struct nand_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return (details::is_true(t1) && details::is_true(t2)) ? T(0) : T(1); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nand; }
         static inline details::operator_type operation() { return details::e_nand; }
      };

      template <typename T>
      struct or_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return (details::is_true(t1) || details::is_true(t2)) ? T(1) : T(0); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_or; }
         static inline details::operator_type operation() { return details::e_or; }
      };

      template <typename T>
      struct nor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return (details::is_true(t1) || details::is_true(t2)) ? T(0) : T(1); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_nor; }
      };

      template <typename T>
      struct xor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return numeric::xor_opr<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_xor; }
      };

      template <typename T>
      struct xnor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(Type t1, Type t2) { return numeric::xnor_opr<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_xnor; }
      };

      template <typename T>
      struct in_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((std::string::npos != t2.find(t1)) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_in; }
         static inline details::operator_type operation() { return details::e_in; }
      };

      template <typename T>
      struct like_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return (details::wc_match(t2,t1) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_like; }
         static inline details::operator_type operation() { return details::e_like; }
      };

      template <typename T>
      struct ilike_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return (details::wc_imatch(t2,t1) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_ilike; }
         static inline details::operator_type operation() { return details::e_ilike; }
      };

      template <typename T>
      struct inrange_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         static inline T process(const T& t0, const T& t1, const T& t2) { return ((t0 <= t1) && (t1 <= t2)) ? T(1) : T(0); }
         static inline T process(const std::string& t0, const std::string& t1, const std::string& t2)
         {
            return ((t0 <= t1) && (t1 <= t2)) ? T(1) : T(0);
         }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_inranges; }
         static inline details::operator_type operation() { return details::e_inrange; }
      };

      template <typename T>
      inline T value(details::expression_node<T>* n)
      {
         return n->value();
      }

      template <typename T>
      inline T value(std::pair<details::expression_node<T>*,bool> n)
      {
         return n.first->value();
      }

      template <typename T>
      inline T value(const T* t)
      {
         return (*t);
      }

      template <typename T>
      inline T value(const T& t)
      {
         return t;
      }

      template <typename T>
      struct vararg_add_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(0);

                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                               result += value(arg_list[i]);
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]) ;
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]) + value(arg_list[3]) ;
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]) + value(arg_list[3]) +
                   value(arg_list[4]) ;
         }
      };

      template <typename T>
      struct vararg_mul_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               result *= value(arg_list[i]);
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]) ;
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]) * value(arg_list[3]) ;
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]) * value(arg_list[3]) *
                   value(arg_list[4]) ;
         }
      };

      template <typename T>
      struct vararg_avg_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default : return vararg_add_op<T>::process(arg_list) / T(arg_list.size());
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1])) / T(2);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) + value(arg_list[2])) / T(3);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) +
                    value(arg_list[2]) + value(arg_list[3])) / T(4);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) +
                    value(arg_list[2]) + value(arg_list[3]) +
                    value(arg_list[4])) / T(5);
         }
      };

      template <typename T>
      struct vararg_min_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               const T v = value(arg_list[i]);

                               if (v < result)
                                  result = v;
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return std::min<T>(value(arg_list[0]),value(arg_list[1]));
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return std::min<T>(std::min<T>(value(arg_list[0]),value(arg_list[1])),value(arg_list[2]));
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return std::min<T>(
                        std::min<T>(value(arg_list[0]), value(arg_list[1])),
                        std::min<T>(value(arg_list[2]), value(arg_list[3])));
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return std::min<T>(
                   std::min<T>(std::min<T>(value(arg_list[0]), value(arg_list[1])),
                               std::min<T>(value(arg_list[2]), value(arg_list[3]))),
                               value(arg_list[4]));
         }
      };

      template <typename T>
      struct vararg_max_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               const T v = value(arg_list[i]);

                               if (v > result)
                                  result = v;
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return std::max<T>(value(arg_list[0]),value(arg_list[1]));
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return std::max<T>(std::max<T>(value(arg_list[0]),value(arg_list[1])),value(arg_list[2]));
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return std::max<T>(
                        std::max<T>(value(arg_list[0]), value(arg_list[1])),
                        std::max<T>(value(arg_list[2]), value(arg_list[3])));
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return std::max<T>(
                   std::max<T>(std::max<T>(value(arg_list[0]), value(arg_list[1])),
                               std::max<T>(value(arg_list[2]), value(arg_list[3]))),
                               value(arg_list[4]));
         }
      };

      template <typename T>
      struct vararg_mand_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                               if (std::equal_to<T>()(T(0), value(arg_list[i])))
                                  return T(0);
                            }

                            return T(1);
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return std::not_equal_to<T>()
                      (T(0), value(arg_list[0])) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[1]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[2]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[2])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[3]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[2])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[3])) &&
                     std::not_equal_to<T>()(T(0), value(arg_list[4]))
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      struct vararg_mor_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                               if (std::not_equal_to<T>()(T(0), value(arg_list[i])))
                                  return T(1);
                            }

                            return T(0);
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return std::not_equal_to<T>()
                      (T(0), value(arg_list[0])) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[1]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[2]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[2])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[3]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0), value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[2])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[3])) ||
                     std::not_equal_to<T>()(T(0), value(arg_list[4]))
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      struct vararg_multi_op exprtk_final : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return std::numeric_limits<T>::quiet_NaN();
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               case 6  : return process_6(arg_list);
               case 7  : return process_7(arg_list);
               case 8  : return process_8(arg_list);
               default :
                        {
                           for (std::size_t i = 0; i < (arg_list.size() - 1); ++i)
                           {
                              value(arg_list[i]);
                           }
                           return value(arg_list.back());
                        }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
                   value(arg_list[0]);
            return value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
            return value(arg_list[2]);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
            return value(arg_list[3]);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
            return value(arg_list[4]);
         }

         template <typename Sequence>
         static inline T process_6(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
            return value(arg_list[5]);
         }

         template <typename Sequence>
         static inline T process_7(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
                   value(arg_list[5]);
            return value(arg_list[6]);
         }

         template <typename Sequence>
         static inline T process_8(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
                   value(arg_list[5]);
                   value(arg_list[6]);
            return value(arg_list[7]);
         }
      };

      template <typename T>
      struct vec_add_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            const T* vec = v->vec()->vds().data();
            const std::size_t vec_size = v->size();

            loop_unroll::details lud(vec_size);

            if (vec_size <= static_cast<std::size_t>(lud.batch_size))
            {
               T result = T(0);
               int i    = 0;

               switch (vec_size)
               {
                  #define case_stmt(N,fall_through) \
                  case N : result += vec[i++];      \
                  fall_through                      \

                  #ifndef exprtk_disable_superscalar_unroll
                  case_stmt(16, exprtk_fallthrough) case_stmt(15, exprtk_fallthrough)
                  case_stmt(14, exprtk_fallthrough) case_stmt(13, exprtk_fallthrough)
                  case_stmt(12, exprtk_fallthrough) case_stmt(11, exprtk_fallthrough)
                  case_stmt(10, exprtk_fallthrough) case_stmt( 9, exprtk_fallthrough)
                  case_stmt( 8, exprtk_fallthrough) case_stmt( 7, exprtk_fallthrough)
                  case_stmt( 6, exprtk_fallthrough) case_stmt( 5, exprtk_fallthrough)

                  #endif
                  case_stmt( 4, exprtk_fallthrough) case_stmt( 3, exprtk_fallthrough)
                  case_stmt( 2, exprtk_fallthrough) case_stmt( 1, (void)0;)
               }

               #undef case_stmt

               return result;
            }

            T r[] = {
                      T(0), T(0), T(0), T(0), T(0), T(0), T(0), T(0),
                      T(0), T(0), T(0), T(0), T(0), T(0), T(0), T(0)
                    };

            const T* upper_bound = vec + lud.upper_bound;

            while (vec < upper_bound)
            {
               #define exprtk_loop(N) \
               r[N] += vec[N];        \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through) \
               case N : r[0] += vec[i++];        \
               fall_through                      \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return (r[ 0] + r[ 1] + r[ 2] + r[ 3])
                   #ifndef exprtk_disable_superscalar_unroll
                 + (r[ 4] + r[ 5] + r[ 6] + r[ 7])
                 + (r[ 8] + r[ 9] + r[10] + r[11])
                 + (r[12] + r[13] + r[14] + r[15])
                   #endif
                   ;
         }
      };

      template <typename T>
      struct vec_mul_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            const T* vec = v->vec()->vds().data();
            const std::size_t vec_size = v->vec()->size();

            loop_unroll::details lud(vec_size);

            if (vec_size <= static_cast<std::size_t>(lud.batch_size))
            {
               T result = T(1);
               int i    = 0;

               switch (vec_size)
               {
                  #define case_stmt(N,fall_through) \
                  case N : result *= vec[i++];      \
                  fall_through                      \

                  #ifndef exprtk_disable_superscalar_unroll
                  case_stmt(16, exprtk_fallthrough) case_stmt(15, exprtk_fallthrough)
                  case_stmt(14, exprtk_fallthrough) case_stmt(13, exprtk_fallthrough)
                  case_stmt(12, exprtk_fallthrough) case_stmt(11, exprtk_fallthrough)
                  case_stmt(10, exprtk_fallthrough) case_stmt( 9, exprtk_fallthrough)
                  case_stmt( 8, exprtk_fallthrough) case_stmt( 7, exprtk_fallthrough)
                  case_stmt( 6, exprtk_fallthrough) case_stmt( 5, exprtk_fallthrough)
                  #endif
                  case_stmt( 4, exprtk_fallthrough) case_stmt( 3, exprtk_fallthrough)
                  case_stmt( 2, exprtk_fallthrough) case_stmt( 1, (void)0;)
               }

               #undef case_stmt

               return result;
            }

            T r[] = {
                      T(1), T(1), T(1), T(1), T(1), T(1), T(1), T(1),
                      T(1), T(1), T(1), T(1), T(1), T(1), T(1), T(1)
                    };

            const T* upper_bound = vec + lud.upper_bound;

            while (vec < upper_bound)
            {
               #define exprtk_loop(N) \
               r[N] *= vec[N];        \

               exprtk_loop( 0) exprtk_loop( 1)
               exprtk_loop( 2) exprtk_loop( 3)
               #ifndef exprtk_disable_superscalar_unroll
               exprtk_loop( 4) exprtk_loop( 5)
               exprtk_loop( 6) exprtk_loop( 7)
               exprtk_loop( 8) exprtk_loop( 9)
               exprtk_loop(10) exprtk_loop(11)
               exprtk_loop(12) exprtk_loop(13)
               exprtk_loop(14) exprtk_loop(15)
               #endif

               vec += lud.batch_size;
            }

            int i = 0;

            switch (lud.remainder)
            {
               #define case_stmt(N,fall_through) \
               case N : r[0] *= vec[i++];        \
               fall_through                      \

               #ifndef exprtk_disable_superscalar_unroll
               case_stmt(15, exprtk_fallthrough) case_stmt(14, exprtk_fallthrough)
               case_stmt(13, exprtk_fallthrough) case_stmt(12, exprtk_fallthrough)
               case_stmt(11, exprtk_fallthrough) case_stmt(10, exprtk_fallthrough)
               case_stmt( 9, exprtk_fallthrough) case_stmt( 8, exprtk_fallthrough)
               case_stmt( 7, exprtk_fallthrough) case_stmt( 6, exprtk_fallthrough)
               case_stmt( 5, exprtk_fallthrough) case_stmt( 4, exprtk_fallthrough)
               #endif
               case_stmt( 3, exprtk_fallthrough) case_stmt( 2, exprtk_fallthrough)
               case_stmt( 1, (void)0;)
            }

            #undef exprtk_loop
            #undef case_stmt

            return (r[ 0] * r[ 1] * r[ 2] * r[ 3])
                   #ifndef exprtk_disable_superscalar_unroll
                 * (r[ 4] * r[ 5] * r[ 6] * r[ 7])
                 * (r[ 8] * r[ 9] * r[10] * r[11])
                 * (r[12] * r[13] * r[14] * r[15])
                   #endif
                   ;
         }
      };

      template <typename T>
      struct vec_avg_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            const T vec_size = T(v->vec()->size());
            return vec_add_op<T>::process(v) / vec_size;
         }
      };

      template <typename T>
      struct vec_min_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            const T* vec = v->vec()->vds().data();
            const std::size_t vec_size = v->vec()->size();

            T result = vec[0];

            for (std::size_t i = 1; i < vec_size; ++i)
            {
               const T v_i = vec[i];

               if (v_i < result)
                  result = v_i;
            }

            return result;
         }
      };

      template <typename T>
      struct vec_max_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            const T* vec = v->vec()->vds().data();
            const std::size_t vec_size = v->vec()->size();

            T result = vec[0];

            for (std::size_t i = 1; i < vec_size; ++i)
            {
               const T v_i = vec[i];

               if (v_i > result)
                  result = v_i;
            }

            return result;
         }
      };

      template <typename T>
      class vov_base_node : public expression_node<T>
      {
      public:

         virtual ~vov_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T& v0() const = 0;

         virtual const T& v1() const = 0;
      };

      template <typename T>
      class cov_base_node : public expression_node<T>
      {
      public:

         virtual ~cov_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual const T& v() const = 0;
      };

      template <typename T>
      class voc_base_node : public expression_node<T>
      {
      public:

         virtual ~voc_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual const T& v() const = 0;
      };

      template <typename T>
      class vob_base_node : public expression_node<T>
      {
      public:

         virtual ~vob_base_node()
         {}

         virtual const T& v() const = 0;
      };

      template <typename T>
      class bov_base_node : public expression_node<T>
      {
      public:

         virtual ~bov_base_node()
         {}

         virtual const T& v() const = 0;
      };

      template <typename T>
      class cob_base_node : public expression_node<T>
      {
      public:

         virtual ~cob_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual void set_c(const T) = 0;

         virtual expression_node<T>* move_branch(const std::size_t& index) = 0;
      };

      template <typename T>
      class boc_base_node : public expression_node<T>
      {
      public:

         virtual ~boc_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual void set_c(const T) = 0;

         virtual expression_node<T>* move_branch(const std::size_t& index) = 0;
      };

      template <typename T>
      class uv_base_node : public expression_node<T>
      {
      public:

         virtual ~uv_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T& v() const = 0;
      };

      template <typename T>
      class sos_base_node : public expression_node<T>
      {
      public:

         virtual ~sos_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }
      };

      template <typename T>
      class sosos_base_node : public expression_node<T>
      {
      public:

         virtual ~sosos_base_node()
         {}

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }
      };

      template <typename T>
      class T0oT1oT2_base_node : public expression_node<T>
      {
      public:

         virtual ~T0oT1oT2_base_node()
         {}

         virtual std::string type_id() const = 0;
      };

      template <typename T>
      class T0oT1oT2oT3_base_node : public expression_node<T>
      {
      public:

         virtual ~T0oT1oT2oT3_base_node()
         {}

         virtual std::string type_id() const = 0;
      };

      template <typename T, typename Operation>
      class unary_variable_node exprtk_final : public uv_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         explicit unary_variable_node(const T& var)
         : v_(var)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(v_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T& v() const exprtk_override
         {
            return v_;
         }

      private:

         unary_variable_node(const unary_variable_node<T,Operation>&) exprtk_delete;
         unary_variable_node<T,Operation>& operator=(const unary_variable_node<T,Operation>&) exprtk_delete;

         const T& v_;
      };

      template <typename T>
      class uvouv_node exprtk_final : public expression_node<T>
      {
      public:

         // UOpr1(v0) Op UOpr2(v1)
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;
         typedef typename functor_t::ufunc_t    ufunc_t;
         typedef expression_node<T>*            expression_ptr;

         explicit uvouv_node(const T& var0,const T& var1,
                             ufunc_t uf0, ufunc_t uf1, bfunc_t bf)
         : v0_(var0)
         , v1_(var1)
         , u0_(uf0 )
         , u1_(uf1 )
         , f_ (bf  )
         {}

         inline T value() const exprtk_override
         {
            return f_(u0_(v0_),u1_(v1_));
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_uvouv;
         }

         inline const T& v0()
         {
            return v0_;
         }

         inline const T& v1()
         {
            return v1_;
         }

         inline ufunc_t u0()
         {
            return u0_;
         }

         inline ufunc_t u1()
         {
            return u1_;
         }

         inline ufunc_t f()
         {
            return f_;
         }

      private:

         uvouv_node(const uvouv_node<T>&) exprtk_delete;
         uvouv_node<T>& operator=(const uvouv_node<T>&) exprtk_delete;

         const T& v0_;
         const T& v1_;
         const ufunc_t u0_;
         const ufunc_t u1_;
         const bfunc_t f_;
      };

      template <typename T, typename Operation>
      class unary_branch_node exprtk_final : public expression_node<T>
      {
      public:

         typedef Operation                      operation_t;
         typedef expression_node<T>*            expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         explicit unary_branch_node(expression_ptr branch)
         {
            construct_branch_pair(branch_, branch);
         }

         inline T value() const exprtk_override
         {
            return Operation::process(branch_.first->value());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline operator_type operation()
         {
            return Operation::operation();
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         inline void release()
         {
            branch_.second = false;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         unary_branch_node(const unary_branch_node<T,Operation>&) exprtk_delete;
         unary_branch_node<T,Operation>& operator=(const unary_branch_node<T,Operation>&) exprtk_delete;

         branch_t branch_;
      };

      template <typename T> struct is_const                { enum {result = 0}; };
      template <typename T> struct is_const <const T>      { enum {result = 1}; };
      template <typename T> struct is_const_ref            { enum {result = 0}; };
      template <typename T> struct is_const_ref <const T&> { enum {result = 1}; };
      template <typename T> struct is_ref                  { enum {result = 0}; };
      template <typename T> struct is_ref<T&>              { enum {result = 1}; };
      template <typename T> struct is_ref<const T&>        { enum {result = 0}; };

      template <std::size_t State>
      struct param_to_str { static std::string result() { static const std::string r("v"); return r; } };

      template <>
      struct param_to_str<0> { static std::string result() { static const std::string r("c"); return r; } };

      #define exprtk_crtype(Type)                          \
      param_to_str<is_const_ref< Type >::result>::result() \

      template <typename T>
      struct T0oT1oT2process
      {
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;

         struct mode0
         {
            static inline T process(const T& t0, const T& t1, const T& t2, const bfunc_t bf0, const bfunc_t bf1)
            {
               // (T0 o0 T1) o1 T2
               return bf1(bf0(t0,t1),t2);
            }

            template <typename T0, typename T1, typename T2>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + "o"   +
                                                       exprtk_crtype(T1) + ")o(" +
                                                       exprtk_crtype(T2) + ")"   ;
               return result;
            }
         };

         struct mode1
         {
            static inline T process(const T& t0, const T& t1, const T& t2, const bfunc_t bf0, const bfunc_t bf1)
            {
               // T0 o0 (T1 o1 T2)
               return bf0(t0,bf1(t1,t2));
            }

            template <typename T0, typename T1, typename T2>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + ")o(" +
                                                       exprtk_crtype(T1) + "o"   +
                                                       exprtk_crtype(T2) + ")"   ;
               return result;
            }
         };
      };

      template <typename T>
      struct T0oT1oT20T3process
      {
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;

         struct mode0
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 T1) o1 (T2 o2 T3)
               return bf1(bf0(t0,t1),bf2(t2,t3));
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + "o"  +
                                                       exprtk_crtype(T1) + ")o" +
                                                 "(" + exprtk_crtype(T2) + "o"  +
                                                       exprtk_crtype(T3) + ")"  ;
               return result;
            }
         };

         struct mode1
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 (T1 o1 (T2 o2 T3))
               return bf0(t0,bf1(t1,bf2(t2,t3)));
            }
            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) +  ")o((" +
                                                       exprtk_crtype(T1) +  ")o("  +
                                                       exprtk_crtype(T2) +  "o"    +
                                                       exprtk_crtype(T3) +  "))"   ;
               return result;
            }
         };

         struct mode2
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 ((T1 o1 T2) o2 T3)
               return bf0(t0,bf2(bf1(t1,t2),t3));
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + ")o((" +
                                                       exprtk_crtype(T1) + "o"    +
                                                       exprtk_crtype(T2) + ")o("  +
                                                       exprtk_crtype(T3) + "))"   ;
               return result;
            }
         };

         struct mode3
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (((T0 o0 T1) o1 T2) o2 T3)
               return bf2(bf1(bf0(t0,t1),t2),t3);
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "((" + exprtk_crtype(T0) + "o"    +
                                                        exprtk_crtype(T1) + ")o("  +
                                                        exprtk_crtype(T2) + "))o(" +
                                                        exprtk_crtype(T3) + ")";
               return result;
            }
         };

         struct mode4
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // ((T0 o0 (T1 o1 T2)) o2 T3
               return bf2(bf0(t0,bf1(t1,t2)),t3);
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "((" + exprtk_crtype(T0) + ")o("  +
                                                        exprtk_crtype(T1) + "o"    +
                                                        exprtk_crtype(T2) + "))o(" +
                                                        exprtk_crtype(T3) + ")"    ;
               return result;
            }
         };
      };

      #undef exprtk_crtype

      template <typename T, typename T0, typename T1>
      struct nodetype_T0oT1 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1>
      const typename expression_node<T>::node_type nodetype_T0oT1<T,T0,T1>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_, T1_, v_)                                                          \
      template <typename T, typename T0, typename T1>                                                           \
      struct nodetype_T0oT1<T,T0_,T1_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1>                                                           \
      const typename expression_node<T>::node_type nodetype_T0oT1<T,T0_,T1_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&, const T1&,  e_vov)
      synthesis_node_type_define(const T0&, const T1 ,  e_voc)
      synthesis_node_type_define(const T0 , const T1&,  e_cov)
      synthesis_node_type_define(      T0&,       T1&, e_none)
      synthesis_node_type_define(const T0 , const T1 , e_none)
      synthesis_node_type_define(      T0&, const T1 , e_none)
      synthesis_node_type_define(const T0 ,       T1&, e_none)
      synthesis_node_type_define(const T0&,       T1&, e_none)
      synthesis_node_type_define(      T0&, const T1&, e_none)
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1, typename T2>
      struct nodetype_T0oT1oT2 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1, typename T2>
      const typename expression_node<T>::node_type nodetype_T0oT1oT2<T,T0,T1,T2>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_, T1_, T2_, v_)                                                            \
      template <typename T, typename T0, typename T1, typename T2>                                                     \
      struct nodetype_T0oT1oT2<T,T0_,T1_,T2_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1, typename T2>                                                     \
      const typename expression_node<T>::node_type nodetype_T0oT1oT2<T,T0_,T1_,T2_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&, const T1&, const T2&, e_vovov)
      synthesis_node_type_define(const T0&, const T1&, const T2 , e_vovoc)
      synthesis_node_type_define(const T0&, const T1 , const T2&, e_vocov)
      synthesis_node_type_define(const T0 , const T1&, const T2&, e_covov)
      synthesis_node_type_define(const T0 , const T1&, const T2 , e_covoc)
      synthesis_node_type_define(const T0 , const T1 , const T2 , e_none )
      synthesis_node_type_define(const T0 , const T1 , const T2&, e_none )
      synthesis_node_type_define(const T0&, const T1 , const T2 , e_none )
      synthesis_node_type_define(      T0&,       T1&,       T2&, e_none )
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      struct nodetype_T0oT1oT2oT3 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1, typename T2, typename T3>
      const typename expression_node<T>::node_type nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_, T1_, T2_, T3_, v_)                                                              \
      template <typename T, typename T0, typename T1, typename T2, typename T3>                                               \
      struct nodetype_T0oT1oT2oT3<T,T0_,T1_,T2_,T3_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1, typename T2, typename T3>                                               \
      const typename expression_node<T>::node_type nodetype_T0oT1oT2oT3<T,T0_,T1_,T2_,T3_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&, const T1&, const T2&, const T3&, e_vovovov)
      synthesis_node_type_define(const T0&, const T1&, const T2&, const T3 , e_vovovoc)
      synthesis_node_type_define(const T0&, const T1&, const T2 , const T3&, e_vovocov)
      synthesis_node_type_define(const T0&, const T1 , const T2&, const T3&, e_vocovov)
      synthesis_node_type_define(const T0 , const T1&, const T2&, const T3&, e_covovov)
      synthesis_node_type_define(const T0 , const T1&, const T2 , const T3&, e_covocov)
      synthesis_node_type_define(const T0&, const T1 , const T2&, const T3 , e_vocovoc)
      synthesis_node_type_define(const T0 , const T1&, const T2&, const T3 , e_covovoc)
      synthesis_node_type_define(const T0&, const T1 , const T2 , const T3&, e_vococov)
      synthesis_node_type_define(const T0 , const T1 , const T2 , const T3 , e_none   )
      synthesis_node_type_define(const T0 , const T1 , const T2 , const T3&, e_none   )
      synthesis_node_type_define(const T0 , const T1 , const T2&, const T3 , e_none   )
      synthesis_node_type_define(const T0 , const T1&, const T2 , const T3 , e_none   )
      synthesis_node_type_define(const T0&, const T1 , const T2 , const T3 , e_none   )
      synthesis_node_type_define(const T0 , const T1 , const T2&, const T3&, e_none   )
      synthesis_node_type_define(const T0&, const T1&, const T2 , const T3 , e_none   )
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1>
      class T0oT1 exprtk_final : public expression_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;
         typedef T value_type;
         typedef T0oT1<T,T0,T1> node_type;

         T0oT1(T0 p0, T1 p1, const bfunc_t p2)
         : t0_(p0)
         , t1_(p1)
         , f_ (p2)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1<T,T0,T1>::result;
            return result;
         }

         inline operator_type operation() const exprtk_override
         {
            return e_default;
         }

         inline T value() const exprtk_override
         {
            return f_(t0_,t1_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline bfunc_t f() const
         {
            return f_;
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator,
                                                    T0 p0, T1 p1,
                                                    bfunc_t p2)
         {
            return allocator
                     .template allocate_type<node_type, T0, T1, bfunc_t&>
                        (p0, p1, p2);
         }

      private:

         T0oT1(const T0oT1<T,T0,T1>&) exprtk_delete;
         T0oT1<T,T0,T1>& operator=(const T0oT1<T,T0,T1>&) { return (*this); }

         T0 t0_;
         T1 t1_;
         const bfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2, typename ProcessMode>
      class T0oT1oT2 exprtk_final : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;
         typedef T value_type;
         typedef T0oT1oT2<T,T0,T1,T2,ProcessMode> node_type;
         typedef ProcessMode process_mode_t;

         T0oT1oT2(T0 p0, T1 p1, T2 p2, const bfunc_t p3, const bfunc_t p4)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         , f0_(p3)
         , f1_(p4)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation()
         {
            return e_default;
         }

         inline T value() const exprtk_override
         {
            return ProcessMode::process(t0_, t1_, t2_, f0_, f1_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         bfunc_t f0() const
         {
            return f0_;
         }

         bfunc_t f1() const
         {
            return f1_;
         }

         std::string type_id() const exprtk_override
         {
            return id();
         }

         static inline std::string id()
         {
            return process_mode_t::template id<T0,T1,T2>();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, bfunc_t p3, bfunc_t p4)
         {
            return allocator
                      .template allocate_type<node_type, T0, T1, T2, bfunc_t, bfunc_t>
                         (p0, p1, p2, p3, p4);
         }

      private:

         T0oT1oT2(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
         const bfunc_t f0_;
         const bfunc_t f1_;
      };

      template <typename T, typename T0_, typename T1_, typename T2_, typename T3_, typename ProcessMode>
      class T0oT1oT2oT3 exprtk_final : public T0oT1oT2oT3_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t    bfunc_t;
         typedef T value_type;
         typedef T0_ T0;
         typedef T1_ T1;
         typedef T2_ T2;
         typedef T3_ T3;
         typedef T0oT1oT2oT3<T,T0,T1,T2,T3,ProcessMode> node_type;
         typedef ProcessMode process_mode_t;

         T0oT1oT2oT3(T0 p0, T1 p1, T2 p2, T3 p3, bfunc_t p4, bfunc_t p5, bfunc_t p6)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         , t3_(p3)
         , f0_(p4)
         , f1_(p5)
         , f2_(p6)
         {}

         inline T value() const exprtk_override
         {
            return ProcessMode::process(t0_, t1_, t2_, t3_, f0_, f1_, f2_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t3_;
         }

         inline bfunc_t f0() const
         {
            return f0_;
         }

         inline bfunc_t f1() const
         {
            return f1_;
         }

         inline bfunc_t f2() const
         {
            return f2_;
         }

         inline std::string type_id() const exprtk_override
         {
            return id();
         }

         static inline std::string id()
         {
            return process_mode_t::template id<T0, T1, T2, T3>();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator,
                                                    T0 p0, T1 p1, T2 p2, T3 p3,
                                                    bfunc_t p4, bfunc_t p5, bfunc_t p6)
         {
            return allocator
                      .template allocate_type<node_type, T0, T1, T2, T3, bfunc_t, bfunc_t>
                         (p0, p1, p2, p3, p4, p5, p6);
         }

      private:

         T0oT1oT2oT3(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
         const bfunc_t f0_;
         const bfunc_t f1_;
         const bfunc_t f2_;
      };

      template <typename T, typename T0, typename T1, typename T2>
      class T0oT1oT2_sf3 exprtk_final : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::tfunc_t    tfunc_t;
         typedef T value_type;
         typedef T0oT1oT2_sf3<T,T0,T1,T2> node_type;

         T0oT1oT2_sf3(T0 p0, T1 p1, T2 p2, const tfunc_t p3)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         , f_ (p3)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation() const exprtk_override
         {
            return e_default;
         }

         inline T value() const exprtk_override
         {
            return f_(t0_, t1_, t2_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         tfunc_t f() const
         {
            return f_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return "sf3";
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, tfunc_t p3)
         {
            return allocator
                     .template allocate_type<node_type, T0, T1, T2, tfunc_t>
                        (p0, p1, p2, p3);
         }

      private:

         T0oT1oT2_sf3(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
         const tfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2>
      class sf3ext_type_node : public T0oT1oT2_base_node<T>
      {
      public:

         virtual ~sf3ext_type_node()
         {}

         virtual T0 t0() const = 0;

         virtual T1 t1() const = 0;

         virtual T2 t2() const = 0;
      };

      template <typename T, typename T0, typename T1, typename T2, typename SF3Operation>
      class T0oT1oT2_sf3ext exprtk_final : public sf3ext_type_node<T,T0,T1,T2>
      {
      public:

         typedef T value_type;
         typedef T0oT1oT2_sf3ext<T, T0, T1, T2, SF3Operation> node_type;

         T0oT1oT2_sf3ext(T0 p0, T1 p1, T2 p2)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation()
         {
            return e_default;
         }

         inline T value() const exprtk_override
         {
            return SF3Operation::process(t0_, t1_, t2_);
         }

         T0 t0() const exprtk_override
         {
            return t0_;
         }

         T1 t1() const exprtk_override
         {
            return t1_;
         }

         T2 t2() const exprtk_override
         {
            return t2_;
         }

         std::string type_id() const exprtk_override
         {
            return id();
         }

         static inline std::string id()
         {
            return SF3Operation::id();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2)
         {
            return allocator
                     .template allocate_type<node_type, T0, T1, T2>
                        (p0, p1, p2);
         }

      private:

         T0oT1oT2_sf3ext(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
      };

      template <typename T>
      inline bool is_sf3ext_node(const expression_node<T>* n)
      {
         switch (n->type())
         {
            case expression_node<T>::e_vovov : return true;
            case expression_node<T>::e_vovoc : return true;
            case expression_node<T>::e_vocov : return true;
            case expression_node<T>::e_covov : return true;
            case expression_node<T>::e_covoc : return true;
            default                          : return false;
         }
      }

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      class T0oT1oT2oT3_sf4 exprtk_final : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t    qfunc_t;
         typedef T value_type;
         typedef T0oT1oT2oT3_sf4<T, T0, T1, T2, T3> node_type;

         T0oT1oT2oT3_sf4(T0 p0, T1 p1, T2 p2, T3 p3, const qfunc_t p4)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         , t3_(p3)
         , f_ (p4)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result;
            return result;
         }

         inline operator_type operation() const exprtk_override
         {
            return e_default;
         }

         inline T value() const exprtk_override
         {
            return f_(t0_, t1_, t2_, t3_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t3_;
         }

         qfunc_t f() const
         {
            return f_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return "sf4";
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, T3 p3, qfunc_t p4)
         {
            return allocator
                     .template allocate_type<node_type, T0, T1, T2, T3, qfunc_t>
                        (p0, p1, p2, p3, p4);
         }

      private:

         T0oT1oT2oT3_sf4(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
         const qfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2, typename T3, typename SF4Operation>
      class T0oT1oT2oT3_sf4ext exprtk_final : public T0oT1oT2oT3_base_node<T>
      {
      public:

         typedef T value_type;
         typedef T0oT1oT2oT3_sf4ext<T, T0, T1, T2, T3, SF4Operation> node_type;

         T0oT1oT2oT3_sf4ext(T0 p0, T1 p1, T2 p2, T3 p3)
         : t0_(p0)
         , t1_(p1)
         , t2_(p2)
         , t3_(p3)
         {}

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result;
            return result;
         }

         inline T value() const exprtk_override
         {
            return SF4Operation::process(t0_, t1_, t2_, t3_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t3_;
         }

         std::string type_id() const exprtk_override
         {
            return id();
         }

         static inline std::string id()
         {
            return SF4Operation::id();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, T3 p3)
         {
            return allocator
                     .template allocate_type<node_type, T0, T1, T2, T3>
                        (p0, p1, p2, p3);
         }

      private:

         T0oT1oT2oT3_sf4ext(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
      };

      template <typename T>
      inline bool is_sf4ext_node(const expression_node<T>* n)
      {
         switch (n->type())
         {
            case expression_node<T>::e_vovovov : return true;
            case expression_node<T>::e_vovovoc : return true;
            case expression_node<T>::e_vovocov : return true;
            case expression_node<T>::e_vocovov : return true;
            case expression_node<T>::e_covovov : return true;
            case expression_node<T>::e_covocov : return true;
            case expression_node<T>::e_vocovoc : return true;
            case expression_node<T>::e_covovoc : return true;
            case expression_node<T>::e_vococov : return true;
            default                            : return false;
         }
      }

      template <typename T, typename T0, typename T1>
      struct T0oT1_define
      {
         typedef details::T0oT1<T, T0, T1> type0;
      };

      template <typename T, typename T0, typename T1, typename T2>
      struct T0oT1oT2_define
      {
         typedef details::T0oT1oT2<T, T0, T1, T2, typename T0oT1oT2process<T>::mode0> type0;
         typedef details::T0oT1oT2<T, T0, T1, T2, typename T0oT1oT2process<T>::mode1> type1;
         typedef details::T0oT1oT2_sf3<T, T0, T1, T2> sf3_type;
         typedef details::sf3ext_type_node<T, T0, T1, T2> sf3_type_node;
      };

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      struct T0oT1oT2oT3_define
      {
         typedef details::T0oT1oT2oT3<T, T0, T1, T2, T3, typename T0oT1oT20T3process<T>::mode0> type0;
         typedef details::T0oT1oT2oT3<T, T0, T1, T2, T3, typename T0oT1oT20T3process<T>::mode1> type1;
         typedef details::T0oT1oT2oT3<T, T0, T1, T2, T3, typename T0oT1oT20T3process<T>::mode2> type2;
         typedef details::T0oT1oT2oT3<T, T0, T1, T2, T3, typename T0oT1oT20T3process<T>::mode3> type3;
         typedef details::T0oT1oT2oT3<T, T0, T1, T2, T3, typename T0oT1oT20T3process<T>::mode4> type4;
         typedef details::T0oT1oT2oT3_sf4<T, T0, T1, T2, T3> sf4_type;
      };

      template <typename T, typename Operation>
      class vov_node exprtk_final : public vov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // variable op variable node
         explicit vov_node(const T& var0, const T& var1)
         : v0_(var0)
         , v1_(var1)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(v0_,v1_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T& v0() const exprtk_override
         {
            return v0_;
         }

         inline const T& v1() const exprtk_override
         {
            return v1_;
         }

      protected:

         const T& v0_;
         const T& v1_;

      private:

         vov_node(const vov_node<T,Operation>&) exprtk_delete;
         vov_node<T,Operation>& operator=(const vov_node<T,Operation>&) exprtk_delete;
      };

      template <typename T, typename Operation>
      class cov_node exprtk_final : public cov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // constant op variable node
         explicit cov_node(const T& const_var, const T& var)
         : c_(const_var)
         , v_(var)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(c_,v_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T c() const exprtk_override
         {
            return c_;
         }

         inline const T& v() const exprtk_override
         {
            return v_;
         }

      protected:

         const T  c_;
         const T& v_;

      private:

         cov_node(const cov_node<T,Operation>&) exprtk_delete;
         cov_node<T,Operation>& operator=(const cov_node<T,Operation>&) exprtk_delete;
      };

      template <typename T, typename Operation>
      class voc_node exprtk_final : public voc_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // variable op constant node
         explicit voc_node(const T& var, const T& const_var)
         : v_(var)
         , c_(const_var)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(v_,c_);
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T c() const exprtk_override
         {
            return c_;
         }

         inline const T& v() const exprtk_override
         {
            return v_;
         }

      protected:

         const T& v_;
         const T  c_;

      private:

         voc_node(const voc_node<T,Operation>&) exprtk_delete;
         voc_node<T,Operation>& operator=(const voc_node<T,Operation>&) exprtk_delete;
      };

      template <typename T, typename Operation>
      class vob_node exprtk_final : public vob_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // variable op binary node
         explicit vob_node(const T& var, const expression_ptr branch)
         : v_(var)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return Operation::process(v_,branch_.first->value());
         }

         inline const T& v() const exprtk_override
         {
            return v_;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         vob_node(const vob_node<T,Operation>&) exprtk_delete;
         vob_node<T,Operation>& operator=(const vob_node<T,Operation>&) exprtk_delete;

         const T& v_;
         branch_t branch_;
      };

      template <typename T, typename Operation>
      class bov_node exprtk_final : public bov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // binary node op variable node
         explicit bov_node(const expression_ptr branch, const T& var)
         : v_(var)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return Operation::process(branch_.first->value(),v_);
         }

         inline const T& v() const exprtk_override
         {
            return v_;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         bov_node(const bov_node<T,Operation>&) exprtk_delete;
         bov_node<T,Operation>& operator=(const bov_node<T,Operation>&) exprtk_delete;

         const T& v_;
         branch_t branch_;
      };

      template <typename T, typename Operation>
      class cob_node exprtk_final : public cob_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // constant op variable node
         explicit cob_node(const T const_var, const expression_ptr branch)
         : c_(const_var)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return Operation::process(c_,branch_.first->value());
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T c() const exprtk_override
         {
            return c_;
         }

         inline void set_c(const T new_c) exprtk_override
         {
            (*const_cast<T*>(&c_)) = new_c;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         inline expression_node<T>* move_branch(const std::size_t&) exprtk_override
         {
            branch_.second = false;
            return branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         cob_node(const cob_node<T,Operation>&) exprtk_delete;
         cob_node<T,Operation>& operator=(const cob_node<T,Operation>&) exprtk_delete;

         const T  c_;
         branch_t branch_;
      };

      template <typename T, typename Operation>
      class boc_node exprtk_final : public boc_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // binary node op constant node
         explicit boc_node(const expression_ptr branch, const T const_var)
         : c_(const_var)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return Operation::process(branch_.first->value(),c_);
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline const T c() const exprtk_override
         {
            return c_;
         }

         inline void set_c(const T new_c) exprtk_override
         {
            (*const_cast<T*>(&c_)) = new_c;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         inline expression_node<T>* branch(const std::size_t&) const exprtk_override
         {
            return branch_.first;
         }

         inline expression_node<T>* move_branch(const std::size_t&) exprtk_override
         {
            branch_.second = false;
            return branch_.first;
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         boc_node(const boc_node<T,Operation>&) exprtk_delete;
         boc_node<T,Operation>& operator=(const boc_node<T,Operation>&) exprtk_delete;

         const T  c_;
         branch_t branch_;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T, typename SType0, typename SType1, typename Operation>
      class sos_node exprtk_final : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // string op string node
         explicit sos_node(SType0 p0, SType1 p1)
         : s0_(p0)
         , s1_(p1)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(s0_,s1_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0 s0_;
         SType1 s1_;

      private:

         sos_node(const sos_node<T,SType0,SType1,Operation>&) exprtk_delete;
         sos_node<T,SType0,SType1,Operation>& operator=(const sos_node<T,SType0,SType1,Operation>&) exprtk_delete;
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xrox_node exprtk_final : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;
         typedef str_xrox_node<T,SType0,SType1,RangePack,Operation> node_type;

         // string-range op string node
         explicit str_xrox_node(SType0 p0, SType1 p1, RangePack rp0)
         : s0_ (p0 )
         , s1_ (p1 )
         , rp0_(rp0)
         {}

        ~str_xrox_node()
         {
            rp0_.free();
         }

         inline T value() const exprtk_override
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            if (rp0_(r0, r1, s0_.size()))
               return Operation::process(s0_.substr(r0, (r1 - r0) + 1), s1_);
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp0_;

      private:

         str_xrox_node(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xoxr_node exprtk_final : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;
         typedef str_xoxr_node<T,SType0,SType1,RangePack,Operation> node_type;

         // string op string range node
         explicit str_xoxr_node(SType0 p0, SType1 p1, RangePack rp1)
         : s0_ (p0 )
         , s1_ (p1 )
         , rp1_(rp1)
         {}

        ~str_xoxr_node()
         {
            rp1_.free();
         }

         inline T value() const exprtk_override
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            if (rp1_(r0, r1, s1_.size()))
            {
               return Operation::process
                      (
                         s0_,
                         s1_.substr(r0, (r1 - r0) + 1)
                      );
            }
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp1_;

      private:

         str_xoxr_node(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xroxr_node exprtk_final : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;
         typedef str_xroxr_node<T,SType0,SType1,RangePack,Operation> node_type;

         // string-range op string-range node
         explicit str_xroxr_node(SType0 p0, SType1 p1, RangePack rp0, RangePack rp1)
         : s0_ (p0 )
         , s1_ (p1 )
         , rp0_(rp0)
         , rp1_(rp1)
         {}

        ~str_xroxr_node()
         {
            rp0_.free();
            rp1_.free();
         }

         inline T value() const exprtk_override
         {
            std::size_t r0_0 = 0;
            std::size_t r0_1 = 0;
            std::size_t r1_0 = 0;
            std::size_t r1_1 = 0;

            if (
                 rp0_(r0_0, r1_0, s0_.size()) &&
                 rp1_(r0_1, r1_1, s1_.size())
               )
            {
               return Operation::process
                      (
                         s0_.substr(r0_0, (r1_0 - r0_0) + 1),
                         s1_.substr(r0_1, (r1_1 - r0_1) + 1)
                      );
            }
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp0_;
         RangePack rp1_;

      private:

         str_xroxr_node(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;
      };

      template <typename T, typename Operation>
      class str_sogens_node exprtk_final : public binary_node<T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>* str_base_ptr;
         typedef range_pack      <T>  range_t;
         typedef range_t*             range_ptr;
         typedef range_interface <T>  irange_t;
         typedef irange_t*            irange_ptr;

         using binary_node<T>::branch;

         str_sogens_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1)
         : binary_node<T>(opr, branch0, branch1)
         , str0_base_ptr_ (0)
         , str1_base_ptr_ (0)
         , str0_range_ptr_(0)
         , str1_range_ptr_(0)
         , initialised_   (false)
         {
            if (is_generally_string_node(branch(0)))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(branch(0));

               if (0 == str0_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(0));

               if (0 == range)
                  return;

               str0_range_ptr_ = &(range->range_ref());
            }

            if (is_generally_string_node(branch(1)))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(branch(1));

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range = dynamic_cast<irange_ptr>(branch(1));

               if (0 == range)
                  return;

               str1_range_ptr_ = &(range->range_ref());
            }

            initialised_ =
               str0_base_ptr_  &&
               str1_base_ptr_  &&
               str0_range_ptr_ &&
               str1_range_ptr_;

            assert(valid());
         }

         inline T value() const exprtk_override
         {
            branch(0)->value();
            branch(1)->value();

            std::size_t str0_r0 = 0;
            std::size_t str0_r1 = 0;

            std::size_t str1_r0 = 0;
            std::size_t str1_r1 = 0;

            const range_t& range0 = (*str0_range_ptr_);
            const range_t& range1 = (*str1_range_ptr_);

            if (
                 range0(str0_r0, str0_r1, str0_base_ptr_->size()) &&
                 range1(str1_r0, str1_r1, str1_base_ptr_->size())
               )
            {
               return Operation::process
                      (
                         str0_base_ptr_->str().substr(str0_r0,(str0_r1 - str0_r0)),
                         str1_base_ptr_->str().substr(str1_r0,(str1_r1 - str1_r0))
                      );
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline bool valid() const exprtk_override
         {
            return initialised_;
         }

      private:

         str_sogens_node(const str_sogens_node<T,Operation>&) exprtk_delete;
         str_sogens_node<T,Operation>& operator=(const str_sogens_node<T,Operation>&) exprtk_delete;

         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         range_ptr    str0_range_ptr_;
         range_ptr    str1_range_ptr_;
         bool         initialised_;
      };

      template <typename T, typename SType0, typename SType1, typename SType2, typename Operation>
      class sosos_node exprtk_final : public sosos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;
         typedef sosos_node<T, SType0, SType1, SType2, Operation> node_type;

         // string op string op string node
         explicit sosos_node(SType0 p0, SType1 p1, SType2 p2)
         : s0_(p0)
         , s1_(p1)
         , s2_(p2)
         {}

         inline T value() const exprtk_override
         {
            return Operation::process(s0_, s1_, s2_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return Operation::type();
         }

         inline operator_type operation() const exprtk_override
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

         inline std::string& s2()
         {
            return s2_;
         }

      protected:

         SType0 s0_;
         SType1 s1_;
         SType2 s2_;

      private:

         sosos_node(const node_type&) exprtk_delete;
         node_type& operator=(const node_type&) exprtk_delete;
      };
      #endif

      template <typename T, typename PowOp>
      class ipow_node exprtk_final: public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef PowOp operation_t;

         explicit ipow_node(const T& v)
         : v_(v)
         {}

         inline T value() const exprtk_override
         {
            return PowOp::result(v_);
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_ipow;
         }

      private:

         ipow_node(const ipow_node<T,PowOp>&) exprtk_delete;
         ipow_node<T,PowOp>& operator=(const ipow_node<T,PowOp>&) exprtk_delete;

         const T& v_;
      };

      template <typename T, typename PowOp>
      class bipow_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr, bool> branch_t;
         typedef PowOp operation_t;

         explicit bipow_node(expression_ptr branch)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return PowOp::result(branch_.first->value());
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_ipow;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         bipow_node(const bipow_node<T,PowOp>&) exprtk_delete;
         bipow_node<T,PowOp>& operator=(const bipow_node<T,PowOp>&) exprtk_delete;

         branch_t branch_;
      };

      template <typename T, typename PowOp>
      class ipowinv_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef PowOp operation_t;

         explicit ipowinv_node(const T& v)
         : v_(v)
         {}

         inline T value() const exprtk_override
         {
            return (T(1) / PowOp::result(v_));
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_ipowinv;
         }

      private:

         ipowinv_node(const ipowinv_node<T,PowOp>&) exprtk_delete;
         ipowinv_node<T,PowOp>& operator=(const ipowinv_node<T,PowOp>&) exprtk_delete;

         const T& v_;
      };

      template <typename T, typename PowOp>
      class bipowinv_node exprtk_final : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr, bool> branch_t;
         typedef PowOp operation_t;

         explicit bipowinv_node(expression_ptr branch)
         {
            construct_branch_pair(branch_, branch);
            assert(valid());
         }

         inline T value() const exprtk_override
         {
            return (T(1) / PowOp::result(branch_.first->value()));
         }

         inline typename expression_node<T>::node_type type() const exprtk_override
         {
            return expression_node<T>::e_ipowinv;
         }

         inline bool valid() const exprtk_override
         {
            return branch_.first && branch_.first->valid();
         }

         void collect_nodes(typename expression_node<T>::noderef_list_t& node_delete_list) exprtk_override
         {
            expression_node<T>::ndb_t::collect(branch_, node_delete_list);
         }

         std::size_t node_depth() const exprtk_override
         {
            return expression_node<T>::ndb_t::compute_node_depth(branch_);
         }

      private:

         bipowinv_node(const bipowinv_node<T,PowOp>&) exprtk_delete;
         bipowinv_node<T,PowOp>& operator=(const bipowinv_node<T,PowOp>&) exprtk_delete;

         branch_t branch_;
      };

      template <typename T>
      inline bool is_vov_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const vov_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_cov_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const cov_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_voc_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const voc_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_cob_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const cob_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_boc_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const boc_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_t0ot1ot2_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const T0oT1oT2_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_t0ot1ot2ot3_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const T0oT1oT2oT3_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_uv_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const uv_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_string_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringvar == node->type());
      }

      template <typename T>
      inline bool is_string_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringvarrng == node->type());
      }

      template <typename T>
      inline bool is_const_string_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringconst == node->type());
      }

      template <typename T>
      inline bool is_const_string_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_cstringvarrng == node->type());
      }

      template <typename T>
      inline bool is_string_assignment_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strass == node->type());
      }

      template <typename T>
      inline bool is_string_concat_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strconcat == node->type());
      }

      template <typename T>
      inline bool is_string_function_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strfunction == node->type());
      }

      template <typename T>
      inline bool is_string_condition_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strcondition == node->type());
      }

      template <typename T>
      inline bool is_string_ccondition_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strccondition == node->type());
      }

      template <typename T>
      inline bool is_string_vararg_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringvararg == node->type());
      }

      template <typename T>
      inline bool is_genricstring_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strgenrange == node->type());
      }

      template <typename T>
      inline bool is_generally_string_node(const expression_node<T>* node)
      {
         if (node)
         {
            switch (node->type())
            {
               case expression_node<T>::e_stringvar     :
               case expression_node<T>::e_stringconst   :
               case expression_node<T>::e_stringvarrng  :
               case expression_node<T>::e_cstringvarrng :
               case expression_node<T>::e_strgenrange   :
               case expression_node<T>::e_strass        :
               case expression_node<T>::e_strconcat     :
               case expression_node<T>::e_strfunction   :
               case expression_node<T>::e_strcondition  :
               case expression_node<T>::e_strccondition :
               case expression_node<T>::e_stringvararg  : return true;
               default                                  : return false;
            }
         }

         return false;
      }

      class node_allocator
      {
      public:

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[1])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0]);
            result->node_depth();
            return result;
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[2])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0], branch[1]);
            result->node_depth();
            return result;
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[3])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0], branch[1], branch[2]);
            result->node_depth();
            return result;
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[4])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0], branch[1], branch[2], branch[3]);
            result->node_depth();
            return result;
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[5])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0],branch[1], branch[2], branch[3], branch[4]);
            result->node_depth();
            return result;
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[6])
         {
            expression_node<typename ResultNode::value_type>* result =
               allocate<ResultNode>(operation, branch[0], branch[1], branch[2], branch[3], branch[4], branch[5]);
            result->node_depth();
            return result;
         }

         template <typename node_type>
         inline expression_node<typename node_type::value_type>* allocate() const
         {
            return (new node_type());
         }

         template <typename node_type,
                   typename Type,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node<typename node_type::value_type>* allocate(const Sequence<Type,Allocator>& seq) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(seq));
            result->node_depth();
            return result;
         }

         template <typename node_type, typename T1>
         inline expression_node<typename node_type::value_type>* allocate(T1& t1) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1));
            result->node_depth();
            return result;
         }

         template <typename node_type, typename T1>
         inline expression_node<typename node_type::value_type>* allocate_c(const T1& t1) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_cr(const T1& t1, T2& t2) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_rc(T1& t1, const T2& t2) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_rr(T1& t1, T2& t2) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_tt(T1 t1, T2 t2) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_ttt(T1 t1, T2 t2, T3 t3) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_tttt(T1 t1, T2 t2, T3 t3, T4 t4) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_rrr(T1& t1, T2& t2, T3& t3) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_rrrr(T1& t1, T2& t2, T3& t3, T4& t4) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4, typename T5>
         inline expression_node<typename node_type::value_type>* allocate_rrrrr(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4, typename T5>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4, typename T5, typename T6>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6, typename T7>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6, t7));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7, const T8& t8) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6, t7, t8));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8, typename T9>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7, const T8& t8,
                                                                          const T9& t9) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6, t7, t8, t9));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8,
                   typename T9, typename T10>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const  T2&  t2,
                                                                          const T3& t3, const  T4&  t4,
                                                                          const T5& t5, const  T6&  t6,
                                                                          const T7& t7, const  T8&  t8,
                                                                          const T9& t9, const T10& t10) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2, T3 t3) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4,
                                                                               T5 t5) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4,
                                                                               T5 t5, T6 t6) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6));
            result->node_depth();
            return result;
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6, typename T7>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4,
                                                                               T5 t5, T6 t6,
                                                                               T7 t7) const
         {
            expression_node<typename node_type::value_type>*
            result = (new node_type(t1, t2, t3, t4, t5, t6, t7));
            result->node_depth();
            return result;
         }

         template <typename T>
         void inline free(expression_node<T>*& e) const
         {
            exprtk_debug(("node_allocator::free() - deleting expression_node "
                          "type: %03d addr: %p\n",
                          static_cast<int>(e->type()),
                          reinterpret_cast<void*>(e)));
            delete e;
            e = 0;
         }
      };

      inline void load_operations_map(std::multimap<std::string,details::base_operation_t,details::ilesscompare>& m)
      {
         #define register_op(Symbol, Type, Args)                                             \
         m.insert(std::make_pair(std::string(Symbol),details::base_operation_t(Type,Args))); \

         register_op("abs"       , e_abs     , 1)
         register_op("acos"      , e_acos    , 1)
         register_op("acosh"     , e_acosh   , 1)
         register_op("asin"      , e_asin    , 1)
         register_op("asinh"     , e_asinh   , 1)
         register_op("atan"      , e_atan    , 1)
         register_op("atanh"     , e_atanh   , 1)
         register_op("ceil"      , e_ceil    , 1)
         register_op("cos"       , e_cos     , 1)
         register_op("cosh"      , e_cosh    , 1)
         register_op("exp"       , e_exp     , 1)
         register_op("expm1"     , e_expm1   , 1)
         register_op("floor"     , e_floor   , 1)
         register_op("log"       , e_log     , 1)
         register_op("log10"     , e_log10   , 1)
         register_op("log2"      , e_log2    , 1)
         register_op("log1p"     , e_log1p   , 1)
         register_op("round"     , e_round   , 1)
         register_op("sin"       , e_sin     , 1)
         register_op("sinc"      , e_sinc    , 1)
         register_op("sinh"      , e_sinh    , 1)
         register_op("sec"       , e_sec     , 1)
         register_op("csc"       , e_csc     , 1)
         register_op("sqrt"      , e_sqrt    , 1)
         register_op("tan"       , e_tan     , 1)
         register_op("tanh"      , e_tanh    , 1)
         register_op("cot"       , e_cot     , 1)
         register_op("rad2deg"   , e_r2d     , 1)
         register_op("deg2rad"   , e_d2r     , 1)
         register_op("deg2grad"  , e_d2g     , 1)
         register_op("grad2deg"  , e_g2d     , 1)
         register_op("sgn"       , e_sgn     , 1)
         register_op("not"       , e_notl    , 1)
         register_op("erf"       , e_erf     , 1)
         register_op("erfc"      , e_erfc    , 1)
         register_op("ncdf"      , e_ncdf    , 1)
         register_op("frac"      , e_frac    , 1)
         register_op("trunc"     , e_trunc   , 1)
         register_op("atan2"     , e_atan2   , 2)
         register_op("mod"       , e_mod     , 2)
         register_op("logn"      , e_logn    , 2)
         register_op("pow"       , e_pow     , 2)
         register_op("root"      , e_root    , 2)
         register_op("roundn"    , e_roundn  , 2)
         register_op("equal"     , e_equal   , 2)
         register_op("not_equal" , e_nequal  , 2)
         register_op("hypot"     , e_hypot   , 2)
         register_op("shr"       , e_shr     , 2)
         register_op("shl"       , e_shl     , 2)
         register_op("clamp"     , e_clamp   , 3)
         register_op("iclamp"    , e_iclamp  , 3)
         register_op("inrange"   , e_inrange , 3)
         #undef register_op
      }

   } // namespace details

   class function_traits
   {
   public:

      function_traits()
      : allow_zero_parameters_(false)
      , has_side_effects_(true)
      , min_num_args_(0)
      , max_num_args_(std::numeric_limits<std::size_t>::max())
      {}

      inline bool& allow_zero_parameters()
      {
         return allow_zero_parameters_;
      }

      inline bool& has_side_effects()
      {
         return has_side_effects_;
      }

      std::size_t& min_num_args()
      {
         return min_num_args_;
      }

      std::size_t& max_num_args()
      {
         return max_num_args_;
      }

   private:

      bool allow_zero_parameters_;
      bool has_side_effects_;
      std::size_t min_num_args_;
      std::size_t max_num_args_;
   };

   template <typename FunctionType>
   void enable_zero_parameters(FunctionType& func)
   {
      func.allow_zero_parameters() = true;

      if (0 != func.min_num_args())
      {
         func.min_num_args() = 0;
      }
   }

   template <typename FunctionType>
   void disable_zero_parameters(FunctionType& func)
   {
      func.allow_zero_parameters() = false;
   }

   template <typename FunctionType>
   void enable_has_side_effects(FunctionType& func)
   {
      func.has_side_effects() = true;
   }

   template <typename FunctionType>
   void disable_has_side_effects(FunctionType& func)
   {
      func.has_side_effects() = false;
   }

   template <typename FunctionType>
   void set_min_num_args(FunctionType& func, const std::size_t& num_args)
   {
      func.min_num_args() = num_args;

      if ((0 != func.min_num_args()) && func.allow_zero_parameters())
         func.allow_zero_parameters() = false;
   }

   template <typename FunctionType>
   void set_max_num_args(FunctionType& func, const std::size_t& num_args)
   {
      func.max_num_args() = num_args;
   }

   template <typename T>
   class ifunction : public function_traits
   {
   public:

      explicit ifunction(const std::size_t& pc)
      : param_count(pc)
      {}

      virtual ~ifunction()
      {}

      #define empty_method_body(N)                   \
      {                                              \
         exprtk_debug(("ifunction::operator() - Operator(" #N ") has not been overridden\n")); \
         return std::numeric_limits<T>::quiet_NaN(); \
      }                                              \

      inline virtual T operator() ()
      empty_method_body(0)

      inline virtual T operator() (const T&)
      empty_method_body(1)

      inline virtual T operator() (const T&,const T&)
      empty_method_body(2)

      inline virtual T operator() (const T&, const T&, const T&)
      empty_method_body(3)

      inline virtual T operator() (const T&, const T&, const T&, const T&)
      empty_method_body(4)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&)
      empty_method_body(5)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(6)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(7)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(8)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(9)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(10)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&)
      empty_method_body(11)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&)
      empty_method_body(12)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&)
      empty_method_body(13)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&)
      empty_method_body(14)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&)
      empty_method_body(15)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(16)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(17)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(18)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(19)

      inline virtual T operator() (const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                   const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      empty_method_body(20)

      #undef empty_method_body

      std::size_t param_count;
   };

   template <typename T>
   class ivararg_function : public function_traits
   {
   public:

      virtual ~ivararg_function()
      {}

      inline virtual T operator() (const std::vector<T>&)
      {
         exprtk_debug(("ivararg_function::operator() - Operator has not been overridden\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }
   };

   template <typename T>
   class igeneric_function : public function_traits
   {
   public:

      enum return_type
      {
         e_rtrn_scalar   = 0,
         e_rtrn_string   = 1,
         e_rtrn_overload = 2
      };

      typedef T type;
      typedef type_store<T> generic_type;
      typedef typename generic_type::parameter_list parameter_list_t;

      explicit igeneric_function(const std::string& param_seq = "", const return_type rtr_type = e_rtrn_scalar)
      : parameter_sequence(param_seq)
      , rtrn_type(rtr_type)
      {}

      virtual ~igeneric_function()
      {}

      #define igeneric_function_empty_body(N)        \
      {                                              \
         exprtk_debug(("igeneric_function::operator() - Operator(" #N ") has not been overridden\n")); \
         return std::numeric_limits<T>::quiet_NaN(); \
      }                                              \

      // f(i_0,i_1,....,i_N) --> Scalar
      inline virtual T operator() (parameter_list_t)
      igeneric_function_empty_body(1)

      // f(i_0,i_1,....,i_N) --> String
      inline virtual T operator() (std::string&, parameter_list_t)
      igeneric_function_empty_body(2)

      // f(psi,i_0,i_1,....,i_N) --> Scalar
      inline virtual T operator() (const std::size_t&, parameter_list_t)
      igeneric_function_empty_body(3)

      // f(psi,i_0,i_1,....,i_N) --> String
      inline virtual T operator() (const std::size_t&, std::string&, parameter_list_t)
      igeneric_function_empty_body(4)

      #undef igeneric_function_empty_body

      std::string parameter_sequence;
      return_type rtrn_type;
   };

   #ifndef exprtk_disable_string_capabilities
   template <typename T>
   class stringvar_base
   {
   public:

      typedef typename details::stringvar_node<T> stringvar_node_t;

      stringvar_base(const std::string& name, stringvar_node_t* svn)
      : name_(name)
      , string_varnode_(svn)
      {}

      bool valid() const
      {
         return !name_.empty() && (0 != string_varnode_);
      }

      std::string name() const
      {
         assert(string_varnode_);
         return name_;
      }

      void rebase(std::string& s)
      {
         assert(string_varnode_);
         string_varnode_->rebase(s);
      }

   private:

      std::string name_;
      stringvar_node_t* string_varnode_;
   };
   #endif

   template <typename T> class parser;
   template <typename T> class expression_helper;

   template <typename T>
   class symbol_table
   {
   public:

     enum symtab_mutability_type
     {
       e_unknown   = 0,
       e_mutable   = 1,
       e_immutable = 2
     };

     typedef T (*ff00_functor)();
     typedef T (*ff01_functor)(T);
     typedef T (*ff02_functor)(T, T);
     typedef T (*ff03_functor)(T, T, T);
     typedef T (*ff04_functor)(T, T, T, T);
     typedef T (*ff05_functor)(T, T, T, T, T);
     typedef T (*ff06_functor)(T, T, T, T, T, T);
     typedef T (*ff07_functor)(T, T, T, T, T, T, T);
     typedef T (*ff08_functor)(T, T, T, T, T, T, T, T);
     typedef T (*ff09_functor)(T, T, T, T, T, T, T, T, T);
     typedef T (*ff10_functor)(T, T, T, T, T, T, T, T, T, T);
     typedef T (*ff11_functor)(T, T, T, T, T, T, T, T, T, T, T);
     typedef T (*ff12_functor)(T, T, T, T, T, T, T, T, T, T, T, T);
     typedef T (*ff13_functor)(T, T, T, T, T, T, T, T, T, T, T, T, T);
     typedef T (*ff14_functor)(T, T, T, T, T, T, T, T, T, T, T, T, T, T);
     typedef T (*ff15_functor)(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T);

   protected:

       struct freefunc00 exprtk_final : public exprtk::ifunction<T>
       {
          using exprtk::ifunction<T>::operator();

          explicit freefunc00(ff00_functor ff) : exprtk::ifunction<T>(0), f(ff) {}
          inline T operator() () exprtk_override
          { return f(); }
          ff00_functor f;
       };

      struct freefunc01 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc01(ff01_functor ff) : exprtk::ifunction<T>(1), f(ff) {}
         inline T operator() (const T& v0) exprtk_override
         { return f(v0); }
         ff01_functor f;
      };

      struct freefunc02 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc02(ff02_functor ff) : exprtk::ifunction<T>(2), f(ff) {}
         inline T operator() (const T& v0, const T& v1) exprtk_override
         { return f(v0, v1); }
         ff02_functor f;
      };

      struct freefunc03 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc03(ff03_functor ff) : exprtk::ifunction<T>(3), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2) exprtk_override
         { return f(v0, v1, v2); }
         ff03_functor f;
      };

      struct freefunc04 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc04(ff04_functor ff) : exprtk::ifunction<T>(4), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3) exprtk_override
         { return f(v0, v1, v2, v3); }
         ff04_functor f;
      };

      struct freefunc05 : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc05(ff05_functor ff) : exprtk::ifunction<T>(5), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4) exprtk_override
         { return f(v0, v1, v2, v3, v4); }
         ff05_functor f;
      };

      struct freefunc06 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc06(ff06_functor ff) : exprtk::ifunction<T>(6), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4, const T& v5) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5); }
         ff06_functor f;
      };

      struct freefunc07 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc07(ff07_functor ff) : exprtk::ifunction<T>(7), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4,
                              const T& v5, const T& v6) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5, v6); }
         ff07_functor f;
      };

      struct freefunc08 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc08(ff08_functor ff) : exprtk::ifunction<T>(8), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4,
                              const T& v5, const T& v6, const T& v7) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5, v6, v7); }
         ff08_functor f;
      };

      struct freefunc09 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc09(ff09_functor ff) : exprtk::ifunction<T>(9), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4,
                              const T& v5, const T& v6, const T& v7, const T& v8) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5, v6, v7, v8); }
         ff09_functor f;
      };

      struct freefunc10 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc10(ff10_functor ff) : exprtk::ifunction<T>(10), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4,
                              const T& v5, const T& v6, const T& v7, const T& v8, const T& v9) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9); }
         ff10_functor f;
      };

      struct freefunc11 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc11(ff11_functor ff) : exprtk::ifunction<T>(11), f(ff) {}
         inline T operator() (const T& v0, const T& v1, const T& v2, const T& v3, const T& v4,
                              const T& v5, const T& v6, const T& v7, const T& v8, const T& v9, const T& v10) exprtk_override
         { return f(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10); }
         ff11_functor f;
      };

      struct freefunc12 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc12(ff12_functor ff) : exprtk::ifunction<T>(12), f(ff) {}
         inline T operator() (const T& v00, const T& v01, const T& v02, const T& v03, const T& v04,
                              const T& v05, const T& v06, const T& v07, const T& v08, const T& v09,
                              const T& v10, const T& v11) exprtk_override
         { return f(v00, v01, v02, v03, v04, v05, v06, v07, v08, v09, v10, v11); }
         ff12_functor f;
      };

      struct freefunc13 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc13(ff13_functor ff) : exprtk::ifunction<T>(13), f(ff) {}
         inline T operator() (const T& v00, const T& v01, const T& v02, const T& v03, const T& v04,
                              const T& v05, const T& v06, const T& v07, const T& v08, const T& v09,
                              const T& v10, const T& v11, const T& v12) exprtk_override
         { return f(v00, v01, v02, v03, v04, v05, v06, v07, v08, v09, v10, v11, v12); }
         ff13_functor f;
      };

      struct freefunc14 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc14(ff14_functor ff) : exprtk::ifunction<T>(14), f(ff) {}
         inline T operator() (const T& v00, const T& v01, const T& v02, const T& v03, const T& v04,
                              const T& v05, const T& v06, const T& v07, const T& v08, const T& v09,
                              const T& v10, const T& v11, const T& v12, const T& v13) exprtk_override
         { return f(v00, v01, v02, v03, v04, v05, v06, v07, v08, v09, v10, v11, v12, v13); }
         ff14_functor f;
      };

      struct freefunc15 exprtk_final : public exprtk::ifunction<T>
      {
         using exprtk::ifunction<T>::operator();

         explicit freefunc15(ff15_functor ff) : exprtk::ifunction<T>(15), f(ff) {}
         inline T operator() (const T& v00, const T& v01, const T& v02, const T& v03, const T& v04,
                              const T& v05, const T& v06, const T& v07, const T& v08, const T& v09,
                              const T& v10, const T& v11, const T& v12, const T& v13, const T& v14) exprtk_override
         { return f(v00, v01, v02, v03, v04, v05, v06, v07, v08, v09, v10, v11, v12, v13, v14); }
         ff15_functor f;
      };

      template <typename Type, typename RawType>
      struct type_store
      {
         typedef details::expression_node<T>*        expression_ptr;
         typedef typename details::variable_node<T>  variable_node_t;
         typedef ifunction<T>                        ifunction_t;
         typedef ivararg_function<T>                 ivararg_function_t;
         typedef igeneric_function<T>                igeneric_function_t;
         typedef details::vector_holder<T>           vector_t;
         #ifndef exprtk_disable_string_capabilities
         typedef typename details::stringvar_node<T> stringvar_node_t;
         #endif

         typedef Type type_t;
         typedef type_t* type_ptr;
         typedef std::pair<bool,type_ptr> type_pair_t;
         typedef std::map<std::string,type_pair_t,details::ilesscompare> type_map_t;
         typedef typename type_map_t::iterator tm_itr_t;
         typedef typename type_map_t::const_iterator tm_const_itr_t;

         enum { lut_size = 256 };

         type_map_t  map;
         std::size_t size;

         type_store()
         : size(0)
         {}

         struct deleter
         {
            #define exprtk_define_process(Type)                  \
            static inline void process(std::pair<bool,Type*>& n) \
            {                                                    \
               delete n.second;                                  \
            }                                                    \

            exprtk_define_process(variable_node_t )
            exprtk_define_process(vector_t        )
            #ifndef exprtk_disable_string_capabilities
            exprtk_define_process(stringvar_node_t)
            #endif

            #undef exprtk_define_process

            template <typename DeleteType>
            static inline void process(std::pair<bool,DeleteType*>&)
            {}
         };

         inline bool symbol_exists(const std::string& symbol_name) const
         {
            if (symbol_name.empty())
               return false;
            else if (map.end() != map.find(symbol_name))
               return true;
            else
               return false;
         }

         template <typename PtrType>
         inline std::string entity_name(const PtrType& ptr) const
         {
            if (map.empty())
               return std::string();

            tm_const_itr_t itr = map.begin();

            while (map.end() != itr)
            {
               if (itr->second.second == ptr)
               {
                  return itr->first;
               }
               else
                  ++itr;
            }

            return std::string();
         }

         inline bool is_constant(const std::string& symbol_name) const
         {
            if (symbol_name.empty())
               return false;
            else
            {
               const tm_const_itr_t itr = map.find(symbol_name);

               if (map.end() == itr)
                  return false;
               else
                  return (*itr).second.first;
            }
         }

         template <typename Tie, typename RType>
         inline bool add_impl(const std::string& symbol_name, RType t, const bool is_const)
         {
            if (symbol_name.size() > 1)
            {
               for (std::size_t i = 0; i < details::reserved_symbols_size; ++i)
               {
                  if (details::imatch(symbol_name, details::reserved_symbols[i]))
                  {
                     return false;
                  }
               }
            }

            const tm_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
            {
               map[symbol_name] = Tie::make(t,is_const);
               ++size;
            }

            return true;
         }

         struct tie_array
         {
            static inline std::pair<bool,vector_t*> make(std::pair<T*,std::size_t> v, const bool is_const = false)
            {
               return std::make_pair(is_const, new vector_t(v.first, v.second));
            }
         };

         struct tie_stdvec
         {
            template <typename Allocator>
            static inline std::pair<bool,vector_t*> make(std::vector<T,Allocator>& v, const bool is_const = false)
            {
               return std::make_pair(is_const, new vector_t(v));
            }
         };

         struct tie_vecview
         {
            static inline std::pair<bool,vector_t*> make(exprtk::vector_view<T>& v, const bool is_const = false)
            {
               return std::make_pair(is_const, new vector_t(v));
            }
         };

         struct tie_stddeq
         {
            template <typename Allocator>
            static inline std::pair<bool,vector_t*> make(std::deque<T,Allocator>& v, const bool is_const = false)
            {
               return std::make_pair(is_const, new vector_t(v));
            }
         };

         template <std::size_t v_size>
         inline bool add(const std::string& symbol_name, T (&v)[v_size], const bool is_const = false)
         {
            return add_impl<tie_array,std::pair<T*,std::size_t> >
                      (symbol_name, std::make_pair(v,v_size), is_const);
         }

         inline bool add(const std::string& symbol_name, T* v, const std::size_t v_size, const bool is_const = false)
         {
            return add_impl<tie_array,std::pair<T*,std::size_t> >
                     (symbol_name, std::make_pair(v,v_size), is_const);
         }

         template <typename Allocator>
         inline bool add(const std::string& symbol_name, std::vector<T,Allocator>& v, const bool is_const = false)
         {
            return add_impl<tie_stdvec,std::vector<T,Allocator>&>
                      (symbol_name, v, is_const);
         }

         inline bool add(const std::string& symbol_name, exprtk::vector_view<T>& v, const bool is_const = false)
         {
            return add_impl<tie_vecview,exprtk::vector_view<T>&>
                      (symbol_name, v, is_const);
         }

         template <typename Allocator>
         inline bool add(const std::string& symbol_name, std::deque<T,Allocator>& v, const bool is_const = false)
         {
            return add_impl<tie_stddeq,std::deque<T,Allocator>&>
                      (symbol_name, v, is_const);
         }

         inline bool add(const std::string& symbol_name, RawType& t_, const bool is_const = false)
         {
            struct tie
            {
               static inline std::pair<bool,variable_node_t*> make(T& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant, new variable_node_t(t));
               }

               #ifndef exprtk_disable_string_capabilities
               static inline std::pair<bool,stringvar_node_t*> make(std::string& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant, new stringvar_node_t(t));
               }
               #endif

               static inline std::pair<bool,function_t*> make(function_t& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant,&t);
               }

               static inline std::pair<bool,vararg_function_t*> make(vararg_function_t& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant,&t);
               }

               static inline std::pair<bool,generic_function_t*> make(generic_function_t& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant,&t);
               }
            };

            const tm_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
            {
               map[symbol_name] = tie::make(t_,is_const);
               ++size;
            }

            return true;
         }

         inline type_ptr get(const std::string& symbol_name) const
         {
            const tm_const_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
               return reinterpret_cast<type_ptr>(0);
            else
               return itr->second.second;
         }

         template <typename TType, typename TRawType, typename PtrType>
         struct ptr_match
         {
            static inline bool test(const PtrType, const void*)
            {
               return false;
            }
         };

         template <typename TType, typename TRawType>
         struct ptr_match<TType,TRawType,variable_node_t*>
         {
            static inline bool test(const variable_node_t* p, const void* ptr)
            {
               exprtk_debug(("ptr_match::test() - %p <--> %p\n", reinterpret_cast<const void*>(&(p->ref())), ptr));
               return (&(p->ref()) == ptr);
            }
         };

         inline type_ptr get_from_varptr(const void* ptr) const
         {
            tm_const_itr_t itr = map.begin();

            while (map.end() != itr)
            {
               type_ptr ret_ptr = itr->second.second;

               if (ptr_match<Type,RawType,type_ptr>::test(ret_ptr,ptr))
               {
                  return ret_ptr;
               }

               ++itr;
            }

            return type_ptr(0);
         }

         inline bool remove(const std::string& symbol_name, const bool delete_node = true)
         {
            const tm_itr_t itr = map.find(symbol_name);

            if (map.end() != itr)
            {
               if (delete_node)
               {
                  deleter::process((*itr).second);
               }

               map.erase(itr);
               --size;

               return true;
            }
            else
               return false;
         }

         inline RawType& type_ref(const std::string& symbol_name)
         {
            struct init_type
            {
               static inline double set(double)           { return (0.0);           }
               static inline double set(long double)      { return (0.0);           }
               static inline float  set(float)            { return (0.0f);          }
               static inline std::string set(std::string) { return std::string(""); }
            };

            static RawType null_type = init_type::set(RawType());

            const tm_const_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
               return null_type;
            else
               return itr->second.second->ref();
         }

         inline void clear(const bool delete_node = true)
         {
            if (!map.empty())
            {
               if (delete_node)
               {
                  tm_itr_t itr = map.begin();
                  tm_itr_t end = map.end  ();

                  while (end != itr)
                  {
                     deleter::process((*itr).second);
                     ++itr;
                  }
               }

               map.clear();
            }

            size = 0;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t get_list(Sequence<std::pair<std::string,RawType>,Allocator>& list) const
         {
            std::size_t count = 0;

            if (!map.empty())
            {
               tm_const_itr_t itr = map.begin();
               tm_const_itr_t end = map.end  ();

               while (end != itr)
               {
                  list.push_back(std::make_pair((*itr).first,itr->second.second->ref()));
                  ++itr;
                  ++count;
               }
            }

            return count;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t get_list(Sequence<std::string,Allocator>& vlist) const
         {
            std::size_t count = 0;

            if (!map.empty())
            {
               tm_const_itr_t itr = map.begin();
               tm_const_itr_t end = map.end  ();

               while (end != itr)
               {
                  vlist.push_back((*itr).first);
                  ++itr;
                  ++count;
               }
            }

            return count;
         }
      };

      typedef details::expression_node<T>*        expression_ptr;
      typedef typename details::variable_node<T>  variable_t;
      typedef typename details::vector_holder<T>  vector_holder_t;
      typedef variable_t*                         variable_ptr;
      #ifndef exprtk_disable_string_capabilities
      typedef typename details::stringvar_node<T> stringvar_t;
      typedef stringvar_t*                        stringvar_ptr;
      #endif
      typedef ifunction        <T>                function_t;
      typedef ivararg_function <T>                vararg_function_t;
      typedef igeneric_function<T>                generic_function_t;
      typedef function_t*                         function_ptr;
      typedef vararg_function_t*                  vararg_function_ptr;
      typedef generic_function_t*                 generic_function_ptr;

      static const std::size_t lut_size = 256;

      // Symbol Table Holder
      struct control_block
      {
         struct st_data
         {
            type_store<variable_t        , T                 > variable_store;
            type_store<function_t        , function_t        > function_store;
            type_store<vararg_function_t , vararg_function_t > vararg_function_store;
            type_store<generic_function_t, generic_function_t> generic_function_store;
            type_store<generic_function_t, generic_function_t> string_function_store;
            type_store<generic_function_t, generic_function_t> overload_function_store;
            type_store<vector_holder_t   , vector_holder_t   > vector_store;
            #ifndef exprtk_disable_string_capabilities
            type_store<stringvar_t       , std::string       > stringvar_store;
            #endif

            st_data()
            {
               for (std::size_t i = 0; i < details::reserved_words_size; ++i)
               {
                  reserved_symbol_table_.insert(details::reserved_words[i]);
               }

               for (std::size_t i = 0; i < details::reserved_symbols_size; ++i)
               {
                  reserved_symbol_table_.insert(details::reserved_symbols[i]);
               }
            }

           ~st_data()
            {
               for (std::size_t i = 0; i < free_function_list_.size(); ++i)
               {
                  delete free_function_list_[i];
               }
            }

            inline bool is_reserved_symbol(const std::string& symbol) const
            {
               return (reserved_symbol_table_.end() != reserved_symbol_table_.find(symbol));
            }

            static inline st_data* create()
            {
               return (new st_data);
            }

            static inline void destroy(st_data*& sd)
            {
               delete sd;
               sd = reinterpret_cast<st_data*>(0);
            }

            std::list<T>               local_symbol_list_;
            std::list<std::string>     local_stringvar_list_;
            std::set<std::string>      reserved_symbol_table_;
            std::vector<ifunction<T>*> free_function_list_;
         };

         control_block()
         : ref_count(1)
         , data_(st_data::create())
         , mutability_(e_mutable)
         {}

         explicit control_block(st_data* data)
         : ref_count(1)
         , data_(data)
         , mutability_(e_mutable)
         {}

        ~control_block()
         {
            if (data_ && (0 == ref_count))
            {
               st_data::destroy(data_);
            }
         }

         static inline control_block* create()
         {
            return (new control_block);
         }

         template <typename SymTab>
         static inline void destroy(control_block*& cntrl_blck, SymTab* sym_tab)
         {
            if (cntrl_blck)
            {
               if (
                    (0 !=   cntrl_blck->ref_count) &&
                    (0 == --cntrl_blck->ref_count)
                  )
               {
                  if (sym_tab)
                     sym_tab->clear();

                  delete cntrl_blck;
               }

               cntrl_blck = 0;
            }
         }

         void set_mutability(const symtab_mutability_type mutability)
         {
            mutability_ = mutability;
         }

         std::size_t ref_count;
         st_data* data_;
         symtab_mutability_type mutability_;
      };

   public:

      explicit symbol_table(const symtab_mutability_type mutability = e_mutable)
      : control_block_(control_block::create())
      {
         control_block_->set_mutability(mutability);
         clear();
      }

     ~symbol_table()
      {
         exprtk::details::dump_ptr("~symbol_table", this);
         control_block::destroy(control_block_, this);
      }

      symbol_table(const symbol_table<T>& st)
      {
         control_block_ = st.control_block_;
         control_block_->ref_count++;
      }

      inline symbol_table<T>& operator=(const symbol_table<T>& st)
      {
         if (this != &st)
         {
            control_block::destroy(control_block_,reinterpret_cast<symbol_table<T>*>(0));

            control_block_ = st.control_block_;
            control_block_->ref_count++;
         }

         return (*this);
      }

      inline bool operator==(const symbol_table<T>& st) const
      {
         return (this == &st) || (control_block_ == st.control_block_);
      }

      inline symtab_mutability_type mutability() const
      {
         return valid() ? control_block_->mutability_ : e_unknown;
      }

      inline void clear_variables(const bool delete_node = true)
      {
         local_data().variable_store.clear(delete_node);
      }

      inline void clear_functions()
      {
         local_data().function_store.clear();
      }

      inline void clear_strings()
      {
         #ifndef exprtk_disable_string_capabilities
         local_data().stringvar_store.clear();
         #endif
      }

      inline void clear_vectors()
      {
         local_data().vector_store.clear();
      }

      inline void clear_local_constants()
      {
         local_data().local_symbol_list_.clear();
      }

      inline void clear()
      {
         if (!valid()) return;
         clear_variables      ();
         clear_functions      ();
         clear_strings        ();
         clear_vectors        ();
         clear_local_constants();
      }

      inline std::size_t variable_count() const
      {
         if (valid())
            return local_data().variable_store.size;
         else
            return 0;
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::size_t stringvar_count() const
      {
         if (valid())
            return local_data().stringvar_store.size;
         else
            return 0;
      }
      #endif

      inline std::size_t function_count() const
      {
         if (valid())
            return local_data().function_store.size;
         else
            return 0;
      }

      inline std::size_t vector_count() const
      {
         if (valid())
            return local_data().vector_store.size;
         else
            return 0;
      }

      inline variable_ptr get_variable(const std::string& variable_name) const
      {
         if (!valid())
            return reinterpret_cast<variable_ptr>(0);
         else if (!valid_symbol(variable_name))
            return reinterpret_cast<variable_ptr>(0);
         else
            return local_data().variable_store.get(variable_name);
      }

      inline variable_ptr get_variable(const T& var_ref) const
      {
         if (!valid())
            return reinterpret_cast<variable_ptr>(0);
         else
            return local_data().variable_store.get_from_varptr(
                                                  reinterpret_cast<const void*>(&var_ref));
      }

      #ifndef exprtk_disable_string_capabilities
      inline stringvar_ptr get_stringvar(const std::string& string_name) const
      {
         if (!valid())
            return reinterpret_cast<stringvar_ptr>(0);
         else if (!valid_symbol(string_name))
            return reinterpret_cast<stringvar_ptr>(0);
         else
            return local_data().stringvar_store.get(string_name);
      }

      inline stringvar_base<T> get_stringvar_base(const std::string& string_name) const
      {
         static stringvar_base<T> null_stringvar_base("",reinterpret_cast<stringvar_ptr>(0));
         if (!valid())
            return null_stringvar_base;
         else if (!valid_symbol(string_name))
            return null_stringvar_base;

         stringvar_ptr stringvar = local_data().stringvar_store.get(string_name);

         if (0 == stringvar)
         {
            return null_stringvar_base;
         }

         return stringvar_base<T>(string_name,stringvar);
      }
      #endif

      inline function_ptr get_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<function_ptr>(0);
         else
            return local_data().function_store.get(function_name);
      }

      inline vararg_function_ptr get_vararg_function(const std::string& vararg_function_name) const
      {
         if (!valid())
            return reinterpret_cast<vararg_function_ptr>(0);
         else if (!valid_symbol(vararg_function_name))
            return reinterpret_cast<vararg_function_ptr>(0);
         else
            return local_data().vararg_function_store.get(vararg_function_name);
      }

      inline generic_function_ptr get_generic_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<generic_function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<generic_function_ptr>(0);
         else
            return local_data().generic_function_store.get(function_name);
      }

      inline generic_function_ptr get_string_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<generic_function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<generic_function_ptr>(0);
         else
            return local_data().string_function_store.get(function_name);
      }

      inline generic_function_ptr get_overload_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<generic_function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<generic_function_ptr>(0);
         else
            return local_data().overload_function_store.get(function_name);
      }

      typedef vector_holder_t* vector_holder_ptr;

      inline vector_holder_ptr get_vector(const std::string& vector_name) const
      {
         if (!valid())
            return reinterpret_cast<vector_holder_ptr>(0);
         else if (!valid_symbol(vector_name))
            return reinterpret_cast<vector_holder_ptr>(0);
         else
            return local_data().vector_store.get(vector_name);
      }

      inline T& variable_ref(const std::string& symbol_name)
      {
         static T null_var = T(0);
         if (!valid())
            return null_var;
         else if (!valid_symbol(symbol_name))
            return null_var;
         else
            return local_data().variable_store.type_ref(symbol_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::string& stringvar_ref(const std::string& symbol_name)
      {
         static std::string null_stringvar;
         if (!valid())
            return null_stringvar;
         else if (!valid_symbol(symbol_name))
            return null_stringvar;
         else
            return local_data().stringvar_store.type_ref(symbol_name);
      }
      #endif

      inline bool is_constant_node(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else
            return local_data().variable_store.is_constant(symbol_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool is_constant_string(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else if (!local_data().stringvar_store.symbol_exists(symbol_name))
            return false;
         else
            return local_data().stringvar_store.is_constant(symbol_name);
      }
      #endif

      inline bool create_variable(const std::string& variable_name, const T& value = T(0))
      {
         if (!valid())
            return false;
         else if (!valid_symbol(variable_name))
            return false;
         else if (symbol_exists(variable_name))
            return false;

         local_data().local_symbol_list_.push_back(value);
         T& t = local_data().local_symbol_list_.back();

         return add_variable(variable_name,t);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool create_stringvar(const std::string& stringvar_name, const std::string& value = std::string(""))
      {
         if (!valid())
            return false;
         else if (!valid_symbol(stringvar_name))
            return false;
         else if (symbol_exists(stringvar_name))
            return false;

         local_data().local_stringvar_list_.push_back(value);
         std::string& s = local_data().local_stringvar_list_.back();

         return add_stringvar(stringvar_name,s);
      }
      #endif

      inline bool add_variable(const std::string& variable_name, T& t, const bool is_constant = false)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(variable_name))
            return false;
         else if (symbol_exists(variable_name))
            return false;
         else
            return local_data().variable_store.add(variable_name, t, is_constant);
      }

      inline bool add_constant(const std::string& constant_name, const T& value)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(constant_name))
            return false;
         else if (symbol_exists(constant_name))
            return false;

         local_data().local_symbol_list_.push_back(value);
         T& t = local_data().local_symbol_list_.back();

         return add_variable(constant_name, t, true);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool add_stringvar(const std::string& stringvar_name, std::string& s, const bool is_constant = false)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(stringvar_name))
            return false;
         else if (symbol_exists(stringvar_name))
            return false;
         else
            return local_data().stringvar_store.add(stringvar_name, s, is_constant);
      }
      #endif

      inline bool add_function(const std::string& function_name, function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name))
            return false;
         else if (symbol_exists(function_name))
            return false;
         else
            return local_data().function_store.add(function_name,function);
      }

      inline bool add_function(const std::string& vararg_function_name, vararg_function_t& vararg_function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vararg_function_name))
            return false;
         else if (symbol_exists(vararg_function_name))
            return false;
         else
            return local_data().vararg_function_store.add(vararg_function_name,vararg_function);
      }

      inline bool add_function(const std::string& function_name, generic_function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name))
            return false;
         else if (symbol_exists(function_name))
            return false;
         else
         {
            switch (function.rtrn_type)
            {
               case generic_function_t::e_rtrn_scalar :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|")) ?
                         local_data().generic_function_store.add(function_name,function) : false;

               case generic_function_t::e_rtrn_string :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|")) ?
                         local_data().string_function_store.add(function_name,function)  : false;

               case generic_function_t::e_rtrn_overload :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|:")) ?
                         local_data().overload_function_store.add(function_name,function) : false;
            }
         }

         return false;
      }

      #define exprtk_define_freefunction(NN)                                                \
      inline bool add_function(const std::string& function_name, ff##NN##_functor function) \
      {                                                                                     \
         if (!valid())                                                                      \
         { return false; }                                                                  \
         if (!valid_symbol(function_name))                                                  \
         { return false; }                                                                  \
         if (symbol_exists(function_name))                                                  \
         { return false; }                                                                  \
                                                                                            \
         exprtk::ifunction<T>* ifunc = new freefunc##NN(function);                          \
                                                                                            \
         local_data().free_function_list_.push_back(ifunc);                                 \
                                                                                            \
         return add_function(function_name,(*local_data().free_function_list_.back()));     \
      }                                                                                     \

      exprtk_define_freefunction(00) exprtk_define_freefunction(01)
      exprtk_define_freefunction(02) exprtk_define_freefunction(03)
      exprtk_define_freefunction(04) exprtk_define_freefunction(05)
      exprtk_define_freefunction(06) exprtk_define_freefunction(07)
      exprtk_define_freefunction(08) exprtk_define_freefunction(09)
      exprtk_define_freefunction(10) exprtk_define_freefunction(11)
      exprtk_define_freefunction(12) exprtk_define_freefunction(13)
      exprtk_define_freefunction(14) exprtk_define_freefunction(15)

      #undef exprtk_define_freefunction

      inline bool add_reserved_function(const std::string& function_name, function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name,false))
            return false;
         else if (symbol_exists(function_name,false))
            return false;
         else
            return local_data().function_store.add(function_name,function);
      }

      inline bool add_reserved_function(const std::string& vararg_function_name, vararg_function_t& vararg_function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vararg_function_name,false))
            return false;
         else if (symbol_exists(vararg_function_name,false))
            return false;
         else
            return local_data().vararg_function_store.add(vararg_function_name,vararg_function);
      }

      inline bool add_reserved_function(const std::string& function_name, generic_function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name,false))
            return false;
         else if (symbol_exists(function_name,false))
            return false;
         else
         {
            switch (function.rtrn_type)
            {
               case generic_function_t::e_rtrn_scalar :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|")) ?
                         local_data().generic_function_store.add(function_name,function) : false;

               case generic_function_t::e_rtrn_string :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|")) ?
                         local_data().string_function_store.add(function_name,function)  : false;

               case generic_function_t::e_rtrn_overload :
                  return (std::string::npos == function.parameter_sequence.find_first_not_of("STVZ*?|:")) ?
                         local_data().overload_function_store.add(function_name,function) : false;
            }
         }

         return false;
      }

      #define exprtk_define_reserved_function(NN)                                                    \
      inline bool add_reserved_function(const std::string& function_name, ff##NN##_functor function) \
      {                                                                                              \
         if (!valid())                                                                               \
         { return false; }                                                                           \
         if (!valid_symbol(function_name,false))                                                     \
         { return false; }                                                                           \
         if (symbol_exists(function_name,false))                                                     \
         { return false; }                                                                           \
                                                                                                     \
         exprtk::ifunction<T>* ifunc = new freefunc##NN(function);                                   \
                                                                                                     \
         local_data().free_function_list_.push_back(ifunc);                                          \
                                                                                                     \
         return add_reserved_function(function_name,(*local_data().free_function_list_.back()));     \
      }                                                                                              \

      exprtk_define_reserved_function(00) exprtk_define_reserved_function(01)
      exprtk_define_reserved_function(02) exprtk_define_reserved_function(03)
      exprtk_define_reserved_function(04) exprtk_define_reserved_function(05)
      exprtk_define_reserved_function(06) exprtk_define_reserved_function(07)
      exprtk_define_reserved_function(08) exprtk_define_reserved_function(09)
      exprtk_define_reserved_function(10) exprtk_define_reserved_function(11)
      exprtk_define_reserved_function(12) exprtk_define_reserved_function(13)
      exprtk_define_reserved_function(14) exprtk_define_reserved_function(15)

      #undef exprtk_define_reserved_function

      template <std::size_t N>
      inline bool add_vector(const std::string& vector_name, T (&v)[N])
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      inline bool add_vector(const std::string& vector_name, T* v, const std::size_t& v_size)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else if (0 == v_size)
            return false;
         else
            return local_data().vector_store.add(vector_name, v, v_size);
      }

      template <typename Allocator>
      inline bool add_vector(const std::string& vector_name, std::vector<T,Allocator>& v)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else if (0 == v.size())
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      inline bool add_vector(const std::string& vector_name, exprtk::vector_view<T>& v)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else if (0 == v.size())
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      inline bool remove_variable(const std::string& variable_name, const bool delete_node = true)
      {
         if (!valid())
            return false;
         else
            return local_data().variable_store.remove(variable_name, delete_node);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool remove_stringvar(const std::string& string_name)
      {
         if (!valid())
            return false;
         else
            return local_data().stringvar_store.remove(string_name);
      }
      #endif

      inline bool remove_function(const std::string& function_name)
      {
         if (!valid())
            return false;
         else
            return local_data().function_store.remove(function_name);
      }

      inline bool remove_vararg_function(const std::string& vararg_function_name)
      {
         if (!valid())
            return false;
         else
            return local_data().vararg_function_store.remove(vararg_function_name);
      }

      inline bool remove_vector(const std::string& vector_name)
      {
         if (!valid())
            return false;
         else
            return local_data().vector_store.remove(vector_name);
      }

      inline bool add_constants()
      {
         return add_pi      () &&
                add_epsilon () &&
                add_infinity() ;
      }

      inline bool add_pi()
      {
         const typename details::numeric::details::number_type<T>::type num_type;
         static const T local_pi = details::numeric::details::const_pi_impl<T>(num_type);
         return add_constant("pi",local_pi);
      }

      inline bool add_epsilon()
      {
         static const T local_epsilon = details::numeric::details::epsilon_type<T>::value();
         return add_constant("epsilon",local_epsilon);
      }

      inline bool add_infinity()
      {
         static const T local_infinity = std::numeric_limits<T>::infinity();
         return add_constant("inf",local_infinity);
      }

      template <typename Package>
      inline bool add_package(Package& package)
      {
         return package.register_package(*this);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_variable_list(Sequence<std::pair<std::string,T>,Allocator>& vlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().variable_store.get_list(vlist);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_variable_list(Sequence<std::string,Allocator>& vlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().variable_store.get_list(vlist);
      }

      #ifndef exprtk_disable_string_capabilities
      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_stringvar_list(Sequence<std::pair<std::string,std::string>,Allocator>& svlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().stringvar_store.get_list(svlist);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_stringvar_list(Sequence<std::string,Allocator>& svlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().stringvar_store.get_list(svlist);
      }
      #endif

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_vector_list(Sequence<std::string,Allocator>& vec_list) const
      {
         if (!valid())
            return 0;
         else
            return local_data().vector_store.get_list(vec_list);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_function_list(Sequence<std::string,Allocator>& function_list) const
      {
         if (!valid())
            return 0;

         std::vector<std::string> function_names;
         std::size_t count = 0;

         count += local_data().function_store         .get_list(function_names);
         count += local_data().vararg_function_store  .get_list(function_names);
         count += local_data().generic_function_store .get_list(function_names);
         count += local_data().string_function_store  .get_list(function_names);
         count += local_data().overload_function_store.get_list(function_names);

         std::set<std::string> function_set;

         for (std::size_t i = 0; i < function_names.size(); ++i)
         {
            function_set.insert(function_names[i]);
         }

         std::copy(function_set.begin(), function_set.end(),
                   std::back_inserter(function_list));

         return count;
      }

      inline std::vector<std::string> get_function_list() const
      {
         std::vector<std::string> result;
         get_function_list(result);
         return result;
      }

      inline bool symbol_exists(const std::string& symbol_name, const bool check_reserved_symb = true) const
      {
         /*
            Function will return true if symbol_name exists as either a
            reserved symbol, variable, stringvar, vector or function name
            in any of the type stores.
         */
         if (!valid())
            return false;
         else if (local_data().variable_store.symbol_exists(symbol_name))
            return true;
         #ifndef exprtk_disable_string_capabilities
         else if (local_data().stringvar_store.symbol_exists(symbol_name))
            return true;
         #endif
         else if (local_data().vector_store.symbol_exists(symbol_name))
            return true;
         else if (local_data().function_store.symbol_exists(symbol_name))
            return true;
         else if (check_reserved_symb && local_data().is_reserved_symbol(symbol_name))
            return true;
         else
            return false;
      }

      inline bool is_variable(const std::string& variable_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().variable_store.symbol_exists(variable_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool is_stringvar(const std::string& stringvar_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().stringvar_store.symbol_exists(stringvar_name);
      }

      inline bool is_conststr_stringvar(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else if (!local_data().stringvar_store.symbol_exists(symbol_name))
            return false;

         return (
                  local_data().stringvar_store.symbol_exists(symbol_name) ||
                  local_data().stringvar_store.is_constant  (symbol_name)
                );
      }
      #endif

      inline bool is_function(const std::string& function_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().function_store.symbol_exists(function_name);
      }

      inline bool is_vararg_function(const std::string& vararg_function_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().vararg_function_store.symbol_exists(vararg_function_name);
      }

      inline bool is_vector(const std::string& vector_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().vector_store.symbol_exists(vector_name);
      }

      inline std::string get_variable_name(const expression_ptr& ptr) const
      {
         return local_data().variable_store.entity_name(ptr);
      }

      inline std::string get_vector_name(const vector_holder_ptr& ptr) const
      {
         return local_data().vector_store.entity_name(ptr);
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::string get_stringvar_name(const expression_ptr& ptr) const
      {
         return local_data().stringvar_store.entity_name(ptr);
      }

      inline std::string get_conststr_stringvar_name(const expression_ptr& ptr) const
      {
         return local_data().stringvar_store.entity_name(ptr);
      }
      #endif

      inline bool valid() const
      {
         // Symbol table sanity check.
         return control_block_ && control_block_->data_;
      }

      inline void load_from(const symbol_table<T>& st)
      {
         {
            std::vector<std::string> name_list;

            st.local_data().function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::ifunction<T>& ifunc = *st.get_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().vararg_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::ivararg_function<T>& ivafunc = *st.get_vararg_function(name_list[i]);
                  add_function(name_list[i],ivafunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().generic_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::igeneric_function<T>& ifunc = *st.get_generic_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().string_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::igeneric_function<T>& ifunc = *st.get_string_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().overload_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::igeneric_function<T>& ifunc = *st.get_overload_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }
      }

      inline void load_variables_from(const symbol_table<T>& st)
      {
         std::vector<std::string> name_list;

         st.local_data().variable_store.get_list(name_list);

         if (!name_list.empty())
         {
            for (std::size_t i = 0; i < name_list.size(); ++i)
            {
               T& variable = st.get_variable(name_list[i])->ref();
               add_variable(name_list[i], variable);
            }
         }
      }

      inline void load_vectors_from(const symbol_table<T>& st)
      {
         std::vector<std::string> name_list;

         st.local_data().vector_store.get_list(name_list);

         if (!name_list.empty())
         {
            for (std::size_t i = 0; i < name_list.size(); ++i)
            {
               vector_holder_t& vecholder = *st.get_vector(name_list[i]);
               add_vector(name_list[i], vecholder.data(), vecholder.size());
            }
         }
      }

   private:

      inline bool valid_symbol(const std::string& symbol, const bool check_reserved_symb = true) const
      {
         if (symbol.empty())
            return false;
         else if (!details::is_letter(symbol[0]))
            return false;
         else if (symbol.size() > 1)
         {
            for (std::size_t i = 1; i < symbol.size(); ++i)
            {
               if (
                    !details::is_letter_or_digit(symbol[i]) &&
                    ('_' != symbol[i])
                  )
               {
                  if ((i < (symbol.size() - 1)) && ('.' == symbol[i]))
                     continue;
                  else
                     return false;
               }
            }
         }

         return (check_reserved_symb) ? (!local_data().is_reserved_symbol(symbol)) : true;
      }

      inline bool valid_function(const std::string& symbol) const
      {
         if (symbol.empty())
            return false;
         else if (!details::is_letter(symbol[0]))
            return false;
         else if (symbol.size() > 1)
         {
            for (std::size_t i = 1; i < symbol.size(); ++i)
            {
               if (
                    !details::is_letter_or_digit(symbol[i]) &&
                    ('_' != symbol[i])
                  )
               {
                  if ((i < (symbol.size() - 1)) && ('.' == symbol[i]))
                     continue;
                  else
                     return false;
               }
            }
         }

         return true;
      }

      typedef typename control_block::st_data local_data_t;

      inline local_data_t& local_data()
      {
         return *(control_block_->data_);
      }

      inline const local_data_t& local_data() const
      {
         return *(control_block_->data_);
      }

      control_block* control_block_;

      friend class parser<T>;
   }; // class symbol_table

   template <typename T>
   class function_compositor;

   template <typename T>
   class expression
   {
   private:

      typedef details::expression_node<T>*  expression_ptr;
      typedef details::vector_holder<T>*    vector_holder_ptr;
      typedef std::vector<symbol_table<T> > symtab_list_t;

      struct control_block
      {
         enum data_type
         {
            e_unknown  ,
            e_expr     ,
            e_vecholder,
            e_data     ,
            e_vecdata  ,
            e_string
         };

         static std::string to_str(data_type dt)
         {
            switch(dt)
            {
               case e_unknown   : return "e_unknown  ";
               case e_expr      : return "e_expr"     ;
               case e_vecholder : return "e_vecholder";
               case e_data      : return "e_data"     ;
               case e_vecdata   : return "e_vecdata"  ;
               case e_string    : return "e_string"   ;
            }

            return "";
         }

         struct data_pack
         {
            data_pack()
            : pointer(0)
            , type(e_unknown)
            , size(0)
            {}

            data_pack(void* ptr, const data_type dt, const std::size_t sz = 0)
            : pointer(ptr)
            , type(dt)
            , size(sz)
            {}

            void*       pointer;
            data_type   type;
            std::size_t size;
         };

         typedef std::vector<data_pack> local_data_list_t;
         typedef results_context<T>     results_context_t;
         typedef control_block*         cntrl_blck_ptr_t;

         control_block()
         : ref_count(0)
         , expr     (0)
         , results  (0)
         , retinv_null(false)
         , return_invoked(&retinv_null)
         {}

         explicit control_block(expression_ptr e)
         : ref_count(1)
         , expr     (e)
         , results  (0)
         , retinv_null(false)
         , return_invoked(&retinv_null)
         {}

        ~control_block()
         {
            if (expr && details::branch_deletable(expr))
            {
               destroy_node(expr);
            }

            if (!local_data_list.empty())
            {
               for (std::size_t i = 0; i < local_data_list.size(); ++i)
               {
                  switch (local_data_list[i].type)
                  {
                     case e_expr      : delete reinterpret_cast<expression_ptr>(local_data_list[i].pointer);
                                        break;

                     case e_vecholder : delete reinterpret_cast<vector_holder_ptr>(local_data_list[i].pointer);
                                        break;

                     case e_data      : delete reinterpret_cast<T*>(local_data_list[i].pointer);
                                        break;

                     case e_vecdata   : delete [] reinterpret_cast<T*>(local_data_list[i].pointer);
                                        break;

                     case e_string    : delete reinterpret_cast<std::string*>(local_data_list[i].pointer);
                                        break;

                     default          : break;
                  }
               }
            }

            if (results)
            {
               delete results;
            }
         }

         static inline cntrl_blck_ptr_t create(expression_ptr e)
         {
            return new control_block(e);
         }

         static inline void destroy(cntrl_blck_ptr_t& cntrl_blck)
         {
            if (cntrl_blck)
            {
               if (
                    (0 !=   cntrl_blck->ref_count) &&
                    (0 == --cntrl_blck->ref_count)
                  )
               {
                  delete cntrl_blck;
               }

               cntrl_blck = 0;
            }
         }

         std::size_t ref_count;
         expression_ptr expr;
         local_data_list_t local_data_list;
         results_context_t* results;
         bool  retinv_null;
         bool* return_invoked;

         friend class function_compositor<T>;
      };

   public:

      expression()
      : control_block_(0)
      {
         set_expression(new details::null_node<T>());
      }

      expression(const expression<T>& e)
      : control_block_    (e.control_block_    )
      , symbol_table_list_(e.symbol_table_list_)
      {
         control_block_->ref_count++;
      }

      explicit expression(const symbol_table<T>& symbol_table)
      : control_block_(0)
      {
         set_expression(new details::null_node<T>());
         symbol_table_list_.push_back(symbol_table);
      }

      inline expression<T>& operator=(const expression<T>& e)
      {
         if (this != &e)
         {
            if (control_block_)
            {
               if (
                    (0 !=   control_block_->ref_count) &&
                    (0 == --control_block_->ref_count)
                  )
               {
                  delete control_block_;
               }

               control_block_ = 0;
            }

            control_block_ = e.control_block_;
            control_block_->ref_count++;
            symbol_table_list_ = e.symbol_table_list_;
         }

         return *this;
      }

      inline bool operator==(const expression<T>& e) const
      {
         return (this == &e);
      }

      inline bool operator!() const
      {
         return (
                  (0 == control_block_      ) ||
                  (0 == control_block_->expr)
                );
      }

      inline expression<T>& release()
      {
         exprtk::details::dump_ptr("expression::release", this);
         control_block::destroy(control_block_);

         return (*this);
      }

     ~expression()
      {
         control_block::destroy(control_block_);
      }

      inline T value() const
      {
         assert(control_block_      );
         assert(control_block_->expr);

         return control_block_->expr->value();
      }

      inline T operator() () const
      {
         return value();
      }

      inline operator T() const
      {
         return value();
      }

      inline operator bool() const
      {
         return details::is_true(value());
      }

      inline bool register_symbol_table(symbol_table<T>& st)
      {
         for (std::size_t i = 0; i < symbol_table_list_.size(); ++i)
         {
            if (st == symbol_table_list_[i])
            {
               return false;
            }
         }

         symbol_table_list_.push_back(st);
         return true;
      }

      inline const symbol_table<T>& get_symbol_table(const std::size_t& index = 0) const
      {
         return symbol_table_list_[index];
      }

      inline symbol_table<T>& get_symbol_table(const std::size_t& index = 0)
      {
         return symbol_table_list_[index];
      }

      std::size_t num_symbol_tables() const
      {
         return symbol_table_list_.size();
      }

      typedef results_context<T> results_context_t;

      inline const results_context_t& results() const
      {
         if (control_block_->results)
            return (*control_block_->results);
         else
         {
            static const results_context_t null_results;
            return null_results;
         }
      }

      inline bool return_invoked() const
      {
         return (*control_block_->return_invoked);
      }

   private:

      inline symtab_list_t get_symbol_table_list() const
      {
         return symbol_table_list_;
      }

      inline void set_expression(const expression_ptr expr)
      {
         if (expr)
         {
            if (control_block_)
            {
               if (0 == --control_block_->ref_count)
               {
                  delete control_block_;
               }
            }

            control_block_ = control_block::create(expr);
         }
      }

      inline void register_local_var(expression_ptr expr)
      {
         if (expr)
         {
            if (control_block_)
            {
               control_block_->
                  local_data_list.push_back(
                     typename expression<T>::control_block::
                        data_pack(reinterpret_cast<void*>(expr),
                                  control_block::e_expr));
            }
         }
      }

      inline void register_local_var(vector_holder_ptr vec_holder)
      {
         if (vec_holder)
         {
            if (control_block_)
            {
               control_block_->
                  local_data_list.push_back(
                     typename expression<T>::control_block::
                        data_pack(reinterpret_cast<void*>(vec_holder),
                                  control_block::e_vecholder));
            }
         }
      }

      inline void register_local_data(void* data, const std::size_t& size = 0, const std::size_t data_mode = 0)
      {
         if (data)
         {
            if (control_block_)
            {
               typename control_block::data_type dt = control_block::e_data;

               switch (data_mode)
               {
                  case 0 : dt = control_block::e_data;    break;
                  case 1 : dt = control_block::e_vecdata; break;
                  case 2 : dt = control_block::e_string;  break;
               }

               control_block_->
                  local_data_list.push_back(
                     typename expression<T>::control_block::
                        data_pack(reinterpret_cast<void*>(data), dt, size));
            }
         }
      }

      inline const typename control_block::local_data_list_t& local_data_list()
      {
         if (control_block_)
         {
            return control_block_->local_data_list;
         }
         else
         {
            static typename control_block::local_data_list_t null_local_data_list;
            return null_local_data_list;
         }
      }

      inline void register_return_results(results_context_t* rc)
      {
         if (control_block_ && rc)
         {
            control_block_->results = rc;
         }
      }

      inline void set_retinvk(bool* retinvk_ptr)
      {
         if (control_block_)
         {
            control_block_->return_invoked = retinvk_ptr;
         }
      }

      control_block* control_block_;
      symtab_list_t  symbol_table_list_;

      friend class parser<T>;
      friend class expression_helper<T>;
      friend class function_compositor<T>;
      template <typename TT>
      friend bool is_valid(const expression<TT>& expr);
   }; // class expression

   template <typename T>
   class expression_helper
   {
   public:

      enum node_types
      {
         e_literal,
         e_variable,
         e_string,
         e_unary,
         e_binary,
         e_function,
         e_vararg,
         e_null,
         e_assert,
         e_sf3ext,
         e_sf4ext
      };

      static inline bool is_literal(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_literal_node(expr.control_block_->expr);
      }

      static inline bool is_variable(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_variable_node(expr.control_block_->expr);
      }

      static inline bool is_string(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_generally_string_node(expr.control_block_->expr);
      }

      static inline bool is_unary(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_unary_node(expr.control_block_->expr);
      }

      static inline bool is_binary(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_binary_node(expr.control_block_->expr);
      }

      static inline bool is_function(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_function(expr.control_block_->expr);
      }

      static inline bool is_vararg(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_vararg_node(expr.control_block_->expr);
      }

      static inline bool is_null(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_null_node(expr.control_block_->expr);
      }

      static inline bool is_assert(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_assert_node(expr.control_block_->expr);
      }

      static inline bool is_sf3ext(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_sf3ext_node(expr.control_block_->expr);
      }

      static inline bool is_sf4ext(const expression<T>& expr)
      {
         return expr.control_block_ && details::is_sf4ext_node(expr.control_block_->expr);
      }

      static inline bool is_type(const expression<T>& expr, const node_types node_type)
      {
         if (0 == expr.control_block_)
         {
            return false;
         }

         switch (node_type)
         {
            case e_literal  : return is_literal_node(expr);
            case e_variable : return is_variable    (expr);
            case e_string   : return is_string      (expr);
            case e_unary    : return is_unary       (expr);
            case e_binary   : return is_binary      (expr);
            case e_function : return is_function    (expr);
            case e_null     : return is_null        (expr);
            case e_assert   : return is_assert      (expr);
            case e_sf3ext   : return is_sf3ext      (expr);
            case e_sf4ext   : return is_sf4ext      (expr);
         };

         return false;
      }

      static inline bool match_type_sequence(const expression<T>& expr, const std::vector<node_types>& type_seq)
      {
         if ((0 == expr.control_block_) || !is_vararg(expr))
         {
            return false;
         }

         typedef details::vararg_node<T, exprtk::details::vararg_multi_op<T> > mo_vararg_t;

         mo_vararg_t* vnode = dynamic_cast<mo_vararg_t*>(expr.control_block_->expr);

         if (
              (0 == vnode) ||
              type_seq.empty() ||
              (vnode->size() < type_seq.size())
            )
         {
            return false;
         }

         for (std::size_t i = 0; i < type_seq.size(); ++i)
         {
            assert((*vnode)[i]);

            switch(type_seq[i])
            {
               case e_literal  : { if (details::is_literal_node         ((*vnode)[i])) continue; } break;
               case e_variable : { if (details::is_variable_node        ((*vnode)[i])) continue; } break;
               case e_string   : { if (details::is_generally_string_node((*vnode)[i])) continue; } break;
               case e_unary    : { if (details::is_unary_node           ((*vnode)[i])) continue; } break;
               case e_binary   : { if (details::is_binary_node          ((*vnode)[i])) continue; } break;
               case e_function : { if (details::is_function             ((*vnode)[i])) continue; } break;
               case e_null     : { if (details::is_null_node            ((*vnode)[i])) continue; } break;
               case e_assert   : { if (details::is_assert_node          ((*vnode)[i])) continue; } break;
               case e_sf3ext   : { if (details::is_sf3ext_node          ((*vnode)[i])) continue; } break;
               case e_sf4ext   : { if (details::is_sf4ext_node          ((*vnode)[i])) continue; } break;
               case e_vararg   : break;
            }

            return false;
         }

         return true;
      }
   };

   template <typename T>
   inline bool is_valid(const expression<T>& expr)
   {
      return expr.control_block_ && !expression_helper<T>::is_null(expr);
   }

   namespace parser_error
   {
      enum error_mode
      {
         e_unknown   = 0,
         e_syntax    = 1,
         e_token     = 2,
         e_numeric   = 4,
         e_symtab    = 5,
         e_lexer     = 6,
         e_synthesis = 7,
         e_helper    = 8,
         e_parser    = 9
      };

      struct type
      {
         type()
         : mode(parser_error::e_unknown)
         , line_no  (0)
         , column_no(0)
         {}

         lexer::token token;
         error_mode mode;
         std::string diagnostic;
         std::string src_location;
         std::string error_line;
         std::size_t line_no;
         std::size_t column_no;
      };

      inline type make_error(const error_mode mode,
                             const std::string& diagnostic   = "",
                             const std::string& src_location = "")
      {
         type t;
         t.mode         = mode;
         t.token.type   = lexer::token::e_error;
         t.diagnostic   = diagnostic;
         t.src_location = src_location;
         exprtk_debug(("%s\n", diagnostic .c_str()));
         return t;
      }

      inline type make_error(const error_mode mode,
                             const lexer::token& tk,
                             const std::string& diagnostic   = "",
                             const std::string& src_location = "")
      {
         type t;
         t.mode         = mode;
         t.token        = tk;
         t.diagnostic   = diagnostic;
         t.src_location = src_location;
         exprtk_debug(("%s\n", diagnostic .c_str()));
         return t;
      }

      inline std::string to_str(error_mode mode)
      {
         switch (mode)
         {
            case e_unknown : return std::string("Unknown Error");
            case e_syntax  : return std::string("Syntax Error" );
            case e_token   : return std::string("Token Error"  );
            case e_numeric : return std::string("Numeric Error");
            case e_symtab  : return std::string("Symbol Error" );
            case e_lexer   : return std::string("Lexer Error"  );
            case e_helper  : return std::string("Helper Error" );
            case e_parser  : return std::string("Parser Error" );
            default        : return std::string("Unknown Error");
         }
      }

      inline bool update_error(type& error, const std::string& expression)
      {
         if (
              expression.empty()                         ||
              (error.token.position > expression.size()) ||
              (std::numeric_limits<std::size_t>::max() == error.token.position)
            )
         {
            return false;
         }

         std::size_t error_line_start = 0;

         for (std::size_t i = error.token.position; i > 0; --i)
         {
            const details::char_t c = expression[i];

            if (('\n' == c) || ('\r' == c))
            {
               error_line_start = i + 1;
               break;
            }
         }

         std::size_t next_nl_position = std::min(expression.size(),
                                                 expression.find_first_of('\n',error.token.position + 1));

         error.column_no  = error.token.position - error_line_start;
         error.error_line = expression.substr(error_line_start,
                                              next_nl_position - error_line_start);

         error.line_no = 0;

         for (std::size_t i = 0; i < next_nl_position; ++i)
         {
            if ('\n' == expression[i])
               ++error.line_no;
         }

         return true;
      }

      inline void dump_error(const type& error)
      {
         printf("Position: %02d   Type: [%s]   Msg: %s\n",
                static_cast<int>(error.token.position),
                exprtk::parser_error::to_str(error.mode).c_str(),
                error.diagnostic.c_str());
      }
   }

   namespace details
   {
      template <typename Parser>
      inline void disable_type_checking(Parser& p)
      {
         p.state_.type_check_enabled = false;
      }
   }

   template <typename T>
   class parser : public lexer::parser_helper
   {
   private:

      enum precedence_level
      {
         e_level00, e_level01, e_level02, e_level03, e_level04,
         e_level05, e_level06, e_level07, e_level08, e_level09,
         e_level10, e_level11, e_level12, e_level13, e_level14
      };

      typedef const T&                                       cref_t;
      typedef const T                                        const_t;
      typedef ifunction<T>                                   F;
      typedef ivararg_function<T>                            VAF;
      typedef igeneric_function<T>                           GF;
      typedef ifunction<T>                                   ifunction_t;
      typedef ivararg_function<T>                            ivararg_function_t;
      typedef igeneric_function<T>                           igeneric_function_t;
      typedef details::expression_node<T>                    expression_node_t;
      typedef details::literal_node<T>                       literal_node_t;
      typedef details::unary_node<T>                         unary_node_t;
      typedef details::binary_node<T>                        binary_node_t;
      typedef details::trinary_node<T>                       trinary_node_t;
      typedef details::quaternary_node<T>                    quaternary_node_t;
      typedef details::conditional_node<T>                   conditional_node_t;
      typedef details::cons_conditional_node<T>              cons_conditional_node_t;
      typedef details::while_loop_node<T>                    while_loop_node_t;
      typedef details::repeat_until_loop_node<T>             repeat_until_loop_node_t;
      typedef details::for_loop_node<T>                      for_loop_node_t;
      typedef details::while_loop_rtc_node<T>                while_loop_rtc_node_t;
      typedef details::repeat_until_loop_rtc_node<T>         repeat_until_loop_rtc_node_t;
      typedef details::for_loop_rtc_node<T>                  for_loop_rtc_node_t;
      #ifndef exprtk_disable_break_continue
      typedef details::while_loop_bc_node<T>                 while_loop_bc_node_t;
      typedef details::repeat_until_loop_bc_node<T>          repeat_until_loop_bc_node_t;
      typedef details::for_loop_bc_node<T>                   for_loop_bc_node_t;
      typedef details::while_loop_bc_rtc_node<T>             while_loop_bc_rtc_node_t;
      typedef details::repeat_until_loop_bc_rtc_node<T>      repeat_until_loop_bc_rtc_node_t;
      typedef details::for_loop_bc_rtc_node<T>               for_loop_bc_rtc_node_t;
      #endif
      typedef details::switch_node<T>                        switch_node_t;
      typedef details::variable_node<T>                      variable_node_t;
      typedef details::vector_elem_node<T>                   vector_elem_node_t;
      typedef details::vector_celem_node<T>                  vector_celem_node_t;
      typedef details::vector_elem_rtc_node<T>               vector_elem_rtc_node_t;
      typedef details::vector_celem_rtc_node<T>              vector_celem_rtc_node_t;
      typedef details::rebasevector_elem_node<T>             rebasevector_elem_node_t;
      typedef details::rebasevector_celem_node<T>            rebasevector_celem_node_t;
      typedef details::rebasevector_elem_rtc_node<T>         rebasevector_elem_rtc_node_t;
      typedef details::rebasevector_celem_rtc_node<T>        rebasevector_celem_rtc_node_t;
      typedef details::vector_node<T>                        vector_node_t;
      typedef details::vector_size_node<T>                   vector_size_node_t;
      typedef details::range_pack<T>                         range_t;
      #ifndef exprtk_disable_string_capabilities
      typedef details::stringvar_node<T>                     stringvar_node_t;
      typedef details::string_literal_node<T>                string_literal_node_t;
      typedef details::string_range_node<T>                  string_range_node_t;
      typedef details::const_string_range_node<T>            const_string_range_node_t;
      typedef details::generic_string_range_node<T>          generic_string_range_node_t;
      typedef details::string_concat_node<T>                 string_concat_node_t;
      typedef details::assignment_string_node<T>             assignment_string_node_t;
      typedef details::assignment_string_range_node<T>       assignment_string_range_node_t;
      typedef details::conditional_string_node<T>            conditional_string_node_t;
      typedef details::cons_conditional_str_node<T>          cons_conditional_str_node_t;
      #endif
      typedef details::assignment_node<T>                    assignment_node_t;
      typedef details::assignment_vec_elem_node<T>           assignment_vec_elem_node_t;
      typedef details::assignment_vec_elem_rtc_node<T>       assignment_vec_elem_rtc_node_t;
      typedef details::assignment_rebasevec_elem_node<T>     assignment_rebasevec_elem_node_t;
      typedef details::assignment_rebasevec_elem_rtc_node<T> assignment_rebasevec_elem_rtc_node_t;
      typedef details::assignment_rebasevec_celem_node<T>    assignment_rebasevec_celem_node_t;
      typedef details::assignment_vec_node<T>                assignment_vec_node_t;
      typedef details::assignment_vecvec_node<T>             assignment_vecvec_node_t;
      typedef details::conditional_vector_node<T>            conditional_vector_node_t;
      typedef details::scand_node<T>                         scand_node_t;
      typedef details::scor_node<T>                          scor_node_t;
      typedef lexer::token                                   token_t;
      typedef expression_node_t*                             expression_node_ptr;
      typedef expression<T>                                  expression_t;
      typedef symbol_table<T>                                symbol_table_t;
      typedef typename expression<T>::symtab_list_t          symbol_table_list_t;
      typedef details::vector_holder<T>                      vector_holder_t;
      typedef vector_holder_t*                               vector_holder_ptr;

      typedef typename details::functor_t<T> functor_t;
      typedef typename functor_t::qfunc_t    quaternary_functor_t;
      typedef typename functor_t::tfunc_t    trinary_functor_t;
      typedef typename functor_t::bfunc_t    binary_functor_t;
      typedef typename functor_t::ufunc_t    unary_functor_t;

      typedef details::operator_type operator_t;

      typedef std::map<operator_t, unary_functor_t  > unary_op_map_t;
      typedef std::map<operator_t, binary_functor_t > binary_op_map_t;
      typedef std::map<operator_t, trinary_functor_t> trinary_op_map_t;

      typedef std::map<std::string,std::pair<trinary_functor_t   ,operator_t> > sf3_map_t;
      typedef std::map<std::string,std::pair<quaternary_functor_t,operator_t> > sf4_map_t;

      typedef std::map<binary_functor_t,operator_t> inv_binary_op_map_t;
      typedef std::multimap<std::string,details::base_operation_t,details::ilesscompare> base_ops_map_t;
      typedef std::set<std::string,details::ilesscompare> disabled_func_set_t;

      typedef details::T0oT1_define<T, cref_t , cref_t > vov_t;
      typedef details::T0oT1_define<T, const_t, cref_t > cov_t;
      typedef details::T0oT1_define<T, cref_t , const_t> voc_t;

      typedef details::T0oT1oT2_define<T, cref_t , cref_t , cref_t > vovov_t;
      typedef details::T0oT1oT2_define<T, cref_t , cref_t , const_t> vovoc_t;
      typedef details::T0oT1oT2_define<T, cref_t , const_t, cref_t > vocov_t;
      typedef details::T0oT1oT2_define<T, const_t, cref_t , cref_t > covov_t;
      typedef details::T0oT1oT2_define<T, const_t, cref_t , const_t> covoc_t;
      typedef details::T0oT1oT2_define<T, const_t, const_t, cref_t > cocov_t;
      typedef details::T0oT1oT2_define<T, cref_t , const_t, const_t> vococ_t;

      typedef details::T0oT1oT2oT3_define<T, cref_t , cref_t , cref_t , cref_t > vovovov_t;
      typedef details::T0oT1oT2oT3_define<T, cref_t , cref_t , cref_t , const_t> vovovoc_t;
      typedef details::T0oT1oT2oT3_define<T, cref_t , cref_t , const_t, cref_t > vovocov_t;
      typedef details::T0oT1oT2oT3_define<T, cref_t , const_t, cref_t , cref_t > vocovov_t;
      typedef details::T0oT1oT2oT3_define<T, const_t, cref_t , cref_t , cref_t > covovov_t;

      typedef details::T0oT1oT2oT3_define<T, const_t, cref_t , const_t, cref_t > covocov_t;
      typedef details::T0oT1oT2oT3_define<T, cref_t , const_t, cref_t , const_t> vocovoc_t;
      typedef details::T0oT1oT2oT3_define<T, const_t, cref_t , cref_t , const_t> covovoc_t;
      typedef details::T0oT1oT2oT3_define<T, cref_t , const_t, const_t, cref_t > vococov_t;

      typedef results_context<T> results_context_t;

      typedef parser_helper prsrhlpr_t;

      struct scope_element
      {
         enum element_type
         {
            e_none    ,
            e_literal ,
            e_variable,
            e_vector  ,
            e_vecelem ,
            e_string
         };

         typedef details::vector_holder<T> vector_holder_t;
         typedef literal_node_t*           literal_node_ptr;
         typedef variable_node_t*          variable_node_ptr;
         typedef vector_holder_t*          vector_holder_ptr;
         typedef expression_node_t*        expression_node_ptr;
         #ifndef exprtk_disable_string_capabilities
         typedef stringvar_node_t*         stringvar_node_ptr;
         #endif

         scope_element()
         : name("???")
         , size (std::numeric_limits<std::size_t>::max())
         , index(std::numeric_limits<std::size_t>::max())
         , depth(std::numeric_limits<std::size_t>::max())
         , ref_count(0)
         , ip_index (0)
         , type     (e_none)
         , active   (false)
         , data     (0)
         , var_node (0)
         , vec_node (0)
         #ifndef exprtk_disable_string_capabilities
         , str_node(0)
         #endif
         {}

         bool operator < (const scope_element& se) const
         {
            if (ip_index < se.ip_index)
               return true;
            else if (ip_index > se.ip_index)
               return false;
            else if (depth < se.depth)
               return true;
            else if (depth > se.depth)
               return false;
            else if (index < se.index)
               return true;
            else if (index > se.index)
               return false;
            else
               return (name < se.name);
         }

         void clear()
         {
            name   = "???";
            size   = std::numeric_limits<std::size_t>::max();
            index  = std::numeric_limits<std::size_t>::max();
            depth  = std::numeric_limits<std::size_t>::max();
            type   = e_none;
            active = false;
            ref_count = 0;
            ip_index  = 0;
            data      = 0;
            var_node  = 0;
            vec_node  = 0;
            #ifndef exprtk_disable_string_capabilities
            str_node  = 0;
            #endif
         }

         std::string  name;
         std::size_t  size;
         std::size_t  index;
         std::size_t  depth;
         std::size_t  ref_count;
         std::size_t  ip_index;
         element_type type;
         bool         active;
         void*        data;
         expression_node_ptr var_node;
         vector_holder_ptr   vec_node;
         #ifndef exprtk_disable_string_capabilities
         stringvar_node_ptr str_node;
         #endif
      };

      class scope_element_manager
      {
      public:

         typedef expression_node_t* expression_node_ptr;
         typedef variable_node_t*   variable_node_ptr;
         typedef parser<T>          parser_t;

         explicit scope_element_manager(parser<T>& p)
         : parser_(p)
         , input_param_cnt_(0)
         {}

         inline std::size_t size() const
         {
            return element_.size();
         }

         inline bool empty() const
         {
            return element_.empty();
         }

         inline scope_element& get_element(const std::size_t& index)
         {
            if (index < element_.size())
               return element_[index];
            else
               return null_element_;
         }

         inline scope_element& get_element(const std::string& var_name,
                                           const std::size_t index = std::numeric_limits<std::size_t>::max())
         {
            const std::size_t current_depth = parser_.state_.scope_depth;

            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& se = element_[i];

               if (se.depth > current_depth)
                  continue;
               else if (
                         details::imatch(se.name, var_name) &&
                         (se.index == index)
                       )
                  return se;
            }

            return null_element_;
         }

         inline scope_element& get_active_element(const std::string& var_name,
                                                  const std::size_t index = std::numeric_limits<std::size_t>::max())
         {
            const std::size_t current_depth = parser_.state_.scope_depth;

            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& se = element_[i];

               if (se.depth > current_depth)
                  continue;
               else if (
                         details::imatch(se.name, var_name) &&
                         (se.index == index)                &&
                         (se.active)
                       )
                  return se;
            }

            return null_element_;
         }

         inline bool add_element(const scope_element& se)
         {
            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& cse = element_[i];

               if (
                    details::imatch(cse.name, se.name) &&
                    (cse.depth <= se.depth)            &&
                    (cse.index == se.index)            &&
                    (cse.size  == se.size )            &&
                    (cse.type  == se.type )            &&
                    (cse.active)
                  )
                  return false;
            }

            element_.push_back(se);
            std::sort(element_.begin(),element_.end());

            return true;
         }

         inline void deactivate(const std::size_t& scope_depth)
         {
            exprtk_debug(("deactivate() - Scope depth: %d\n",
                          static_cast<int>(parser_.state_.scope_depth)));

            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& se = element_[i];

               if (se.active && (se.depth >= scope_depth))
               {
                  exprtk_debug(("deactivate() - element[%02d] '%s'\n",
                                static_cast<int>(i),
                                se.name.c_str()));

                  se.active = false;
               }
            }
         }

         inline void free_element(scope_element& se)
         {
            exprtk_debug(("free_element() - se[%s]\n", se.name.c_str()));

            switch (se.type)
            {
               case scope_element::e_literal    : delete reinterpret_cast<T*>(se.data);
                                                  delete se.var_node;
                                                  break;

               case scope_element::e_variable   : delete reinterpret_cast<T*>(se.data);
                                                  delete se.var_node;
                                                  break;

               case scope_element::e_vector     : delete[] reinterpret_cast<T*>(se.data);
                                                  delete se.vec_node;
                                                  break;

               case scope_element::e_vecelem    : delete se.var_node;
                                                  break;

               #ifndef exprtk_disable_string_capabilities
               case scope_element::e_string     : delete reinterpret_cast<std::string*>(se.data);
                                                  delete se.str_node;
                                                  break;
               #endif

               default                          : return;
            }

            se.clear();
         }

         inline void cleanup()
         {
            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               free_element(element_[i]);
            }

            element_.clear();

            input_param_cnt_ = 0;
         }

         inline std::size_t next_ip_index()
         {
            return ++input_param_cnt_;
         }

         inline expression_node_ptr get_variable(const T& v)
         {
            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& se = element_[i];

               if (
                    se.active   &&
                    se.var_node &&
                    details::is_variable_node(se.var_node)
                  )
               {
                  variable_node_ptr vn = reinterpret_cast<variable_node_ptr>(se.var_node);

                  if (&(vn->ref()) == (&v))
                  {
                     return se.var_node;
                  }
               }
            }

            return expression_node_ptr(0);
         }

         inline std::string get_vector_name(const T* data)
         {
            for (std::size_t i = 0; i < element_.size(); ++i)
            {
               scope_element& se = element_[i];

               if (
                    se.active   &&
                    se.vec_node &&
                    (se.vec_node->data() == data)
                  )
               {
                  return se.name;
               }
            }

            return "neo-vector";
         }

      private:

         scope_element_manager(const scope_element_manager&) exprtk_delete;
         scope_element_manager& operator=(const scope_element_manager&) exprtk_delete;

         parser_t& parser_;
         std::vector<scope_element> element_;
         scope_element null_element_;
         std::size_t input_param_cnt_;
      };

      class scope_handler
      {
      public:

         typedef parser<T> parser_t;

         explicit scope_handler(parser<T>& p)
         : parser_(p)
         {
            parser_.state_.scope_depth++;
            #ifdef exprtk_enable_debugging
            const std::string depth(2 * parser_.state_.scope_depth,'-');
            exprtk_debug(("%s> Scope Depth: %02d\n",
                          depth.c_str(),
                          static_cast<int>(parser_.state_.scope_depth)));
            #endif
         }

        ~scope_handler()
         {
            parser_.sem_.deactivate(parser_.state_.scope_depth);
            parser_.state_.scope_depth--;
            #ifdef exprtk_enable_debugging
            const std::string depth(2 * parser_.state_.scope_depth,'-');
            exprtk_debug(("<%s Scope Depth: %02d\n",
                          depth.c_str(),
                          static_cast<int>(parser_.state_.scope_depth)));
            #endif
         }

      private:

         scope_handler(const scope_handler&) exprtk_delete;
         scope_handler& operator=(const scope_handler&) exprtk_delete;

         parser_t& parser_;
      };

      template <typename T_>
      struct halfopen_range_policy
      {
         static inline bool is_within(const T_& v, const T_& begin, const T_& end)
         {
            assert(begin <= end);
            return (begin <= v) && (v < end);
         }

         static inline bool is_less(const T_& v, const T_& begin)
         {
            return (v < begin);
         }

         static inline bool is_greater(const T_& v, const T_& end)
         {
            return (end <= v);
         }

         static inline bool end_inclusive()
         {
            return false;
         }
      };

      template <typename T_>
      struct closed_range_policy
      {
         static inline bool is_within(const T_& v, const T_& begin, const T_& end)
         {
            assert(begin <= end);
            return (begin <= v) && (v <= end);
         }

         static inline bool is_less(const T_& v, const T_& begin)
         {
            return (v < begin);
         }

         static inline bool is_greater(const T_& v, const T_& end)
         {
            return (end < v);
         }

         static inline bool end_inclusive()
         {
            return true;
         }
      };

      template <typename IntervalPointType,
                typename RangePolicy = halfopen_range_policy<IntervalPointType> >
      class interval_container_t
      {
      public:

         typedef IntervalPointType interval_point_t;
         typedef std::pair<interval_point_t, interval_point_t> interval_t;
         typedef std::map<interval_point_t, interval_t> interval_map_t;
         typedef typename interval_map_t::const_iterator interval_map_citr_t;

         std::size_t size() const
         {
            return interval_map_.size();
         }

         void reset()
         {
            interval_map_.clear();
         }

         bool in_interval(const interval_point_t point, interval_t& interval) const
         {
            interval_map_citr_t itr = RangePolicy::end_inclusive() ?
                                      interval_map_.lower_bound(point):
                                      interval_map_.upper_bound(point);

            for (; itr != interval_map_.end(); ++itr)
            {
               const interval_point_t& begin = itr->second.first;
               const interval_point_t& end   = itr->second.second;

               if (RangePolicy::is_within(point, begin, end))
               {
                  interval = interval_t(begin,end);
                  return true;
               }
               else if (RangePolicy::is_greater(point, end))
               {
                  break;
               }
            }

            return false;
         }

         bool in_interval(const interval_point_t point) const
         {
            interval_t interval;
            return in_interval(point,interval);
         }

         bool add_interval(const interval_point_t begin, const interval_point_t end)
         {
            if ((end <= begin) || in_interval(begin) || in_interval(end))
            {
               return false;
            }

            interval_map_[end] = std::make_pair(begin, end);

            return true;
         }

         bool add_interval(const interval_t interval)
         {
            return add_interval(interval.first, interval.second);
         }

      private:

         interval_map_t interval_map_;
      };

      class stack_limit_handler
      {
      public:

         typedef parser<T> parser_t;

         explicit stack_limit_handler(parser<T>& p)
         : parser_(p)
         , limit_exceeded_(false)
         {
            if (++parser_.state_.stack_depth > parser_.settings_.max_stack_depth_)
            {
               limit_exceeded_ = true;
               parser_.set_error(make_error(
                  parser_error::e_parser,
                  "ERR000 - Current stack depth " + details::to_str(parser_.state_.stack_depth) +
                  " exceeds maximum allowed stack depth of " + details::to_str(parser_.settings_.max_stack_depth_),
                  exprtk_error_location));
            }
         }

        ~stack_limit_handler()
         {
            assert(parser_.state_.stack_depth > 0);
            parser_.state_.stack_depth--;
         }

         bool operator!()
         {
            return limit_exceeded_;
         }

      private:

         stack_limit_handler(const stack_limit_handler&) exprtk_delete;
         stack_limit_handler& operator=(const stack_limit_handler&) exprtk_delete;

         parser_t& parser_;
         bool limit_exceeded_;
      };

      struct symtab_store
      {
         symbol_table_list_t symtab_list_;

         typedef typename symbol_table_t::local_data_t local_data_t;
         typedef typename symbol_table_t::variable_ptr variable_ptr;
         typedef typename symbol_table_t::function_ptr function_ptr;
         #ifndef exprtk_disable_string_capabilities
         typedef typename symbol_table_t::stringvar_ptr stringvar_ptr;
         #endif
         typedef typename symbol_table_t::vector_holder_ptr    vector_holder_ptr;
         typedef typename symbol_table_t::vararg_function_ptr  vararg_function_ptr;
         typedef typename symbol_table_t::generic_function_ptr generic_function_ptr;

         struct variable_context
         {
            variable_context()
            : symbol_table(0)
            , variable(0)
            {}

            const symbol_table_t* symbol_table;
            variable_ptr variable;
         };

         struct vector_context
         {
            vector_context()
            : symbol_table(0)
            , vector_holder(0)
            {}

            const symbol_table_t* symbol_table;
            vector_holder_ptr vector_holder;
         };

         #ifndef exprtk_disable_string_capabilities
         struct string_context
         {
            string_context()
            : symbol_table(0)
            , str_var(0)
            {}

            const symbol_table_t* symbol_table;
            stringvar_ptr str_var;
         };
         #endif

         inline bool empty() const
         {
            return symtab_list_.empty();
         }

         inline void clear()
         {
            symtab_list_.clear();
         }

         inline bool valid() const
         {
            if (!empty())
            {
               for (std::size_t i = 0; i < symtab_list_.size(); ++i)
               {
                  if (symtab_list_[i].valid())
                     return true;
               }
            }

            return false;
         }

         inline bool valid_symbol(const std::string& symbol) const
         {
            if (!symtab_list_.empty())
               return symtab_list_[0].valid_symbol(symbol);
            else
               return false;
         }

         inline bool valid_function_name(const std::string& symbol) const
         {
            if (!symtab_list_.empty())
               return symtab_list_[0].valid_function(symbol);
            else
               return false;
         }

         inline variable_context get_variable_context(const std::string& variable_name) const
         {
            variable_context result;

            if (valid_symbol(variable_name))
            {
               for (std::size_t i = 0; i < symtab_list_.size(); ++i)
               {
                  if (!symtab_list_[i].valid())
                  {
                     continue;
                  }

                  result.variable = local_data(i)
                                       .variable_store.get(variable_name);
                  if (result.variable)
                  {
                     result.symbol_table = &symtab_list_[i];
                     break;
                  }
               }
            }

            return result;
         }

         inline variable_ptr get_variable(const std::string& variable_name) const
         {
            if (!valid_symbol(variable_name))
               return reinterpret_cast<variable_ptr>(0);

            variable_ptr result = reinterpret_cast<variable_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i)
                              .variable_store.get(variable_name);

               if (result) break;
            }

            return result;
         }

         inline variable_ptr get_variable(const T& var_ref) const
         {
            variable_ptr result = reinterpret_cast<variable_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i).variable_store
                              .get_from_varptr(reinterpret_cast<const void*>(&var_ref));

               if (result) break;
            }

            return result;
         }

         #ifndef exprtk_disable_string_capabilities
         inline string_context get_string_context(const std::string& string_name) const
         {
            string_context result;

            if (!valid_symbol(string_name))
               return result;

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
               {
                  continue;
               }

               result.str_var = local_data(i).stringvar_store.get(string_name);

               if (result.str_var)
               {
                  result.symbol_table = &symtab_list_[i];
                  break;
               }
            }

            return result;
         }

         inline stringvar_ptr get_stringvar(const std::string& string_name) const
         {
            if (!valid_symbol(string_name))
               return reinterpret_cast<stringvar_ptr>(0);

            stringvar_ptr result = reinterpret_cast<stringvar_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i)
                              .stringvar_store.get(string_name);

               if (result) break;
            }

            return result;
         }
         #endif

         inline function_ptr get_function(const std::string& function_name) const
         {
            if (!valid_function_name(function_name))
               return reinterpret_cast<function_ptr>(0);

            function_ptr result = reinterpret_cast<function_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i)
                              .function_store.get(function_name);

               if (result) break;
            }

            return result;
         }

         inline vararg_function_ptr get_vararg_function(const std::string& vararg_function_name) const
         {
            if (!valid_function_name(vararg_function_name))
               return reinterpret_cast<vararg_function_ptr>(0);

            vararg_function_ptr result = reinterpret_cast<vararg_function_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i)
                              .vararg_function_store.get(vararg_function_name);

               if (result) break;
            }

            return result;
         }

         inline generic_function_ptr get_generic_function(const std::string& function_name) const
         {
            if (!valid_function_name(function_name))
               return reinterpret_cast<generic_function_ptr>(0);

            generic_function_ptr result = reinterpret_cast<generic_function_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result = local_data(i)
                              .generic_function_store.get(function_name);

               if (result) break;
            }

            return result;
         }

         inline generic_function_ptr get_string_function(const std::string& function_name) const
         {
            if (!valid_function_name(function_name))
               return reinterpret_cast<generic_function_ptr>(0);

            generic_function_ptr result = reinterpret_cast<generic_function_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result =
                     local_data(i).string_function_store.get(function_name);

               if (result) break;
            }

            return result;
         }

         inline generic_function_ptr get_overload_function(const std::string& function_name) const
         {
            if (!valid_function_name(function_name))
               return reinterpret_cast<generic_function_ptr>(0);

            generic_function_ptr result = reinterpret_cast<generic_function_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else
                  result =
                     local_data(i).overload_function_store.get(function_name);

               if (result) break;
            }

            return result;
         }

         inline vector_context get_vector_context(const std::string& vector_name) const
         {
            vector_context result;
            if (!valid_symbol(vector_name))
               return result;

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
               {
                  continue;
               }

               result.vector_holder = local_data(i).vector_store.get(vector_name);

               if (result.vector_holder)
               {
                  result.symbol_table = &symtab_list_[i];
                  break;
               }
            }

            return result;
         }

         inline vector_holder_ptr get_vector(const std::string& vector_name) const
         {
            if (!valid_symbol(vector_name))
               return reinterpret_cast<vector_holder_ptr>(0);

            vector_holder_ptr result = reinterpret_cast<vector_holder_ptr>(0);

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
               {
                  continue;
               }

               result = local_data(i).vector_store.get(vector_name);

               if (result)
               {
                  break;
               }
            }

            return result;
         }

         inline bool is_constant_node(const std::string& symbol_name) const
         {
            if (!valid_symbol(symbol_name))
               return false;

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
               {
                  continue;
               }

               if (local_data(i).variable_store.is_constant(symbol_name))
               {
                  return true;
               }
            }

            return false;
         }

         #ifndef exprtk_disable_string_capabilities
         inline bool is_constant_string(const std::string& symbol_name) const
         {
            if (!valid_symbol(symbol_name))
               return false;

            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (!local_data(i).stringvar_store.symbol_exists(symbol_name))
                  continue;
               else if (local_data(i).stringvar_store.is_constant(symbol_name))
                  return true;
            }

            return false;
         }
         #endif

         inline bool symbol_exists(const std::string& symbol) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
               {
                  continue;
               }

               if (symtab_list_[i].symbol_exists(symbol))
               {
                  return true;
               }
            }

            return false;
         }

         inline bool is_variable(const std::string& variable_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         symtab_list_[i].local_data().variable_store
                           .symbol_exists(variable_name)
                       )
                  return true;
            }

            return false;
         }

         #ifndef exprtk_disable_string_capabilities
         inline bool is_stringvar(const std::string& stringvar_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         symtab_list_[i].local_data().stringvar_store
                           .symbol_exists(stringvar_name)
                       )
                  return true;
            }

            return false;
         }

         inline bool is_conststr_stringvar(const std::string& symbol_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         symtab_list_[i].local_data().stringvar_store
                           .symbol_exists(symbol_name)
                       )
               {
                  return (
                           local_data(i).stringvar_store.symbol_exists(symbol_name) ||
                           local_data(i).stringvar_store.is_constant  (symbol_name)
                         );

               }
            }

            return false;
         }
         #endif

         inline bool is_function(const std::string& function_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         local_data(i).vararg_function_store
                           .symbol_exists(function_name)
                       )
                  return true;
            }

            return false;
         }

         inline bool is_vararg_function(const std::string& vararg_function_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         local_data(i).vararg_function_store
                           .symbol_exists(vararg_function_name)
                       )
                  return true;
            }

            return false;
         }

         inline bool is_vector(const std::string& vector_name) const
         {
            for (std::size_t i = 0; i < symtab_list_.size(); ++i)
            {
               if (!symtab_list_[i].valid())
                  continue;
               else if (
                         local_data(i).vector_store
                           .symbol_exists(vector_name)
                       )
                  return true;
            }

            return false;
         }

         inline std::string get_variable_name(const expression_node_ptr& ptr) const
         {
            return local_data().variable_store.entity_name(ptr);
         }

         inline std::string get_vector_name(const vector_holder_ptr& ptr) const
         {
            return local_data().vector_store.entity_name(ptr);
         }

         #ifndef exprtk_disable_string_capabilities
         inline std::string get_stringvar_name(const expression_node_ptr& ptr) const
         {
            return local_data().stringvar_store.entity_name(ptr);
         }

         inline std::string get_conststr_stringvar_name(const expression_node_ptr& ptr) const
         {
            return local_data().stringvar_store.entity_name(ptr);
         }
         #endif

         inline local_data_t& local_data(const std::size_t& index = 0)
         {
            return symtab_list_[index].local_data();
         }

         inline const local_data_t& local_data(const std::size_t& index = 0) const
         {
            return symtab_list_[index].local_data();
         }

         inline symbol_table_t& get_symbol_table(const std::size_t& index = 0)
         {
            return symtab_list_[index];
         }
      };

      struct parser_state
      {
         parser_state()
         : type_check_enabled(true)
         {
            reset();
         }

         void reset()
         {
            parsing_return_stmt     = false;
            parsing_break_stmt      = false;
            parsing_assert_stmt     = false;
            return_stmt_present     = false;
            side_effect_present     = false;
            scope_depth             = 0;
            stack_depth             = 0;
            parsing_loop_stmt_count = 0;
         }

         #ifndef exprtk_enable_debugging
         void activate_side_effect(const std::string&)
         #else
         void activate_side_effect(const std::string& source)
         #endif
         {
            if (!side_effect_present)
            {
               side_effect_present = true;

               exprtk_debug(("activate_side_effect() - caller: %s\n", source.c_str()));
            }
         }

         bool parsing_return_stmt;
         bool parsing_break_stmt;
         bool parsing_assert_stmt;
         bool return_stmt_present;
         bool side_effect_present;
         bool type_check_enabled;
         std::size_t scope_depth;
         std::size_t stack_depth;
         std::size_t parsing_loop_stmt_count;
      };

   public:

      struct unknown_symbol_resolver
      {

         enum usr_symbol_type
         {
            e_usr_unknown_type  = 0,
            e_usr_variable_type = 1,
            e_usr_constant_type = 2
         };

         enum usr_mode
         {
            e_usrmode_default  = 0,
            e_usrmode_extended = 1
         };

         usr_mode mode;

         unknown_symbol_resolver(const usr_mode m = e_usrmode_default)
         : mode(m)
         {}

         virtual ~unknown_symbol_resolver()
         {}

         virtual bool process(const std::string& /*unknown_symbol*/,
                              usr_symbol_type&   st,
                              T&                 default_value,
                              std::string&       error_message)
         {
            if (e_usrmode_default != mode)
               return false;

            st = e_usr_variable_type;
            default_value = T(0);
            error_message.clear();

            return true;
         }

         virtual bool process(const std::string& /* unknown_symbol */,
                              symbol_table_t&    /* symbol_table   */,
                              std::string&       /* error_message  */)
         {
            return false;
         }
      };

      enum collect_type
      {
         e_ct_none        = 0,
         e_ct_variables   = 1,
         e_ct_functions   = 2,
         e_ct_assignments = 4
      };

      enum symbol_type
      {
         e_st_unknown        = 0,
         e_st_variable       = 1,
         e_st_vector         = 2,
         e_st_vecelem        = 3,
         e_st_string         = 4,
         e_st_function       = 5,
         e_st_local_variable = 6,
         e_st_local_vector   = 7,
         e_st_local_string   = 8
      };

      class dependent_entity_collector
      {
      public:

         typedef std::pair<std::string,symbol_type> symbol_t;
         typedef std::vector<symbol_t> symbol_list_t;

         dependent_entity_collector(const std::size_t options = e_ct_none)
         : options_(options)
         , collect_variables_  ((options_ & e_ct_variables  ) == e_ct_variables  )
         , collect_functions_  ((options_ & e_ct_functions  ) == e_ct_functions  )
         , collect_assignments_((options_ & e_ct_assignments) == e_ct_assignments)
         , return_present_   (false)
         , final_stmt_return_(false)
         {}

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t symbols(Sequence<symbol_t,Allocator>& symbols_list)
         {
            if (!collect_variables_ && !collect_functions_)
               return 0;
            else if (symbol_name_list_.empty())
               return 0;

            for (std::size_t i = 0; i < symbol_name_list_.size(); ++i)
            {
               details::case_normalise(symbol_name_list_[i].first);
            }

            std::sort(symbol_name_list_.begin(), symbol_name_list_.end());

            std::unique_copy
            (
               symbol_name_list_.begin(),
               symbol_name_list_.end  (),
               std::back_inserter(symbols_list)
            );

            return symbols_list.size();
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t assignment_symbols(Sequence<symbol_t,Allocator>& assignment_list)
         {
            if (!collect_assignments_)
               return 0;
            else if (assignment_name_list_.empty())
               return 0;

            for (std::size_t i = 0; i < assignment_name_list_.size(); ++i)
            {
               details::case_normalise(assignment_name_list_[i].first);
            }

            std::sort(assignment_name_list_.begin(),assignment_name_list_.end());

            std::unique_copy
            (
               assignment_name_list_.begin(),
               assignment_name_list_.end  (),
               std::back_inserter(assignment_list)
            );

            return assignment_list.size();
         }

         void clear()
         {
            symbol_name_list_    .clear();
            assignment_name_list_.clear();
            retparam_list_       .clear();
            return_present_    = false;
            final_stmt_return_ = false;
         }

         bool& collect_variables()
         {
            return collect_variables_;
         }

         bool& collect_functions()
         {
            return collect_functions_;
         }

         bool& collect_assignments()
         {
            return collect_assignments_;
         }

         bool return_present() const
         {
            return return_present_;
         }

         bool final_stmt_return() const
         {
            return final_stmt_return_;
         }

         typedef std::vector<std::string> retparam_list_t;

         retparam_list_t return_param_type_list() const
         {
            return retparam_list_;
         }

      private:

         inline void add_symbol(const std::string& symbol, const symbol_type st)
         {
            switch (st)
            {
               case e_st_variable       :
               case e_st_vector         :
               case e_st_string         :
               case e_st_local_variable :
               case e_st_local_vector   :
               case e_st_local_string   : if (collect_variables_)
                                             symbol_name_list_
                                                .push_back(std::make_pair(symbol, st));
                                          break;

               case e_st_function       : if (collect_functions_)
                                             symbol_name_list_
                                                .push_back(std::make_pair(symbol, st));
                                          break;

               default                  : return;
            }
         }

         inline void add_assignment(const std::string& symbol, const symbol_type st)
         {
            switch (st)
            {
               case e_st_variable       :
               case e_st_vector         :
               case e_st_string         : if (collect_assignments_)
                                             assignment_name_list_
                                                .push_back(std::make_pair(symbol, st));
                                          break;

               default                  : return;
            }
         }

         std::size_t options_;
         bool collect_variables_;
         bool collect_functions_;
         bool collect_assignments_;
         bool return_present_;
         bool final_stmt_return_;
         symbol_list_t symbol_name_list_;
         symbol_list_t assignment_name_list_;
         retparam_list_t retparam_list_;

         friend class parser<T>;
      };

      class settings_store
      {
      private:

         typedef std::set<std::string,details::ilesscompare> disabled_entity_set_t;
         typedef disabled_entity_set_t::iterator des_itr_t;

      public:

         enum settings_compilation_options
         {
            e_unknown              =    0,
            e_replacer             =    1,
            e_joiner               =    2,
            e_numeric_check        =    4,
            e_bracket_check        =    8,
            e_sequence_check       =   16,
            e_commutative_check    =   32,
            e_strength_reduction   =   64,
            e_disable_vardef       =  128,
            e_collect_vars         =  256,
            e_collect_funcs        =  512,
            e_collect_assings      = 1024,
            e_disable_usr_on_rsrvd = 2048,
            e_disable_zero_return  = 4096
         };

         enum settings_base_funcs
         {
            e_bf_unknown = 0,
            e_bf_abs       , e_bf_acos     , e_bf_acosh    , e_bf_asin    ,
            e_bf_asinh     , e_bf_atan     , e_bf_atan2    , e_bf_atanh   ,
            e_bf_avg       , e_bf_ceil     , e_bf_clamp    , e_bf_cos     ,
            e_bf_cosh      , e_bf_cot      , e_bf_csc      , e_bf_equal   ,
            e_bf_erf       , e_bf_erfc     , e_bf_exp      , e_bf_expm1   ,
            e_bf_floor     , e_bf_frac     , e_bf_hypot    , e_bf_iclamp  ,
            e_bf_like      , e_bf_log      , e_bf_log10    , e_bf_log1p   ,
            e_bf_log2      , e_bf_logn     , e_bf_mand     , e_bf_max     ,
            e_bf_min       , e_bf_mod      , e_bf_mor      , e_bf_mul     ,
            e_bf_ncdf      , e_bf_pow      , e_bf_root     , e_bf_round   ,
            e_bf_roundn    , e_bf_sec      , e_bf_sgn      , e_bf_sin     ,
            e_bf_sinc      , e_bf_sinh     , e_bf_sqrt     , e_bf_sum     ,
            e_bf_swap      , e_bf_tan      , e_bf_tanh     , e_bf_trunc   ,
            e_bf_not_equal , e_bf_inrange  , e_bf_deg2grad , e_bf_deg2rad ,
            e_bf_rad2deg   , e_bf_grad2deg
         };

         enum settings_control_structs
         {
            e_ctrl_unknown = 0,
            e_ctrl_ifelse,
            e_ctrl_switch,
            e_ctrl_for_loop,
            e_ctrl_while_loop,
            e_ctrl_repeat_loop,
            e_ctrl_return
         };

         enum settings_logic_opr
         {
            e_logic_unknown = 0,
            e_logic_and, e_logic_nand , e_logic_nor ,
            e_logic_not, e_logic_or   , e_logic_xnor,
            e_logic_xor, e_logic_scand, e_logic_scor
         };

         enum settings_arithmetic_opr
         {
            e_arith_unknown = 0,
            e_arith_add, e_arith_sub, e_arith_mul,
            e_arith_div, e_arith_mod, e_arith_pow
         };

         enum settings_assignment_opr
         {
            e_assign_unknown = 0,
            e_assign_assign, e_assign_addass, e_assign_subass,
            e_assign_mulass, e_assign_divass, e_assign_modass
         };

         enum settings_inequality_opr
         {
            e_ineq_unknown = 0,
            e_ineq_lt   , e_ineq_lte, e_ineq_eq    ,
            e_ineq_equal, e_ineq_ne , e_ineq_nequal,
            e_ineq_gte  , e_ineq_gt
         };

         static const std::size_t default_compile_all_opts =
                                     e_replacer          +
                                     e_joiner            +
                                     e_numeric_check     +
                                     e_bracket_check     +
                                     e_sequence_check    +
                                     e_commutative_check +
                                     e_strength_reduction;

         settings_store(const std::size_t compile_options = default_compile_all_opts)
         : max_stack_depth_(400)
         , max_node_depth_(10000)
         , max_local_vector_size_(2000000000)
         {
           load_compile_options(compile_options);
         }

         settings_store& enable_all_base_functions()
         {
            disabled_func_set_.clear();
            return (*this);
         }

         settings_store& enable_all_control_structures()
         {
            disabled_ctrl_set_.clear();
            return (*this);
         }

         settings_store& enable_all_logic_ops()
         {
            disabled_logic_set_.clear();
            return (*this);
         }

         settings_store& enable_all_arithmetic_ops()
         {
            disabled_arithmetic_set_.clear();
            return (*this);
         }

         settings_store& enable_all_assignment_ops()
         {
            disabled_assignment_set_.clear();
            return (*this);
         }

         settings_store& enable_all_inequality_ops()
         {
            disabled_inequality_set_.clear();
            return (*this);
         }

         settings_store& enable_local_vardef()
         {
            disable_vardef_ = false;
            return (*this);
         }

         settings_store& enable_commutative_check()
         {
            enable_commutative_check_ = true;
            return (*this);
         }

         settings_store& enable_strength_reduction()
         {
            enable_strength_reduction_ = true;
            return (*this);
         }

         settings_store& disable_all_base_functions()
         {
            std::copy(details::base_function_list,
                      details::base_function_list + details::base_function_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                         (disabled_func_set_, disabled_func_set_.begin()));
            return (*this);
         }

         settings_store& disable_all_control_structures()
         {
            std::copy(details::cntrl_struct_list,
                      details::cntrl_struct_list + details::cntrl_struct_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                         (disabled_ctrl_set_, disabled_ctrl_set_.begin()));
            return (*this);
         }

         settings_store& disable_all_logic_ops()
         {
            std::copy(details::logic_ops_list,
                      details::logic_ops_list + details::logic_ops_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                        (disabled_logic_set_, disabled_logic_set_.begin()));
            return (*this);
         }

         settings_store& disable_all_arithmetic_ops()
         {
            std::copy(details::arithmetic_ops_list,
                      details::arithmetic_ops_list + details::arithmetic_ops_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                         (disabled_arithmetic_set_, disabled_arithmetic_set_.begin()));
            return (*this);
         }

         settings_store& disable_all_assignment_ops()
         {
            std::copy(details::assignment_ops_list,
                      details::assignment_ops_list + details::assignment_ops_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                         (disabled_assignment_set_, disabled_assignment_set_.begin()));
            return (*this);
         }

         settings_store& disable_all_inequality_ops()
         {
            std::copy(details::inequality_ops_list,
                      details::inequality_ops_list + details::inequality_ops_list_size,
                      std::insert_iterator<disabled_entity_set_t>
                         (disabled_inequality_set_, disabled_inequality_set_.begin()));
            return (*this);
         }

         settings_store& disable_local_vardef()
         {
            disable_vardef_ = true;
            return (*this);
         }

         settings_store& disable_commutative_check()
         {
            enable_commutative_check_ = false;
            return (*this);
         }

         settings_store& disable_strength_reduction()
         {
            enable_strength_reduction_ = false;
            return (*this);
         }

         bool replacer_enabled           () const { return enable_replacer_;           }
         bool commutative_check_enabled  () const { return enable_commutative_check_;  }
         bool joiner_enabled             () const { return enable_joiner_;             }
         bool numeric_check_enabled      () const { return enable_numeric_check_;      }
         bool bracket_check_enabled      () const { return enable_bracket_check_;      }
         bool sequence_check_enabled     () const { return enable_sequence_check_;     }
         bool strength_reduction_enabled () const { return enable_strength_reduction_; }
         bool collect_variables_enabled  () const { return enable_collect_vars_;       }
         bool collect_functions_enabled  () const { return enable_collect_funcs_;      }
         bool collect_assignments_enabled() const { return enable_collect_assings_;    }
         bool vardef_disabled            () const { return disable_vardef_;            }
         bool rsrvd_sym_usr_disabled     () const { return disable_rsrvd_sym_usr_;     }
         bool zero_return_disabled       () const { return disable_zero_return_;       }

         bool function_enabled(const std::string& function_name) const
         {
            if (disabled_func_set_.empty())
               return true;
            else
               return (disabled_func_set_.end() == disabled_func_set_.find(function_name));
         }

         bool control_struct_enabled(const std::string& control_struct) const
         {
            if (disabled_ctrl_set_.empty())
               return true;
            else
               return (disabled_ctrl_set_.end() == disabled_ctrl_set_.find(control_struct));
         }

         bool logic_enabled(const std::string& logic_operation) const
         {
            if (disabled_logic_set_.empty())
               return true;
            else
               return (disabled_logic_set_.end() == disabled_logic_set_.find(logic_operation));
         }

         bool arithmetic_enabled(const details::operator_type& arithmetic_operation) const
         {
            if (disabled_logic_set_.empty())
               return true;
            else
               return disabled_arithmetic_set_.end() == disabled_arithmetic_set_
                                                            .find(arith_opr_to_string(arithmetic_operation));
         }

         bool assignment_enabled(const details::operator_type& assignment) const
         {
            if (disabled_assignment_set_.empty())
               return true;
            else
               return disabled_assignment_set_.end() == disabled_assignment_set_
                                                           .find(assign_opr_to_string(assignment));
         }

         bool inequality_enabled(const details::operator_type& inequality) const
         {
            if (disabled_inequality_set_.empty())
               return true;
            else
               return disabled_inequality_set_.end() == disabled_inequality_set_
                                                           .find(inequality_opr_to_string(inequality));
         }

         bool function_disabled(const std::string& function_name) const
         {
            if (disabled_func_set_.empty())
               return false;
            else
               return (disabled_func_set_.end() != disabled_func_set_.find(function_name));
         }

         bool control_struct_disabled(const std::string& control_struct) const
         {
            if (disabled_ctrl_set_.empty())
               return false;
            else
               return (disabled_ctrl_set_.end() != disabled_ctrl_set_.find(control_struct));
         }

         bool logic_disabled(const std::string& logic_operation) const
         {
            if (disabled_logic_set_.empty())
               return false;
            else
               return (disabled_logic_set_.end() != disabled_logic_set_.find(logic_operation));
         }

         bool assignment_disabled(const details::operator_type assignment_operation) const
         {
            if (disabled_assignment_set_.empty())
               return false;
            else
               return disabled_assignment_set_.end() != disabled_assignment_set_
                                                           .find(assign_opr_to_string(assignment_operation));
         }

         bool logic_disabled(const details::operator_type logic_operation) const
         {
            if (disabled_logic_set_.empty())
               return false;
            else
               return disabled_logic_set_.end() != disabled_logic_set_
                                                           .find(logic_opr_to_string(logic_operation));
         }

         bool arithmetic_disabled(const details::operator_type arithmetic_operation) const
         {
            if (disabled_arithmetic_set_.empty())
               return false;
            else
               return disabled_arithmetic_set_.end() != disabled_arithmetic_set_
                                                           .find(arith_opr_to_string(arithmetic_operation));
         }

         bool inequality_disabled(const details::operator_type& inequality) const
         {
            if (disabled_inequality_set_.empty())
               return false;
            else
               return disabled_inequality_set_.end() != disabled_inequality_set_
                                                           .find(inequality_opr_to_string(inequality));
         }

         settings_store& disable_base_function(const settings_base_funcs bf)
         {
            if (
                 (e_bf_unknown != bf) &&
                 (static_cast<std::size_t>(bf) < (details::base_function_list_size + 1))
               )
            {
               disabled_func_set_.insert(details::base_function_list[bf - 1]);
            }

            return (*this);
         }

         settings_store& disable_control_structure(const settings_control_structs ctrl_struct)
         {
            if (
                 (e_ctrl_unknown != ctrl_struct) &&
                 (static_cast<std::size_t>(ctrl_struct) < (details::cntrl_struct_list_size + 1))
               )
            {
               disabled_ctrl_set_.insert(details::cntrl_struct_list[ctrl_struct - 1]);
            }

            return (*this);
         }

         settings_store& disable_logic_operation(const settings_logic_opr logic)
         {
            if (
                 (e_logic_unknown != logic) &&
                 (static_cast<std::size_t>(logic) < (details::logic_ops_list_size + 1))
               )
            {
               disabled_logic_set_.insert(details::logic_ops_list[logic - 1]);
            }

            return (*this);
         }

         settings_store& disable_arithmetic_operation(const settings_arithmetic_opr arithmetic)
         {
            if (
                 (e_arith_unknown != arithmetic) &&
                 (static_cast<std::size_t>(arithmetic) < (details::arithmetic_ops_list_size + 1))
               )
            {
               disabled_arithmetic_set_.insert(details::arithmetic_ops_list[arithmetic - 1]);
            }

            return (*this);
         }

         settings_store& disable_assignment_operation(const settings_assignment_opr assignment)
         {
            if (
                 (e_assign_unknown != assignment) &&
                 (static_cast<std::size_t>(assignment) < (details::assignment_ops_list_size + 1))
               )
            {
               disabled_assignment_set_.insert(details::assignment_ops_list[assignment - 1]);
            }

            return (*this);
         }

         settings_store& disable_inequality_operation(const settings_inequality_opr inequality)
         {
            if (
                 (e_ineq_unknown != inequality) &&
                 (static_cast<std::size_t>(inequality) < (details::inequality_ops_list_size + 1))
               )
            {
               disabled_inequality_set_.insert(details::inequality_ops_list[inequality - 1]);
            }

            return (*this);
         }

         settings_store& enable_base_function(const settings_base_funcs bf)
         {
            if (
                 (e_bf_unknown != bf) &&
                 (static_cast<std::size_t>(bf) < (details::base_function_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_func_set_.find(details::base_function_list[bf - 1]);

               if (disabled_func_set_.end() != itr)
               {
                  disabled_func_set_.erase(itr);
               }
            }

            return (*this);
         }

         settings_store& enable_control_structure(const settings_control_structs ctrl_struct)
         {
            if (
                 (e_ctrl_unknown != ctrl_struct) &&
                 (static_cast<std::size_t>(ctrl_struct) < (details::cntrl_struct_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_ctrl_set_.find(details::cntrl_struct_list[ctrl_struct - 1]);

               if (disabled_ctrl_set_.end() != itr)
               {
                  disabled_ctrl_set_.erase(itr);
               }
            }

            return (*this);
         }

         settings_store& enable_logic_operation(const settings_logic_opr logic)
         {
            if (
                 (e_logic_unknown != logic) &&
                 (static_cast<std::size_t>(logic) < (details::logic_ops_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_logic_set_.find(details::logic_ops_list[logic - 1]);

               if (disabled_logic_set_.end() != itr)
               {
                  disabled_logic_set_.erase(itr);
               }
            }

            return (*this);
         }

         settings_store& enable_arithmetic_operation(const settings_arithmetic_opr arithmetic)
         {
            if (
                 (e_arith_unknown != arithmetic) &&
                 (static_cast<std::size_t>(arithmetic) < (details::arithmetic_ops_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_arithmetic_set_.find(details::arithmetic_ops_list[arithmetic - 1]);

               if (disabled_arithmetic_set_.end() != itr)
               {
                  disabled_arithmetic_set_.erase(itr);
               }
            }

            return (*this);
         }

         settings_store& enable_assignment_operation(const settings_assignment_opr assignment)
         {
            if (
                 (e_assign_unknown != assignment) &&
                 (static_cast<std::size_t>(assignment) < (details::assignment_ops_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_assignment_set_.find(details::assignment_ops_list[assignment - 1]);

               if (disabled_assignment_set_.end() != itr)
               {
                  disabled_assignment_set_.erase(itr);
               }
            }

            return (*this);
         }

         settings_store& enable_inequality_operation(const settings_inequality_opr inequality)
         {
            if (
                 (e_ineq_unknown != inequality) &&
                 (static_cast<std::size_t>(inequality) < (details::inequality_ops_list_size + 1))
               )
            {
               const des_itr_t itr = disabled_inequality_set_.find(details::inequality_ops_list[inequality - 1]);

               if (disabled_inequality_set_.end() != itr)
               {
                  disabled_inequality_set_.erase(itr);
               }
            }

            return (*this);
         }

         void set_max_stack_depth(const std::size_t max_stack_depth)
         {
            max_stack_depth_ = max_stack_depth;
         }

         void set_max_node_depth(const std::size_t max_node_depth)
         {
            max_node_depth_ = max_node_depth;
         }

         void set_max_local_vector_size(const std::size_t max_local_vector_size)
         {
            max_local_vector_size_ = max_local_vector_size;
         }

         std::size_t max_stack_depth() const
         {
            return max_stack_depth_;
         }

         std::size_t max_node_depth() const
         {
            return max_node_depth_;
         }

         std::size_t max_local_vector_size() const
         {
            return max_local_vector_size_;
         }

      private:

         void load_compile_options(const std::size_t compile_options)
         {
            enable_replacer_           = (compile_options & e_replacer            ) == e_replacer;
            enable_joiner_             = (compile_options & e_joiner              ) == e_joiner;
            enable_numeric_check_      = (compile_options & e_numeric_check       ) == e_numeric_check;
            enable_bracket_check_      = (compile_options & e_bracket_check       ) == e_bracket_check;
            enable_sequence_check_     = (compile_options & e_sequence_check      ) == e_sequence_check;
            enable_commutative_check_  = (compile_options & e_commutative_check   ) == e_commutative_check;
            enable_strength_reduction_ = (compile_options & e_strength_reduction  ) == e_strength_reduction;
            enable_collect_vars_       = (compile_options & e_collect_vars        ) == e_collect_vars;
            enable_collect_funcs_      = (compile_options & e_collect_funcs       ) == e_collect_funcs;
            enable_collect_assings_    = (compile_options & e_collect_assings     ) == e_collect_assings;
            disable_vardef_            = (compile_options & e_disable_vardef      ) == e_disable_vardef;
            disable_rsrvd_sym_usr_     = (compile_options & e_disable_usr_on_rsrvd) == e_disable_usr_on_rsrvd;
            disable_zero_return_       = (compile_options & e_disable_zero_return ) == e_disable_zero_return;
         }

         std::string assign_opr_to_string(details::operator_type opr) const
         {
            switch (opr)
            {
               case details::e_assign : return ":=";
               case details::e_addass : return "+=";
               case details::e_subass : return "-=";
               case details::e_mulass : return "*=";
               case details::e_divass : return "/=";
               case details::e_modass : return "%=";
               default                : return ""  ;
            }
         }

         std::string arith_opr_to_string(details::operator_type opr) const
         {
            switch (opr)
            {
               case details::e_add : return "+";
               case details::e_sub : return "-";
               case details::e_mul : return "*";
               case details::e_div : return "/";
               case details::e_mod : return "%";
               case details::e_pow : return "^";
               default             : return "" ;
            }
         }

         std::string inequality_opr_to_string(details::operator_type opr) const
         {
            switch (opr)
            {
               case details::e_lt    : return "<" ;
               case details::e_lte   : return "<=";
               case details::e_eq    : return "==";
               case details::e_equal : return "=" ;
               case details::e_ne    : return "!=";
               case details::e_nequal: return "<>";
               case details::e_gte   : return ">=";
               case details::e_gt    : return ">" ;
               default               : return ""  ;
            }
         }

         std::string logic_opr_to_string(details::operator_type opr) const
         {
            switch (opr)
            {
               case details::e_and  : return "and" ;
               case details::e_or   : return "or"  ;
               case details::e_xor  : return "xor" ;
               case details::e_nand : return "nand";
               case details::e_nor  : return "nor" ;
               case details::e_xnor : return "xnor";
               case details::e_notl : return "not" ;
               default              : return ""    ;
            }
         }

         bool enable_replacer_;
         bool enable_joiner_;
         bool enable_numeric_check_;
         bool enable_bracket_check_;
         bool enable_sequence_check_;
         bool enable_commutative_check_;
         bool enable_strength_reduction_;
         bool enable_collect_vars_;
         bool enable_collect_funcs_;
         bool enable_collect_assings_;
         bool disable_vardef_;
         bool disable_rsrvd_sym_usr_;
         bool disable_zero_return_;

         disabled_entity_set_t disabled_func_set_ ;
         disabled_entity_set_t disabled_ctrl_set_ ;
         disabled_entity_set_t disabled_logic_set_;
         disabled_entity_set_t disabled_arithmetic_set_;
         disabled_entity_set_t disabled_assignment_set_;
         disabled_entity_set_t disabled_inequality_set_;

         std::size_t max_stack_depth_;
         std::size_t max_node_depth_;
         std::size_t max_local_vector_size_;

         friend class parser<T>;
      };

      typedef settings_store settings_t;

      explicit parser(const settings_t& settings = settings_t())
      : settings_(settings)
      , resolve_unknown_symbol_(false)
      , results_context_(0)
      , unknown_symbol_resolver_(reinterpret_cast<unknown_symbol_resolver*>(0))
        #ifdef _MSC_VER
        #pragma warning(push)
        #pragma warning (disable:4355)
        #endif
      , sem_(*this)
        #ifdef _MSC_VER
        #pragma warning(pop)
        #endif
      , operator_joiner_2_(2)
      , operator_joiner_3_(3)
      , loop_runtime_check_(0)
      , vector_access_runtime_check_(0)
      , compilation_check_ptr_(0)
      , assert_check_(0)
      {
         init_precompilation();

         load_operations_map           (base_ops_map_     );
         load_unary_operations_map     (unary_op_map_     );
         load_binary_operations_map    (binary_op_map_    );
         load_inv_binary_operations_map(inv_binary_op_map_);
         load_sf3_map                  (sf3_map_          );
         load_sf4_map                  (sf4_map_          );

         expression_generator_.init_synthesize_map();
         expression_generator_.set_parser(*this);
         expression_generator_.set_uom (unary_op_map_     );
         expression_generator_.set_bom (binary_op_map_    );
         expression_generator_.set_ibom(inv_binary_op_map_);
         expression_generator_.set_sf3m(sf3_map_          );
         expression_generator_.set_sf4m(sf4_map_          );
         expression_generator_.set_strength_reduction_state(settings_.strength_reduction_enabled());
      }

     ~parser()
      {}

      inline void init_precompilation()
      {
         dec_.collect_variables() =
            settings_.collect_variables_enabled();

         dec_.collect_functions() =
            settings_.collect_functions_enabled();

         dec_.collect_assignments() =
            settings_.collect_assignments_enabled();

         if (settings_.replacer_enabled())
         {
            symbol_replacer_.clear();
            symbol_replacer_.add_replace("true" , "1", lexer::token::e_number);
            symbol_replacer_.add_replace("false", "0", lexer::token::e_number);
            helper_assembly_.token_modifier_list.clear();
            helper_assembly_.register_modifier(&symbol_replacer_);
         }

         if (settings_.commutative_check_enabled())
         {
            for (std::size_t i = 0; i < details::reserved_words_size; ++i)
            {
               commutative_inserter_.ignore_symbol(details::reserved_words[i]);
            }

            helper_assembly_.token_inserter_list.clear();
            helper_assembly_.register_inserter(&commutative_inserter_);
         }

         if (settings_.joiner_enabled())
         {
            helper_assembly_.token_joiner_list.clear();
            helper_assembly_.register_joiner(&operator_joiner_2_);
            helper_assembly_.register_joiner(&operator_joiner_3_);
         }

         if (
              settings_.numeric_check_enabled () ||
              settings_.bracket_check_enabled () ||
              settings_.sequence_check_enabled()
            )
         {
            helper_assembly_.token_scanner_list.clear();

            if (settings_.numeric_check_enabled())
            {
               helper_assembly_.register_scanner(&numeric_checker_);
            }

            if (settings_.bracket_check_enabled())
            {
               helper_assembly_.register_scanner(&bracket_checker_);
            }

            if (settings_.sequence_check_enabled())
            {
               helper_assembly_.register_scanner(&sequence_validator_      );
               helper_assembly_.register_scanner(&sequence_validator_3tkns_);
            }
         }
      }

      inline bool compile(const std::string& expression_string, expression<T>& expr)
      {
         state_               .reset();
         error_list_          .clear();
         brkcnt_list_         .clear();
         synthesis_error_     .clear();
         immutable_memory_map_.reset();
         immutable_symtok_map_.clear();
         current_state_stack_ .clear();
         assert_ids_          .clear();
         sem_                 .cleanup();

         return_cleanup();

         expression_generator_.set_allocator(node_allocator_);

         if (expression_string.empty())
         {
            set_error(make_error(
               parser_error::e_syntax,
               "ERR001 - Empty expression!",
               exprtk_error_location));

            return false;
         }

         if (!init(expression_string))
         {
            process_lexer_errors();
            return false;
         }

         if (lexer().empty())
         {
            set_error(make_error(
               parser_error::e_syntax,
               "ERR002 - Empty expression!",
               exprtk_error_location));

            return false;
         }

         if (halt_compilation_check())
         {
            exprtk_debug(("halt_compilation_check() - compile checkpoint 0\n"));
            return false;
         }

         if (!run_assemblies())
         {
            return false;
         }

         if (halt_compilation_check())
         {
            exprtk_debug(("halt_compilation_check() - compile checkpoint 1\n"));
            return false;
         }

         symtab_store_.symtab_list_ = expr.get_symbol_table_list();
         dec_.clear();

         lexer().begin();

         next_token();

         expression_node_ptr e = parse_corpus();

         if ((0 != e) && (token_t::e_eof == current_token().type))
         {
            bool* retinvk_ptr = 0;

            if (state_.return_stmt_present)
            {
               dec_.return_present_ = true;

               e = expression_generator_
                     .return_envelope(e, results_context_, retinvk_ptr);
            }

            expr.set_expression(e);
            expr.set_retinvk(retinvk_ptr);

            register_local_vars(expr);
            register_return_results(expr);

            return !(!expr);
         }
         else
         {
            if (error_list_.empty())
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR003 - Invalid expression encountered",
                  exprtk_error_location));
            }

            if ((0 != e) && branch_deletable(e))
            {
               destroy_node(e);
            }

            dec_.clear    ();
            sem_.cleanup  ();
            return_cleanup();

            return false;
         }
      }

      inline expression_t compile(const std::string& expression_string, symbol_table_t& symtab)
      {
         expression_t expression;
         expression.register_symbol_table(symtab);
         compile(expression_string,expression);
         return expression;
      }

      void process_lexer_errors()
      {
         for (std::size_t i = 0; i < lexer().size(); ++i)
         {
            if (lexer()[i].is_error())
            {
               std::string diagnostic = "ERR004 - ";

               switch (lexer()[i].type)
               {
                  case lexer::token::e_error      : diagnostic += "General token error";
                                                    break;

                  case lexer::token::e_err_symbol : diagnostic += "Symbol error";
                                                    break;

                  case lexer::token::e_err_number : diagnostic += "Invalid numeric token";
                                                    break;

                  case lexer::token::e_err_string : diagnostic += "Invalid string token";
                                                    break;

                  case lexer::token::e_err_sfunc  : diagnostic += "Invalid special function token";
                                                    break;

                  default                         : diagnostic += "Unknown compiler error";
               }

               set_error(make_error(
                  parser_error::e_lexer,
                  lexer()[i],
                  diagnostic + ": " + lexer()[i].value,
                  exprtk_error_location));
            }
         }
      }

      inline bool run_assemblies()
      {
         if (settings_.commutative_check_enabled())
         {
            helper_assembly_.run_inserters(lexer());
         }

         if (settings_.joiner_enabled())
         {
            helper_assembly_.run_joiners(lexer());
         }

         if (settings_.replacer_enabled())
         {
            helper_assembly_.run_modifiers(lexer());
         }

         if (
              settings_.numeric_check_enabled () ||
              settings_.bracket_check_enabled () ||
              settings_.sequence_check_enabled()
            )
         {
            if (!helper_assembly_.run_scanners(lexer()))
            {
               if (helper_assembly_.error_token_scanner)
               {
                  lexer::helper::bracket_checker*            bracket_checker_ptr     = 0;
                  lexer::helper::numeric_checker<T>*         numeric_checker_ptr     = 0;
                  lexer::helper::sequence_validator*         sequence_validator_ptr  = 0;
                  lexer::helper::sequence_validator_3tokens* sequence_validator3_ptr = 0;

                  if (0 != (bracket_checker_ptr = dynamic_cast<lexer::helper::bracket_checker*>(helper_assembly_.error_token_scanner)))
                  {
                     set_error(make_error(
                        parser_error::e_token,
                        bracket_checker_ptr->error_token(),
                        "ERR005 - Mismatched brackets: '" + bracket_checker_ptr->error_token().value + "'",
                        exprtk_error_location));
                  }
                  else if (0 != (numeric_checker_ptr = dynamic_cast<lexer::helper::numeric_checker<T>*>(helper_assembly_.error_token_scanner)))
                  {
                     for (std::size_t i = 0; i < numeric_checker_ptr->error_count(); ++i)
                     {
                        lexer::token error_token = lexer()[numeric_checker_ptr->error_index(i)];

                        set_error(make_error(
                           parser_error::e_token,
                           error_token,
                           "ERR006 - Invalid numeric token: '" + error_token.value + "'",
                           exprtk_error_location));
                     }

                     if (numeric_checker_ptr->error_count())
                     {
                        numeric_checker_ptr->clear_errors();
                     }
                  }
                  else if (0 != (sequence_validator_ptr = dynamic_cast<lexer::helper::sequence_validator*>(helper_assembly_.error_token_scanner)))
                  {
                     for (std::size_t i = 0; i < sequence_validator_ptr->error_count(); ++i)
                     {
                        std::pair<lexer::token,lexer::token> error_token = sequence_validator_ptr->error(i);

                        set_error(make_error(
                           parser_error::e_token,
                           error_token.first,
                           "ERR007 - Invalid token sequence: '" +
                           error_token.first.value  + "' and '" +
                           error_token.second.value + "'",
                           exprtk_error_location));
                     }

                     if (sequence_validator_ptr->error_count())
                     {
                        sequence_validator_ptr->clear_errors();
                     }
                  }
                  else if (0 != (sequence_validator3_ptr = dynamic_cast<lexer::helper::sequence_validator_3tokens*>(helper_assembly_.error_token_scanner)))
                  {
                     for (std::size_t i = 0; i < sequence_validator3_ptr->error_count(); ++i)
                     {
                        std::pair<lexer::token,lexer::token> error_token = sequence_validator3_ptr->error(i);

                        set_error(make_error(
                           parser_error::e_token,
                           error_token.first,
                           "ERR008 - Invalid token sequence: '" +
                           error_token.first.value  + "' and '" +
                           error_token.second.value + "'",
                           exprtk_error_location));
                     }

                     if (sequence_validator3_ptr->error_count())
                     {
                        sequence_validator3_ptr->clear_errors();
                     }
                  }
               }

               return false;
            }
         }

         return true;
      }

      inline settings_store& settings()
      {
         return settings_;
      }

      inline parser_error::type get_error(const std::size_t& index) const
      {
         if (index < error_list_.size())
         {
            return error_list_[index];
         }

         throw std::invalid_argument("parser::get_error() - Invalid error index specified");
      }

      inline std::string error() const
      {
         if (!error_list_.empty())
         {
            return error_list_[0].diagnostic;
         }
         else
            return std::string("No Error");
      }

      inline std::size_t error_count() const
      {
         return error_list_.size();
      }

      inline dependent_entity_collector& dec()
      {
         return dec_;
      }

      inline bool replace_symbol(const std::string& old_symbol, const std::string& new_symbol)
      {
         if (!settings_.replacer_enabled())
            return false;
         else if (details::is_reserved_word(old_symbol))
            return false;
         else
            return symbol_replacer_.add_replace(old_symbol,new_symbol,lexer::token::e_symbol);
      }

      inline bool remove_replace_symbol(const std::string& symbol)
      {
         if (!settings_.replacer_enabled())
            return false;
         else if (details::is_reserved_word(symbol))
            return false;
         else
            return symbol_replacer_.remove(symbol);
      }

      inline void enable_unknown_symbol_resolver(unknown_symbol_resolver* usr = reinterpret_cast<unknown_symbol_resolver*>(0))
      {
         resolve_unknown_symbol_ = true;

         if (usr)
            unknown_symbol_resolver_ = usr;
         else
            unknown_symbol_resolver_ = &default_usr_;
      }

      inline void enable_unknown_symbol_resolver(unknown_symbol_resolver& usr)
      {
         enable_unknown_symbol_resolver(&usr);
      }

      inline void disable_unknown_symbol_resolver()
      {
         resolve_unknown_symbol_  = false;
         unknown_symbol_resolver_ = &default_usr_;
      }

      inline void register_loop_runtime_check(loop_runtime_check& lrtchk)
      {
         loop_runtime_check_ = &lrtchk;
      }

      inline void register_vector_access_runtime_check(vector_access_runtime_check& vartchk)
      {
         vector_access_runtime_check_ = &vartchk;
      }

      inline void register_compilation_timeout_check(compilation_check& compchk)
      {
         compilation_check_ptr_ = &compchk;
      }

      inline void register_assert_check(assert_check& assrt_chck)
      {
         assert_check_ = &assrt_chck;
      }

      inline void clear_loop_runtime_check()
      {
         loop_runtime_check_ = loop_runtime_check_ptr(0);
      }

      inline void clear_vector_access_runtime_check()
      {
         vector_access_runtime_check_ = vector_access_runtime_check_ptr(0);
      }

      inline void clear_compilation_timeout_check()
      {
         compilation_check_ptr_ = compilation_check_ptr(0);
      }

      inline void clear_assert_check()
      {
         assert_check_ = assert_check_ptr(0);
      }

   private:

      inline bool valid_base_operation(const std::string& symbol) const
      {
         const std::size_t length = symbol.size();

         if (
              (length < 3) || // Shortest base op symbol length
              (length > 9)    // Longest base op symbol length
            )
            return false;
         else
            return settings_.function_enabled(symbol) &&
                   (base_ops_map_.end() != base_ops_map_.find(symbol));
      }

      inline bool valid_vararg_operation(const std::string& symbol) const
      {
         static const std::string s_sum     = "sum" ;
         static const std::string s_mul     = "mul" ;
         static const std::string s_avg     = "avg" ;
         static const std::string s_min     = "min" ;
         static const std::string s_max     = "max" ;
         static const std::string s_mand    = "mand";
         static const std::string s_mor     = "mor" ;
         static const std::string s_multi   = "~"   ;
         static const std::string s_mswitch = "[*]" ;

         return
               (
                  details::imatch(symbol,s_sum    ) ||
                  details::imatch(symbol,s_mul    ) ||
                  details::imatch(symbol,s_avg    ) ||
                  details::imatch(symbol,s_min    ) ||
                  details::imatch(symbol,s_max    ) ||
                  details::imatch(symbol,s_mand   ) ||
                  details::imatch(symbol,s_mor    ) ||
                  details::imatch(symbol,s_multi  ) ||
                  details::imatch(symbol,s_mswitch)
               ) &&
               settings_.function_enabled(symbol);
      }

      bool is_invalid_logic_operation(const details::operator_type operation) const
      {
         return settings_.logic_disabled(operation);
      }

      bool is_invalid_arithmetic_operation(const details::operator_type operation) const
      {
         return settings_.arithmetic_disabled(operation);
      }

      bool is_invalid_assignment_operation(const details::operator_type operation) const
      {
         return settings_.assignment_disabled(operation);
      }

      bool is_invalid_inequality_operation(const details::operator_type operation) const
      {
         return settings_.inequality_disabled(operation);
      }

      #ifdef exprtk_enable_debugging
      inline void next_token()
      {
         const std::string ct_str = current_token().value;
         const std::size_t ct_pos = current_token().position;
         parser_helper::next_token();
         const std::string depth(2 * state_.scope_depth,' ');
         exprtk_debug(("%s"
                       "prev[%s | %04d] --> curr[%s | %04d]  stack_level: %3d\n",
                       depth.c_str(),
                       ct_str.c_str(),
                       static_cast<unsigned int>(ct_pos),
                       current_token().value.c_str(),
                       static_cast<unsigned int>(current_token().position),
                       static_cast<unsigned int>(state_.stack_depth)));
      }
      #endif

      inline expression_node_ptr parse_corpus()
      {
         std::vector<expression_node_ptr> arg_list;
         std::vector<bool> side_effect_list;

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         lexer::token begin_token;
         lexer::token end_token;

         for ( ; ; )
         {
            state_.side_effect_present = false;

            begin_token = current_token();

            expression_node_ptr arg = parse_expression();

            if (0 == arg)
            {
               if (error_list_.empty())
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR009 - Invalid expression encountered",
                     exprtk_error_location));
               }

               return error_node();
            }
            else
            {
               arg_list.push_back(arg);

               side_effect_list.push_back(state_.side_effect_present);

               end_token = current_token();

               const std::string sub_expr = construct_subexpr(begin_token, end_token);

               exprtk_debug(("parse_corpus(%02d) Subexpr: %s\n",
                             static_cast<int>(arg_list.size() - 1),
                             sub_expr.c_str()));

               exprtk_debug(("parse_corpus(%02d) - Side effect present: %s\n",
                             static_cast<int>(arg_list.size() - 1),
                             state_.side_effect_present ? "true" : "false"));

               exprtk_debug(("-------------------------------------------------\n"));
            }

            if (token_is(token_t::e_eof,prsrhlpr_t::e_hold))
            {
               if (lexer().finished())
                  break;
               else
                  next_token();
            }
         }

         if (
              !arg_list.empty() &&
              is_return_node(arg_list.back())
            )
         {
            dec_.final_stmt_return_ = true;
         }

         const expression_node_ptr result = simplify(arg_list,side_effect_list);

         sdd.delete_ptr = (0 == result);

         return result;
      }

      std::string construct_subexpr(lexer::token& begin_token,
                                    lexer::token& end_token,
                                    const bool cleanup_whitespace = true)
      {
         std::string result = lexer().substr(begin_token.position,end_token.position);
         if (cleanup_whitespace)
         {
            for (std::size_t i = 0; i < result.size(); ++i)
            {
               if (details::is_whitespace(result[i])) result[i] = ' ';
            }
         }

         return result;
      }

      static const precedence_level default_precedence = e_level00;

      struct state_t
      {
         inline void set(const precedence_level& l,
                         const precedence_level& r,
                         const details::operator_type& o,
                         const token_t tkn = token_t())
         {
            left      = l;
            right     = r;
            operation = o;
            token     = tkn;
         }

         inline void reset()
         {
            left      = e_level00;
            right     = e_level00;
            operation = details::e_default;
         }

         precedence_level left;
         precedence_level right;
         details::operator_type operation;
         token_t token;
      };

      inline void push_current_state(const state_t current_state)
      {
         current_state_stack_.push_back(current_state);
      }

      inline void pop_current_state()
      {
         if (!current_state_stack_.empty())
         {
            current_state_stack_.pop_back();
         }
      }

      inline state_t current_state() const
      {
         return (!current_state_stack_.empty()) ?
                current_state_stack_.back()     :
                state_t();
      }

      inline bool halt_compilation_check()
      {
         compilation_check::compilation_context context;

         if (compilation_check_ptr_ && !compilation_check_ptr_->continue_compilation(context))
         {
            const std::string error_message =
               !context.error_message.empty() ? " Details: " + context.error_message : "";

            set_error(make_error(
               parser_error::e_parser,
               token_t(),
               "ERR010 - Internal compilation check failed." + error_message,
               exprtk_error_location));

            return true;
         }

         return false;
      }

      inline expression_node_ptr parse_expression(precedence_level precedence = e_level00)
      {
         if (halt_compilation_check())
         {
            exprtk_debug(("halt_compilation_check() - parse_expression checkpoint 2\n"));
            return error_node();
         }

         stack_limit_handler slh(*this);

         if (!slh)
         {
            return error_node();
         }

         expression_node_ptr expression = parse_branch(precedence);

         if (0 == expression)
         {
            return error_node();
         }

         bool break_loop = false;

         state_t current_state;

         for ( ; ; )
         {
            current_state.reset();

            switch (current_token().type)
            {
               case token_t::e_assign : current_state.set(e_level00, e_level00, details::e_assign, current_token()); break;
               case token_t::e_addass : current_state.set(e_level00, e_level00, details::e_addass, current_token()); break;
               case token_t::e_subass : current_state.set(e_level00, e_level00, details::e_subass, current_token()); break;
               case token_t::e_mulass : current_state.set(e_level00, e_level00, details::e_mulass, current_token()); break;
               case token_t::e_divass : current_state.set(e_level00, e_level00, details::e_divass, current_token()); break;
               case token_t::e_modass : current_state.set(e_level00, e_level00, details::e_modass, current_token()); break;
               case token_t::e_swap   : current_state.set(e_level00, e_level00, details::e_swap  , current_token()); break;
               case token_t::e_lt     : current_state.set(e_level05, e_level06, details::e_lt    , current_token()); break;
               case token_t::e_lte    : current_state.set(e_level05, e_level06, details::e_lte   , current_token()); break;
               case token_t::e_eq     : current_state.set(e_level05, e_level06, details::e_eq    , current_token()); break;
               case token_t::e_ne     : current_state.set(e_level05, e_level06, details::e_ne    , current_token()); break;
               case token_t::e_gte    : current_state.set(e_level05, e_level06, details::e_gte   , current_token()); break;
               case token_t::e_gt     : current_state.set(e_level05, e_level06, details::e_gt    , current_token()); break;
               case token_t::e_add    : current_state.set(e_level07, e_level08, details::e_add   , current_token()); break;
               case token_t::e_sub    : current_state.set(e_level07, e_level08, details::e_sub   , current_token()); break;
               case token_t::e_div    : current_state.set(e_level10, e_level11, details::e_div   , current_token()); break;
               case token_t::e_mul    : current_state.set(e_level10, e_level11, details::e_mul   , current_token()); break;
               case token_t::e_mod    : current_state.set(e_level10, e_level11, details::e_mod   , current_token()); break;
               case token_t::e_pow    : current_state.set(e_level12, e_level12, details::e_pow   , current_token()); break;
               default                :
                  if (token_t::e_symbol == current_token().type)
                  {
                     static const std::string s_and   = "and"  ;
                     static const std::string s_nand  = "nand" ;
                     static const std::string s_or    = "or"   ;
                     static const std::string s_nor   = "nor"  ;
                     static const std::string s_xor   = "xor"  ;
                     static const std::string s_xnor  = "xnor" ;
                     static const std::string s_in    = "in"   ;
                     static const std::string s_like  = "like" ;
                     static const std::string s_ilike = "ilike";
                     static const std::string s_and1  = "&"    ;
                     static const std::string s_or1   = "|"    ;
                     static const std::string s_not   = "not"  ;

                     if (details::imatch(current_token().value,s_and))
                     {
                        current_state.set(e_level03, e_level04, details::e_and, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_and1))
                     {
                        #ifndef exprtk_disable_sc_andor
                        current_state.set(e_level03, e_level04, details::e_scand, current_token());
                        #else
                        current_state.set(e_level03, e_level04, details::e_and, current_token());
                        #endif
                        break;
                     }
                     else if (details::imatch(current_token().value,s_nand))
                     {
                        current_state.set(e_level03, e_level04, details::e_nand, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_or))
                     {
                        current_state.set(e_level01, e_level02, details::e_or, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_or1))
                     {
                        #ifndef exprtk_disable_sc_andor
                        current_state.set(e_level01, e_level02, details::e_scor, current_token());
                        #else
                        current_state.set(e_level01, e_level02, details::e_or, current_token());
                        #endif
                        break;
                     }
                     else if (details::imatch(current_token().value,s_nor))
                     {
                        current_state.set(e_level01, e_level02, details::e_nor, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_xor))
                     {
                        current_state.set(e_level01, e_level02, details::e_xor, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_xnor))
                     {
                        current_state.set(e_level01, e_level02, details::e_xnor, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_in))
                     {
                        current_state.set(e_level04, e_level04, details::e_in, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_like))
                     {
                        current_state.set(e_level04, e_level04, details::e_like, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_ilike))
                     {
                        current_state.set(e_level04, e_level04, details::e_ilike, current_token());
                        break;
                     }
                     else if (details::imatch(current_token().value,s_not))
                     {
                        break;
                     }
                  }

                  break_loop = true;
            }

            if (break_loop)
            {
               parse_pending_string_rangesize(expression);
               break;
            }
            else if (current_state.left < precedence)
               break;

            const lexer::token prev_token = current_token();

            next_token();

            expression_node_ptr right_branch   = error_node();
            expression_node_ptr new_expression = error_node();

            if (is_invalid_logic_operation(current_state.operation))
            {
               free_node(node_allocator_, expression);

               set_error(make_error(
                  parser_error::e_syntax,
                  prev_token,
                  "ERR011 - Invalid or disabled logic operation '" + details::to_str(current_state.operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_arithmetic_operation(current_state.operation))
            {
               free_node(node_allocator_, expression);

               set_error(make_error(
                  parser_error::e_syntax,
                  prev_token,
                  "ERR012 - Invalid or disabled arithmetic operation '" + details::to_str(current_state.operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_inequality_operation(current_state.operation))
            {
               free_node(node_allocator_, expression);

               set_error(make_error(
                  parser_error::e_syntax,
                  prev_token,
                  "ERR013 - Invalid inequality operation '" + details::to_str(current_state.operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_assignment_operation(current_state.operation))
            {
               free_node(node_allocator_, expression);

               set_error(make_error(
                  parser_error::e_syntax,
                  prev_token,
                  "ERR014 - Invalid or disabled assignment operation '" + details::to_str(current_state.operation) + "'",
                  exprtk_error_location));

               return error_node();
            }

            if (0 != (right_branch = parse_expression(current_state.right)))
            {
               if (
                    details::is_return_node(expression  ) ||
                    details::is_return_node(right_branch)
                  )
               {
                  free_node(node_allocator_, expression  );
                  free_node(node_allocator_, right_branch);

                  set_error(make_error(
                     parser_error::e_syntax,
                     prev_token,
                     "ERR015 - Return statements cannot be part of sub-expressions",
                     exprtk_error_location));

                  return error_node();
               }

               push_current_state(current_state);

               new_expression = expression_generator_
                                  (
                                    current_state.operation,
                                    expression,
                                    right_branch
                                  );

               pop_current_state();
            }

            if (0 == new_expression)
            {
               if (error_list_.empty())
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     prev_token,
                     !synthesis_error_.empty() ?
                     synthesis_error_ :
                     "ERR016 - General parsing error at token: '" + prev_token.value + "'",
                     exprtk_error_location));
               }

               free_node(node_allocator_, expression  );
               free_node(node_allocator_, right_branch);

               return error_node();
            }
            else
            {
               if (
                    token_is(token_t::e_ternary,prsrhlpr_t::e_hold) &&
                    (e_level00 == precedence)
                  )
               {
                  expression = parse_ternary_conditional_statement(new_expression);
               }
               else
                  expression = new_expression;

               parse_pending_string_rangesize(expression);
            }
         }

         if ((0 != expression) && (expression->node_depth() > settings_.max_node_depth_))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR017 - Expression depth of " + details::to_str(static_cast<int>(expression->node_depth())) +
               " exceeds maximum allowed expression depth of " + details::to_str(static_cast<int>(settings_.max_node_depth_)),
               exprtk_error_location));

            free_node(node_allocator_, expression);

            return error_node();
         }

         return expression;
      }

      bool simplify_unary_negation_branch(expression_node_ptr& node)
      {
         {
            typedef details::unary_branch_node<T,details::neg_op<T> > ubn_t;
            ubn_t* n = dynamic_cast<ubn_t*>(node);

            if (n)
            {
               expression_node_ptr un_r = n->branch(0);
               n->release();
               free_node(node_allocator_, node);
               node = un_r;

               return true;
            }
         }

         {
            typedef details::unary_variable_node<T,details::neg_op<T> > uvn_t;

            uvn_t* n = dynamic_cast<uvn_t*>(node);

            if (n)
            {
               const T& v = n->v();
               expression_node_ptr return_node = error_node();

               if (
                    (0 != (return_node = symtab_store_.get_variable(v))) ||
                    (0 != (return_node = sem_         .get_variable(v)))
                  )
               {
                  free_node(node_allocator_, node);
                  node = return_node;

                  return true;
               }
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR018 - Failed to find variable node in symbol table",
                     exprtk_error_location));

                  free_node(node_allocator_, node);

                  return false;
               }
            }
         }

         return false;
      }

      static inline expression_node_ptr error_node()
      {
         return reinterpret_cast<expression_node_ptr>(0);
      }

      struct scoped_expression_delete
      {
         scoped_expression_delete(parser<T>& pr, expression_node_ptr& expression)
         : delete_ptr(true)
         , parser_(pr)
         , expression_(expression)
         {}

        ~scoped_expression_delete()
         {
            if (delete_ptr)
            {
               free_node(parser_.node_allocator_, expression_);
            }
         }

         bool delete_ptr;
         parser<T>& parser_;
         expression_node_ptr& expression_;

      private:

         scoped_expression_delete(const scoped_expression_delete&) exprtk_delete;
         scoped_expression_delete& operator=(const scoped_expression_delete&) exprtk_delete;
      };

      template <typename Type, std::size_t N>
      struct scoped_delete
      {
         typedef Type* ptr_t;

         scoped_delete(parser<T>& pr, ptr_t& p)
         : delete_ptr(true)
         , parser_(pr)
         , p_(&p)
         {}

         scoped_delete(parser<T>& pr, ptr_t (&p)[N])
         : delete_ptr(true)
         , parser_(pr)
         , p_(&p[0])
         {}

        ~scoped_delete()
         {
            if (delete_ptr)
            {
               for (std::size_t i = 0; i < N; ++i)
               {
                  free_node(parser_.node_allocator_, p_[i]);
               }
            }
         }

         bool delete_ptr;
         parser<T>& parser_;
         ptr_t* p_;

      private:

         scoped_delete(const scoped_delete<Type,N>&) exprtk_delete;
         scoped_delete<Type,N>& operator=(const scoped_delete<Type,N>&) exprtk_delete;
      };

      template <typename Type>
      struct scoped_deq_delete
      {
         typedef Type* ptr_t;

         scoped_deq_delete(parser<T>& pr, std::deque<ptr_t>& deq)
         : delete_ptr(true)
         , parser_(pr)
         , deq_(deq)
         {}

        ~scoped_deq_delete()
         {
            if (delete_ptr && !deq_.empty())
            {
               for (std::size_t i = 0; i < deq_.size(); ++i)
               {
                  exprtk_debug(("~scoped_deq_delete() - deleting node: %p\n", reinterpret_cast<void*>(deq_[i])));
                  free_node(parser_.node_allocator_,deq_[i]);
               }

               deq_.clear();
            }
         }

         bool delete_ptr;
         parser<T>& parser_;
         std::deque<ptr_t>& deq_;

      private:

         scoped_deq_delete(const scoped_deq_delete<Type>&) exprtk_delete;
         scoped_deq_delete<Type>& operator=(const scoped_deq_delete<Type>&) exprtk_delete;
      };

      template <typename Type>
      struct scoped_vec_delete
      {
         typedef Type* ptr_t;

         scoped_vec_delete(parser<T>& pr, std::vector<ptr_t>& vec)
         : delete_ptr(true)
         , parser_(pr)
         , vec_(vec)
         {}

        ~scoped_vec_delete()
         {
            if (delete_ptr && !vec_.empty())
            {
               for (std::size_t i = 0; i < vec_.size(); ++i)
               {
                  exprtk_debug(("~scoped_vec_delete() - deleting node: %p\n", reinterpret_cast<void*>(vec_[i])));
                  free_node(parser_.node_allocator_,vec_[i]);
               }

               vec_.clear();
            }
         }

         ptr_t operator[](const std::size_t index)
         {
            return vec_[index];
         }

         bool delete_ptr;
         parser<T>& parser_;
         std::vector<ptr_t>& vec_;

      private:

         scoped_vec_delete(const scoped_vec_delete<Type>&) exprtk_delete;
         scoped_vec_delete<Type>& operator=(const scoped_vec_delete<Type>&) exprtk_delete;
      };

      struct scoped_bool_negator
      {
         explicit scoped_bool_negator(bool& bb)
         : b(bb)
         { b = !b; }

        ~scoped_bool_negator()
         { b = !b; }

         bool& b;
      };

      struct scoped_bool_or_restorer
      {
         explicit scoped_bool_or_restorer(bool& bb)
         : b(bb)
         , original_value_(bb)
         {}

        ~scoped_bool_or_restorer()
         {
            b = b || original_value_;
         }

         bool& b;
         bool original_value_;
      };

      struct scoped_inc_dec
      {
         explicit scoped_inc_dec(std::size_t& v)
         : v_(v)
         { ++v_; }

        ~scoped_inc_dec()
         {
           assert(v_ > 0);
           --v_;
         }

         std::size_t& v_;
      };

      inline expression_node_ptr parse_function_invocation(ifunction<T>* function, const std::string& function_name)
      {
         expression_node_ptr func_node = reinterpret_cast<expression_node_ptr>(0);

         switch (function->param_count)
         {
            case  0 : func_node = parse_function_call_0  (function,function_name); break;
            case  1 : func_node = parse_function_call< 1>(function,function_name); break;
            case  2 : func_node = parse_function_call< 2>(function,function_name); break;
            case  3 : func_node = parse_function_call< 3>(function,function_name); break;
            case  4 : func_node = parse_function_call< 4>(function,function_name); break;
            case  5 : func_node = parse_function_call< 5>(function,function_name); break;
            case  6 : func_node = parse_function_call< 6>(function,function_name); break;
            case  7 : func_node = parse_function_call< 7>(function,function_name); break;
            case  8 : func_node = parse_function_call< 8>(function,function_name); break;
            case  9 : func_node = parse_function_call< 9>(function,function_name); break;
            case 10 : func_node = parse_function_call<10>(function,function_name); break;
            case 11 : func_node = parse_function_call<11>(function,function_name); break;
            case 12 : func_node = parse_function_call<12>(function,function_name); break;
            case 13 : func_node = parse_function_call<13>(function,function_name); break;
            case 14 : func_node = parse_function_call<14>(function,function_name); break;
            case 15 : func_node = parse_function_call<15>(function,function_name); break;
            case 16 : func_node = parse_function_call<16>(function,function_name); break;
            case 17 : func_node = parse_function_call<17>(function,function_name); break;
            case 18 : func_node = parse_function_call<18>(function,function_name); break;
            case 19 : func_node = parse_function_call<19>(function,function_name); break;
            case 20 : func_node = parse_function_call<20>(function,function_name); break;
            default : {
                         set_error(make_error(
                           parser_error::e_syntax,
                           current_token(),
                           "ERR019 - Invalid number of parameters for function: '" + function_name + "'",
                           exprtk_error_location));

                         return error_node();
                      }
         }

         if (func_node)
            return func_node;
         else
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR020 - Failed to generate call to function: '" + function_name + "'",
               exprtk_error_location));

            return error_node();
         }
      }

      template <std::size_t NumberofParameters>
      inline expression_node_ptr parse_function_call(ifunction<T>* function, const std::string& function_name)
      {
         #ifdef _MSC_VER
            #pragma warning(push)
            #pragma warning(disable: 4127)
         #endif
         if (0 == NumberofParameters)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR021 - Expecting ifunction '" + function_name + "' to have non-zero parameter count",
               exprtk_error_location));

            return error_node();
         }
         #ifdef _MSC_VER
            #pragma warning(pop)
         #endif

         expression_node_ptr branch[NumberofParameters];
         expression_node_ptr result  = error_node();

         std::fill_n(branch, NumberofParameters, reinterpret_cast<expression_node_ptr>(0));

         scoped_delete<expression_node_t,NumberofParameters> sd((*this),branch);

         next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR022 - Expecting argument list for function: '" + function_name + "'",
               exprtk_error_location));

            return error_node();
         }

         for (int i = 0; i < static_cast<int>(NumberofParameters); ++i)
         {
            branch[i] = parse_expression();

            if (0 == branch[i])
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR023 - Failed to parse argument " + details::to_str(i) + " for function: '" + function_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (i < static_cast<int>(NumberofParameters - 1))
            {
               if (!token_is(token_t::e_comma))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR024 - Invalid number of arguments for function: '" + function_name + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         if (!token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR025 - Invalid number of arguments for function: '" + function_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else
            result = expression_generator_.function(function,branch);

         sd.delete_ptr = (0 == result);

         return result;
      }

      inline expression_node_ptr parse_function_call_0(ifunction<T>* function, const std::string& function_name)
      {
         expression_node_ptr result = expression_generator_.function(function);

         state_.side_effect_present = function->has_side_effects();

         next_token();

         if (
               token_is(token_t::e_lbracket) &&
              !token_is(token_t::e_rbracket)
            )
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR026 - Expecting '()' to proceed call to function: '" + function_name + "'",
               exprtk_error_location));

            free_node(node_allocator_, result);

            return error_node();
         }
         else
            return result;
      }

      template <std::size_t MaxNumberofParameters>
      inline std::size_t parse_base_function_call(expression_node_ptr (&param_list)[MaxNumberofParameters], const std::string& function_name = "")
      {
         std::fill_n(param_list, MaxNumberofParameters, reinterpret_cast<expression_node_ptr>(0));

         scoped_delete<expression_node_t,MaxNumberofParameters> sd((*this),param_list);

         next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR027 - Expected a '(' at start of function call to '" + function_name  +
               "', instead got: '" + current_token().value + "'",
               exprtk_error_location));

            return 0;
         }

         if (token_is(token_t::e_rbracket, e_hold))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR028 - Expected at least one input parameter for function call '" + function_name + "'",
               exprtk_error_location));

            return 0;
         }

         std::size_t param_index = 0;

         for (; param_index < MaxNumberofParameters; ++param_index)
         {
            param_list[param_index] = parse_expression();

            if (0 == param_list[param_index])
               return 0;
            else if (token_is(token_t::e_rbracket))
            {
               sd.delete_ptr = false;
               break;
            }
            else if (token_is(token_t::e_comma))
               continue;
            else
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR029 - Expected a ',' between function input parameters, instead got: '" + current_token().value + "'",
                  exprtk_error_location));

               return 0;
            }
         }

         if (sd.delete_ptr)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR030 - Invalid number of input parameters passed to function '" + function_name  + "'",
               exprtk_error_location));

            return 0;
         }

         return (param_index + 1);
      }

      inline expression_node_ptr parse_base_operation()
      {
         typedef std::pair<base_ops_map_t::iterator,base_ops_map_t::iterator> map_range_t;

         const std::string operation_name   = current_token().value;
         const token_t     diagnostic_token = current_token();

         map_range_t itr_range = base_ops_map_.equal_range(operation_name);

         if (0 == std::distance(itr_range.first,itr_range.second))
         {
            set_error(make_error(
               parser_error::e_syntax,
               diagnostic_token,
               "ERR031 - No entry found for base operation: " + operation_name,
               exprtk_error_location));

            return error_node();
         }

         static const std::size_t MaxNumberofParameters = 4;
         expression_node_ptr param_list[MaxNumberofParameters] = {0};

         const std::size_t parameter_count = parse_base_function_call(param_list, operation_name);

         if ((parameter_count > 0) && (parameter_count <= MaxNumberofParameters))
         {
            for (base_ops_map_t::iterator itr = itr_range.first; itr != itr_range.second; ++itr)
            {
               const details::base_operation_t& operation = itr->second;

               if (operation.num_params == parameter_count)
               {
                  switch (parameter_count)
                  {
                     #define base_opr_case(N)                                         \
                     case N : {                                                       \
                                 expression_node_ptr pl##N[N] = {0};                  \
                                 std::copy(param_list, param_list + N, pl##N);        \
                                 lodge_symbol(operation_name, e_st_function);         \
                                 return expression_generator_(operation.type, pl##N); \
                              }                                                       \

                     base_opr_case(1)
                     base_opr_case(2)
                     base_opr_case(3)
                     base_opr_case(4)
                     #undef base_opr_case
                  }
               }
            }
         }

         for (std::size_t i = 0; i < MaxNumberofParameters; ++i)
         {
            free_node(node_allocator_, param_list[i]);
         }

         set_error(make_error(
            parser_error::e_syntax,
            diagnostic_token,
            "ERR032 - Invalid number of input parameters for call to function: '" + operation_name + "'",
            exprtk_error_location));

         return error_node();
      }

      inline expression_node_ptr parse_conditional_statement_01(expression_node_ptr condition)
      {
         // Parse: [if][(][condition][,][consequent][,][alternative][)]

         expression_node_ptr consequent  = error_node();
         expression_node_ptr alternative = error_node();

         bool result = true;

         if (!token_is(token_t::e_comma))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR033 - Expected ',' between if-statement condition and consequent",
               exprtk_error_location));

            result = false;
         }
         else if (0 == (consequent = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR034 - Failed to parse consequent for if-statement",
               exprtk_error_location));

            result = false;
         }
         else if (!token_is(token_t::e_comma))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR035 - Expected ',' between if-statement consequent and alternative",
               exprtk_error_location));

            result = false;
         }
         else if (0 == (alternative = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR036 - Failed to parse alternative for if-statement",
               exprtk_error_location));

            result = false;
         }
         else if (!token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR037 - Expected ')' at the end of if-statement",
               exprtk_error_location));

            result = false;
         }

         #ifndef exprtk_disable_string_capabilities
         if (result)
         {
            const bool consq_is_str = is_generally_string_node(consequent );
            const bool alter_is_str = is_generally_string_node(alternative);

            if (consq_is_str || alter_is_str)
            {
               if (consq_is_str && alter_is_str)
               {
                  expression_node_ptr result_node =
                     expression_generator_
                        .conditional_string(condition, consequent, alternative);

                  if (result_node && result_node->valid())
                  {
                     return result_node;
                  }

                  set_error(make_error(
                     parser_error::e_synthesis,
                     current_token(),
                     "ERR038 - Failed to synthesize node: conditional_string",
                     exprtk_error_location));

                  free_node(node_allocator_, result_node);
                  return error_node();
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR039 - Return types of if-statement differ: string/non-string",
                  exprtk_error_location));

               result = false;
            }
         }
         #endif

         if (result)
         {
            const bool consq_is_vec = is_ivector_node(consequent );
            const bool alter_is_vec = is_ivector_node(alternative);

            if (consq_is_vec || alter_is_vec)
            {
               if (consq_is_vec && alter_is_vec)
               {
                  return expression_generator_
                           .conditional_vector(condition, consequent, alternative);
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR040 - Return types of if-statement differ: vector/non-vector",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!result)
         {
            free_node(node_allocator_, condition  );
            free_node(node_allocator_, consequent );
            free_node(node_allocator_, alternative);

            return error_node();
         }
         else
            return expression_generator_
                      .conditional(condition, consequent, alternative);
      }

      inline expression_node_ptr parse_conditional_statement_02(expression_node_ptr condition)
      {
         expression_node_ptr consequent  = error_node();
         expression_node_ptr alternative = error_node();

         bool result = true;

         if (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold))
         {
            if (0 == (consequent = parse_multi_sequence("if-statement-01")))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR041 - Failed to parse body of consequent for if-statement",
                  exprtk_error_location));

               result = false;
            }
            else if
            (
              !settings_.commutative_check_enabled()           &&
              !token_is("else",prsrhlpr_t::e_hold)             &&
              !token_is_loop(prsrhlpr_t::e_hold)               &&
              !token_is_arithmetic_opr(prsrhlpr_t::e_hold)     &&
              !token_is_right_bracket (prsrhlpr_t::e_hold)     &&
              !token_is_ineq_opr      (prsrhlpr_t::e_hold)     &&
              !token_is(token_t::e_ternary,prsrhlpr_t::e_hold) &&
              !token_is(token_t::e_eof)
            )
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR042 - Expected ';' at the end of the consequent for if-statement (1)",
                  exprtk_error_location));

               result = false;
            }
         }
         else
         {
            if (
                 settings_.commutative_check_enabled() &&
                 token_is(token_t::e_mul,prsrhlpr_t::e_hold)
               )
            {
               next_token();
            }

            if (0 != (consequent = parse_expression()))
            {
               if (!token_is(token_t::e_eof))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR043 - Expected ';' at the end of the consequent for if-statement (2)",
                     exprtk_error_location));

                  result = false;
               }
            }
            else
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR044 - Failed to parse body of consequent for if-statement",
                  exprtk_error_location));

               result = false;
            }
         }

         if (result)
         {
            if (details::imatch(current_token().value,"else"))
            {
               next_token();

               if (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold))
               {
                  if (0 == (alternative = parse_multi_sequence("else-statement-01")))
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR045 - Failed to parse body of the 'else' for if-statement",
                        exprtk_error_location));

                     result = false;
                  }
               }
               else if (details::imatch(current_token().value,"if"))
               {
                  if (0 == (alternative = parse_conditional_statement()))
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR046 - Failed to parse body of if-else statement",
                        exprtk_error_location));

                     result = false;
                  }
               }
               else if (0 != (alternative = parse_expression()))
               {
                  if (
                       !token_is(token_t::e_ternary,prsrhlpr_t::e_hold) &&
                       !token_is(token_t::e_eof)
                     )
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR047 - Expected ';' at the end of the 'else-if' for the if-statement",
                        exprtk_error_location));

                     result = false;
                  }
               }
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR048 - Failed to parse body of the 'else' for if-statement",
                     exprtk_error_location));

                  result = false;
               }
            }
         }

         #ifndef exprtk_disable_string_capabilities
         if (result)
         {
            const bool consq_is_str = is_generally_string_node(consequent );
            const bool alter_is_str = is_generally_string_node(alternative);

            if (consq_is_str || alter_is_str)
            {
               if (consq_is_str && alter_is_str)
               {
                  return expression_generator_
                           .conditional_string(condition, consequent, alternative);
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR049 - Return types of if-statement differ: string/non-string",
                  exprtk_error_location));

               result = false;
            }
         }
         #endif

         if (result)
         {
            const bool consq_is_vec = is_ivector_node(consequent );
            const bool alter_is_vec = is_ivector_node(alternative);

            if (consq_is_vec || alter_is_vec)
            {
               if (consq_is_vec && alter_is_vec)
               {
                  return expression_generator_
                           .conditional_vector(condition, consequent, alternative);
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR050 - Return types of if-statement differ: vector/non-vector",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!result)
         {
            free_node(node_allocator_, condition  );
            free_node(node_allocator_, consequent );
            free_node(node_allocator_, alternative);

            return error_node();
         }
         else
            return expression_generator_
                      .conditional(condition, consequent, alternative);
      }

      inline expression_node_ptr parse_conditional_statement()
      {
         expression_node_ptr condition = error_node();

         next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR051 - Expected '(' at start of if-statement, instead got: '" + current_token().value + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (0 == (condition = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR052 - Failed to parse condition for if-statement",
               exprtk_error_location));

            return error_node();
         }
         else if (token_is(token_t::e_comma,prsrhlpr_t::e_hold))
         {
            // if (x,y,z)
            return parse_conditional_statement_01(condition);
         }
         else if (token_is(token_t::e_rbracket))
         {
            /*
               00. if (x) y;
               01. if (x) y; else z;
               02. if (x) y; else {z0; ... zn;}
               03. if (x) y; else if (z) w;
               04. if (x) y; else if (z) w; else u;
               05. if (x) y; else if (z) w; else {u0; ... un;}
               06. if (x) y; else if (z) {w0; ... wn;}
               07. if (x) {y0; ... yn;}
               08. if (x) {y0; ... yn;} else z;
               09. if (x) {y0; ... yn;} else {z0; ... zn;};
               10. if (x) {y0; ... yn;} else if (z) w;
               11. if (x) {y0; ... yn;} else if (z) w; else u;
               12. if (x) {y0; ... nex;} else if (z) w; else {u0 ... un;}
               13. if (x) {y0; ... yn;} else if (z) {w0; ... wn;}
            */
            return parse_conditional_statement_02(condition);
         }

         set_error(make_error(
            parser_error::e_syntax,
            current_token(),
            "ERR053 - Invalid if-statement",
            exprtk_error_location));

         free_node(node_allocator_, condition);

         return error_node();
      }

      inline expression_node_ptr parse_ternary_conditional_statement(expression_node_ptr condition)
      {
         // Parse: [condition][?][consequent][:][alternative]
         expression_node_ptr consequent  = error_node();
         expression_node_ptr alternative = error_node();

         bool result = true;

         if (0 == condition)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR054 - Encountered invalid condition branch for ternary if-statement",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_ternary))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR055 - Expected '?' after condition of ternary if-statement",
               exprtk_error_location));

            result = false;
         }
         else if (0 == (consequent = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR056 - Failed to parse consequent for ternary if-statement",
               exprtk_error_location));

            result = false;
         }
         else if (!token_is(token_t::e_colon))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR057 - Expected ':' between ternary if-statement consequent and alternative",
               exprtk_error_location));

            result = false;
         }
         else if (0 == (alternative = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR058 - Failed to parse alternative for ternary if-statement",
               exprtk_error_location));

            result = false;
         }

         #ifndef exprtk_disable_string_capabilities
         if (result)
         {
            const bool consq_is_str = is_generally_string_node(consequent );
            const bool alter_is_str = is_generally_string_node(alternative);

            if (consq_is_str || alter_is_str)
            {
               if (consq_is_str && alter_is_str)
               {
                  return expression_generator_
                           .conditional_string(condition, consequent, alternative);
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR059 - Return types of ternary differ: string/non-string",
                  exprtk_error_location));

               result = false;
            }
         }
         #endif

         if (result)
         {
            const bool consq_is_vec = is_ivector_node(consequent );
            const bool alter_is_vec = is_ivector_node(alternative);

            if (consq_is_vec || alter_is_vec)
            {
               if (consq_is_vec && alter_is_vec)
               {
                  return expression_generator_
                           .conditional_vector(condition, consequent, alternative);
               }

               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR060 - Return types of ternary differ: vector/non-vector",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!result)
         {
            free_node(node_allocator_, condition  );
            free_node(node_allocator_, consequent );
            free_node(node_allocator_, alternative);

            return error_node();
         }
         else
            return expression_generator_
                      .conditional(condition, consequent, alternative);
      }

      inline expression_node_ptr parse_not_statement()
      {
         if (settings_.logic_disabled("not"))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR061 - Invalid or disabled logic operation 'not'",
               exprtk_error_location));

            return error_node();
         }

         return parse_base_operation();
      }

      void handle_brkcnt_scope_exit()
      {
         assert(!brkcnt_list_.empty());
         brkcnt_list_.pop_front();
      }

      inline expression_node_ptr parse_while_loop()
      {
         // Parse: [while][(][test expr][)][{][expression][}]
         expression_node_ptr condition   = error_node();
         expression_node_ptr branch      = error_node();
         expression_node_ptr result_node = error_node();

         bool result = true;

         next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR062 - Expected '(' at start of while-loop condition statement",
               exprtk_error_location));

            return error_node();
         }
         else if (0 == (condition = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR063 - Failed to parse condition for while-loop",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR064 - Expected ')' at end of while-loop condition statement",
               exprtk_error_location));

            result = false;
         }

         brkcnt_list_.push_front(false);

         if (result)
         {
            scoped_inc_dec sid(state_.parsing_loop_stmt_count);

            if (0 == (branch = parse_multi_sequence("while-loop", true)))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR065 - Failed to parse body of while-loop"));
               result = false;
            }
            else if (0 == (result_node = expression_generator_.while_loop(condition,
                                                                          branch,
                                                                          brkcnt_list_.front())))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR066 - Failed to synthesize while-loop",
                  exprtk_error_location));

               result = false;
            }
         }

         handle_brkcnt_scope_exit();

         if (!result)
         {
            free_node(node_allocator_, branch     );
            free_node(node_allocator_, condition  );
            free_node(node_allocator_, result_node);

            return error_node();
         }

         if (result_node && result_node->valid())
         {
            return result_node;
         }

         set_error(make_error(
            parser_error::e_synthesis,
            current_token(),
            "ERR067 - Failed to synthesize 'valid' while-loop",
            exprtk_error_location));

         free_node(node_allocator_, result_node);

         return error_node();
      }

      inline expression_node_ptr parse_repeat_until_loop()
      {
         // Parse: [repeat][{][expression][}][until][(][test expr][)]
         expression_node_ptr condition = error_node();
         expression_node_ptr branch    = error_node();
         next_token();

         std::vector<expression_node_ptr> arg_list;
         std::vector<bool> side_effect_list;

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         brkcnt_list_.push_front(false);

         if (details::imatch(current_token().value,"until"))
         {
            next_token();
            branch = node_allocator_.allocate<details::null_node<T> >();
         }
         else
         {
            const token_t::token_type separator = token_t::e_eof;

            scope_handler sh(*this);

            scoped_bool_or_restorer sbr(state_.side_effect_present);

            scoped_inc_dec sid(state_.parsing_loop_stmt_count);

            for ( ; ; )
            {
               state_.side_effect_present = false;

               expression_node_ptr arg = parse_expression();

               if (0 == arg)
                  return error_node();
               else
               {
                  arg_list.push_back(arg);
                  side_effect_list.push_back(state_.side_effect_present);
               }

               if (details::imatch(current_token().value,"until"))
               {
                  next_token();
                  break;
               }

               const bool is_next_until = peek_token_is(token_t::e_symbol) &&
                                          peek_token_is("until");

               if (!token_is(separator) && is_next_until)
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR068 - Expected '" + token_t::to_str(separator) + "' in body of repeat until loop",
                     exprtk_error_location));

                  return error_node();
               }

               if (details::imatch(current_token().value,"until"))
               {
                  next_token();
                  break;
               }
            }

            branch = simplify(arg_list,side_effect_list);

            sdd.delete_ptr = (0 == branch);

            if (sdd.delete_ptr)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR069 - Failed to parse body of repeat until loop",
                  exprtk_error_location));

               return error_node();
            }
         }

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR070 - Expected '(' before condition statement of repeat until loop",
               exprtk_error_location));

            free_node(node_allocator_, branch);
            return error_node();
         }
         else if (0 == (condition = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR071 - Failed to parse condition for repeat until loop",
               exprtk_error_location));

            free_node(node_allocator_, branch);
            return error_node();
         }
         else if (!token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR072 - Expected ')' after condition of repeat until loop",
               exprtk_error_location));

            free_node(node_allocator_, branch   );
            free_node(node_allocator_, condition);

            return error_node();
         }

         expression_node_ptr result_node =
            expression_generator_
               .repeat_until_loop(
                  condition,
                  branch,
                  brkcnt_list_.front());

         if (0 == result_node)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR073 - Failed to synthesize repeat until loop",
               exprtk_error_location));

            free_node(node_allocator_, condition);

            return error_node();
         }

         handle_brkcnt_scope_exit();

         if (result_node && result_node->valid())
         {
            return result_node;
         }

         set_error(make_error(
            parser_error::e_synthesis,
            current_token(),
            "ERR074 - Failed to synthesize 'valid' repeat until loop",
            exprtk_error_location));

         free_node(node_allocator_, result_node);

         return error_node();
      }

      inline expression_node_ptr parse_for_loop()
      {
         expression_node_ptr initialiser = error_node();
         expression_node_ptr condition   = error_node();
         expression_node_ptr incrementor = error_node();
         expression_node_ptr loop_body   = error_node();

         scope_element* se = 0;
         bool result       = true;

         next_token();

         scope_handler sh(*this);

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR075 - Expected '(' at start of for-loop",
               exprtk_error_location));

            return error_node();
         }

         if (!token_is(token_t::e_eof))
         {
            if (
                 !token_is(token_t::e_symbol,prsrhlpr_t::e_hold) &&
                 details::imatch(current_token().value,"var")
               )
            {
               next_token();

               if (!token_is(token_t::e_symbol,prsrhlpr_t::e_hold))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR076 - Expected a variable at the start of initialiser section of for-loop",
                     exprtk_error_location));

                  return error_node();
               }
               else if (!peek_token_is(token_t::e_assign))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR077 - Expected variable assignment of initialiser section of for-loop",
                     exprtk_error_location));

                  return error_node();
               }

               const std::string loop_counter_symbol = current_token().value;

               se = &sem_.get_element(loop_counter_symbol);

               if ((se->name == loop_counter_symbol) && se->active)
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR078 - For-loop variable '" + loop_counter_symbol+ "' is being shadowed by a previous declaration",
                     exprtk_error_location));

                  return error_node();
               }
               else if (!symtab_store_.is_variable(loop_counter_symbol))
               {
                  if (
                       !se->active &&
                       (se->name == loop_counter_symbol) &&
                       (se->type == scope_element::e_variable)
                     )
                  {
                     se->active = true;
                     se->ref_count++;
                  }
                  else
                  {
                     scope_element nse;
                     nse.name      = loop_counter_symbol;
                     nse.active    = true;
                     nse.ref_count = 1;
                     nse.type      = scope_element::e_variable;
                     nse.depth     = state_.scope_depth;
                     nse.data      = new T(T(0));
                     nse.var_node  = node_allocator_.allocate<variable_node_t>(*reinterpret_cast<T*>(nse.data));

                     if (!sem_.add_element(nse))
                     {
                        set_error(make_error(
                           parser_error::e_syntax,
                           current_token(),
                           "ERR079 - Failed to add new local variable '" + loop_counter_symbol + "' to SEM",
                           exprtk_error_location));

                        sem_.free_element(nse);

                        result = false;
                     }
                     else
                     {
                        exprtk_debug(("parse_for_loop() - INFO - Added new local variable: %s\n", nse.name.c_str()));

                        state_.activate_side_effect("parse_for_loop()");
                     }
                  }
               }
            }

            if (0 == (initialiser = parse_expression()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR080 - Failed to parse initialiser of for-loop",
                  exprtk_error_location));

               result = false;
            }
            else if (!token_is(token_t::e_eof))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR081 - Expected ';' after initialiser of for-loop",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!token_is(token_t::e_eof))
         {
            if (0 == (condition = parse_expression()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR082 - Failed to parse condition of for-loop",
                  exprtk_error_location));

               result = false;
            }
            else if (!token_is(token_t::e_eof))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR083 - Expected ';' after condition section of for-loop",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!token_is(token_t::e_rbracket))
         {
            if (0 == (incrementor = parse_expression()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR084 - Failed to parse incrementor of for-loop",
                  exprtk_error_location));

               result = false;
            }
            else if (!token_is(token_t::e_rbracket))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR085 - Expected ')' after incrementor section of for-loop",
                  exprtk_error_location));

               result = false;
            }
         }

         if (result)
         {
            brkcnt_list_.push_front(false);

            scoped_inc_dec sid(state_.parsing_loop_stmt_count);

            if (0 == (loop_body = parse_multi_sequence("for-loop", true)))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR086 - Failed to parse body of for-loop",
                  exprtk_error_location));

               result = false;
            }
         }

         if (!result)
         {
            if (se)
            {
               se->ref_count--;
            }

            free_node(node_allocator_, initialiser);
            free_node(node_allocator_, condition  );
            free_node(node_allocator_, incrementor);
            free_node(node_allocator_, loop_body  );
            return error_node();
         }

         expression_node_ptr result_node =
            expression_generator_.for_loop(initialiser,
                                           condition,
                                           incrementor,
                                           loop_body,
                                           brkcnt_list_.front());
         handle_brkcnt_scope_exit();

         if (result_node && result_node->valid())
         {
            return result_node;
         }

         set_error(make_error(
            parser_error::e_synthesis,
            current_token(),
            "ERR087 - Failed to synthesize 'valid' for-loop",
            exprtk_error_location));

         free_node(node_allocator_, result_node);

         return error_node();
      }

      inline expression_node_ptr parse_switch_statement()
      {
         std::vector<expression_node_ptr> arg_list;
         expression_node_ptr result = error_node();

         if (!details::imatch(current_token().value,"switch"))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR088 - Expected keyword 'switch'",
               exprtk_error_location));

            return error_node();
         }

         scoped_vec_delete<expression_node_t> svd((*this),arg_list);

         next_token();

         if (!token_is(token_t::e_lcrlbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR089 - Expected '{' for call to switch statement",
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr default_statement = error_node();

         scoped_expression_delete defstmt_delete((*this), default_statement);

         for ( ; ; )
         {
            if (details::imatch("case",current_token().value))
            {
               next_token();

               expression_node_ptr condition = parse_expression();

               if (0 == condition)
                  return error_node();
               else if (!token_is(token_t::e_colon))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR090 - Expected ':' for case of switch statement",
                     exprtk_error_location));

                  free_node(node_allocator_, condition);

                  return error_node();
               }

               expression_node_ptr consequent =
                  (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold)) ?
                  parse_multi_sequence("switch-consequent") :
                  parse_expression();

               if (0 == consequent)
               {
                  free_node(node_allocator_, condition);

                  return error_node();
               }
               else if (!token_is(token_t::e_eof))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR091 - Expected ';' at end of case for switch statement",
                     exprtk_error_location));

                  free_node(node_allocator_, condition );
                  free_node(node_allocator_, consequent);

                  return error_node();
               }

               // Can we optimise away the case statement?
               if (is_constant_node(condition) && is_false(condition))
               {
                  free_node(node_allocator_, condition );
                  free_node(node_allocator_, consequent);
               }
               else
               {
                  arg_list.push_back(condition );
                  arg_list.push_back(consequent);
               }

            }
            else if (details::imatch("default",current_token().value))
            {
               if (0 != default_statement)
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR092 - Multiple default cases for switch statement",
                     exprtk_error_location));

                  return error_node();
               }

               next_token();

               if (!token_is(token_t::e_colon))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR093 - Expected ':' for default of switch statement",
                     exprtk_error_location));

                  return error_node();
               }

               default_statement =
                  (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold)) ?
                  parse_multi_sequence("switch-default"):
                  parse_expression();

               if (0 == default_statement)
                  return error_node();
               else if (!token_is(token_t::e_eof))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR094 - Expected ';' at end of default for switch statement",
                     exprtk_error_location));

                  return error_node();
               }
            }
            else if (token_is(token_t::e_rcrlbracket))
               break;
            else
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR095 - Expected '}' at end of switch statement",
                  exprtk_error_location));

               return error_node();
            }
         }

         const bool default_statement_present = (0 != default_statement);

         if (default_statement_present)
         {
            arg_list.push_back(default_statement);
         }
         else
         {
            arg_list.push_back(node_allocator_.allocate_c<literal_node_t>(std::numeric_limits<T>::quiet_NaN()));
         }

         result = expression_generator_.switch_statement(arg_list, (0 != default_statement));

         svd.delete_ptr = (0 == result);
         defstmt_delete.delete_ptr = (0 == result);

         return result;
      }

      inline expression_node_ptr parse_multi_switch_statement()
      {
         std::vector<expression_node_ptr> arg_list;

         if (!details::imatch(current_token().value,"[*]"))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR096 - Expected token '[*]'",
               exprtk_error_location));

            return error_node();
         }

         scoped_vec_delete<expression_node_t> svd((*this),arg_list);

         next_token();

         if (!token_is(token_t::e_lcrlbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR097 - Expected '{' for call to [*] statement",
               exprtk_error_location));

            return error_node();
         }

         for ( ; ; )
         {
            if (!details::imatch("case",current_token().value))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR098 - Expected a 'case' statement for multi-switch",
                  exprtk_error_location));

               return error_node();
            }

            next_token();

            expression_node_ptr condition = parse_expression();

            if (0 == condition)
               return error_node();

            if (!token_is(token_t::e_colon))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR099 - Expected ':' for case of [*] statement",
                  exprtk_error_location));

               return error_node();
            }

            expression_node_ptr consequent =
               (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold)) ?
               parse_multi_sequence("multi-switch-consequent") :
               parse_expression();

            if (0 == consequent)
               return error_node();

            if (!token_is(token_t::e_eof))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR100 - Expected ';' at end of case for [*] statement",
                  exprtk_error_location));

               return error_node();
            }

            // Can we optimise away the case statement?
            if (is_constant_node(condition) && is_false(condition))
            {
               free_node(node_allocator_, condition );
               free_node(node_allocator_, consequent);
            }
            else
            {
               arg_list.push_back(condition );
               arg_list.push_back(consequent);
            }

            if (token_is(token_t::e_rcrlbracket,prsrhlpr_t::e_hold))
            {
               break;
            }
         }

         if (!token_is(token_t::e_rcrlbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR101 - Expected '}' at end of [*] statement",
               exprtk_error_location));

            return error_node();
         }

         const expression_node_ptr result = expression_generator_.multi_switch_statement(arg_list);

         svd.delete_ptr = (0 == result);

         return result;
      }

      inline expression_node_ptr parse_vararg_function()
      {
         std::vector<expression_node_ptr> arg_list;

         details::operator_type opt_type = details::e_default;
         const std::string symbol = current_token().value;

         if (details::imatch(symbol,"~"))
         {
            next_token();
            return parse_multi_sequence();
         }
         else if (details::imatch(symbol,"[*]"))
         {
            return parse_multi_switch_statement();
         }
         else if (details::imatch(symbol, "avg" )) opt_type = details::e_avg ;
         else if (details::imatch(symbol, "mand")) opt_type = details::e_mand;
         else if (details::imatch(symbol, "max" )) opt_type = details::e_max ;
         else if (details::imatch(symbol, "min" )) opt_type = details::e_min ;
         else if (details::imatch(symbol, "mor" )) opt_type = details::e_mor ;
         else if (details::imatch(symbol, "mul" )) opt_type = details::e_prod;
         else if (details::imatch(symbol, "sum" )) opt_type = details::e_sum ;
         else
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR102 - Unsupported built-in vararg function: " + symbol,
               exprtk_error_location));

            return error_node();
         }

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         lodge_symbol(symbol, e_st_function);

         next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR103 - Expected '(' for call to vararg function: " + symbol,
               exprtk_error_location));

            return error_node();
         }

         if (token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR104 - vararg function: " + symbol +
               " requires at least one input parameter",
               exprtk_error_location));

            return error_node();
         }

         for ( ; ; )
         {
            expression_node_ptr arg = parse_expression();

            if (0 == arg)
               return error_node();
            else
               arg_list.push_back(arg);

            if (token_is(token_t::e_rbracket))
               break;
            else if (!token_is(token_t::e_comma))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR105 - Expected ',' for call to vararg function: " + symbol,
                  exprtk_error_location));

               return error_node();
            }
         }

         const expression_node_ptr result = expression_generator_.vararg_function(opt_type,arg_list);

         sdd.delete_ptr = (0 == result);
         return result;
      }

      #ifndef exprtk_disable_string_capabilities
      inline expression_node_ptr parse_string_range_statement(expression_node_ptr& expression)
      {
         if (!token_is(token_t::e_lsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR106 - Expected '[' as start of string range definition",
               exprtk_error_location));

            free_node(node_allocator_, expression);

            return error_node();
         }
         else if (token_is(token_t::e_rsqrbracket))
         {
            return node_allocator_.allocate<details::string_size_node<T> >(expression);
         }

         range_t rp;

         if (!parse_range(rp,true))
         {
            free_node(node_allocator_, expression);

            return error_node();
         }

         expression_node_ptr result = expression_generator_(expression,rp);

         if (0 == result)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR107 - Failed to generate string range node",
               exprtk_error_location));

            free_node(node_allocator_, expression);
            rp.free();
         }

         rp.clear();

         if (result && result->valid())
         {
            return result;
         }

         set_error(make_error(
            parser_error::e_synthesis,
            current_token(),
            "ERR108 - Failed to synthesize node: string_range_node",
            exprtk_error_location));

         free_node(node_allocator_, result);
         rp.free();
         return error_node();
      }
      #else
      inline expression_node_ptr parse_string_range_statement(expression_node_ptr&)
      {
         return error_node();
      }
      #endif

      inline bool parse_pending_string_rangesize(expression_node_ptr& expression)
      {
         // Allow no more than 100 range calls, eg: s[][][]...[][]
         const std::size_t max_rangesize_parses = 100;

         std::size_t i = 0;

         while
            (
              (0 != expression)                     &&
              (i++ < max_rangesize_parses)          &&
              error_list_.empty()                   &&
              is_generally_string_node(expression)  &&
              token_is(token_t::e_lsqrbracket,prsrhlpr_t::e_hold)
            )
         {
            expression = parse_string_range_statement(expression);
         }

         return (i > 1);
      }

      inline void parse_pending_vector_index_operator(expression_node_ptr& expression)
      {
         if
            (
              (0 != expression)           &&
              error_list_.empty()         &&
              is_ivector_node(expression)
            )
         {
            if (
                 settings_.commutative_check_enabled()       &&
                 token_is(token_t::e_mul,prsrhlpr_t::e_hold) &&
                 peek_token_is(token_t::e_lsqrbracket)
               )
            {
               token_is(token_t::e_mul);
               token_is(token_t::e_lsqrbracket);
            }
            else if (token_is(token_t::e_lsqrbracket,prsrhlpr_t::e_hold))
            {
               token_is(token_t::e_lsqrbracket);
            }
            else if (
                      token_is(token_t::e_rbracket,prsrhlpr_t::e_hold) &&
                      peek_token_is(token_t::e_lsqrbracket)
                    )
            {
               token_is(token_t::e_rbracket   );
               token_is(token_t::e_lsqrbracket);
            }
            else
               return;

            details::vector_interface<T>* vi = dynamic_cast<details::vector_interface<T>*>(expression);

            if (vi)
            {
               details::vector_holder<T>& vec = vi->vec()->vec_holder();
               const std::string vector_name  = sem_.get_vector_name(vec.data());
               expression_node_ptr index      = parse_vector_index(vector_name);

               if (index)
               {
                  expression = synthesize_vector_element(vector_name, &vec, expression, index);
                  return;
               }
            }

            free_node(node_allocator_, expression);
            expression = error_node();
         }
      }

      template <typename Allocator1,
                typename Allocator2,
                template <typename, typename> class Sequence>
      inline expression_node_ptr simplify(Sequence<expression_node_ptr,Allocator1>& expression_list,
                                          Sequence<bool,Allocator2>& side_effect_list,
                                          const bool specialise_on_final_type = false)
      {
         if (expression_list.empty())
            return error_node();
         else if (1 == expression_list.size())
            return expression_list[0];

         Sequence<expression_node_ptr,Allocator1> tmp_expression_list;

         bool return_node_present = false;

         for (std::size_t i = 0; i < (expression_list.size() - 1); ++i)
         {
            if (is_variable_node(expression_list[i]))
               continue;
            else if (
                      is_return_node  (expression_list[i]) ||
                      is_break_node   (expression_list[i]) ||
                      is_continue_node(expression_list[i])
                    )
            {
               tmp_expression_list.push_back(expression_list[i]);

               // Remove all subexpressions after first short-circuit
               // node has been encountered.

               for (std::size_t j = i + 1; j < expression_list.size(); ++j)
               {
                  free_node(node_allocator_, expression_list[j]);
               }

               return_node_present = true;

               break;
            }
            else if (
                      is_constant_node(expression_list[i]) ||
                      is_null_node    (expression_list[i]) ||
                      !side_effect_list[i]
                    )
            {
               free_node(node_allocator_, expression_list[i]);
               continue;
            }
            else
               tmp_expression_list.push_back(expression_list[i]);
         }

         if (!return_node_present)
         {
            tmp_expression_list.push_back(expression_list.back());
         }

         expression_list.swap(tmp_expression_list);

         if (tmp_expression_list.size() > expression_list.size())
         {
            exprtk_debug(("simplify() - Reduced subexpressions from %d to %d\n",
                          static_cast<int>(tmp_expression_list.size()),
                          static_cast<int>(expression_list    .size())));
         }

         if (
              return_node_present     ||
              side_effect_list.back() ||
              (expression_list.size() > 1)
            )
            state_.activate_side_effect("simplify()");

         if (1 == expression_list.size())
            return expression_list[0];
         else if (specialise_on_final_type && is_generally_string_node(expression_list.back()))
            return expression_generator_.vararg_function(details::e_smulti,expression_list);
         else
            return expression_generator_.vararg_function(details::e_multi,expression_list);
      }

      inline expression_node_ptr parse_multi_sequence(const std::string& source = "",
                                                      const bool enforce_crlbrackets = false)
      {
         token_t::token_type open_bracket  = token_t::e_lcrlbracket;
         token_t::token_type close_bracket = token_t::e_rcrlbracket;
         token_t::token_type separator     = token_t::e_eof;

         if (!token_is(open_bracket))
         {
            if (!enforce_crlbrackets && token_is(token_t::e_lbracket))
            {
               open_bracket  = token_t::e_lbracket;
               close_bracket = token_t::e_rbracket;
               separator     = token_t::e_comma;
            }
            else
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR109 - Expected '" + token_t::to_str(open_bracket) + "' for call to multi-sequence" +
                  ((!source.empty()) ? std::string(" section of " + source): ""),
                  exprtk_error_location));

               return error_node();
            }
         }
         else if (token_is(close_bracket))
         {
            return node_allocator_.allocate<details::null_node<T> >();
         }

         std::vector<expression_node_ptr> arg_list;
         std::vector<bool> side_effect_list;

         expression_node_ptr result = error_node();

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         scope_handler sh(*this);

         scoped_bool_or_restorer sbr(state_.side_effect_present);

         for ( ; ; )
         {
            state_.side_effect_present = false;

            expression_node_ptr arg = parse_expression();

            if (0 == arg)
               return error_node();
            else
            {
               arg_list.push_back(arg);
               side_effect_list.push_back(state_.side_effect_present);
            }

            if (token_is(close_bracket))
               break;

            const bool is_next_close = peek_token_is(close_bracket);

            if (!token_is(separator) && is_next_close)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR110 - Expected '" + details::to_str(separator) + "' for call to multi-sequence section of " + source,
                  exprtk_error_location));

               return error_node();
            }

            if (token_is(close_bracket))
               break;
         }

         result = simplify(arg_list, side_effect_list, source.empty());

         sdd.delete_ptr = (0 == result);
         return result;
      }

      inline bool parse_range(range_t& rp, const bool skip_lsqr = false)
      {
         // Examples of valid ranges:
         // 1. [1:5]     -> [1,5)
         // 2. [ :5]     -> [0,5)
         // 3. [1: ]     -> [1,end)
         // 4. [x:y]     -> [x,y) where x <= y
         // 5. [x+1:y/2] -> [x+1,y/2) where x+1 <= y/2
         // 6. [ :y]     -> [0,y) where 0 <= y
         // 7. [x: ]     -> [x,end) where x <= end

         rp.clear();

         if (!skip_lsqr && !token_is(token_t::e_lsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR111 - Expected '[' for start of range",
               exprtk_error_location));

            return false;
         }

         if (token_is(token_t::e_colon))
         {
            rp.n0_c.first  = true;
            rp.n0_c.second = 0;
            rp.cache.first = 0;
         }
         else
         {
            expression_node_ptr r0 = parse_expression();

            if (0 == r0)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR112 - Failed parse begin section of range",
                  exprtk_error_location));

               return false;
            }
            else if (is_constant_node(r0))
            {
               const T r0_value = r0->value();

               if (r0_value >= T(0))
               {
                  rp.n0_c.first  = true;
                  rp.n0_c.second = static_cast<std::size_t>(details::numeric::to_int64(r0_value));
                  rp.cache.first = rp.n0_c.second;
               }

               free_node(node_allocator_, r0);

               if (r0_value < T(0))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR113 - Range lower bound less than zero! Constraint: r0 >= 0",
                     exprtk_error_location));

                  return false;
               }
            }
            else
            {
               rp.n0_e.first  = true;
               rp.n0_e.second = r0;
            }

            if (!token_is(token_t::e_colon))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR114 - Expected ':' for break  in range",
                  exprtk_error_location));

               rp.free();

               return false;
            }
         }

         if (token_is(token_t::e_rsqrbracket))
         {
            rp.n1_c.first  = true;
            rp.n1_c.second = std::numeric_limits<std::size_t>::max();
         }
         else
         {
            expression_node_ptr r1 = parse_expression();

            if (0 == r1)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR115 - Failed parse end section of range",
                  exprtk_error_location));

               rp.free();

               return false;
            }
            else if (is_constant_node(r1))
            {
               const T r1_value = r1->value();

               if (r1_value >= T(0))
               {
                  rp.n1_c.first   = true;
                  rp.n1_c.second  = static_cast<std::size_t>(details::numeric::to_int64(r1_value));
                  rp.cache.second = rp.n1_c.second;
               }

               free_node(node_allocator_, r1);

               if (r1_value < T(0))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR116 - Range upper bound less than zero! Constraint: r1 >= 0",
                     exprtk_error_location));

                  rp.free();

                  return false;
               }
            }
            else
            {
               rp.n1_e.first  = true;
               rp.n1_e.second = r1;
            }

            if (!token_is(token_t::e_rsqrbracket))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR117 - Expected ']' for start of range",
                  exprtk_error_location));

               rp.free();

               return false;
            }
         }

         if (rp.const_range())
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            bool rp_result = false;

            try
            {
               rp_result = rp(r0, r1);
            }
            catch (std::runtime_error&)
            {}

            if (!rp_result || (r0 > r1))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR118 - Invalid range, Constraint: r0 <= r1",
                  exprtk_error_location));

               return false;
            }
         }

         return true;
      }

      inline void lodge_symbol(const std::string& symbol,
                               const symbol_type st)
      {
         dec_.add_symbol(symbol,st);
      }

      #ifndef exprtk_disable_string_capabilities
      inline expression_node_ptr parse_string()
      {
         const std::string symbol = current_token().value;

         typedef details::stringvar_node<T>* strvar_node_t;

         expression_node_ptr result   = error_node();
         strvar_node_t const_str_node = static_cast<strvar_node_t>(0);

         scope_element& se = sem_.get_active_element(symbol);

         if (scope_element::e_string == se.type)
         {
            se.active = true;
            result    = se.str_node;
            lodge_symbol(symbol, e_st_local_string);
         }
         else
         {
            typedef typename symtab_store::string_context str_ctxt_t;
            str_ctxt_t str_ctx = symtab_store_.get_string_context(symbol);

            if ((0 == str_ctx.str_var) || !symtab_store_.is_conststr_stringvar(symbol))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR119 - Unknown string symbol",
                  exprtk_error_location));

               return error_node();
            }

            assert(str_ctx.str_var != 0);
            assert(str_ctx.symbol_table != 0);

            result = str_ctx.str_var;

            if (symtab_store_.is_constant_string(symbol))
            {
               const_str_node = static_cast<strvar_node_t>(result);
               result = expression_generator_(const_str_node->str());
            }
            else if (symbol_table_t::e_immutable == str_ctx.symbol_table->mutability())
            {
               lodge_immutable_symbol(
                  current_token(),
                  make_memory_range(str_ctx.str_var->base(), str_ctx.str_var->size()));
            }

            lodge_symbol(symbol, e_st_string);
         }

         if (peek_token_is(token_t::e_lsqrbracket))
         {
            next_token();

            if (peek_token_is(token_t::e_rsqrbracket))
            {
               next_token();
               next_token();

               if (const_str_node)
               {
                  free_node(node_allocator_, result);

                  return expression_generator_(T(const_str_node->size()));
               }
               else
                  return node_allocator_.allocate<details::stringvar_size_node<T> >
                            (static_cast<details::stringvar_node<T>*>(result)->ref());
            }

            range_t rp;

            if (!parse_range(rp))
            {
               free_node(node_allocator_, result);

               return error_node();
            }
            else if (const_str_node)
            {
               free_node(node_allocator_, result);
               result = expression_generator_(const_str_node->ref(),rp);
            }
            else
               result = expression_generator_(static_cast<details::stringvar_node<T>*>
                           (result)->ref(), rp);

            if (result)
               rp.clear();
         }
         else
            next_token();

         return result;
      }
      #else
      inline expression_node_ptr parse_string()
      {
         return error_node();
      }
      #endif

      #ifndef exprtk_disable_string_capabilities
      inline expression_node_ptr parse_const_string()
      {
         const std::string   const_str = current_token().value;
         expression_node_ptr result    = expression_generator_(const_str);

         if (peek_token_is(token_t::e_lsqrbracket))
         {
            next_token();

            if (peek_token_is(token_t::e_rsqrbracket))
            {
               next_token();
               next_token();

               free_node(node_allocator_, result);

               return expression_generator_(T(const_str.size()));
            }

            range_t rp;

            if (!parse_range(rp))
            {
               free_node(node_allocator_, result);
               rp.free();

               return error_node();
            }

            free_node(node_allocator_, result);

            if (rp.n1_c.first && (rp.n1_c.second == std::numeric_limits<std::size_t>::max()))
            {
               rp.n1_c.second  = const_str.size() - 1;
               rp.cache.second = rp.n1_c.second;
            }

            if (
                 (rp.n0_c.first && (rp.n0_c.second >= const_str.size())) ||
                 (rp.n1_c.first && (rp.n1_c.second >= const_str.size()))
               )
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR120 - Overflow in range for string: '" + const_str + "'[" +
                  (rp.n0_c.first ? details::to_str(static_cast<int>(rp.n0_c.second)) : "?") + ":" +
                  (rp.n1_c.first ? details::to_str(static_cast<int>(rp.n1_c.second)) : "?") + "]",
                  exprtk_error_location));

               rp.free();

               return error_node();
            }

            result = expression_generator_(const_str,rp);

            if (result)
               rp.clear();
         }
         else
            next_token();

         return result;
      }
      #else
      inline expression_node_ptr parse_const_string()
      {
         return error_node();
      }
      #endif

      inline expression_node_ptr parse_vector_index(const std::string& vector_name = "")
      {
         expression_node_ptr index_expr = error_node();

         if (0 == (index_expr = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR121 - Failed to parse index for vector: '" + vector_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_rsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR122 - Expected ']' for index of vector: '" + vector_name + "'",
               exprtk_error_location));

            free_node(node_allocator_, index_expr);

            return error_node();
         }

         return index_expr;
      }

      inline expression_node_ptr parse_vector()
      {
         const std::string vector_name = current_token().value;

         vector_holder_ptr vec = vector_holder_ptr(0);

         const scope_element& se = sem_.get_active_element(vector_name);

         if (
              !details::imatch(se.name, vector_name) ||
              (se.depth > state_.scope_depth)   ||
              (scope_element::e_vector != se.type)
            )
         {
            typedef typename symtab_store::vector_context vec_ctxt_t;
            vec_ctxt_t vec_ctx = symtab_store_.get_vector_context(vector_name);

            if (0 == vec_ctx.vector_holder)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR123 - Symbol '" + vector_name + " not a vector",
                  exprtk_error_location));

               return error_node();
            }

            assert(0 != vec_ctx.vector_holder);
            assert(0 != vec_ctx.symbol_table );

            vec = vec_ctx.vector_holder;

            if (symbol_table_t::e_immutable == vec_ctx.symbol_table->mutability())
            {
               lodge_immutable_symbol(
                  current_token(),
                  make_memory_range(vec->data(), vec->size()));
            }
         }
         else
         {
            vec = se.vec_node;
         }

         assert(0 != vec);

         next_token();

         if (!token_is(token_t::e_lsqrbracket))
         {
            return node_allocator_.allocate<vector_node_t>(vec);
         }
         else if (token_is(token_t::e_rsqrbracket))
         {
            return (vec->rebaseable()) ?
               node_allocator_.allocate<vector_size_node_t>(vec) :
               expression_generator_(T(vec->size()));
         }

         expression_node_ptr index_expr = parse_vector_index(vector_name);

         if (index_expr)
         {
            expression_node_ptr vec_node = node_allocator_.allocate<vector_node_t>(vec);

            return synthesize_vector_element(vector_name, vec, vec_node, index_expr);
         }

         return error_node();
      }

      inline expression_node_ptr synthesize_vector_element(const std::string& vector_name,
                                                           vector_holder_ptr vec,
                                                           expression_node_ptr vec_node,
                                                           expression_node_ptr index_expr)
      {
         // Perform compile-time range check
         if (details::is_constant_node(index_expr))
         {
            const std::size_t index    = static_cast<std::size_t>(details::numeric::to_int32(index_expr->value()));
            const std::size_t vec_size = vec->size();

            if (index >= vec_size)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR124 - Index of " + details::to_str(index) + " out of range for "
                  "vector '" + vector_name + "' of size " + details::to_str(vec_size),
                  exprtk_error_location));

               free_node(node_allocator_, vec_node  );
               free_node(node_allocator_, index_expr);

               return error_node();
            }
         }

         return expression_generator_.vector_element(vector_name, vec, vec_node, index_expr);
      }

      inline expression_node_ptr parse_vararg_function_call(ivararg_function<T>* vararg_function, const std::string& vararg_function_name)
      {
         std::vector<expression_node_ptr> arg_list;

         expression_node_ptr result = error_node();

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         next_token();

         if (token_is(token_t::e_lbracket))
         {
            if (token_is(token_t::e_rbracket))
            {
               if (!vararg_function->allow_zero_parameters())
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR125 - Zero parameter call to vararg function: "
                     + vararg_function_name + " not allowed",
                     exprtk_error_location));

                  return error_node();
               }
            }
            else
            {
               for ( ; ; )
               {
                  expression_node_ptr arg = parse_expression();

                  if (0 == arg)
                     return error_node();
                  else
                     arg_list.push_back(arg);

                  if (token_is(token_t::e_rbracket))
                     break;
                  else if (!token_is(token_t::e_comma))
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR126 - Expected ',' for call to vararg function: "
                        + vararg_function_name,
                        exprtk_error_location));

                     return error_node();
                  }
               }
            }
         }
         else if (!vararg_function->allow_zero_parameters())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR127 - Zero parameter call to vararg function: "
               + vararg_function_name + " not allowed",
               exprtk_error_location));

            return error_node();
         }

         if (arg_list.size() < vararg_function->min_num_args())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR128 - Invalid number of parameters to call to vararg function: "
               + vararg_function_name + ", require at least "
               + details::to_str(static_cast<int>(vararg_function->min_num_args())) + " parameters",
               exprtk_error_location));

            return error_node();
         }
         else if (arg_list.size() > vararg_function->max_num_args())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR129 - Invalid number of parameters to call to vararg function: "
               + vararg_function_name + ", require no more than "
               + details::to_str(static_cast<int>(vararg_function->max_num_args())) + " parameters",
               exprtk_error_location));

            return error_node();
         }

         result = expression_generator_.vararg_function_call(vararg_function,arg_list);

         sdd.delete_ptr = (0 == result);

         return result;
      }

      class type_checker
      {
      public:

         enum return_type_t
         {
            e_overload = ' ',
            e_numeric  = 'T',
            e_string   = 'S'
         };

         struct function_prototype_t
         {
             return_type_t return_type;
             std::string   param_seq;
         };

         typedef parser<T> parser_t;
         typedef std::vector<function_prototype_t> function_definition_list_t;

         type_checker(parser_t& p,
                      const std::string& func_name,
                      const std::string& func_prototypes,
                      const return_type_t default_return_type)
         : invalid_state_(true)
         , parser_(p)
         , function_name_(func_name)
         , default_return_type_(default_return_type)
         {
            parse_function_prototypes(func_prototypes);
         }

         bool verify(const std::string& param_seq, std::size_t& pseq_index)
         {
            if (function_definition_list_.empty())
               return true;

            std::vector<std::pair<std::size_t,char> > error_list;

            for (std::size_t i = 0; i < function_definition_list_.size(); ++i)
            {
               details::char_t diff_value = 0;
               std::size_t     diff_index = 0;

               const bool result = details::sequence_match(function_definition_list_[i].param_seq,
                                                           param_seq,
                                                           diff_index, diff_value);

              if (result)
              {
                 pseq_index = i;
                 return true;
              }
              else
                 error_list.push_back(std::make_pair(diff_index, diff_value));
            }

            if (1 == error_list.size())
            {
               parser_.set_error(make_error(
                  parser_error::e_syntax,
                  parser_.current_token(),
                  "ERR130 - Failed parameter type check for function '" + function_name_ + "', "
                  "Expected '" + function_definition_list_[0].param_seq +
                  "' call set: '" + param_seq + "'",
                  exprtk_error_location));
            }
            else
            {
               // find first with largest diff_index;
               std::size_t max_diff_index = 0;

               for (std::size_t i = 1; i < error_list.size(); ++i)
               {
                  if (error_list[i].first > error_list[max_diff_index].first)
                  {
                     max_diff_index = i;
                  }
               }

               parser_.set_error(make_error(
                  parser_error::e_syntax,
                  parser_.current_token(),
                  "ERR131 - Failed parameter type check for function '" + function_name_ + "', "
                  "Best match: '" + function_definition_list_[max_diff_index].param_seq +
                  "' call set: '" + param_seq + "'",
                  exprtk_error_location));
            }

            return false;
         }

         std::size_t paramseq_count() const
         {
            return function_definition_list_.size();
         }

         std::string paramseq(const std::size_t& index) const
         {
            return function_definition_list_[index].param_seq;
         }

         return_type_t return_type(const std::size_t& index) const
         {
            return function_definition_list_[index].return_type;
         }

         bool invalid() const
         {
            return !invalid_state_;
         }

         bool allow_zero_parameters() const
         {

            for (std::size_t i = 0; i < function_definition_list_.size(); ++i)
            {
               if (std::string::npos != function_definition_list_[i].param_seq.find("Z"))
               {
                  return true;
               }
            }

            return false;
         }

      private:

         std::vector<std::string> split_param_seq(const std::string& param_seq, const details::char_t delimiter = '|') const
         {
             std::string::const_iterator current_begin = param_seq.begin();
             std::string::const_iterator iter          = param_seq.begin();

             std::vector<std::string> result;

             while (iter != param_seq.end())
             {
                 if (*iter == delimiter)
                 {
                     result.push_back(std::string(current_begin, iter));
                     current_begin = ++iter;
                 }
                 else
                     ++iter;
             }

             if (current_begin != iter)
             {
                 result.push_back(std::string(current_begin, iter));
             }

             return result;
         }

         inline bool is_valid_token(std::string param_seq,
                                    function_prototype_t& funcproto) const
         {
            // Determine return type
            funcproto.return_type = default_return_type_;

            if (param_seq.size() > 2)
            {
               if (':' == param_seq[1])
               {
                  // Note: Only overloaded igeneric functions can have return
                  // type definitions.
                  if (type_checker::e_overload != default_return_type_)
                     return false;

                  switch (param_seq[0])
                  {
                     case 'T' : funcproto.return_type = type_checker::e_numeric;
                                break;

                     case 'S' : funcproto.return_type = type_checker::e_string;
                                break;

                     default  : return false;
                  }

                  param_seq.erase(0,2);
               }
            }

            if (
                 (std::string::npos != param_seq.find("?*")) ||
                 (std::string::npos != param_seq.find("**"))
               )
            {
               return false;
            }
            else if (
                      (std::string::npos == param_seq.find_first_not_of("STV*?|")) ||
                      ("Z" == param_seq)
                    )
            {
               funcproto.param_seq = param_seq;
               return true;
            }

            return false;
         }

         void parse_function_prototypes(const std::string& func_prototypes)
         {
            if (func_prototypes.empty())
               return;

            std::vector<std::string> param_seq_list = split_param_seq(func_prototypes);

            typedef std::map<std::string,std::size_t> param_seq_map_t;
            param_seq_map_t param_seq_map;

            for (std::size_t i = 0; i < param_seq_list.size(); ++i)
            {
               function_prototype_t func_proto;

               if (!is_valid_token(param_seq_list[i], func_proto))
               {
                  invalid_state_ = false;

                  parser_.set_error(make_error(
                     parser_error::e_syntax,
                     parser_.current_token(),
                     "ERR132 - Invalid parameter sequence of '" + param_seq_list[i] +
                     "' for function: " + function_name_,
                     exprtk_error_location));
                  return;
               }

               param_seq_map_t::const_iterator seq_itr = param_seq_map.find(param_seq_list[i]);

               if (param_seq_map.end() != seq_itr)
               {
                  invalid_state_ = false;

                  parser_.set_error(make_error(
                     parser_error::e_syntax,
                     parser_.current_token(),
                     "ERR133 - Function '" + function_name_ + "' has a parameter sequence conflict between " +
                     "pseq_idx[" + details::to_str(seq_itr->second) + "] and" +
                     "pseq_idx[" + details::to_str(i) + "] " +
                     "param seq: " + param_seq_list[i],
                     exprtk_error_location));
                  return;
               }

               function_definition_list_.push_back(func_proto);
            }
         }

         type_checker(const type_checker&) exprtk_delete;
         type_checker& operator=(const type_checker&) exprtk_delete;

         bool invalid_state_;
         parser_t& parser_;
         std::string function_name_;
         const return_type_t default_return_type_;
         function_definition_list_t function_definition_list_;
      };

      inline expression_node_ptr parse_generic_function_call(igeneric_function<T>* function, const std::string& function_name)
      {
         std::vector<expression_node_ptr> arg_list;

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         next_token();

         std::string param_type_list;

         type_checker tc(
            (*this),
            function_name,
            function->parameter_sequence,
            type_checker::e_string);

         if (tc.invalid())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR134 - Type checker instantiation failure for generic function: " + function_name,
               exprtk_error_location));

            return error_node();
         }

         if (token_is(token_t::e_lbracket))
         {
            if (token_is(token_t::e_rbracket))
            {
               if (
                    !function->allow_zero_parameters() &&
                    !tc       .allow_zero_parameters()
                  )
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR135 - Zero parameter call to generic function: "
                     + function_name + " not allowed",
                     exprtk_error_location));

                  return error_node();
               }
            }
            else
            {
               for ( ; ; )
               {
                  expression_node_ptr arg = parse_expression();

                  if (0 == arg)
                     return error_node();

                  if (is_ivector_node(arg))
                     param_type_list += 'V';
                  else if (is_generally_string_node(arg))
                     param_type_list += 'S';
                  else // Everything else is assumed to be a scalar returning expression
                     param_type_list += 'T';

                  arg_list.push_back(arg);

                  if (token_is(token_t::e_rbracket))
                     break;
                  else if (!token_is(token_t::e_comma))
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR136 - Expected ',' for call to generic function: " + function_name,
                        exprtk_error_location));

                     return error_node();
                  }
               }
            }
         }
         else if (
                   !function->parameter_sequence.empty() &&
                   function->allow_zero_parameters    () &&
                   !tc      .allow_zero_parameters    ()
                 )
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR137 - Zero parameter call to generic function: "
               + function_name + " not allowed",
               exprtk_error_location));

            return error_node();
         }

         std::size_t param_seq_index = 0;

         if (
              state_.type_check_enabled &&
              !tc.verify(param_type_list, param_seq_index)
            )
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR138 - Invalid input parameter sequence for call to generic function: " + function_name,
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr result = error_node();

         result = (tc.paramseq_count() <= 1) ?
                  expression_generator_
                       .generic_function_call(function, arg_list) :
                  expression_generator_
                       .generic_function_call(function, arg_list, param_seq_index);

         sdd.delete_ptr = (0 == result);

         return result;
      }

      inline bool parse_igeneric_function_params(std::string& param_type_list,
                                                 std::vector<expression_node_ptr>& arg_list,
                                                 const std::string& function_name,
                                                 igeneric_function<T>* function,
                                                 const type_checker& tc)
      {
         if (token_is(token_t::e_lbracket))
         {
            if (token_is(token_t::e_rbracket))
            {
               if (
                    !function->allow_zero_parameters() &&
                    !tc       .allow_zero_parameters()
                  )
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR139 - Zero parameter call to generic function: "
                     + function_name + " not allowed",
                     exprtk_error_location));

                  return false;
               }
            }
            else
            {
               for ( ; ; )
               {
                  expression_node_ptr arg = parse_expression();

                  if (0 == arg)
                     return false;

                  if (is_ivector_node(arg))
                     param_type_list += 'V';
                  else if (is_generally_string_node(arg))
                     param_type_list += 'S';
                  else // Everything else is a scalar returning expression
                     param_type_list += 'T';

                  arg_list.push_back(arg);

                  if (token_is(token_t::e_rbracket))
                     break;
                  else if (!token_is(token_t::e_comma))
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR140 - Expected ',' for call to string function: " + function_name,
                        exprtk_error_location));

                     return false;
                  }
               }
            }

            return true;
         }
         else
            return false;
      }

      #ifndef exprtk_disable_string_capabilities
      inline expression_node_ptr parse_string_function_call(igeneric_function<T>* function, const std::string& function_name)
      {
         // Move pass the function name
         next_token();

         std::string param_type_list;

         type_checker tc((*this), function_name, function->parameter_sequence, type_checker::e_string);

         if (
              (!function->parameter_sequence.empty()) &&
              (0 == tc.paramseq_count())
            )
         {
            return error_node();
         }

         std::vector<expression_node_ptr> arg_list;
         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         if (!parse_igeneric_function_params(param_type_list, arg_list, function_name, function, tc))
         {
            return error_node();
         }

         std::size_t param_seq_index = 0;

         if (!tc.verify(param_type_list, param_seq_index))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR141 - Invalid input parameter sequence for call to string function: " + function_name,
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr result = error_node();

         result = (tc.paramseq_count() <= 1) ?
                  expression_generator_
                       .string_function_call(function, arg_list) :
                  expression_generator_
                       .string_function_call(function, arg_list, param_seq_index);

         sdd.delete_ptr = (0 == result);

         return result;
      }

      inline expression_node_ptr parse_overload_function_call(igeneric_function<T>* function, const std::string& function_name)
      {
         // Move pass the function name
         next_token();

         std::string param_type_list;

         type_checker tc((*this), function_name, function->parameter_sequence, type_checker::e_overload);

         if (
              (!function->parameter_sequence.empty()) &&
              (0 == tc.paramseq_count())
            )
         {
            return error_node();
         }

         std::vector<expression_node_ptr> arg_list;
         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         if (!parse_igeneric_function_params(param_type_list, arg_list, function_name, function, tc))
         {
            return error_node();
         }

         std::size_t param_seq_index = 0;

         if (!tc.verify(param_type_list, param_seq_index))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR142 - Invalid input parameter sequence for call to overloaded function: " + function_name,
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr result = error_node();

         if (type_checker::e_numeric == tc.return_type(param_seq_index))
         {
            if (tc.paramseq_count() <= 1)
               result = expression_generator_
                          .generic_function_call(function, arg_list);
            else
               result = expression_generator_
                          .generic_function_call(function, arg_list, param_seq_index);
         }
         else if (type_checker::e_string == tc.return_type(param_seq_index))
         {
            if (tc.paramseq_count() <= 1)
               result = expression_generator_
                          .string_function_call(function, arg_list);
            else
               result = expression_generator_
                          .string_function_call(function, arg_list, param_seq_index);
         }
         else
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR143 - Invalid return type for call to overloaded function: " + function_name,
               exprtk_error_location));
         }

         sdd.delete_ptr = (0 == result);
         return result;
      }
      #endif

      template <typename Type, std::size_t NumberOfParameters>
      struct parse_special_function_impl
      {
         static inline expression_node_ptr process(parser<Type>& p, const details::operator_type opt_type, const std::string& sf_name)
         {
            expression_node_ptr branch[NumberOfParameters];
            expression_node_ptr result = error_node();

            std::fill_n(branch, NumberOfParameters, reinterpret_cast<expression_node_ptr>(0));

            scoped_delete<expression_node_t,NumberOfParameters> sd(p,branch);

            p.next_token();

            if (!p.token_is(token_t::e_lbracket))
            {
               p.set_error(make_error(
                  parser_error::e_syntax,
                  p.current_token(),
                  "ERR144 - Expected '(' for special function '" + sf_name + "'",
                  exprtk_error_location));

               return error_node();
            }

            for (std::size_t i = 0; i < NumberOfParameters; ++i)
            {
               branch[i] = p.parse_expression();

               if (0 == branch[i])
               {
                  return p.error_node();
               }
               else if (i < (NumberOfParameters - 1))
               {
                  if (!p.token_is(token_t::e_comma))
                  {
                     p.set_error(make_error(
                        parser_error::e_syntax,
                        p.current_token(),
                        "ERR145 - Expected ',' before next parameter of special function '" + sf_name + "'",
                        exprtk_error_location));

                     return p.error_node();
                  }
               }
            }

            if (!p.token_is(token_t::e_rbracket))
            {
               p.set_error(make_error(
                  parser_error::e_syntax,
                  p.current_token(),
                  "ERR146 - Invalid number of parameters for special function '" + sf_name + "'",
                  exprtk_error_location));

               return p.error_node();
            }
            else
               result = p.expression_generator_.special_function(opt_type,branch);

            sd.delete_ptr = (0 == result);

            return result;
         }
      };

      inline expression_node_ptr parse_special_function()
      {
         const std::string sf_name = current_token().value;

         // Expect: $fDD(expr0,expr1,expr2) or $fDD(expr0,expr1,expr2,expr3)
         if (
              !details::is_digit(sf_name[2]) ||
              !details::is_digit(sf_name[3])
            )
         {
            set_error(make_error(
               parser_error::e_token,
               current_token(),
               "ERR147 - Invalid special function[1]: " + sf_name,
               exprtk_error_location));

            return error_node();
         }

         const int id = (sf_name[2] - '0') * 10 +
                        (sf_name[3] - '0');

         if (id >= details::e_sffinal)
         {
            set_error(make_error(
               parser_error::e_token,
               current_token(),
               "ERR148 - Invalid special function[2]: " + sf_name,
               exprtk_error_location));

            return error_node();
         }

         const int sf_3_to_4                   = details::e_sf48;
         const details::operator_type opt_type = details::operator_type(id + 1000);
         const std::size_t NumberOfParameters  = (id < (sf_3_to_4 - 1000)) ? 3U : 4U;

         switch (NumberOfParameters)
         {
            case 3  : return parse_special_function_impl<T,3>::process((*this), opt_type, sf_name);
            case 4  : return parse_special_function_impl<T,4>::process((*this), opt_type, sf_name);
            default : return error_node();
         }
      }

      inline expression_node_ptr parse_null_statement()
      {
         next_token();
         return node_allocator_.allocate<details::null_node<T> >();
      }

      #ifndef exprtk_disable_break_continue
      inline expression_node_ptr parse_break_statement()
      {
         if (state_.parsing_break_stmt)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR149 - Invoking 'break' within a break call is not allowed",
               exprtk_error_location));

            return error_node();
         }
         else if (0 == state_.parsing_loop_stmt_count)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR150 - Invalid use of 'break', allowed only in the scope of a loop",
               exprtk_error_location));

            return error_node();
         }

         scoped_bool_negator sbn(state_.parsing_break_stmt);

         if (!brkcnt_list_.empty())
         {
            next_token();

            brkcnt_list_.front() = true;

            expression_node_ptr return_expr = error_node();

            if (token_is(token_t::e_lsqrbracket))
            {
               if (0 == (return_expr = parse_expression()))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR151 - Failed to parse return expression for 'break' statement",
                     exprtk_error_location));

                  return error_node();
               }
               else if (!token_is(token_t::e_rsqrbracket))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR152 - Expected ']' at the completion of break's return expression",
                     exprtk_error_location));

                  free_node(node_allocator_, return_expr);

                  return error_node();
               }
            }

            state_.activate_side_effect("parse_break_statement()");

            return node_allocator_.allocate<details::break_node<T> >(return_expr);
         }
         else
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR153 - Invalid use of 'break', allowed only in the scope of a loop",
               exprtk_error_location));
         }

         return error_node();
      }

      inline expression_node_ptr parse_continue_statement()
      {
         if (0 == state_.parsing_loop_stmt_count)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR154 - Invalid use of 'continue', allowed only in the scope of a loop",
               exprtk_error_location));

            return error_node();
         }
         else
         {
            next_token();

            brkcnt_list_.front() = true;
            state_.activate_side_effect("parse_continue_statement()");

            return node_allocator_.allocate<details::continue_node<T> >();
         }
      }
      #endif

      inline expression_node_ptr parse_define_vector_statement(const std::string& vec_name)
      {
         expression_node_ptr size_expression_node = error_node();

         if (!token_is(token_t::e_lsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR155 - Expected '[' as part of vector size definition",
               exprtk_error_location));

            return error_node();
         }
         else if (0 == (size_expression_node = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR156 - Failed to determine size of vector '" + vec_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (!is_constant_node(size_expression_node))
         {
            const bool is_rebaseble_vector =
               (size_expression_node->type() == details::expression_node<T>::e_vecsize) &&
               static_cast<details::vector_size_node<T>*>(size_expression_node)->vec_holder()->rebaseable();

            free_node(node_allocator_, size_expression_node);

            const std::string error_msg = (is_rebaseble_vector) ?
                                          std::string("Rebasable/Resizable vector cannot be used to define the size of vector") :
                                          std::string("Expected a constant literal number as size of vector");
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR157 - " + error_msg + " '" + vec_name + "'",
               exprtk_error_location));

            return error_node();
         }

         const T vector_size = size_expression_node->value();

         free_node(node_allocator_, size_expression_node);

         const std::size_t max_vector_size = settings_.max_local_vector_size();

         if (
              (vector_size <= T(0)) ||
              std::not_equal_to<T>()
              (T(0),vector_size - details::numeric::trunc(vector_size)) ||
              (static_cast<std::size_t>(vector_size) > max_vector_size)
            )
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR158 - Invalid vector size. Must be an integer in the "
               "range [0," + details::to_str(static_cast<std::size_t>(max_vector_size)) + "], size: " +
               details::to_str(details::numeric::to_int32(vector_size)),
               exprtk_error_location));

            return error_node();
         }

         typename symbol_table_t::vector_holder_ptr vec_holder = typename symbol_table_t::vector_holder_ptr(0);

         const std::size_t vec_size = static_cast<std::size_t>(details::numeric::to_int32(vector_size));

         scope_element& se = sem_.get_element(vec_name);

         if (se.name == vec_name)
         {
            if (se.active)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR159 - Illegal redefinition of local vector: '" + vec_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (
                      (se.size == vec_size) &&
                      (scope_element::e_vector == se.type)
                    )
            {
               vec_holder = se.vec_node;
               se.active  = true;
               se.depth   = state_.scope_depth;
               se.ref_count++;
            }
         }

         if (0 == vec_holder)
         {
            scope_element nse;
            nse.name      = vec_name;
            nse.active    = true;
            nse.ref_count = 1;
            nse.type      = scope_element::e_vector;
            nse.depth     = state_.scope_depth;
            nse.size      = vec_size;
            nse.data      = new T[vec_size];
            nse.vec_node  = new typename scope_element::vector_holder_t(reinterpret_cast<T*>(nse.data),nse.size);

            details::set_zero_value(reinterpret_cast<T*>(nse.data),vec_size);

            if (!sem_.add_element(nse))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR160 - Failed to add new local vector '" + vec_name + "' to SEM",
                  exprtk_error_location));

               sem_.free_element(nse);

               return error_node();
            }

            vec_holder = nse.vec_node;

            exprtk_debug(("parse_define_vector_statement() - INFO - Added new local vector: %s[%d]\n",
                          nse.name.c_str(),
                          static_cast<int>(nse.size)));
         }

         state_.activate_side_effect("parse_define_vector_statement()");

         lodge_symbol(vec_name, e_st_local_vector);

         std::vector<expression_node_ptr> vec_initilizer_list;

         scoped_vec_delete<expression_node_t> svd((*this),vec_initilizer_list);

         bool single_value_initialiser = false;
         bool range_value_initialiser  = false;
         bool vec_to_vec_initialiser   = false;
         bool null_initialisation      = false;

         if (!token_is(token_t::e_rsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR161 - Expected ']' as part of vector size definition",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_eof))
         {
            if (!token_is(token_t::e_assign))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR162 - Expected ':=' as part of vector definition",
                  exprtk_error_location));

               return error_node();
            }
            else if (token_is(token_t::e_lsqrbracket))
            {
               expression_node_ptr initialiser_component = parse_expression();

               if (0 == initialiser_component)
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR163 - Failed to parse first component of vector initialiser for vector: " + vec_name,
                     exprtk_error_location));

                  return error_node();
               }

               vec_initilizer_list.push_back(initialiser_component);

               if (token_is(token_t::e_colon))
               {
                  initialiser_component = parse_expression();

                  if (0 == initialiser_component)
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR164 - Failed to parse second component of vector initialiser for vector: " + vec_name,
                        exprtk_error_location));

                     return error_node();
                  }

                  vec_initilizer_list.push_back(initialiser_component);
               }

               if (!token_is(token_t::e_rsqrbracket))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR165 - Expected ']' to close single value vector initialiser",
                     exprtk_error_location));

                  return error_node();
               }

               switch (vec_initilizer_list.size())
               {
                  case 1 : single_value_initialiser = true; break;
                  case 2 : range_value_initialiser  = true; break;
               }
            }
            else if (!token_is(token_t::e_lcrlbracket))
            {
               expression_node_ptr initialiser = error_node();

               // Is this a vector to vector assignment and initialisation?
               if (token_t::e_symbol == current_token().type)
               {
                  // Is it a locally defined vector?
                  const scope_element& lcl_se = sem_.get_active_element(current_token().value);

                  if (scope_element::e_vector == lcl_se.type)
                  {
                     if (0 != (initialiser = parse_expression()))
                        vec_initilizer_list.push_back(initialiser);
                     else
                        return error_node();
                  }
                  // Are we dealing with a user defined vector?
                  else if (symtab_store_.is_vector(current_token().value))
                  {
                     lodge_symbol(current_token().value, e_st_vector);

                     if (0 != (initialiser = parse_expression()))
                        vec_initilizer_list.push_back(initialiser);
                     else
                        return error_node();
                  }
                  // Are we dealing with a null initialisation vector definition?
                  else if (token_is(token_t::e_symbol,"null"))
                     null_initialisation = true;
               }

               if (!null_initialisation)
               {
                  if (0 == initialiser)
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR166 - Expected '{' as part of vector initialiser list",
                        exprtk_error_location));

                     return error_node();
                  }
                  else
                     vec_to_vec_initialiser = true;
               }
            }
            else if (!token_is(token_t::e_rcrlbracket))
            {
               for ( ; ; )
               {
                  expression_node_ptr initialiser = parse_expression();

                  if (0 == initialiser)
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR167 - Expected '{' as part of vector initialiser list",
                        exprtk_error_location));

                     return error_node();
                  }
                  else
                     vec_initilizer_list.push_back(initialiser);

                  if (token_is(token_t::e_rcrlbracket))
                     break;

                  const bool is_next_close = peek_token_is(token_t::e_rcrlbracket);

                  if (!token_is(token_t::e_comma) && is_next_close)
                  {
                     set_error(make_error(
                        parser_error::e_syntax,
                        current_token(),
                        "ERR168 - Expected ',' between vector initialisers",
                        exprtk_error_location));

                     return error_node();
                  }

                  if (token_is(token_t::e_rcrlbracket))
                     break;
               }
            }

            if (
                 !token_is(token_t::e_rbracket   , prsrhlpr_t::e_hold) &&
                 !token_is(token_t::e_rcrlbracket, prsrhlpr_t::e_hold) &&
                 !token_is(token_t::e_rsqrbracket, prsrhlpr_t::e_hold)
               )
            {
               if (!token_is(token_t::e_eof))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR169 - Expected ';' at end of vector definition",
                     exprtk_error_location));

                  return error_node();
               }
            }

            if (
                 !single_value_initialiser &&
                 !range_value_initialiser  &&
                 (T(vec_initilizer_list.size()) > vector_size)
               )
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR170 - Initialiser list larger than the number of elements in the vector: '" + vec_name + "'",
                  exprtk_error_location));

               return error_node();
            }
         }

         expression_node_ptr result = error_node();

         if (
              (vec_initilizer_list.size() == 1) &&
              single_value_initialiser
            )
         {
            if (details::is_constant_node(vec_initilizer_list[0]))
            {
              // vector_init_zero_value_node   var v[10] := [0]
               if (T(0) == vec_initilizer_list[0]->value())
               {
                  result = node_allocator_
                              .allocate<details::vector_init_zero_value_node<T> >(
                                 (*vec_holder)[0],
                                 vec_size,
                                 vec_initilizer_list);
               }
               else
               {
                  // vector_init_single_constvalue_node   var v[10] := [123]
                  result = node_allocator_
                              .allocate<details::vector_init_single_constvalue_node<T> >(
                                 (*vec_holder)[0],
                                 vec_size,
                                 vec_initilizer_list);
               }
            }
            else
            {
               // vector_init_single_value_node   var v[10] := [123 + (x / y)]
               result = node_allocator_
                           .allocate<details::vector_init_single_value_node<T> >(
                              (*vec_holder)[0],
                              vec_size,
                              vec_initilizer_list);
            }
         }
         else if (
                   (vec_initilizer_list.size() == 2) &&
                   range_value_initialiser
                 )
         {
            bool base_const = details::is_constant_node(vec_initilizer_list[0]);
            bool inc_const  = details::is_constant_node(vec_initilizer_list[1]);

            if (base_const && inc_const)
            {
               // vector_init_single_value_node   var v[10] := [1 : 3.5]
               result = node_allocator_
                           .allocate<details::vector_init_iota_constconst_node<T> >(
                              (*vec_holder)[0],
                              vec_size,
                              vec_initilizer_list);
            }
            else if (base_const && !inc_const)
            {
               // vector_init_single_value_node   var v[10] := [1 : x + y]
               result = node_allocator_
                           .allocate<details::vector_init_iota_constnconst_node<T> >(
                              (*vec_holder)[0],
                              vec_size,
                              vec_initilizer_list);
            }
            else if (!base_const && inc_const)
            {
               // vector_init_single_value_node   var v[10] := [x + y : 3]
               result = node_allocator_
                           .allocate<details::vector_init_iota_nconstconst_node<T> >(
                              (*vec_holder)[0],
                              vec_size,
                              vec_initilizer_list);
            }
            else if (!base_const && !inc_const)
            {
               // vector_init_single_value_node   var v[10] := [x + y :  z / w]
               result = node_allocator_
                           .allocate<details::vector_init_iota_nconstnconst_node<T> >(
                              (*vec_holder)[0],
                              vec_size,
                              vec_initilizer_list);
            }
         }
         else if (null_initialisation)
            result = expression_generator_(T(0.0));
         else if (vec_to_vec_initialiser)
         {
            expression_node_ptr vec_node = node_allocator_.allocate<vector_node_t>(vec_holder);

            result = expression_generator_(
                        details::e_assign,
                        vec_node,
                        vec_initilizer_list[0]);
         }
         else
         {
            result = node_allocator_
                        .allocate<details::vector_initialisation_node<T> >(
                           (*vec_holder)[0],
                           vec_size,
                           vec_initilizer_list,
                           single_value_initialiser);
         }

         svd.delete_ptr = false;

         if (result && result->valid())
         {
            return result;
         }

         details::free_node(node_allocator_, result);

         set_error(make_error(
            parser_error::e_synthesis,
            current_token(),
            "ERR171 - Failed to generate initialisation node for vector: " + vec_name,
            exprtk_error_location));

         return error_node();
      }

      #ifndef exprtk_disable_string_capabilities
      inline expression_node_ptr parse_define_string_statement(const std::string& str_name, expression_node_ptr initialisation_expression)
      {
         stringvar_node_t* str_node = reinterpret_cast<stringvar_node_t*>(0);

         scope_element& se = sem_.get_element(str_name);

         if (se.name == str_name)
         {
            if (se.active)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR172 - Illegal redefinition of local variable: '" + str_name + "'",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               return error_node();
            }
            else if (scope_element::e_string == se.type)
            {
               str_node  = se.str_node;
               se.active = true;
               se.depth  = state_.scope_depth;
               se.ref_count++;
            }
         }

         if (0 == str_node)
         {
            scope_element nse;
            nse.name      = str_name;
            nse.active    = true;
            nse.ref_count = 1;
            nse.type      = scope_element::e_string;
            nse.depth     = state_.scope_depth;
            nse.data      = new std::string;
            nse.str_node  = new stringvar_node_t(*reinterpret_cast<std::string*>(nse.data));

            if (!sem_.add_element(nse))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR173 - Failed to add new local string variable '" + str_name + "' to SEM",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               sem_.free_element(nse);

               return error_node();
            }

            str_node = nse.str_node;

            exprtk_debug(("parse_define_string_statement() - INFO - Added new local string variable: %s\n", nse.name.c_str()));
         }

         lodge_symbol(str_name, e_st_local_string);

         state_.activate_side_effect("parse_define_string_statement()");

         expression_node_ptr branch[2] = {0};

         branch[0] = str_node;
         branch[1] = initialisation_expression;

         return expression_generator_(details::e_assign,branch);
      }
      #else
      inline expression_node_ptr parse_define_string_statement(const std::string&, expression_node_ptr)
      {
         return error_node();
      }
      #endif

      inline bool local_variable_is_shadowed(const std::string& symbol)
      {
         const scope_element& se = sem_.get_element(symbol);
         return (se.name == symbol) && se.active;
      }

      inline expression_node_ptr parse_define_var_statement()
      {
         if (settings_.vardef_disabled())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR174 - Illegal variable definition",
               exprtk_error_location));

            return error_node();
         }
         else if (!details::imatch(current_token().value,"var"))
         {
            return error_node();
         }
         else
            next_token();

         const std::string var_name = current_token().value;

         expression_node_ptr initialisation_expression = error_node();

         if (!token_is(token_t::e_symbol))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR175 - Expected a symbol for variable definition",
               exprtk_error_location));

            return error_node();
         }
         else if (details::is_reserved_symbol(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR176 - Illegal redefinition of reserved keyword: '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (symtab_store_.symbol_exists(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR177 - Illegal redefinition of variable '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (local_variable_is_shadowed(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR178 - Illegal redefinition of local variable: '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (token_is(token_t::e_lsqrbracket,prsrhlpr_t::e_hold))
         {
            return parse_define_vector_statement(var_name);
         }
         else if (token_is(token_t::e_lcrlbracket,prsrhlpr_t::e_hold))
         {
            return parse_uninitialised_var_statement(var_name);
         }
         else if (token_is(token_t::e_assign))
         {
            if (0 == (initialisation_expression = parse_expression()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR179 - Failed to parse initialisation expression",
                  exprtk_error_location));

               return error_node();
            }
         }

         if (
              !token_is(token_t::e_rbracket   , prsrhlpr_t::e_hold) &&
              !token_is(token_t::e_rcrlbracket, prsrhlpr_t::e_hold) &&
              !token_is(token_t::e_rsqrbracket, prsrhlpr_t::e_hold)
            )
         {
            if (!token_is(token_t::e_eof,prsrhlpr_t::e_hold))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR180 - Expected ';' after variable definition",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               return error_node();
            }
         }

         if (
              (0 != initialisation_expression) &&
              details::is_generally_string_node(initialisation_expression)
            )
         {
            return parse_define_string_statement(var_name,initialisation_expression);
         }

         expression_node_ptr var_node = reinterpret_cast<expression_node_ptr>(0);

         scope_element& se = sem_.get_element(var_name);

         if (se.name == var_name)
         {
            if (se.active)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR181 - Illegal redefinition of local variable: '" + var_name + "'",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               return error_node();
            }
            else if (scope_element::e_variable == se.type)
            {
               var_node  = se.var_node;
               se.active = true;
               se.depth  = state_.scope_depth;
               se.ref_count++;
            }
         }

         if (0 == var_node)
         {
            scope_element nse;
            nse.name      = var_name;
            nse.active    = true;
            nse.ref_count = 1;
            nse.type      = scope_element::e_variable;
            nse.depth     = state_.scope_depth;
            nse.data      = new T(T(0));
            nse.var_node  = node_allocator_.allocate<variable_node_t>(*reinterpret_cast<T*>(nse.data));

            if (!sem_.add_element(nse))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR182 - Failed to add new local variable '" + var_name + "' to SEM",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               sem_.free_element(nse);

               return error_node();
            }

            var_node = nse.var_node;

            exprtk_debug(("parse_define_var_statement() - INFO - Added new local variable: %s\n", nse.name.c_str()));
         }

         state_.activate_side_effect("parse_define_var_statement()");

         lodge_symbol(var_name, e_st_local_variable);

         expression_node_ptr branch[2] = {0};

         branch[0] = var_node;
         branch[1] = initialisation_expression ? initialisation_expression : expression_generator_(T(0));

         return expression_generator_(details::e_assign,branch);
      }

      inline expression_node_ptr parse_define_constvar_statement()
      {
         if (settings_.vardef_disabled())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR183 - Illegal const variable definition",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is("const"))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR184 - Expected 'const' keyword for const-variable definition",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is("var"))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR185 - Expected 'var' keyword for const-variable definition",
               exprtk_error_location));

            return error_node();
         }

         const std::string var_name = current_token().value;

         expression_node_ptr initialisation_expression = error_node();

         if (!token_is(token_t::e_symbol))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR186 - Expected a symbol for const-variable definition",
               exprtk_error_location));

            return error_node();
         }
         else if (details::is_reserved_symbol(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR187 - Illegal redefinition of reserved keyword: '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (symtab_store_.symbol_exists(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR188 - Illegal redefinition of variable '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (local_variable_is_shadowed(var_name))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR189 - Illegal redefinition of local variable: '" + var_name + "'",
               exprtk_error_location));

            return error_node();
         }
         else if (token_is(token_t::e_assign))
         {
            if (0 == (initialisation_expression = parse_expression()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR190 - Failed to parse initialisation expression for const-variable: '" + var_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (!details::is_literal_node(initialisation_expression))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR191 - initialisation expression for const-variable: '" + var_name + "' must be a constant/literal",
                  exprtk_error_location));

               free_node(node_allocator_, initialisation_expression);

               return error_node();
            }
         }

         const T init_value = initialisation_expression->value();

         free_node(node_allocator_, initialisation_expression);

         expression_node_ptr var_node = reinterpret_cast<expression_node_ptr>(0);

         scope_element& se = sem_.get_element(var_name);

         if (se.name == var_name)
         {
            if (se.active)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR192 - Illegal redefinition of local variable: '" + var_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (scope_element::e_literal == se.type)
            {
               var_node  = se.var_node;
               se.active = true;
               se.depth  = state_.scope_depth;
               se.ref_count++;
            }
         }

         if (0 == var_node)
         {
            scope_element nse;
            nse.name      = var_name;
            nse.active    = true;
            nse.ref_count = 1;
            nse.type      = scope_element::e_literal;
            nse.depth     = state_.scope_depth;
            nse.data      = 0;
            nse.var_node  = node_allocator_.allocate<literal_node_t>(init_value);

            if (!sem_.add_element(nse))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR193 - Failed to add new local const-variable '" + var_name + "' to SEM",
                  exprtk_error_location));

               sem_.free_element(nse);

               return error_node();
            }

            var_node = nse.var_node;

            exprtk_debug(("parse_define_constvar_statement() - INFO - Added new local const-variable: %s\n", nse.name.c_str()));
         }

         state_.activate_side_effect("parse_define_constvar_statement()");

         lodge_symbol(var_name, e_st_local_variable);

         return expression_generator_(var_node->value());
      }

      inline expression_node_ptr parse_uninitialised_var_statement(const std::string& var_name)
      {
         if (
              !token_is(token_t::e_lcrlbracket) ||
              !token_is(token_t::e_rcrlbracket)
            )
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR194 - Expected a '{}' for uninitialised var definition",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_eof,prsrhlpr_t::e_hold))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR195 - Expected ';' after uninitialised variable definition",
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr var_node = reinterpret_cast<expression_node_ptr>(0);

         scope_element& se = sem_.get_element(var_name);

         if (se.name == var_name)
         {
            if (se.active)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR196 - Illegal redefinition of local variable: '" + var_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (scope_element::e_variable == se.type)
            {
               var_node  = se.var_node;
               se.active = true;
               se.ref_count++;
            }
         }

         if (0 == var_node)
         {
            scope_element nse;
            nse.name      = var_name;
            nse.active    = true;
            nse.ref_count = 1;
            nse.type      = scope_element::e_variable;
            nse.depth     = state_.scope_depth;
            nse.ip_index  = sem_.next_ip_index();
            nse.data      = new T(T(0));
            nse.var_node  = node_allocator_.allocate<variable_node_t>(*reinterpret_cast<T*>(nse.data));

            if (!sem_.add_element(nse))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR197 - Failed to add new local variable '" + var_name + "' to SEM",
                  exprtk_error_location));

               sem_.free_element(nse);

               return error_node();
            }

            exprtk_debug(("parse_uninitialised_var_statement() - INFO - Added new local variable: %s\n",
                          nse.name.c_str()));
         }

         lodge_symbol(var_name, e_st_local_variable);

         state_.activate_side_effect("parse_uninitialised_var_statement()");

         return expression_generator_(T(0));
      }

      inline expression_node_ptr parse_swap_statement()
      {
         if (!details::imatch(current_token().value,"swap"))
         {
            return error_node();
         }
         else
            next_token();

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR198 - Expected '(' at start of swap statement",
               exprtk_error_location));

            return error_node();
         }

         expression_node_ptr variable0 = error_node();
         expression_node_ptr variable1 = error_node();

         bool variable0_generated = false;
         bool variable1_generated = false;

         const std::string var0_name = current_token().value;

         if (!token_is(token_t::e_symbol,prsrhlpr_t::e_hold))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR199 - Expected a symbol for variable or vector element definition",
               exprtk_error_location));

            return error_node();
         }
         else if (peek_token_is(token_t::e_lsqrbracket))
         {
            if (0 == (variable0 = parse_vector()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR200 - First parameter to swap is an invalid vector element: '" + var0_name + "'",
                  exprtk_error_location));

               return error_node();
            }

            variable0_generated = true;
         }
         else
         {
            if (symtab_store_.is_variable(var0_name))
            {
               variable0 = symtab_store_.get_variable(var0_name);
            }

            const scope_element& se = sem_.get_element(var0_name);

            if (
                 (se.active)            &&
                 (se.name == var0_name) &&
                 (scope_element::e_variable == se.type)
               )
            {
               variable0 = se.var_node;
            }

            lodge_symbol(var0_name, e_st_variable);

            if (0 == variable0)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR201 - First parameter to swap is an invalid variable: '" + var0_name + "'",
                  exprtk_error_location));

               return error_node();
            }
            else
               next_token();
         }

         if (!token_is(token_t::e_comma))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR202 - Expected ',' between parameters to swap",
               exprtk_error_location));

            if (variable0_generated)
            {
               free_node(node_allocator_, variable0);
            }

            return error_node();
         }

         const std::string var1_name = current_token().value;

         if (!token_is(token_t::e_symbol,prsrhlpr_t::e_hold))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR203 - Expected a symbol for variable or vector element definition",
               exprtk_error_location));

            if (variable0_generated)
            {
               free_node(node_allocator_, variable0);
            }

            return error_node();
         }
         else if (peek_token_is(token_t::e_lsqrbracket))
         {
            if (0 == (variable1 = parse_vector()))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR204 - Second parameter to swap is an invalid vector element: '" + var1_name + "'",
                  exprtk_error_location));

               if (variable0_generated)
               {
                  free_node(node_allocator_, variable0);
               }

               return error_node();
            }

            variable1_generated = true;
         }
         else
         {
            if (symtab_store_.is_variable(var1_name))
            {
               variable1 = symtab_store_.get_variable(var1_name);
            }

            const scope_element& se = sem_.get_element(var1_name);

            if (
                 (se.active) &&
                 (se.name == var1_name) &&
                 (scope_element::e_variable == se.type)
               )
            {
               variable1 = se.var_node;
            }

            lodge_symbol(var1_name, e_st_variable);

            if (0 == variable1)
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR205 - Second parameter to swap is an invalid variable: '" + var1_name + "'",
                  exprtk_error_location));

               if (variable0_generated)
               {
                  free_node(node_allocator_, variable0);
               }

               return error_node();
            }
            else
               next_token();
         }

         if (!token_is(token_t::e_rbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR206 - Expected ')' at end of swap statement",
               exprtk_error_location));

            if (variable0_generated)
            {
               free_node(node_allocator_, variable0);
            }

            if (variable1_generated)
            {
               free_node(node_allocator_, variable1);
            }

            return error_node();
         }

         typedef details::variable_node<T>* variable_node_ptr;

         variable_node_ptr v0 = variable_node_ptr(0);
         variable_node_ptr v1 = variable_node_ptr(0);

         expression_node_ptr result = error_node();

         if (
              (0 != (v0 = dynamic_cast<variable_node_ptr>(variable0))) &&
              (0 != (v1 = dynamic_cast<variable_node_ptr>(variable1)))
            )
         {
            result = node_allocator_.allocate<details::swap_node<T> >(v0, v1);

            if (variable0_generated)
            {
               free_node(node_allocator_, variable0);
            }

            if (variable1_generated)
            {
               free_node(node_allocator_, variable1);
            }
         }
         else
            result = node_allocator_.allocate<details::swap_generic_node<T> >
                        (variable0, variable1);

         state_.activate_side_effect("parse_swap_statement()");

         return result;
      }

      #ifndef exprtk_disable_return_statement
      inline expression_node_ptr parse_return_statement()
      {
         if (state_.parsing_return_stmt)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR207 - Return call within a return call is not allowed",
               exprtk_error_location));

            return error_node();
         }

         scoped_bool_negator sbn(state_.parsing_return_stmt);

         std::vector<expression_node_ptr> arg_list;

         scoped_vec_delete<expression_node_t> sdd((*this),arg_list);

         if (!details::imatch(current_token().value,"return"))
         {
            return error_node();
         }
         else
            next_token();

         if (!token_is(token_t::e_lsqrbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR208 - Expected '[' at start of return statement",
               exprtk_error_location));

            return error_node();
         }
         else if (!token_is(token_t::e_rsqrbracket))
         {
            for ( ; ; )
            {
               expression_node_ptr arg = parse_expression();

               if (0 == arg)
                  return error_node();

               arg_list.push_back(arg);

               if (token_is(token_t::e_rsqrbracket))
                  break;
               else if (!token_is(token_t::e_comma))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR209 - Expected ',' between values during call to return",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }
         else if (settings_.zero_return_disabled())
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR210 - Zero parameter return statement not allowed",
               exprtk_error_location));

            return error_node();
         }

         const lexer::token prev_token = current_token();

         if (token_is(token_t::e_rsqrbracket))
         {
            if (!arg_list.empty())
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  prev_token,
                  "ERR211 - Invalid ']' found during return call",
                  exprtk_error_location));

               return error_node();
            }
         }

         std::string ret_param_type_list;

         for (std::size_t i = 0; i < arg_list.size(); ++i)
         {
            if (0 == arg_list[i])
               return error_node();
            else if (is_ivector_node(arg_list[i]))
               ret_param_type_list += 'V';
            else if (is_generally_string_node(arg_list[i]))
               ret_param_type_list += 'S';
            else
               ret_param_type_list += 'T';
         }

         dec_.retparam_list_.push_back(ret_param_type_list);

         expression_node_ptr result = expression_generator_.return_call(arg_list);

         sdd.delete_ptr = (0 == result);

         state_.return_stmt_present = true;

         state_.activate_side_effect("parse_return_statement()");

         return result;
      }
      #else
      inline expression_node_ptr parse_return_statement()
      {
         return error_node();
      }
      #endif

      inline expression_node_ptr parse_assert_statement()
      {
         assert(details::imatch(current_token().value, "assert"));

         if (state_.parsing_assert_stmt)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR212 - Assert statement within an assert statement is not allowed",
               exprtk_error_location));

            return error_node();
         }

         scoped_bool_negator sbn(state_.parsing_assert_stmt);

         next_token();

         std::vector<expression_node_ptr> assert_arg_list(3, error_node());
         scoped_vec_delete<expression_node_t> sdd((*this), assert_arg_list);

         expression_node_ptr& assert_condition = assert_arg_list[0];
         expression_node_ptr& assert_message   = assert_arg_list[1];
         expression_node_ptr& assert_id        = assert_arg_list[2];

         if (!token_is(token_t::e_lbracket))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR213 - Expected '(' at start of assert statement",
               exprtk_error_location));

            return error_node();
         }

         const token_t start_token = current_token();

         // Parse the assert condition
         if (0 == (assert_condition = parse_expression()))
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR214 - Failed to parse condition for assert statement",
               exprtk_error_location));

            return error_node();
         }

         const token_t end_token = current_token();

         if (!token_is(token_t::e_rbracket))
         {
            if (!token_is(token_t::e_comma))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR215 - Expected ',' between condition and message for assert statement",
                  exprtk_error_location));

               return error_node();
            }
            // Parse the assert message
            else if (
                      (0 == (assert_message = parse_expression())) ||
                      !details::is_generally_string_node(assert_message)
                    )
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR216 - " +
                  (assert_message ?
                  std::string("Expected string for assert message") :
                  std::string("Failed to parse message for assert statement")),
                  exprtk_error_location));

               return error_node();
            }
            else if (!token_is(token_t::e_rbracket))
            {
               if (!token_is(token_t::e_comma))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR217 - Expected ',' between message and ID for assert statement",
                     exprtk_error_location));

                  return error_node();
               }
               // Parse assert ID
               else if (
                         (0 == (assert_id = parse_expression())) ||
                         !details::is_const_string_node(assert_id)
                       )
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR218 - " +
                     (assert_id ?
                     std::string("Expected literal string for assert ID") :
                     std::string("Failed to parse string for assert ID")),
                     exprtk_error_location));

                  return error_node();
               }
               else if (!token_is(token_t::e_rbracket))
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR219 - Expected ')' at start of assert statement",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         exprtk::assert_check::assert_context context;
         context.condition = lexer().substr(start_token.position, end_token.position);
         context.offet     = start_token.position;

         if (0 == assert_check_)
         {
            exprtk_debug(("parse_assert_statement() - assert functionality is disabled. assert condition: %s\n",
                          context.condition.c_str()));

            return new details::null_node<T>();
         }

         #ifndef exprtk_disable_string_capabilities
         if (assert_message && details::is_const_string_node(assert_message))
         {
            context.message = dynamic_cast<details::string_base_node<T>*>(assert_message)->str();
         }

         if (assert_id && details::is_const_string_node(assert_id))
         {
            context.id = dynamic_cast<details::string_base_node<T>*>(assert_id)->str();

            if (assert_ids_.end() != assert_ids_.find(context.id))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR220 - Duplicate assert ID: " + context.id,
                  exprtk_error_location));

               return error_node();
            }

            assert_ids_.insert(context.id);
            free_node(node_allocator_, assert_id);
         }
         #endif

         expression_node_ptr result_node =
            expression_generator_.assert_call(
               assert_condition,
               assert_message,
               context);

         exprtk_debug(("parse_assert_statement() - assert condition: [%s]\n", context.condition.c_str()      ));
         exprtk_debug(("parse_assert_statement() - assert message:   [%s]\n", context.message  .c_str()      ));
         exprtk_debug(("parse_assert_statement() - assert id:        [%s]\n", context.id       .c_str()      ));
         exprtk_debug(("parse_assert_statement() - assert offset:    [%d]\n", static_cast<int>(context.offet)));

         if (0 == result_node)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR221 - Failed to synthesize assert",
               exprtk_error_location));

            return error_node();
         }

         sdd.delete_ptr = false;
         return result_node;
      }

      inline bool post_variable_process(const std::string& symbol)
      {
         if (
              peek_token_is(token_t::e_lbracket   ) ||
              peek_token_is(token_t::e_lcrlbracket) ||
              peek_token_is(token_t::e_lsqrbracket)
            )
         {
            if (!settings_.commutative_check_enabled())
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR222 - Invalid sequence of variable '" + symbol + "' and bracket",
                  exprtk_error_location));

               return false;
            }

            lexer().insert_front(token_t::e_mul);
         }

         return true;
      }

      inline bool post_bracket_process(const typename token_t::token_type& token, expression_node_ptr& branch)
      {
         bool implied_mul = false;

         if (details::is_generally_string_node(branch))
            return true;

         const lexer::parser_helper::token_advance_mode hold = prsrhlpr_t::e_hold;

         switch (token)
         {
            case token_t::e_lcrlbracket : implied_mul = token_is(token_t::e_lbracket   , hold) ||
                                                        token_is(token_t::e_lcrlbracket, hold) ||
                                                        token_is(token_t::e_lsqrbracket, hold) ;
                                          break;

            case token_t::e_lbracket    : implied_mul = token_is(token_t::e_lbracket   , hold) ||
                                                        token_is(token_t::e_lcrlbracket, hold) ||
                                                        token_is(token_t::e_lsqrbracket, hold) ;
                                          break;

            case token_t::e_lsqrbracket : implied_mul = token_is(token_t::e_lbracket   , hold) ||
                                                        token_is(token_t::e_lcrlbracket, hold) ||
                                                        token_is(token_t::e_lsqrbracket, hold) ;
                                          break;

            default                     : return true;
         }

         if (implied_mul)
         {
            if (!settings_.commutative_check_enabled())
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR223 - Invalid sequence of brackets",
                  exprtk_error_location));

               return false;
            }
            else if (token_t::e_eof != current_token().type)
            {
               lexer().insert_front(current_token().type);
               lexer().insert_front(token_t::e_mul);
               next_token();
            }
         }

         return true;
      }

      typedef typename interval_container_t<const void*>::interval_t interval_t;
      typedef interval_container_t<const void*> immutable_memory_map_t;
      typedef std::map<interval_t,token_t> immutable_symtok_map_t;

      inline interval_t make_memory_range(const T& t)
      {
         const T* begin = reinterpret_cast<const T*>(&t);
         const T* end   = begin + 1;
         return interval_t(begin, end);
      }

      inline interval_t make_memory_range(const T* begin, const std::size_t size)
      {
         return interval_t(begin, begin + size);
      }

      inline interval_t make_memory_range(details::char_cptr begin, const std::size_t size)
      {
         return interval_t(begin, begin + size);
      }

      void lodge_immutable_symbol(const lexer::token& token, const interval_t interval)
      {
         immutable_memory_map_.add_interval(interval);
         immutable_symtok_map_[interval] = token;
      }

      inline expression_node_ptr parse_symtab_symbol()
      {
         const std::string symbol = current_token().value;

         // Are we dealing with a variable or a special constant?
         typedef typename symtab_store::variable_context var_ctxt_t;
         var_ctxt_t var_ctx = symtab_store_.get_variable_context(symbol);

         if (var_ctx.variable)
         {
            assert(var_ctx.symbol_table);

            expression_node_ptr result_variable = var_ctx.variable;

            if (symtab_store_.is_constant_node(symbol))
            {
               result_variable = expression_generator_(var_ctx.variable->value());
            }
            else if (symbol_table_t::e_immutable == var_ctx.symbol_table->mutability())
            {
               lodge_immutable_symbol(current_token(), make_memory_range(var_ctx.variable->ref()));
               result_variable = var_ctx.variable;
            }

            if (!post_variable_process(symbol))
               return error_node();

            lodge_symbol(symbol, e_st_variable);

            next_token();

            return result_variable;
         }

         // Are we dealing with a locally defined variable, vector or string?
         if (!sem_.empty())
         {
            scope_element& se = sem_.get_active_element(symbol);

            if (se.active && details::imatch(se.name, symbol))
            {
               if (
                    (scope_element::e_variable == se.type) ||
                    (scope_element::e_literal  == se.type)
                  )
               {
                  se.active = true;
                  lodge_symbol(symbol, e_st_local_variable);

                  if (!post_variable_process(symbol))
                     return error_node();

                  next_token();

                  return (scope_element::e_variable == se.type) ?
                           se.var_node :
                           expression_generator_(se.var_node->value());
               }
               else if (scope_element::e_vector == se.type)
               {
                  return parse_vector();
               }
               #ifndef exprtk_disable_string_capabilities
               else if (scope_element::e_string == se.type)
               {
                  return parse_string();
               }
               #endif
            }
         }

         #ifndef exprtk_disable_string_capabilities
         // Are we dealing with a string variable?
         if (symtab_store_.is_stringvar(symbol))
         {
            return parse_string();
         }
         #endif

         {
            // Are we dealing with a function?
            ifunction<T>* function = symtab_store_.get_function(symbol);

            if (function)
            {
               lodge_symbol(symbol, e_st_function);

               expression_node_ptr func_node =
                                      parse_function_invocation(function,symbol);

               if (func_node)
                  return func_node;
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR224 - Failed to generate node for function: '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         {
            // Are we dealing with a vararg function?
            ivararg_function<T>* vararg_function = symtab_store_.get_vararg_function(symbol);

            if (vararg_function)
            {
               lodge_symbol(symbol, e_st_function);

               expression_node_ptr vararg_func_node =
                                      parse_vararg_function_call(vararg_function, symbol);

               if (vararg_func_node)
                  return vararg_func_node;
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR225 - Failed to generate node for vararg function: '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         {
            // Are we dealing with a vararg generic function?
            igeneric_function<T>* generic_function = symtab_store_.get_generic_function(symbol);

            if (generic_function)
            {
               lodge_symbol(symbol, e_st_function);

               expression_node_ptr genericfunc_node =
                                      parse_generic_function_call(generic_function, symbol);

               if (genericfunc_node)
                  return genericfunc_node;
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR226 - Failed to generate node for generic function: '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         #ifndef exprtk_disable_string_capabilities
         {
            // Are we dealing with a vararg string returning function?
            igeneric_function<T>* string_function = symtab_store_.get_string_function(symbol);

            if (string_function)
            {
               lodge_symbol(symbol, e_st_function);

               expression_node_ptr stringfunc_node =
                                      parse_string_function_call(string_function, symbol);

               if (stringfunc_node)
                  return stringfunc_node;
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR227 - Failed to generate node for string function: '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }

         {
            // Are we dealing with a vararg overloaded scalar/string returning function?
            igeneric_function<T>* overload_function = symtab_store_.get_overload_function(symbol);

            if (overload_function)
            {
               lodge_symbol(symbol, e_st_function);

               expression_node_ptr overloadfunc_node =
                                      parse_overload_function_call(overload_function, symbol);

               if (overloadfunc_node)
                  return overloadfunc_node;
               else
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR228 - Failed to generate node for overload function: '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
            }
         }
         #endif

         // Are we dealing with a vector?
         if (symtab_store_.is_vector(symbol))
         {
            lodge_symbol(symbol, e_st_vector);
            return parse_vector();
         }

         if (details::is_reserved_symbol(symbol))
         {
               if (
                    settings_.function_enabled(symbol) ||
                    !details::is_base_function(symbol)
                  )
               {
                  set_error(make_error(
                     parser_error::e_syntax,
                     current_token(),
                     "ERR229 - Invalid use of reserved symbol '" + symbol + "'",
                     exprtk_error_location));

                  return error_node();
               }
         }

         // Should we handle unknown symbols?
         if (resolve_unknown_symbol_ && unknown_symbol_resolver_)
         {
            if (!(settings_.rsrvd_sym_usr_disabled() && details::is_reserved_symbol(symbol)))
            {
               symbol_table_t& symtab = symtab_store_.get_symbol_table();

               std::string error_message;

               if (unknown_symbol_resolver::e_usrmode_default == unknown_symbol_resolver_->mode)
               {
                  T default_value = T(0);

                  typename unknown_symbol_resolver::usr_symbol_type usr_symbol_type = unknown_symbol_resolver::e_usr_unknown_type;

                  if (unknown_symbol_resolver_->process(symbol, usr_symbol_type, default_value, error_message))
                  {
                     bool create_result = false;

                     switch (usr_symbol_type)
                     {
                        case unknown_symbol_resolver::e_usr_variable_type :
                           create_result = symtab.create_variable(symbol, default_value);
                           break;

                        case unknown_symbol_resolver::e_usr_constant_type :
                           create_result = symtab.add_constant(symbol, default_value);
                           break;

                        default                                           : create_result = false;
                     }

                     if (create_result)
                     {
                        expression_node_ptr var = symtab_store_.get_variable(symbol);

                        if (var)
                        {
                           if (symtab_store_.is_constant_node(symbol))
                           {
                              var = expression_generator_(var->value());
                           }

                           lodge_symbol(symbol, e_st_variable);

                           if (!post_variable_process(symbol))
                              return error_node();

                           next_token();

                           return var;
                        }
                     }
                  }

                  set_error(make_error(
                     parser_error::e_symtab,
                     current_token(),
                     "ERR230 - Failed to create variable: '" + symbol + "'" +
                     (error_message.empty() ? "" : " - " + error_message),
                     exprtk_error_location));

               }
               else if (unknown_symbol_resolver::e_usrmode_extended == unknown_symbol_resolver_->mode)
               {
                  if (unknown_symbol_resolver_->process(symbol, symtab, error_message))
                  {
                     expression_node_ptr result = parse_symtab_symbol();

                     if (result)
                     {
                        return result;
                     }
                  }

                  set_error(make_error(
                     parser_error::e_symtab,
                     current_token(),
                     "ERR231 - Failed to resolve symbol: '" + symbol + "'" +
                     (error_message.empty() ? "" : " - " + error_message),
                     exprtk_error_location));
               }

               return error_node();
            }
         }

         set_error(make_error(
            parser_error::e_syntax,
            current_token(),
            "ERR232 - Undefined symbol: '" + symbol + "'",
            exprtk_error_location));

         return error_node();
      }

      inline expression_node_ptr parse_symbol()
      {
         static const std::string symbol_if       = "if"      ;
         static const std::string symbol_while    = "while"   ;
         static const std::string symbol_repeat   = "repeat"  ;
         static const std::string symbol_for      = "for"     ;
         static const std::string symbol_switch   = "switch"  ;
         static const std::string symbol_null     = "null"    ;
         static const std::string symbol_break    = "break"   ;
         static const std::string symbol_continue = "continue";
         static const std::string symbol_var      = "var"     ;
         static const std::string symbol_const    = "const"   ;
         static const std::string symbol_swap     = "swap"    ;
         static const std::string symbol_return   = "return"  ;
         static const std::string symbol_not      = "not"     ;
         static const std::string symbol_assert   = "assert"  ;

         const std::string symbol = current_token().value;

         if (valid_vararg_operation(symbol))
         {
            return parse_vararg_function();
         }
         else if (details::imatch(symbol, symbol_not))
         {
            return parse_not_statement();
         }
         else if (valid_base_operation(symbol))
         {
            return parse_base_operation();
         }
         else if (
                   details::imatch(symbol, symbol_if) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_conditional_statement();
         }
         else if (
                   details::imatch(symbol, symbol_while) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_while_loop();
         }
         else if (
                   details::imatch(symbol, symbol_repeat) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_repeat_until_loop();
         }
         else if (
                   details::imatch(symbol, symbol_for) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_for_loop();
         }
         else if (
                   details::imatch(symbol, symbol_switch) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_switch_statement();
         }
         else if (details::is_valid_sf_symbol(symbol))
         {
            return parse_special_function();
         }
         else if (details::imatch(symbol, symbol_null))
         {
            return parse_null_statement();
         }
         #ifndef exprtk_disable_break_continue
         else if (details::imatch(symbol, symbol_break))
         {
            return parse_break_statement();
         }
         else if (details::imatch(symbol, symbol_continue))
         {
            return parse_continue_statement();
         }
         #endif
         else if (details::imatch(symbol, symbol_var))
         {
            return parse_define_var_statement();
         }
         else if (details::imatch(symbol, symbol_const))
         {
            return parse_define_constvar_statement();
         }
         else if (details::imatch(symbol, symbol_swap))
         {
            return parse_swap_statement();
         }
         #ifndef exprtk_disable_return_statement
         else if (
                   details::imatch(symbol, symbol_return) &&
                   settings_.control_struct_enabled(symbol)
                 )
         {
            return parse_return_statement();
         }
         #endif
         else if (details::imatch(symbol, symbol_assert))
         {
            return parse_assert_statement();
         }
         else if (symtab_store_.valid() || !sem_.empty())
         {
            return parse_symtab_symbol();
         }
         else
         {
            set_error(make_error(
               parser_error::e_symtab,
               current_token(),
               "ERR233 - Unknown variable or function encountered. Symbol table(s) "
               "is either invalid or does not contain symbol: '" + symbol + "'",
               exprtk_error_location));

            return error_node();
         }
      }

      inline expression_node_ptr parse_branch(precedence_level precedence = e_level00)
      {
         stack_limit_handler slh(*this);

         if (!slh)
         {
            return error_node();
         }

         expression_node_ptr branch = error_node();

         if (token_t::e_number == current_token().type)
         {
            T numeric_value = T(0);

            if (details::string_to_real(current_token().value, numeric_value))
            {
               expression_node_ptr literal_exp = expression_generator_(numeric_value);

               if (0 == literal_exp)
               {
                  set_error(make_error(
                     parser_error::e_numeric,
                     current_token(),
                     "ERR234 - Failed generate node for scalar: '" + current_token().value + "'",
                     exprtk_error_location));

                  return error_node();
               }

               next_token();
               branch = literal_exp;
            }
            else
            {
               set_error(make_error(
                  parser_error::e_numeric,
                  current_token(),
                  "ERR235 - Failed to convert '" + current_token().value + "' to a number",
                  exprtk_error_location));

               return error_node();
            }
         }
         else if (token_t::e_symbol == current_token().type)
         {
            branch = parse_symbol();
         }
         #ifndef exprtk_disable_string_capabilities
         else if (token_t::e_string == current_token().type)
         {
            branch = parse_const_string();
         }
         #endif
         else if (token_t::e_lbracket == current_token().type)
         {
            next_token();

            if (0 == (branch = parse_expression()))
               return error_node();
            else if (token_is(token_t::e_eof))
            {}
            else if (!token_is(token_t::e_rbracket))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR236 - Expected ')' instead of: '" + current_token().value + "'",
                  exprtk_error_location));

               details::free_node(node_allocator_, branch);

               return error_node();
            }
            else if (!post_bracket_process(token_t::e_lbracket,branch))
            {
               details::free_node(node_allocator_, branch);

               return error_node();
            }

            parse_pending_vector_index_operator(branch);
         }
         else if (token_t::e_lsqrbracket == current_token().type)
         {
            next_token();

            if (0 == (branch = parse_expression()))
               return error_node();
            else if (!token_is(token_t::e_rsqrbracket))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR237 - Expected ']' instead of: '" + current_token().value + "'",
                  exprtk_error_location));

               details::free_node(node_allocator_, branch);

               return error_node();
            }
            else if (!post_bracket_process(token_t::e_lsqrbracket,branch))
            {
               details::free_node(node_allocator_, branch);

               return error_node();
            }
         }
         else if (token_t::e_lcrlbracket == current_token().type)
         {
            next_token();

            if (0 == (branch = parse_expression()))
               return error_node();
            else if (!token_is(token_t::e_rcrlbracket))
            {
               set_error(make_error(
                  parser_error::e_syntax,
                  current_token(),
                  "ERR238 - Expected '}' instead of: '" + current_token().value + "'",
                  exprtk_error_location));

               details::free_node(node_allocator_, branch);

               return error_node();
            }
            else if (!post_bracket_process(token_t::e_lcrlbracket,branch))
            {
               details::free_node(node_allocator_, branch);

               return error_node();
            }
         }
         else if (token_t::e_sub == current_token().type)
         {
            next_token();
            branch = parse_expression(e_level11);

            if (
                 branch &&
                 !(
                    details::is_neg_unary_node    (branch) &&
                    simplify_unary_negation_branch(branch)
                  )
               )
            {
               expression_node_ptr result = expression_generator_(details::e_neg,branch);

               if (0 == result)
               {
                  details::free_node(node_allocator_, branch);

                  return error_node();
               }
               else
                  branch = result;
            }
         }
         else if (token_t::e_add == current_token().type)
         {
            next_token();
            branch = parse_expression(e_level13);
         }
         else if (token_t::e_eof == current_token().type)
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR239 - Premature end of expression[1]",
               exprtk_error_location));

            return error_node();
         }
         else
         {
            set_error(make_error(
               parser_error::e_syntax,
               current_token(),
               "ERR240 - Premature end of expression[2]",
               exprtk_error_location));

            return error_node();
         }

         if (
              branch                    &&
              (e_level00 == precedence) &&
              token_is(token_t::e_ternary,prsrhlpr_t::e_hold)
            )
         {
            branch = parse_ternary_conditional_statement(branch);
         }

         parse_pending_string_rangesize(branch);

         return branch;
      }

      template <typename Type>
      class expression_generator
      {
      public:

         typedef details::expression_node<Type>* expression_node_ptr;
         typedef expression_node_ptr (*synthesize_functor_t)(expression_generator<T>&, const details::operator_type& operation, expression_node_ptr (&branch)[2]);
         typedef std::map<std::string,synthesize_functor_t> synthesize_map_t;
         typedef typename exprtk::parser<Type> parser_t;
         typedef const Type& vtype;
         typedef const Type  ctype;

         inline void init_synthesize_map()
         {
            #ifndef exprtk_disable_enhanced_features
            synthesize_map_["(v)o(v)"] = synthesize_vov_expression::process;
            synthesize_map_["(c)o(v)"] = synthesize_cov_expression::process;
            synthesize_map_["(v)o(c)"] = synthesize_voc_expression::process;

            #define register_synthezier(S)                      \
            synthesize_map_[S ::node_type::id()] = S ::process; \

            register_synthezier(synthesize_vovov_expression0)
            register_synthezier(synthesize_vovov_expression1)
            register_synthezier(synthesize_vovoc_expression0)
            register_synthezier(synthesize_vovoc_expression1)
            register_synthezier(synthesize_vocov_expression0)
            register_synthezier(synthesize_vocov_expression1)
            register_synthezier(synthesize_covov_expression0)
            register_synthezier(synthesize_covov_expression1)
            register_synthezier(synthesize_covoc_expression0)
            register_synthezier(synthesize_covoc_expression1)
            register_synthezier(synthesize_cocov_expression1)
            register_synthezier(synthesize_vococ_expression0)

            register_synthezier(synthesize_vovovov_expression0)
            register_synthezier(synthesize_vovovoc_expression0)
            register_synthezier(synthesize_vovocov_expression0)
            register_synthezier(synthesize_vocovov_expression0)
            register_synthezier(synthesize_covovov_expression0)
            register_synthezier(synthesize_covocov_expression0)
            register_synthezier(synthesize_vocovoc_expression0)
            register_synthezier(synthesize_covovoc_expression0)
            register_synthezier(synthesize_vococov_expression0)

            register_synthezier(synthesize_vovovov_expression1)
            register_synthezier(synthesize_vovovoc_expression1)
            register_synthezier(synthesize_vovocov_expression1)
            register_synthezier(synthesize_vocovov_expression1)
            register_synthezier(synthesize_covovov_expression1)
            register_synthezier(synthesize_covocov_expression1)
            register_synthezier(synthesize_vocovoc_expression1)
            register_synthezier(synthesize_covovoc_expression1)
            register_synthezier(synthesize_vococov_expression1)

            register_synthezier(synthesize_vovovov_expression2)
            register_synthezier(synthesize_vovovoc_expression2)
            register_synthezier(synthesize_vovocov_expression2)
            register_synthezier(synthesize_vocovov_expression2)
            register_synthezier(synthesize_covovov_expression2)
            register_synthezier(synthesize_covocov_expression2)
            register_synthezier(synthesize_vocovoc_expression2)
            register_synthezier(synthesize_covovoc_expression2)

            register_synthezier(synthesize_vovovov_expression3)
            register_synthezier(synthesize_vovovoc_expression3)
            register_synthezier(synthesize_vovocov_expression3)
            register_synthezier(synthesize_vocovov_expression3)
            register_synthezier(synthesize_covovov_expression3)
            register_synthezier(synthesize_covocov_expression3)
            register_synthezier(synthesize_vocovoc_expression3)
            register_synthezier(synthesize_covovoc_expression3)
            register_synthezier(synthesize_vococov_expression3)

            register_synthezier(synthesize_vovovov_expression4)
            register_synthezier(synthesize_vovovoc_expression4)
            register_synthezier(synthesize_vovocov_expression4)
            register_synthezier(synthesize_vocovov_expression4)
            register_synthezier(synthesize_covovov_expression4)
            register_synthezier(synthesize_covocov_expression4)
            register_synthezier(synthesize_vocovoc_expression4)
            register_synthezier(synthesize_covovoc_expression4)

            #undef register_synthezier
            #endif
         }

         inline void set_parser(parser_t& p)
         {
            parser_ = &p;
         }

         inline void set_uom(unary_op_map_t& unary_op_map)
         {
            unary_op_map_ = &unary_op_map;
         }

         inline void set_bom(binary_op_map_t& binary_op_map)
         {
            binary_op_map_ = &binary_op_map;
         }

         inline void set_ibom(inv_binary_op_map_t& inv_binary_op_map)
         {
            inv_binary_op_map_ = &inv_binary_op_map;
         }

         inline void set_sf3m(sf3_map_t& sf3_map)
         {
            sf3_map_ = &sf3_map;
         }

         inline void set_sf4m(sf4_map_t& sf4_map)
         {
            sf4_map_ = &sf4_map;
         }

         inline void set_allocator(details::node_allocator& na)
         {
            node_allocator_ = &na;
         }

         inline void set_strength_reduction_state(const bool enabled)
         {
            strength_reduction_enabled_ = enabled;
         }

         inline bool strength_reduction_enabled() const
         {
            return strength_reduction_enabled_;
         }

         inline bool valid_operator(const details::operator_type& operation, binary_functor_t& bop)
         {
            typename binary_op_map_t::iterator bop_itr = binary_op_map_->find(operation);

            if (binary_op_map_->end() == bop_itr)
               return false;

            bop = bop_itr->second;

            return true;
         }

         inline bool valid_operator(const details::operator_type& operation, unary_functor_t& uop)
         {
            typename unary_op_map_t::iterator uop_itr = unary_op_map_->find(operation);

            if ((*unary_op_map_).end() == uop_itr)
               return false;

            uop = uop_itr->second;

            return true;
         }

         inline details::operator_type get_operator(const binary_functor_t& bop) const
         {
            return (*inv_binary_op_map_).find(bop)->second;
         }

         inline expression_node_ptr operator() (const Type& v) const
         {
            return node_allocator_->allocate<literal_node_t>(v);
         }

         #ifndef exprtk_disable_string_capabilities
         inline expression_node_ptr operator() (const std::string& s) const
         {
            return node_allocator_->allocate<string_literal_node_t>(s);
         }

         inline expression_node_ptr operator() (std::string& s, range_t& rp) const
         {
            return node_allocator_->allocate_rr<string_range_node_t>(s,rp);
         }

         inline expression_node_ptr operator() (const std::string& s, range_t& rp) const
         {
            return node_allocator_->allocate_tt<const_string_range_node_t>(s,rp);
         }

         inline expression_node_ptr operator() (expression_node_ptr branch, range_t& rp) const
         {
            if (is_generally_string_node(branch))
               return node_allocator_->allocate_tt<generic_string_range_node_t>(branch,rp);
            else
               return error_node();
         }
         #endif

         inline bool unary_optimisable(const details::operator_type& operation) const
         {
            return (details::e_abs   == operation) || (details::e_acos  == operation) ||
                   (details::e_acosh == operation) || (details::e_asin  == operation) ||
                   (details::e_asinh == operation) || (details::e_atan  == operation) ||
                   (details::e_atanh == operation) || (details::e_ceil  == operation) ||
                   (details::e_cos   == operation) || (details::e_cosh  == operation) ||
                   (details::e_exp   == operation) || (details::e_expm1 == operation) ||
                   (details::e_floor == operation) || (details::e_log   == operation) ||
                   (details::e_log10 == operation) || (details::e_log2  == operation) ||
                   (details::e_log1p == operation) || (details::e_neg   == operation) ||
                   (details::e_pos   == operation) || (details::e_round == operation) ||
                   (details::e_sin   == operation) || (details::e_sinc  == operation) ||
                   (details::e_sinh  == operation) || (details::e_sqrt  == operation) ||
                   (details::e_tan   == operation) || (details::e_tanh  == operation) ||
                   (details::e_cot   == operation) || (details::e_sec   == operation) ||
                   (details::e_csc   == operation) || (details::e_r2d   == operation) ||
                   (details::e_d2r   == operation) || (details::e_d2g   == operation) ||
                   (details::e_g2d   == operation) || (details::e_notl  == operation) ||
                   (details::e_sgn   == operation) || (details::e_erf   == operation) ||
                   (details::e_erfc  == operation) || (details::e_ncdf  == operation) ||
                   (details::e_frac  == operation) || (details::e_trunc == operation) ;
         }

         inline bool sf3_optimisable(const std::string& sf3id, trinary_functor_t& tfunc) const
         {
            typename sf3_map_t::const_iterator itr = sf3_map_->find(sf3id);

            if (sf3_map_->end() == itr)
               return false;
            else
               tfunc = itr->second.first;

            return true;
         }

         inline bool sf4_optimisable(const std::string& sf4id, quaternary_functor_t& qfunc) const
         {
            typename sf4_map_t::const_iterator itr = sf4_map_->find(sf4id);

            if (sf4_map_->end() == itr)
               return false;
            else
               qfunc = itr->second.first;

            return true;
         }

         inline bool sf3_optimisable(const std::string& sf3id, details::operator_type& operation) const
         {
            typename sf3_map_t::const_iterator itr = sf3_map_->find(sf3id);

            if (sf3_map_->end() == itr)
               return false;
            else
               operation = itr->second.second;

            return true;
         }

         inline bool sf4_optimisable(const std::string& sf4id, details::operator_type& operation) const
         {
            typename sf4_map_t::const_iterator itr = sf4_map_->find(sf4id);

            if (sf4_map_->end() == itr)
               return false;
            else
               operation = itr->second.second;

            return true;
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr (&branch)[1])
         {
            if (0 == branch[0])
            {
               return error_node();
            }
            else if (details::is_null_node(branch[0]))
            {
               return branch[0];
            }
            else if (details::is_break_node(branch[0]))
            {
               return error_node();
            }
            else if (details::is_continue_node(branch[0]))
            {
               return error_node();
            }
            else if (details::is_constant_node(branch[0]))
            {
               return synthesize_expression<unary_node_t,1>(operation,branch);
            }
            else if (unary_optimisable(operation) && details::is_variable_node(branch[0]))
            {
               return synthesize_uv_expression(operation,branch);
            }
            else if (unary_optimisable(operation) && details::is_ivector_node(branch[0]))
            {
               return synthesize_uvec_expression(operation,branch);
            }
            else
               return synthesize_unary_expression(operation,branch);
         }

         inline bool is_assignment_operation(const details::operator_type& operation) const
         {
            return (
                     (details::e_addass == operation) ||
                     (details::e_subass == operation) ||
                     (details::e_mulass == operation) ||
                     (details::e_divass == operation) ||
                     (details::e_modass == operation)
                   ) &&
                   parser_->settings_.assignment_enabled(operation);
         }

         #ifndef exprtk_disable_string_capabilities
         inline bool valid_string_operation(const details::operator_type& operation) const
         {
            return (details::e_add    == operation) ||
                   (details::e_lt     == operation) ||
                   (details::e_lte    == operation) ||
                   (details::e_gt     == operation) ||
                   (details::e_gte    == operation) ||
                   (details::e_eq     == operation) ||
                   (details::e_ne     == operation) ||
                   (details::e_in     == operation) ||
                   (details::e_like   == operation) ||
                   (details::e_ilike  == operation) ||
                   (details::e_assign == operation) ||
                   (details::e_addass == operation) ||
                   (details::e_swap   == operation) ;
         }
         #else
         inline bool valid_string_operation(const details::operator_type&) const
         {
            return false;
         }
         #endif

         inline std::string to_str(const details::operator_type& operation) const
         {
            switch (operation)
            {
               case details::e_add  : return "+"      ;
               case details::e_sub  : return "-"      ;
               case details::e_mul  : return "*"      ;
               case details::e_div  : return "/"      ;
               case details::e_mod  : return "%"      ;
               case details::e_pow  : return "^"      ;
               case details::e_lt   : return "<"      ;
               case details::e_lte  : return "<="     ;
               case details::e_gt   : return ">"      ;
               case details::e_gte  : return ">="     ;
               case details::e_eq   : return "=="     ;
               case details::e_ne   : return "!="     ;
               case details::e_and  : return "and"    ;
               case details::e_nand : return "nand"   ;
               case details::e_or   : return "or"     ;
               case details::e_nor  : return "nor"    ;
               case details::e_xor  : return "xor"    ;
               case details::e_xnor : return "xnor"   ;
               default              : return "UNKNOWN";
            }
         }

         inline bool operation_optimisable(const details::operator_type& operation) const
         {
            return (details::e_add  == operation) ||
                   (details::e_sub  == operation) ||
                   (details::e_mul  == operation) ||
                   (details::e_div  == operation) ||
                   (details::e_mod  == operation) ||
                   (details::e_pow  == operation) ||
                   (details::e_lt   == operation) ||
                   (details::e_lte  == operation) ||
                   (details::e_gt   == operation) ||
                   (details::e_gte  == operation) ||
                   (details::e_eq   == operation) ||
                   (details::e_ne   == operation) ||
                   (details::e_and  == operation) ||
                   (details::e_nand == operation) ||
                   (details::e_or   == operation) ||
                   (details::e_nor  == operation) ||
                   (details::e_xor  == operation) ||
                   (details::e_xnor == operation) ;
         }

         inline std::string branch_to_id(expression_node_ptr branch) const
         {
            static const std::string null_str   ("(null)" );
            static const std::string const_str  ("(c)"    );
            static const std::string var_str    ("(v)"    );
            static const std::string vov_str    ("(vov)"  );
            static const std::string cov_str    ("(cov)"  );
            static const std::string voc_str    ("(voc)"  );
            static const std::string str_str    ("(s)"    );
            static const std::string strrng_str ("(rngs)" );
            static const std::string cs_str     ("(cs)"   );
            static const std::string cstrrng_str("(crngs)");

            if (details::is_null_node(branch))
               return null_str;
            else if (details::is_constant_node(branch))
               return const_str;
            else if (details::is_variable_node(branch))
               return var_str;
            else if (details::is_vov_node(branch))
               return vov_str;
            else if (details::is_cov_node(branch))
               return cov_str;
            else if (details::is_voc_node(branch))
               return voc_str;
            else if (details::is_string_node(branch))
               return str_str;
            else if (details::is_const_string_node(branch))
               return cs_str;
            else if (details::is_string_range_node(branch))
               return strrng_str;
            else if (details::is_const_string_range_node(branch))
               return cstrrng_str;
            else if (details::is_t0ot1ot2_node(branch))
               return "(" + dynamic_cast<details::T0oT1oT2_base_node<T>*>(branch)->type_id() + ")";
            else if (details::is_t0ot1ot2ot3_node(branch))
               return "(" + dynamic_cast<details::T0oT1oT2oT3_base_node<T>*>(branch)->type_id() + ")";
            else
               return "ERROR";
         }

         inline std::string branch_to_id(expression_node_ptr (&branch)[2]) const
         {
            return branch_to_id(branch[0]) + std::string("o") + branch_to_id(branch[1]);
         }

         inline bool cov_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_constant_node(branch[0]) &&
                      details::is_variable_node(branch[1]) ;
         }

         inline bool voc_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_variable_node(branch[0]) &&
                      details::is_constant_node(branch[1]) ;
         }

         inline bool vov_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_variable_node(branch[0]) &&
                      details::is_variable_node(branch[1]) ;
         }

         inline bool cob_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_constant_node(branch[0]) &&
                     !details::is_constant_node(branch[1]) ;
         }

         inline bool boc_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return !details::is_constant_node(branch[0]) &&
                       details::is_constant_node(branch[1]) ;
         }

         inline bool cocob_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (
                 (details::e_add == operation) ||
                 (details::e_sub == operation) ||
                 (details::e_mul == operation) ||
                 (details::e_div == operation)
               )
            {
               return (details::is_constant_node(branch[0]) && details::is_cob_node(branch[1])) ||
                      (details::is_constant_node(branch[1]) && details::is_cob_node(branch[0])) ;
            }
            else
               return false;
         }

         inline bool coboc_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (
                 (details::e_add == operation) ||
                 (details::e_sub == operation) ||
                 (details::e_mul == operation) ||
                 (details::e_div == operation)
               )
            {
               return (details::is_constant_node(branch[0]) && details::is_boc_node(branch[1])) ||
                      (details::is_constant_node(branch[1]) && details::is_boc_node(branch[0])) ;
            }
            else
               return false;
         }

         inline bool uvouv_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_uv_node(branch[0]) &&
                      details::is_uv_node(branch[1]) ;
         }

         inline bool vob_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return details::is_variable_node(branch[0]) &&
                     !details::is_variable_node(branch[1]) ;
         }

         inline bool bov_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return !details::is_variable_node(branch[0]) &&
                       details::is_variable_node(branch[1]) ;
         }

         inline bool binext_optimisable(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!operation_optimisable(operation))
               return false;
            else
               return !details::is_constant_node(branch[0]) ||
                      !details::is_constant_node(branch[1]) ;
         }

         inline bool is_invalid_assignment_op(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (is_assignment_operation(operation))
            {
               const bool b1_is_genstring = details::is_generally_string_node(branch[1]);

               if (details::is_string_node(branch[0]))
                  return !b1_is_genstring;
               else if (details::is_literal_node(branch[0]))
                  return true;
               else
                  return (
                           !details::is_variable_node              (branch[0]) &&
                           !details::is_vector_elem_node           (branch[0]) &&
                           !details::is_vector_celem_node          (branch[0]) &&
                           !details::is_vector_elem_rtc_node       (branch[0]) &&
                           !details::is_vector_celem_rtc_node      (branch[0]) &&
                           !details::is_rebasevector_elem_node     (branch[0]) &&
                           !details::is_rebasevector_celem_node    (branch[0]) &&
                           !details::is_rebasevector_elem_rtc_node (branch[0]) &&
                           !details::is_rebasevector_celem_rtc_node(branch[0]) &&
                           !details::is_vector_node                (branch[0])
                         )
                         || b1_is_genstring;
            }
            else
               return false;
         }

         inline bool is_constpow_operation(const details::operator_type& operation, expression_node_ptr(&branch)[2]) const
         {
            if (
                 !details::is_constant_node(branch[1]) ||
                  details::is_constant_node(branch[0]) ||
                  details::is_variable_node(branch[0]) ||
                  details::is_vector_node  (branch[0]) ||
                  details::is_generally_string_node(branch[0])
               )
               return false;

            const Type c = static_cast<details::literal_node<Type>*>(branch[1])->value();

            return cardinal_pow_optimisable(operation, c);
         }

         inline bool is_invalid_break_continue_op(expression_node_ptr (&branch)[2]) const
         {
            return (
                     details::is_break_node   (branch[0]) ||
                     details::is_break_node   (branch[1]) ||
                     details::is_continue_node(branch[0]) ||
                     details::is_continue_node(branch[1])
                   );
         }

         inline bool is_invalid_string_op(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            const bool b0_string = is_generally_string_node(branch[0]);
            const bool b1_string = is_generally_string_node(branch[1]);

            bool result = false;

            if (b0_string != b1_string)
               result = true;
            else if (!valid_string_operation(operation) && b0_string && b1_string)
               result = true;

            if (result)
            {
               parser_->set_synthesis_error("Invalid string operation");
            }

            return result;
         }

         inline bool is_invalid_string_op(const details::operator_type& operation, expression_node_ptr (&branch)[3]) const
         {
            const bool b0_string = is_generally_string_node(branch[0]);
            const bool b1_string = is_generally_string_node(branch[1]);
            const bool b2_string = is_generally_string_node(branch[2]);

            bool result = false;

            if ((b0_string != b1_string) || (b1_string != b2_string))
               result = true;
            else if ((details::e_inrange != operation) && b0_string && b1_string && b2_string)
               result = true;

            if (result)
            {
               parser_->set_synthesis_error("Invalid string operation");
            }

            return result;
         }

         inline bool is_string_operation(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            const bool b0_string = is_generally_string_node(branch[0]);
            const bool b1_string = is_generally_string_node(branch[1]);

            return (b0_string && b1_string && valid_string_operation(operation));
         }

         inline bool is_string_operation(const details::operator_type& operation, expression_node_ptr (&branch)[3]) const
         {
            const bool b0_string = is_generally_string_node(branch[0]);
            const bool b1_string = is_generally_string_node(branch[1]);
            const bool b2_string = is_generally_string_node(branch[2]);

            return (b0_string && b1_string && b2_string && (details::e_inrange == operation));
         }

         #ifndef exprtk_disable_sc_andor
         inline bool is_shortcircuit_expression(const details::operator_type& operation) const
         {
            return (
                     (details::e_scand == operation) ||
                     (details::e_scor  == operation)
                   );
         }
         #else
         inline bool is_shortcircuit_expression(const details::operator_type&) const
         {
            return false;
         }
         #endif

         inline bool is_null_present(expression_node_ptr (&branch)[2]) const
         {
            return (
                     details::is_null_node(branch[0]) ||
                     details::is_null_node(branch[1])
                   );
         }

         inline bool is_vector_eqineq_logic_operation(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!is_ivector_node(branch[0]) && !is_ivector_node(branch[1]))
               return false;
            else
               return (
                        (details::e_lt    == operation) ||
                        (details::e_lte   == operation) ||
                        (details::e_gt    == operation) ||
                        (details::e_gte   == operation) ||
                        (details::e_eq    == operation) ||
                        (details::e_ne    == operation) ||
                        (details::e_equal == operation) ||
                        (details::e_and   == operation) ||
                        (details::e_nand  == operation) ||
                        (details::e_or    == operation) ||
                        (details::e_nor   == operation) ||
                        (details::e_xor   == operation) ||
                        (details::e_xnor  == operation)
                      );
         }

         inline bool is_vector_arithmetic_operation(const details::operator_type& operation, expression_node_ptr (&branch)[2]) const
         {
            if (!is_ivector_node(branch[0]) && !is_ivector_node(branch[1]))
               return false;
            else
               return (
                        (details::e_add == operation) ||
                        (details::e_sub == operation) ||
                        (details::e_mul == operation) ||
                        (details::e_div == operation) ||
                        (details::e_pow == operation)
                      );
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr (&branch)[2])
         {
            if ((0 == branch[0]) || (0 == branch[1]))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR241 - Invalid branches received for operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_string_op(operation,branch))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR242 - Invalid branch pair for string operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_assignment_op(operation,branch))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR243 - Invalid branch pair for assignment operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_break_continue_op(branch))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR244 - Invalid branch pair for break/continue operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (details::e_assign == operation)
            {
               return synthesize_assignment_expression(operation, branch);
            }
            else if (details::e_swap == operation)
            {
               return synthesize_swap_expression(branch);
            }
            else if (is_assignment_operation(operation))
            {
               return synthesize_assignment_operation_expression(operation, branch);
            }
            else if (is_vector_eqineq_logic_operation(operation, branch))
            {
               return synthesize_veceqineqlogic_operation_expression(operation, branch);
            }
            else if (is_vector_arithmetic_operation(operation, branch))
            {
               return synthesize_vecarithmetic_operation_expression(operation, branch);
            }
            else if (is_shortcircuit_expression(operation))
            {
               return synthesize_shortcircuit_expression(operation, branch);
            }
            else if (is_string_operation(operation, branch))
            {
               return synthesize_string_expression(operation, branch);
            }
            else if (is_null_present(branch))
            {
               return synthesize_null_expression(operation, branch);
            }
            #ifndef exprtk_disable_cardinal_pow_optimisation
            else if (is_constpow_operation(operation, branch))
            {
               return cardinal_pow_optimisation(branch);
            }
            #endif

            expression_node_ptr result = error_node();

            #ifndef exprtk_disable_enhanced_features
            if (synthesize_expression(operation, branch, result))
            {
               return result;
            }
            else
            #endif

            {
               /*
                  Possible reductions:
                  1. c o cob -> cob
                  2. cob o c -> cob
                  3. c o boc -> boc
                  4. boc o c -> boc
               */
               result = error_node();

               if (cocob_optimisable(operation, branch))
               {
                  result = synthesize_cocob_expression::process((*this), operation, branch);
               }
               else if (coboc_optimisable(operation, branch) && (0 == result))
               {
                  result = synthesize_coboc_expression::process((*this), operation, branch);
               }

               if (result)
                  return result;
            }

            if (uvouv_optimisable(operation, branch))
            {
               return synthesize_uvouv_expression(operation, branch);
            }
            else if (vob_optimisable(operation, branch))
            {
               return synthesize_vob_expression::process((*this), operation, branch);
            }
            else if (bov_optimisable(operation, branch))
            {
               return synthesize_bov_expression::process((*this), operation, branch);
            }
            else if (cob_optimisable(operation, branch))
            {
               return synthesize_cob_expression::process((*this), operation, branch);
            }
            else if (boc_optimisable(operation, branch))
            {
               return synthesize_boc_expression::process((*this), operation, branch);
            }
            #ifndef exprtk_disable_enhanced_features
            else if (cov_optimisable(operation, branch))
            {
               return synthesize_cov_expression::process((*this), operation, branch);
            }
            #endif
            else if (binext_optimisable(operation, branch))
            {
               return synthesize_binary_ext_expression::process((*this), operation, branch);
            }
            else
               return synthesize_expression<binary_node_t,2>(operation, branch);
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr (&branch)[3])
         {
            if (
                 (0 == branch[0]) ||
                 (0 == branch[1]) ||
                 (0 == branch[2])
               )
            {
               details::free_all_nodes(*node_allocator_,branch);

               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR245 - Invalid branches operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_invalid_string_op(operation, branch))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR246 - Invalid branches for string operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
            else if (is_string_operation(operation, branch))
            {
               return synthesize_string_expression(operation, branch);
            }
            else
               return synthesize_expression<trinary_node_t,3>(operation, branch);
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr (&branch)[4])
         {
            return synthesize_expression<quaternary_node_t,4>(operation,branch);
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr b0)
         {
            expression_node_ptr branch[1] = { b0 };
            return (*this)(operation,branch);
         }

         inline expression_node_ptr operator() (const details::operator_type& operation, expression_node_ptr& b0, expression_node_ptr& b1)
         {
            expression_node_ptr result = error_node();

            if ((0 != b0) && (0 != b1))
            {
               expression_node_ptr branch[2] = { b0, b1 };
               result = expression_generator<Type>::operator()(operation, branch);
               b0 = branch[0];
               b1 = branch[1];
            }

            return result;
         }

         inline expression_node_ptr conditional(expression_node_ptr condition,
                                                expression_node_ptr consequent,
                                                expression_node_ptr alternative) const
         {
            if ((0 == condition) || (0 == consequent))
            {
               details::free_node(*node_allocator_, condition  );
               details::free_node(*node_allocator_, consequent );
               details::free_node(*node_allocator_, alternative);

               const std::string invalid_branches =
                                 ((0 == condition ) ? std::string("condition ") : "") +
                                 ((0 == consequent) ? std::string("consequent") : "") ;

               parser_->set_error(parser_error::make_error(
                  parser_error::e_parser,
                  parser_->current_state().token,
                  "ERR247 - Invalid " + invalid_branches + " for conditional statement",
                  exprtk_error_location));

               return error_node();
            }
            // Can the condition be immediately evaluated? if so optimise.
            else if (details::is_constant_node(condition))
            {
               // True branch
               if (details::is_true(condition))
               {
                  details::free_node(*node_allocator_, condition  );
                  details::free_node(*node_allocator_, alternative);

                  return consequent;
               }
               // False branch
               else
               {
                  details::free_node(*node_allocator_, condition );
                  details::free_node(*node_allocator_, consequent);

                  if (alternative)
                     return alternative;
                  else
                     return node_allocator_->allocate<details::null_node<T> >();
               }
            }

            expression_node_ptr result = error_node();
            std::string node_name      = "Unknown!";

            if ((0 != consequent) && (0 != alternative))
            {
               result = node_allocator_->allocate<conditional_node_t>(condition, consequent, alternative);
               node_name = "conditional_node_t";
            }
            else
            {
               result = node_allocator_->allocate<cons_conditional_node_t>(condition, consequent);
               node_name = "cons_conditional_node_t";
            }

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_parser,
               token_t(),
               "ERR248 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();
         }

         #ifndef exprtk_disable_string_capabilities
         inline expression_node_ptr conditional_string(expression_node_ptr condition,
                                                       expression_node_ptr consequent,
                                                       expression_node_ptr alternative) const
         {
            if ((0 == condition) || (0 == consequent))
            {
               details::free_node(*node_allocator_, condition  );
               details::free_node(*node_allocator_, consequent );
               details::free_node(*node_allocator_, alternative);

               const std::string invalid_branches =
                                 ((0 == condition ) ? std::string("condition ") : "") +
                                 ((0 == consequent) ? std::string("consequent") : "") ;

               parser_->set_error(parser_error::make_error(
                  parser_error::e_parser,
                  parser_->current_state().token,
                  "ERR249 - Invalid " + invalid_branches + " for string conditional statement",
                  exprtk_error_location));

               return error_node();
            }
            // Can the condition be immediately evaluated? if so optimise.
            else if (details::is_constant_node(condition))
            {
               // True branch
               if (details::is_true(condition))
               {
                  details::free_node(*node_allocator_, condition  );
                  details::free_node(*node_allocator_, alternative);

                  return consequent;
               }
               // False branch
               else
               {
                  details::free_node(*node_allocator_, condition );
                  details::free_node(*node_allocator_, consequent);

                  if (alternative)
                     return alternative;
                  else
                     return node_allocator_->
                              allocate_c<details::string_literal_node<Type> >("");
               }
            }
            else if ((0 != consequent) && (0 != alternative))
            {
               expression_node_ptr result =
                  node_allocator_->allocate<conditional_string_node_t>(condition, consequent, alternative);

               if (result && result->valid())
               {
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_parser,
                  token_t(),
                  "ERR250 - Failed to synthesize node: conditional_string_node_t",
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
            }

            return error_node();
         }
         #else
         inline expression_node_ptr conditional_string(expression_node_ptr,
                                                       expression_node_ptr,
                                                       expression_node_ptr) const
         {
            return error_node();
         }
         #endif

         inline expression_node_ptr conditional_vector(expression_node_ptr condition,
                                                       expression_node_ptr consequent,
                                                       expression_node_ptr alternative) const
         {
            if ((0 == condition) || (0 == consequent))
            {
               details::free_node(*node_allocator_, condition  );
               details::free_node(*node_allocator_, consequent );
               details::free_node(*node_allocator_, alternative);

               const std::string invalid_branches =
                                 ((0 == condition ) ? std::string("condition ") : "") +
                                 ((0 == consequent) ? std::string("consequent") : "") ;

               parser_->set_error(parser_error::make_error(
                  parser_error::e_parser,
                  parser_->current_state().token,
                  "ERR251 - Invalid " + invalid_branches + " for vector conditional statement",
                  exprtk_error_location));

               return error_node();
            }
            // Can the condition be immediately evaluated? if so optimise.
            else if (details::is_constant_node(condition))
            {
               // True branch
               if (details::is_true(condition))
               {
                  details::free_node(*node_allocator_, condition  );
                  details::free_node(*node_allocator_, alternative);

                  return consequent;
               }
               // False branch
               else
               {
                  details::free_node(*node_allocator_, condition );
                  details::free_node(*node_allocator_, consequent);

                  if (alternative)
                     return alternative;
                  else
                     return node_allocator_->allocate<details::null_node<T> >();

               }
            }
            else if ((0 != consequent) && (0 != alternative))
            {
               return node_allocator_->
                        allocate<conditional_vector_node_t>(condition, consequent, alternative);
            }
            else
               return error_node();
         }

         inline loop_runtime_check_ptr get_loop_runtime_check(const loop_runtime_check::loop_types loop_type) const
         {
            if (
                 parser_->loop_runtime_check_ &&
                 (loop_type == (parser_->loop_runtime_check_->loop_set & loop_type))
               )
            {
               return parser_->loop_runtime_check_;
            }

            return loop_runtime_check_ptr(0);
         }

         inline vector_access_runtime_check_ptr get_vector_access_runtime_check() const
         {
            return parser_->vector_access_runtime_check_;
         }

         inline expression_node_ptr while_loop(expression_node_ptr& condition,
                                               expression_node_ptr& branch,
                                               const bool break_continue_present = false) const
         {
            if (
                 !break_continue_present              &&
                 !parser_->state_.return_stmt_present &&
                 details::is_constant_node(condition)
               )
            {
               expression_node_ptr result = error_node();
               if (details::is_true(condition))
               {
                  // Infinite loops are not allowed.

                  parser_->set_error(parser_error::make_error(
                     parser_error::e_parser,
                     parser_->current_state().token,
                     "ERR252 - Infinite loop condition without 'break' or 'return' not allowed in while-loops",
                     exprtk_error_location));

                  result = error_node();
               }
               else
                  result = node_allocator_->allocate<details::null_node<Type> >();

               details::free_node(*node_allocator_, condition);
               details::free_node(*node_allocator_, branch   );

               return result;
            }
            else if (details::is_null_node(condition))
            {
               details::free_node(*node_allocator_,condition);

               return branch;
            }

            loop_runtime_check_ptr rtc = get_loop_runtime_check(loop_runtime_check::e_while_loop);

            if (!break_continue_present)
            {
               if (rtc)
                  return node_allocator_->allocate<while_loop_rtc_node_t>
                           (condition, branch,  rtc);
               else
                  return node_allocator_->allocate<while_loop_node_t>
                           (condition, branch);
            }
            #ifndef exprtk_disable_break_continue
            else
            {
               if (rtc)
                  return node_allocator_->allocate<while_loop_bc_rtc_node_t>
                           (condition, branch, rtc);
               else
                  return node_allocator_->allocate<while_loop_bc_node_t>
                           (condition, branch);
            }
            #else
               return error_node();
            #endif
         }

         inline expression_node_ptr repeat_until_loop(expression_node_ptr& condition,
                                                      expression_node_ptr& branch,
                                                      const bool break_continue_present = false) const
         {
            if (!break_continue_present && details::is_constant_node(condition))
            {
               if (
                    details::is_true(condition) &&
                    details::is_constant_node(branch)
                  )
               {
                  free_node(*node_allocator_,condition);

                  return branch;
               }

               details::free_node(*node_allocator_, condition);
               details::free_node(*node_allocator_, branch   );

               return error_node();
            }
            else if (details::is_null_node(condition))
            {
               details::free_node(*node_allocator_,condition);

               return branch;
            }

            loop_runtime_check_ptr rtc = get_loop_runtime_check(loop_runtime_check::e_repeat_until_loop);

            if (!break_continue_present)
            {
               if (rtc)
                  return node_allocator_->allocate<repeat_until_loop_rtc_node_t>
                           (condition, branch,  rtc);
               else
                  return node_allocator_->allocate<repeat_until_loop_node_t>
                           (condition, branch);
            }
            #ifndef exprtk_disable_break_continue
            else
            {
               if (rtc)
                  return node_allocator_->allocate<repeat_until_loop_bc_rtc_node_t>
                           (condition, branch, rtc);
               else
                  return node_allocator_->allocate<repeat_until_loop_bc_node_t>
                           (condition, branch);
            }
            #else
               return error_node();
            #endif
         }

         inline expression_node_ptr for_loop(expression_node_ptr& initialiser,
                                             expression_node_ptr& condition,
                                             expression_node_ptr& incrementor,
                                             expression_node_ptr& loop_body,
                                             bool break_continue_present = false) const
         {
            if (
                 !break_continue_present              &&
                 !parser_->state_.return_stmt_present &&
                 details::is_constant_node(condition)
               )
            {
               expression_node_ptr result = error_node();

               if (details::is_true(condition))
               {
                  // Infinite loops are not allowed.

                  parser_->set_error(parser_error::make_error(
                     parser_error::e_parser,
                     parser_->current_state().token,
                     "ERR253 - Infinite loop condition without 'break' or 'return' not allowed in for-loop",
                     exprtk_error_location));

                  result = error_node();
               }
               else
                  result = node_allocator_->allocate<details::null_node<Type> >();

               details::free_node(*node_allocator_, initialiser);
               details::free_node(*node_allocator_, condition  );
               details::free_node(*node_allocator_, incrementor);
               details::free_node(*node_allocator_, loop_body  );

               return result;
            }
            else if (details::is_null_node(condition) || (0 == condition))
            {
               details::free_node(*node_allocator_, initialiser);
               details::free_node(*node_allocator_, condition  );
               details::free_node(*node_allocator_, incrementor);

               return loop_body;
            }

            loop_runtime_check_ptr rtc = get_loop_runtime_check(loop_runtime_check::e_for_loop);

            if (!break_continue_present)
            {
               if (rtc)
                  return node_allocator_->allocate<for_loop_rtc_node_t>
                                          (
                                             initialiser,
                                             condition,
                                             incrementor,
                                             loop_body,
                                             rtc
                                          );
               else
                  return node_allocator_->allocate<for_loop_node_t>
                                          (
                                             initialiser,
                                             condition,
                                             incrementor,
                                             loop_body
                                          );
            }
            #ifndef exprtk_disable_break_continue
            else
            {
               if (rtc)
                  return node_allocator_->allocate<for_loop_bc_rtc_node_t>
                                          (
                                             initialiser,
                                             condition,
                                             incrementor,
                                             loop_body,
                                             rtc
                                          );
               else
                  return node_allocator_->allocate<for_loop_bc_node_t>
                                          (
                                             initialiser,
                                             condition,
                                             incrementor,
                                             loop_body
                                          );
            }
            #else
               return error_node();
            #endif
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr const_optimise_switch(Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            expression_node_ptr result = error_node();

            for (std::size_t i = 0; i < (arg_list.size() / 2); ++i)
            {
               expression_node_ptr condition  = arg_list[(2 * i)    ];
               expression_node_ptr consequent = arg_list[(2 * i) + 1];

               if ((0 == result) && details::is_true(condition))
               {
                  result = consequent;
                  break;
               }
            }

            if (0 == result)
            {
               result = arg_list.back();
            }

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               expression_node_ptr current_expr = arg_list[i];

               if (current_expr && (current_expr != result))
               {
                  free_node(*node_allocator_,current_expr);
               }
            }

            return result;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr const_optimise_mswitch(Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            expression_node_ptr result = error_node();

            for (std::size_t i = 0; i < (arg_list.size() / 2); ++i)
            {
               expression_node_ptr condition  = arg_list[(2 * i)    ];
               expression_node_ptr consequent = arg_list[(2 * i) + 1];

               if (details::is_true(condition))
               {
                  result = consequent;
               }
            }

            if (0 == result)
            {
               const T zero = T(0);
               result       = node_allocator_->allocate<literal_node_t>(zero);
            }

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               expression_node_ptr& current_expr = arg_list[i];

               if (current_expr && (current_expr != result))
               {
                  details::free_node(*node_allocator_,current_expr);
               }
            }

            return result;
         }

         struct switch_nodes
         {
            typedef std::vector<std::pair<expression_node_ptr,bool> > arg_list_t;

            #define case_stmt(N)                                                         \
            if (is_true(arg[(2 * N)].first)) { return arg[(2 * N) + 1].first->value(); } \

            struct switch_impl_1
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0)

                  assert(arg.size() == ((2 * 1) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_2
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)

                  assert(arg.size() == ((2 * 2) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_3
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)
                  case_stmt(2)

                  assert(arg.size() == ((2 * 3) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_4
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)
                  case_stmt(2) case_stmt(3)

                  assert(arg.size() == ((2 * 4) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_5
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)
                  case_stmt(2) case_stmt(3)
                  case_stmt(4)

                  assert(arg.size() == ((2 * 5) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_6
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)
                  case_stmt(2) case_stmt(3)
                  case_stmt(4) case_stmt(5)

                  assert(arg.size() == ((2 * 6) + 1));

                  return arg.back().first->value();
               }
            };

            struct switch_impl_7
            {
               static inline T process(const arg_list_t& arg)
               {
                  case_stmt(0) case_stmt(1)
                  case_stmt(2) case_stmt(3)
                  case_stmt(4) case_stmt(5)
                  case_stmt(6)

                  assert(arg.size() == ((2 * 7) + 1));

                  return arg.back().first->value();
               }
            };

            #undef case_stmt
         };

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr switch_statement(Sequence<expression_node_ptr,Allocator>& arg_list, const bool default_statement_present)
         {
            if (arg_list.empty())
               return error_node();
            else if (
                      !all_nodes_valid(arg_list) ||
                      (!default_statement_present && (arg_list.size() < 2))
                    )
            {
               details::free_all_nodes(*node_allocator_,arg_list);

               return error_node();
            }
            else if (is_constant_foldable(arg_list))
               return const_optimise_switch(arg_list);

            switch ((arg_list.size() - 1) / 2)
            {
               #define case_stmt(N)                                                       \
               case N :                                                                   \
                  return node_allocator_->                                                \
                            allocate<details::switch_n_node                               \
                              <Type,typename switch_nodes::switch_impl_##N > >(arg_list); \

               case_stmt(1)
               case_stmt(2)
               case_stmt(3)
               case_stmt(4)
               case_stmt(5)
               case_stmt(6)
               case_stmt(7)
               #undef case_stmt

               default : return node_allocator_->allocate<details::switch_node<Type> >(arg_list);
            }
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr multi_switch_statement(Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);

               return error_node();
            }
            else if (is_constant_foldable(arg_list))
               return const_optimise_mswitch(arg_list);
            else
               return node_allocator_->allocate<details::multi_switch_node<Type> >(arg_list);
         }

         inline expression_node_ptr assert_call(expression_node_ptr& assert_condition,
                                                expression_node_ptr& assert_message,
                                                const assert_check::assert_context& context)
         {
            typedef details::assert_node<Type> alloc_type;

            expression_node_ptr result = node_allocator_->allocate_rrrr<alloc_type>
               (assert_condition, assert_message, parser_->assert_check_, context);

            if (result && result->valid())
            {
               parser_->state_.activate_side_effect("assert_call()");
               return result;
            }

            details::free_node(*node_allocator_, result          );
            details::free_node(*node_allocator_, assert_condition);
            details::free_node(*node_allocator_, assert_message  );

            return error_node();
         }

         #define unary_opr_switch_statements             \
         case_stmt(details::e_abs   , details::abs_op  ) \
         case_stmt(details::e_acos  , details::acos_op ) \
         case_stmt(details::e_acosh , details::acosh_op) \
         case_stmt(details::e_asin  , details::asin_op ) \
         case_stmt(details::e_asinh , details::asinh_op) \
         case_stmt(details::e_atan  , details::atan_op ) \
         case_stmt(details::e_atanh , details::atanh_op) \
         case_stmt(details::e_ceil  , details::ceil_op ) \
         case_stmt(details::e_cos   , details::cos_op  ) \
         case_stmt(details::e_cosh  , details::cosh_op ) \
         case_stmt(details::e_exp   , details::exp_op  ) \
         case_stmt(details::e_expm1 , details::expm1_op) \
         case_stmt(details::e_floor , details::floor_op) \
         case_stmt(details::e_log   , details::log_op  ) \
         case_stmt(details::e_log10 , details::log10_op) \
         case_stmt(details::e_log2  , details::log2_op ) \
         case_stmt(details::e_log1p , details::log1p_op) \
         case_stmt(details::e_neg   , details::neg_op  ) \
         case_stmt(details::e_pos   , details::pos_op  ) \
         case_stmt(details::e_round , details::round_op) \
         case_stmt(details::e_sin   , details::sin_op  ) \
         case_stmt(details::e_sinc  , details::sinc_op ) \
         case_stmt(details::e_sinh  , details::sinh_op ) \
         case_stmt(details::e_sqrt  , details::sqrt_op ) \
         case_stmt(details::e_tan   , details::tan_op  ) \
         case_stmt(details::e_tanh  , details::tanh_op ) \
         case_stmt(details::e_cot   , details::cot_op  ) \
         case_stmt(details::e_sec   , details::sec_op  ) \
         case_stmt(details::e_csc   , details::csc_op  ) \
         case_stmt(details::e_r2d   , details::r2d_op  ) \
         case_stmt(details::e_d2r   , details::d2r_op  ) \
         case_stmt(details::e_d2g   , details::d2g_op  ) \
         case_stmt(details::e_g2d   , details::g2d_op  ) \
         case_stmt(details::e_notl  , details::notl_op ) \
         case_stmt(details::e_sgn   , details::sgn_op  ) \
         case_stmt(details::e_erf   , details::erf_op  ) \
         case_stmt(details::e_erfc  , details::erfc_op ) \
         case_stmt(details::e_ncdf  , details::ncdf_op ) \
         case_stmt(details::e_frac  , details::frac_op ) \
         case_stmt(details::e_trunc , details::trunc_op) \

         inline expression_node_ptr synthesize_uv_expression(const details::operator_type& operation,
                                                             expression_node_ptr (&branch)[1])
         {
            T& v = static_cast<details::variable_node<T>*>(branch[0])->ref();

            switch (operation)
            {
               #define case_stmt(op0, op1)                                                         \
               case op0 : return node_allocator_->                                                 \
                             allocate<typename details::unary_variable_node<Type,op1<Type> > >(v); \

               unary_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr synthesize_uvec_expression(const details::operator_type& operation,
                                                               expression_node_ptr (&branch)[1])
         {
            switch (operation)
            {
               #define case_stmt(op0, op1)                                                   \
               case op0 : return node_allocator_->                                           \
                             allocate<typename details::unary_vector_node<Type,op1<Type> > > \
                                (operation, branch[0]);                                      \

               unary_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr synthesize_unary_expression(const details::operator_type& operation,
                                                                expression_node_ptr (&branch)[1])
         {
            switch (operation)
            {
               #define case_stmt(op0, op1)                                                               \
               case op0 : return node_allocator_->                                                       \
                             allocate<typename details::unary_branch_node<Type,op1<Type> > >(branch[0]); \

               unary_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr const_optimise_sf3(const details::operator_type& operation,
                                                       expression_node_ptr (&branch)[3])
         {
            expression_node_ptr temp_node = error_node();

            switch (operation)
            {
               #define case_stmt(op)                                                        \
               case details::e_sf##op : temp_node = node_allocator_->                       \
                             allocate<details::sf3_node<Type,details::sf##op##_op<Type> > > \
                                (operation, branch);                                        \
                             break;                                                         \

               case_stmt(00) case_stmt(01) case_stmt(02) case_stmt(03)
               case_stmt(04) case_stmt(05) case_stmt(06) case_stmt(07)
               case_stmt(08) case_stmt(09) case_stmt(10) case_stmt(11)
               case_stmt(12) case_stmt(13) case_stmt(14) case_stmt(15)
               case_stmt(16) case_stmt(17) case_stmt(18) case_stmt(19)
               case_stmt(20) case_stmt(21) case_stmt(22) case_stmt(23)
               case_stmt(24) case_stmt(25) case_stmt(26) case_stmt(27)
               case_stmt(28) case_stmt(29) case_stmt(30) case_stmt(31)
               case_stmt(32) case_stmt(33) case_stmt(34) case_stmt(35)
               case_stmt(36) case_stmt(37) case_stmt(38) case_stmt(39)
               case_stmt(40) case_stmt(41) case_stmt(42) case_stmt(43)
               case_stmt(44) case_stmt(45) case_stmt(46) case_stmt(47)
               #undef case_stmt
               default : return error_node();
            }

            assert(temp_node);

            const T v = temp_node->value();

            details::free_node(*node_allocator_,temp_node);

            return node_allocator_->allocate<literal_node_t>(v);
         }

         inline expression_node_ptr varnode_optimise_sf3(const details::operator_type& operation, expression_node_ptr (&branch)[3])
         {
            typedef details::variable_node<Type>* variable_ptr;

            const Type& v0 = static_cast<variable_ptr>(branch[0])->ref();
            const Type& v1 = static_cast<variable_ptr>(branch[1])->ref();
            const Type& v2 = static_cast<variable_ptr>(branch[2])->ref();

            switch (operation)
            {
               #define case_stmt(op)                                                                \
               case details::e_sf##op : return node_allocator_->                                    \
                             allocate_rrr<details::sf3_var_node<Type,details::sf##op##_op<Type> > > \
                                (v0, v1, v2);                                                       \

               case_stmt(00) case_stmt(01) case_stmt(02) case_stmt(03)
               case_stmt(04) case_stmt(05) case_stmt(06) case_stmt(07)
               case_stmt(08) case_stmt(09) case_stmt(10) case_stmt(11)
               case_stmt(12) case_stmt(13) case_stmt(14) case_stmt(15)
               case_stmt(16) case_stmt(17) case_stmt(18) case_stmt(19)
               case_stmt(20) case_stmt(21) case_stmt(22) case_stmt(23)
               case_stmt(24) case_stmt(25) case_stmt(26) case_stmt(27)
               case_stmt(28) case_stmt(29) case_stmt(30) case_stmt(31)
               case_stmt(32) case_stmt(33) case_stmt(34) case_stmt(35)
               case_stmt(36) case_stmt(37) case_stmt(38) case_stmt(39)
               case_stmt(40) case_stmt(41) case_stmt(42) case_stmt(43)
               case_stmt(44) case_stmt(45) case_stmt(46) case_stmt(47)
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr special_function(const details::operator_type& operation, expression_node_ptr (&branch)[3])
         {
            if (!all_nodes_valid(branch))
               return error_node();
            else if (is_constant_foldable(branch))
               return const_optimise_sf3(operation,branch);
            else if (all_nodes_variables(branch))
               return varnode_optimise_sf3(operation,branch);
            else
            {
               switch (operation)
               {
                  #define case_stmt(op)                                                        \
                  case details::e_sf##op : return node_allocator_->                            \
                                allocate<details::sf3_node<Type,details::sf##op##_op<Type> > > \
                                   (operation, branch);                                        \

                  case_stmt(00) case_stmt(01) case_stmt(02) case_stmt(03)
                  case_stmt(04) case_stmt(05) case_stmt(06) case_stmt(07)
                  case_stmt(08) case_stmt(09) case_stmt(10) case_stmt(11)
                  case_stmt(12) case_stmt(13) case_stmt(14) case_stmt(15)
                  case_stmt(16) case_stmt(17) case_stmt(18) case_stmt(19)
                  case_stmt(20) case_stmt(21) case_stmt(22) case_stmt(23)
                  case_stmt(24) case_stmt(25) case_stmt(26) case_stmt(27)
                  case_stmt(28) case_stmt(29) case_stmt(30) case_stmt(31)
                  case_stmt(32) case_stmt(33) case_stmt(34) case_stmt(35)
                  case_stmt(36) case_stmt(37) case_stmt(38) case_stmt(39)
                  case_stmt(40) case_stmt(41) case_stmt(42) case_stmt(43)
                  case_stmt(44) case_stmt(45) case_stmt(46) case_stmt(47)
                  #undef case_stmt
                  default : return error_node();
               }
            }
         }

         inline expression_node_ptr const_optimise_sf4(const details::operator_type& operation, expression_node_ptr (&branch)[4])
         {
            expression_node_ptr temp_node = error_node();

            switch (operation)
            {
               #define case_stmt(op)                                                                    \
               case details::e_sf##op : temp_node = node_allocator_->                                   \
                                         allocate<details::sf4_node<Type,details::sf##op##_op<Type> > > \
                                            (operation, branch);                                        \
                                        break;                                                          \

               case_stmt(48) case_stmt(49) case_stmt(50) case_stmt(51)
               case_stmt(52) case_stmt(53) case_stmt(54) case_stmt(55)
               case_stmt(56) case_stmt(57) case_stmt(58) case_stmt(59)
               case_stmt(60) case_stmt(61) case_stmt(62) case_stmt(63)
               case_stmt(64) case_stmt(65) case_stmt(66) case_stmt(67)
               case_stmt(68) case_stmt(69) case_stmt(70) case_stmt(71)
               case_stmt(72) case_stmt(73) case_stmt(74) case_stmt(75)
               case_stmt(76) case_stmt(77) case_stmt(78) case_stmt(79)
               case_stmt(80) case_stmt(81) case_stmt(82) case_stmt(83)
               case_stmt(84) case_stmt(85) case_stmt(86) case_stmt(87)
               case_stmt(88) case_stmt(89) case_stmt(90) case_stmt(91)
               case_stmt(92) case_stmt(93) case_stmt(94) case_stmt(95)
               case_stmt(96) case_stmt(97) case_stmt(98) case_stmt(99)
               #undef case_stmt
               default : return error_node();
            }

            assert(temp_node);

            const T v = temp_node->value();

            details::free_node(*node_allocator_,temp_node);

            return node_allocator_->allocate<literal_node_t>(v);
         }

         inline expression_node_ptr varnode_optimise_sf4(const details::operator_type& operation, expression_node_ptr (&branch)[4])
         {
            typedef details::variable_node<Type>* variable_ptr;

            const Type& v0 = static_cast<variable_ptr>(branch[0])->ref();
            const Type& v1 = static_cast<variable_ptr>(branch[1])->ref();
            const Type& v2 = static_cast<variable_ptr>(branch[2])->ref();
            const Type& v3 = static_cast<variable_ptr>(branch[3])->ref();

            switch (operation)
            {
               #define case_stmt(op)                                                                 \
               case details::e_sf##op : return node_allocator_->                                     \
                             allocate_rrrr<details::sf4_var_node<Type,details::sf##op##_op<Type> > > \
                                (v0, v1, v2, v3);                                                    \

               case_stmt(48) case_stmt(49) case_stmt(50) case_stmt(51)
               case_stmt(52) case_stmt(53) case_stmt(54) case_stmt(55)
               case_stmt(56) case_stmt(57) case_stmt(58) case_stmt(59)
               case_stmt(60) case_stmt(61) case_stmt(62) case_stmt(63)
               case_stmt(64) case_stmt(65) case_stmt(66) case_stmt(67)
               case_stmt(68) case_stmt(69) case_stmt(70) case_stmt(71)
               case_stmt(72) case_stmt(73) case_stmt(74) case_stmt(75)
               case_stmt(76) case_stmt(77) case_stmt(78) case_stmt(79)
               case_stmt(80) case_stmt(81) case_stmt(82) case_stmt(83)
               case_stmt(84) case_stmt(85) case_stmt(86) case_stmt(87)
               case_stmt(88) case_stmt(89) case_stmt(90) case_stmt(91)
               case_stmt(92) case_stmt(93) case_stmt(94) case_stmt(95)
               case_stmt(96) case_stmt(97) case_stmt(98) case_stmt(99)
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr special_function(const details::operator_type& operation, expression_node_ptr (&branch)[4])
         {
            if (!all_nodes_valid(branch))
               return error_node();
            else if (is_constant_foldable(branch))
               return const_optimise_sf4(operation,branch);
            else if (all_nodes_variables(branch))
               return varnode_optimise_sf4(operation,branch);
            switch (operation)
            {
               #define case_stmt(op)                                                        \
               case details::e_sf##op : return node_allocator_->                            \
                             allocate<details::sf4_node<Type,details::sf##op##_op<Type> > > \
                                (operation, branch);                                        \

               case_stmt(48) case_stmt(49) case_stmt(50) case_stmt(51)
               case_stmt(52) case_stmt(53) case_stmt(54) case_stmt(55)
               case_stmt(56) case_stmt(57) case_stmt(58) case_stmt(59)
               case_stmt(60) case_stmt(61) case_stmt(62) case_stmt(63)
               case_stmt(64) case_stmt(65) case_stmt(66) case_stmt(67)
               case_stmt(68) case_stmt(69) case_stmt(70) case_stmt(71)
               case_stmt(72) case_stmt(73) case_stmt(74) case_stmt(75)
               case_stmt(76) case_stmt(77) case_stmt(78) case_stmt(79)
               case_stmt(80) case_stmt(81) case_stmt(82) case_stmt(83)
               case_stmt(84) case_stmt(85) case_stmt(86) case_stmt(87)
               case_stmt(88) case_stmt(89) case_stmt(90) case_stmt(91)
               case_stmt(92) case_stmt(93) case_stmt(94) case_stmt(95)
               case_stmt(96) case_stmt(97) case_stmt(98) case_stmt(99)
               #undef case_stmt
               default : return error_node();
            }
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr const_optimise_varargfunc(const details::operator_type& operation, Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            expression_node_ptr temp_node = error_node();

            switch (operation)
            {
               #define case_stmt(op0, op1)                                                \
               case op0 : temp_node = node_allocator_->                                   \
                                         allocate<details::vararg_node<Type,op1<Type> > > \
                                            (arg_list);                                   \
                          break;                                                          \

               case_stmt(details::e_sum   , details::vararg_add_op  )
               case_stmt(details::e_prod  , details::vararg_mul_op  )
               case_stmt(details::e_avg   , details::vararg_avg_op  )
               case_stmt(details::e_min   , details::vararg_min_op  )
               case_stmt(details::e_max   , details::vararg_max_op  )
               case_stmt(details::e_mand  , details::vararg_mand_op )
               case_stmt(details::e_mor   , details::vararg_mor_op  )
               case_stmt(details::e_multi , details::vararg_multi_op)
               #undef case_stmt
               default : return error_node();
            }

            const T v = temp_node->value();

            details::free_node(*node_allocator_,temp_node);

            return node_allocator_->allocate<literal_node_t>(v);
         }

         inline bool special_one_parameter_vararg(const details::operator_type& operation) const
         {
            return (
                     (details::e_sum  == operation) ||
                     (details::e_prod == operation) ||
                     (details::e_avg  == operation) ||
                     (details::e_min  == operation) ||
                     (details::e_max  == operation)
                   );
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr varnode_optimise_varargfunc(const details::operator_type& operation,
                                                                Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            switch (operation)
            {
               #define case_stmt(op0, op1)                                                  \
               case op0 : return node_allocator_->                                          \
                             allocate<details::vararg_varnode<Type,op1<Type> > >(arg_list); \

               case_stmt(details::e_sum   , details::vararg_add_op  )
               case_stmt(details::e_prod  , details::vararg_mul_op  )
               case_stmt(details::e_avg   , details::vararg_avg_op  )
               case_stmt(details::e_min   , details::vararg_min_op  )
               case_stmt(details::e_max   , details::vararg_max_op  )
               case_stmt(details::e_mand  , details::vararg_mand_op )
               case_stmt(details::e_mor   , details::vararg_mor_op  )
               case_stmt(details::e_multi , details::vararg_multi_op)
               #undef case_stmt
               default : return error_node();
            }
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr vectorize_func(const details::operator_type& operation,
                                                   Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            if (1 == arg_list.size())
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                     \
                  case op0 : return node_allocator_->                                             \
                                allocate<details::vectorize_node<Type,op1<Type> > >(arg_list[0]); \

                  case_stmt(details::e_sum  , details::vec_add_op)
                  case_stmt(details::e_prod , details::vec_mul_op)
                  case_stmt(details::e_avg  , details::vec_avg_op)
                  case_stmt(details::e_min  , details::vec_min_op)
                  case_stmt(details::e_max  , details::vec_max_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else
               return error_node();
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline expression_node_ptr vararg_function(const details::operator_type& operation,
                                                    Sequence<expression_node_ptr,Allocator>& arg_list)
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);

               return error_node();
            }
            else if (is_constant_foldable(arg_list))
               return const_optimise_varargfunc(operation,arg_list);
            else if ((1 == arg_list.size()) && details::is_ivector_node(arg_list[0]))
               return vectorize_func(operation,arg_list);
            else if ((1 == arg_list.size()) && special_one_parameter_vararg(operation))
               return arg_list[0];
            else if (all_nodes_variables(arg_list))
               return varnode_optimise_varargfunc(operation,arg_list);

            #ifndef exprtk_disable_string_capabilities
            if (details::e_smulti == operation)
            {
               expression_node_ptr result = node_allocator_->
                 allocate<details::str_vararg_node<Type,details::vararg_multi_op<Type> > >(arg_list);
               if (result && result->valid())
               {
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR254 - Failed to synthesize node: str_vararg_node<vararg_multi_op>",
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
            }
            else
            #endif
            {
               expression_node_ptr result = error_node();

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                               \
                  case op0 : result = node_allocator_->                                     \
                                allocate<details::vararg_node<Type,op1<Type> > >(arg_list); \
                             break;                                                         \

                  case_stmt(details::e_sum   , details::vararg_add_op  )
                  case_stmt(details::e_prod  , details::vararg_mul_op  )
                  case_stmt(details::e_avg   , details::vararg_avg_op  )
                  case_stmt(details::e_min   , details::vararg_min_op  )
                  case_stmt(details::e_max   , details::vararg_max_op  )
                  case_stmt(details::e_mand  , details::vararg_mand_op )
                  case_stmt(details::e_mor   , details::vararg_mor_op  )
                  case_stmt(details::e_multi , details::vararg_multi_op)
                  #undef case_stmt
                  default : return error_node();
               }

               if (result && result->valid())
               {
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR255 - Failed to synthesize node: vararg_node",
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
            }

            return error_node();
         }

         template <std::size_t N>
         inline expression_node_ptr function(ifunction_t* f, expression_node_ptr (&b)[N])
         {
            typedef typename details::function_N_node<T,ifunction_t,N> function_N_node_t;
            expression_node_ptr result = synthesize_expression<function_N_node_t,N>(f,b);

            if (0 == result)
               return error_node();
            else
            {
               // Can the function call be completely optimised?
               if (details::is_constant_node(result))
                  return result;
               else if (!all_nodes_valid(b))
               {
                  details::free_node(*node_allocator_,result);
                  std::fill_n(b, N, reinterpret_cast<expression_node_ptr>(0));

                  return error_node();
               }
               else if (N != f->param_count)
               {
                  details::free_node(*node_allocator_,result);
                  std::fill_n(b, N, reinterpret_cast<expression_node_ptr>(0));

                  return error_node();
               }

               function_N_node_t* func_node_ptr = reinterpret_cast<function_N_node_t*>(result);

               if (!func_node_ptr->init_branches(b))
               {
                  details::free_node(*node_allocator_,result);
                  std::fill_n(b, N, reinterpret_cast<expression_node_ptr>(0));

                  return error_node();
               }

               if (result && result->valid())
               {
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR256 - Failed to synthesize node: function_N_node_t",
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
               return error_node();
            }
         }

         inline expression_node_ptr function(ifunction_t* f)
         {
            typedef typename details::function_N_node<Type,ifunction_t,0> function_N_node_t;
            return node_allocator_->allocate<function_N_node_t>(f);
         }

         inline expression_node_ptr vararg_function_call(ivararg_function_t* vaf,
                                                         std::vector<expression_node_ptr>& arg_list)
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);

               return error_node();
            }

            typedef details::vararg_function_node<Type,ivararg_function_t> alloc_type;

            expression_node_ptr result = node_allocator_->allocate<alloc_type>(vaf,arg_list);

            if (
                 !arg_list.empty()        &&
                 !vaf->has_side_effects() &&
                 is_constant_foldable(arg_list)
               )
            {
               const Type v = result->value();
               details::free_node(*node_allocator_,result);
               result = node_allocator_->allocate<literal_node_t>(v);
            }

            parser_->state_.activate_side_effect("vararg_function_call()");

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR257 - Failed to synthesize node: vararg_function_node<ivararg_function_t>",
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();
         }

         inline expression_node_ptr generic_function_call(igeneric_function_t* gf,
                                                          std::vector<expression_node_ptr>& arg_list,
                                                          const std::size_t& param_seq_index = std::numeric_limits<std::size_t>::max())
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);
               return error_node();
            }

            typedef details::generic_function_node     <Type,igeneric_function_t> alloc_type1;
            typedef details::multimode_genfunction_node<Type,igeneric_function_t> alloc_type2;

            const std::size_t no_psi = std::numeric_limits<std::size_t>::max();

            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (no_psi == param_seq_index)
            {
               result = node_allocator_->allocate<alloc_type1>(arg_list,gf);
               node_name = "generic_function_node<igeneric_function_t>";
            }
            else
            {
               result = node_allocator_->allocate<alloc_type2>(gf, param_seq_index, arg_list);
               node_name = "multimode_genfunction_node<igeneric_function_t>";
            }

            alloc_type1* genfunc_node_ptr = static_cast<alloc_type1*>(result);

            assert(genfunc_node_ptr);

            if (
                 !arg_list.empty()                  &&
                 !gf->has_side_effects()            &&
                 parser_->state_.type_check_enabled &&
                 is_constant_foldable(arg_list)
               )
            {
               genfunc_node_ptr->init_branches();

               const Type v = result->value();

               details::free_node(*node_allocator_,result);

               return node_allocator_->allocate<literal_node_t>(v);
            }
            else if (genfunc_node_ptr->init_branches())
            {
               if (result && result->valid())
               {
                  parser_->state_.activate_side_effect("generic_function_call()");
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR258 - Failed to synthesize node: " + node_name,
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
               return error_node();
            }
            else
            {
               details::free_node(*node_allocator_, result);
               details::free_all_nodes(*node_allocator_, arg_list);

               return error_node();
            }
         }

         #ifndef exprtk_disable_string_capabilities
         inline expression_node_ptr string_function_call(igeneric_function_t* gf,
                                                         std::vector<expression_node_ptr>& arg_list,
                                                         const std::size_t& param_seq_index = std::numeric_limits<std::size_t>::max())
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);
               return error_node();
            }

            typedef details::string_function_node      <Type,igeneric_function_t> alloc_type1;
            typedef details::multimode_strfunction_node<Type,igeneric_function_t> alloc_type2;

            const std::size_t no_psi = std::numeric_limits<std::size_t>::max();

            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (no_psi == param_seq_index)
            {
               result = node_allocator_->allocate<alloc_type1>(gf,arg_list);
               node_name = "string_function_node<igeneric_function_t>";
            }
            else
            {
               result = node_allocator_->allocate<alloc_type2>(gf, param_seq_index, arg_list);
               node_name = "multimode_strfunction_node<igeneric_function_t>";
            }

            alloc_type1* strfunc_node_ptr = static_cast<alloc_type1*>(result);

            assert(strfunc_node_ptr);

            if (
                 !arg_list.empty()       &&
                 !gf->has_side_effects() &&
                 is_constant_foldable(arg_list)
               )
            {
               strfunc_node_ptr->init_branches();

               const Type v = result->value();

               details::free_node(*node_allocator_,result);

               return node_allocator_->allocate<literal_node_t>(v);
            }
            else if (strfunc_node_ptr->init_branches())
            {
               if (result && result->valid())
               {
                  parser_->state_.activate_side_effect("string_function_call()");
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR259 - Failed to synthesize node: " + node_name,
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
               return error_node();
            }
            else
            {
               details::free_node     (*node_allocator_,result  );
               details::free_all_nodes(*node_allocator_,arg_list);

               return error_node();
            }
         }
         #endif

         #ifndef exprtk_disable_return_statement
         inline expression_node_ptr return_call(std::vector<expression_node_ptr>& arg_list)
         {
            if (!all_nodes_valid(arg_list))
            {
               details::free_all_nodes(*node_allocator_,arg_list);
               return error_node();
            }

            typedef details::return_node<Type> alloc_type;

            expression_node_ptr result = node_allocator_->
                                            allocate_rr<alloc_type>(arg_list,parser_->results_ctx());

            alloc_type* return_node_ptr = static_cast<alloc_type*>(result);

            assert(return_node_ptr);

            if (return_node_ptr->init_branches())
            {
               if (result && result->valid())
               {
                  parser_->state_.activate_side_effect("return_call()");
                  return result;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_synthesis,
                  token_t(),
                  "ERR260 - Failed to synthesize node: return_node",
                  exprtk_error_location));

               details::free_node(*node_allocator_, result);
               return error_node();
            }
            else
            {
               details::free_node     (*node_allocator_, result  );
               details::free_all_nodes(*node_allocator_, arg_list);

               return error_node();
            }
         }

         inline expression_node_ptr return_envelope(expression_node_ptr body,
                                                    results_context_t* rc,
                                                    bool*& return_invoked)
         {
            typedef details::return_envelope_node<Type> alloc_type;

            expression_node_ptr result = node_allocator_->
                                            allocate_cr<alloc_type>(body,(*rc));

            return_invoked = static_cast<alloc_type*>(result)->retinvk_ptr();

            return result;
         }
         #else
         inline expression_node_ptr return_call(std::vector<expression_node_ptr>&)
         {
            return error_node();
         }

         inline expression_node_ptr return_envelope(expression_node_ptr,
                                                    results_context_t*,
                                                    bool*&)
         {
            return error_node();
         }
         #endif

         inline expression_node_ptr vector_element(const std::string&  symbol,
                                                   vector_holder_ptr   vector_base,
                                                   expression_node_ptr vec_node,
                                                   expression_node_ptr index)
         {
            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (details::is_constant_node(index))
            {
               const std::size_t vec_index = static_cast<std::size_t>(details::numeric::to_int64(index->value()));

               details::free_node(*node_allocator_,index);

               if (vec_index >= vector_base->size())
               {
                  parser_->set_error(parser_error::make_error(
                     parser_error::e_parser,
                     token_t(),
                     "ERR261 - Index of " + details::to_str(vec_index) + " out of range for "
                     "vector '" + symbol + "' of size " + details::to_str(vector_base->size()),
                     exprtk_error_location));

                  details::free_node(*node_allocator_,vec_node);

                  return error_node();
               }

               if (vector_base->rebaseable())
               {
                  vector_access_runtime_check_ptr rtc = get_vector_access_runtime_check();

                  result = (rtc) ?
                     node_allocator_->allocate<rebasevector_celem_rtc_node_t>(vec_node, vec_index, vector_base, rtc) :
                     node_allocator_->allocate<rebasevector_celem_node_t    >(vec_node, vec_index, vector_base     ) ;

                  node_name = (rtc) ?
                     "rebasevector_elem_rtc_node_t" :
                     "rebasevector_elem_node_t"     ;

                  if (result && result->valid())
                  {
                     return result;
                  }

                  parser_->set_error(parser_error::make_error(
                     parser_error::e_synthesis,
                     token_t(),
                     "ERR262 - Failed to synthesize node: " + node_name + " for vector: " + symbol,
                     exprtk_error_location));

                  details::free_node(*node_allocator_, result);
                  return error_node();
               }
               else if (details::is_ivector_node(vec_node) && !details::is_vector_node(vec_node))
               {
                  vector_access_runtime_check_ptr rtc = get_vector_access_runtime_check();

                  result = (rtc) ?
                     node_allocator_->allocate<vector_celem_rtc_node_t>(vec_node, vec_index, vector_base, rtc) :
                     node_allocator_->allocate<vector_celem_node_t    >(vec_node, vec_index, vector_base     ) ;

                  node_name = (rtc) ?
                     "vector_elem_rtc_node_t" :
                     "vector_elem_node_t"     ;

                  if (result && result->valid())
                  {
                     return result;
                  }

                  parser_->set_error(parser_error::make_error(
                     parser_error::e_synthesis,
                     token_t(),
                     "ERR263 - Failed to synthesize node: " + node_name + " for vector: " + symbol,
                     exprtk_error_location));

                  details::free_node(*node_allocator_, result);
                  return error_node();
               }

               const scope_element& se = parser_->sem_.get_element(symbol,vec_index);

               if (se.index == vec_index)
               {
                  result = se.var_node;
                  details::free_node(*node_allocator_,vec_node);
               }
               else
               {
                  scope_element nse;
                  nse.name      = symbol;
                  nse.active    = true;
                  nse.ref_count = 1;
                  nse.type      = scope_element::e_vecelem;
                  nse.index     = vec_index;
                  nse.depth     = parser_->state_.scope_depth;
                  nse.data      = 0;
                  nse.var_node  = node_allocator_->allocate<variable_node_t>((*(*vector_base)[vec_index]));

                  if (!parser_->sem_.add_element(nse))
                  {
                     parser_->set_synthesis_error("Failed to add new local vector element to SEM [1]");

                     parser_->sem_.free_element(nse);

                     result = error_node();
                  }

                  details::free_node(*node_allocator_,vec_node);

                  exprtk_debug(("vector_element() - INFO - Added new local vector element: %s\n", nse.name.c_str()));

                  parser_->state_.activate_side_effect("vector_element()");

                  result = nse.var_node;
                  node_name = "variable_node_t";
               }
            }
            else
            {
               vector_access_runtime_check_ptr rtc = get_vector_access_runtime_check();

               if (vector_base->rebaseable())
               {
                  result = (rtc) ?
                     node_allocator_->allocate<rebasevector_elem_rtc_node_t>(vec_node, index, vector_base, rtc) :
                     node_allocator_->allocate<rebasevector_elem_node_t    >(vec_node, index, vector_base     ) ;

                  node_name = (rtc) ?
                     "rebasevector_elem_rtc_node_t" :
                     "rebasevector_elem_node_t"     ;
               }
               else
               {
                  result = rtc ?
                     node_allocator_->allocate<vector_elem_rtc_node_t>(vec_node, index, vector_base, rtc) :
                     node_allocator_->allocate<vector_elem_node_t    >(vec_node, index, vector_base     ) ;

                  node_name = (rtc) ?
                     "vector_elem_rtc_node_t" :
                     "vector_elem_node_t"     ;
               }
            }

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR264 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();
         }

      private:

         template <std::size_t N, typename NodePtr>
         inline bool is_constant_foldable(NodePtr (&b)[N]) const
         {
            for (std::size_t i = 0; i < N; ++i)
            {
               if (0 == b[i])
                  return false;
               else if (!details::is_constant_node(b[i]))
                  return false;
            }

            return true;
         }

         template <typename NodePtr,
                   typename Allocator,
                   template <typename, typename> class Sequence>
         inline bool is_constant_foldable(const Sequence<NodePtr,Allocator>& b) const
         {
            for (std::size_t i = 0; i < b.size(); ++i)
            {
               if (0 == b[i])
                  return false;
               else if (!details::is_constant_node(b[i]))
                  return false;
            }

            return true;
         }

         void lodge_assignment(symbol_type cst, expression_node_ptr node)
         {
            parser_->state_.activate_side_effect("lodge_assignment()");

            if (!parser_->dec_.collect_assignments())
               return;

            std::string symbol_name;

            switch (cst)
            {
               case e_st_variable : symbol_name = parser_->symtab_store_
                                                     .get_variable_name(node);
                                    break;

               #ifndef exprtk_disable_string_capabilities
               case e_st_string   : symbol_name = parser_->symtab_store_
                                                     .get_stringvar_name(node);
                                    break;
               #endif

               case e_st_vector   : {
                                       typedef details::vector_holder<T> vector_holder_t;

                                       vector_holder_t& vh = static_cast<vector_node_t*>(node)->vec_holder();

                                       symbol_name = parser_->symtab_store_.get_vector_name(&vh);
                                    }
                                    break;

               case e_st_vecelem  : {
                                       typedef details::vector_holder<T> vector_holder_t;

                                       vector_holder_t& vh = static_cast<vector_elem_node_t*>(node)->vec_holder();

                                       symbol_name = parser_->symtab_store_.get_vector_name(&vh);

                                       cst = e_st_vector;
                                    }
                                    break;

               default            : return;
            }

            if (!symbol_name.empty())
            {
               parser_->dec_.add_assignment(symbol_name,cst);
            }
         }

         const void* base_ptr(expression_node_ptr node)
         {
            if (node)
            {
               switch(node->type())
               {
                  case details::expression_node<T>::e_variable:
                     return reinterpret_cast<const void*>(&static_cast<variable_node_t*>(node)->ref());

                  case details::expression_node<T>::e_vecelem:
                     return reinterpret_cast<const void*>(&static_cast<vector_elem_node_t*>(node)->ref());

                  case details::expression_node<T>::e_veccelem:
                     return reinterpret_cast<const void*>(&static_cast<vector_celem_node_t*>(node)->ref());

                  case details::expression_node<T>::e_vecelemrtc:
                     return reinterpret_cast<const void*>(&static_cast<vector_elem_rtc_node_t*>(node)->ref());

                  case details::expression_node<T>::e_veccelemrtc:
                     return reinterpret_cast<const void*>(&static_cast<vector_celem_rtc_node_t*>(node)->ref());

                  case details::expression_node<T>::e_rbvecelem:
                     return reinterpret_cast<const void*>(&static_cast<rebasevector_elem_node_t*>(node)->ref());

                  case details::expression_node<T>::e_rbvecelemrtc:
                     return reinterpret_cast<const void*>(&static_cast<rebasevector_elem_rtc_node_t*>(node)->ref());

                  case details::expression_node<T>::e_rbveccelem:
                     return reinterpret_cast<const void*>(&static_cast<rebasevector_celem_node_t*>(node)->ref());

                  case details::expression_node<T>::e_rbveccelemrtc:
                     return reinterpret_cast<const void*>(&static_cast<rebasevector_celem_rtc_node_t*>(node)->ref());

                  case details::expression_node<T>::e_vector:
                     return reinterpret_cast<const void*>(static_cast<vector_node_t*>(node)->vec_holder().data());

                  #ifndef exprtk_disable_string_capabilities
                  case details::expression_node<T>::e_stringvar:
                     return reinterpret_cast<const void*>((static_cast<stringvar_node_t*>(node)->base()));

                  case details::expression_node<T>::e_stringvarrng:
                     return reinterpret_cast<const void*>((static_cast<string_range_node_t*>(node)->base()));
                  #endif
                  default : return reinterpret_cast<const void*>(0);
               }
            }

            return reinterpret_cast<const void*>(0);
         }

         bool assign_immutable_symbol(expression_node_ptr node)
         {
            interval_t interval;
            const void* baseptr_addr = base_ptr(node);

            exprtk_debug(("assign_immutable_symbol - base ptr addr: %p\n", baseptr_addr));

            if (parser_->immutable_memory_map_.in_interval(baseptr_addr,interval))
            {
               typename immutable_symtok_map_t::iterator itr = parser_->immutable_symtok_map_.find(interval);

               if (parser_->immutable_symtok_map_.end() != itr)
               {
                  token_t& token = itr->second;
                  parser_->set_error(parser_error::make_error(
                     parser_error::e_parser,
                     token,
                     "ERR265 - Symbol '" + token.value + "' cannot be assigned-to as it is immutable.",
                     exprtk_error_location));
               }
               else
                  parser_->set_synthesis_error("Unable to assign symbol is immutable.");

               return true;
            }

            return false;
         }

         inline expression_node_ptr synthesize_assignment_expression(const details::operator_type& operation, expression_node_ptr (&branch)[2])
         {
            if (assign_immutable_symbol(branch[0]))
            {
               return error_node();
            }
            else if (details::is_variable_node(branch[0]))
            {
               lodge_assignment(e_st_variable,branch[0]);
               return synthesize_expression<assignment_node_t,2>(operation,branch);
            }
            else if (details::is_vector_elem_node(branch[0]) || details::is_vector_celem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);
               return synthesize_expression<assignment_vec_elem_node_t, 2>(operation, branch);
            }
            else if (details::is_vector_elem_rtc_node(branch[0]) || details::is_vector_celem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);
               return synthesize_expression<assignment_vec_elem_rtc_node_t, 2>(operation, branch);
            }
            else if (details::is_rebasevector_elem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);
               return synthesize_expression<assignment_rebasevec_elem_node_t, 2>(operation, branch);
            }
            else if (details::is_rebasevector_elem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);
               return synthesize_expression<assignment_rebasevec_elem_rtc_node_t, 2>(operation, branch);
            }
            else if (details::is_rebasevector_celem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);
               return synthesize_expression<assignment_rebasevec_celem_node_t, 2>(operation, branch);
            }
            #ifndef exprtk_disable_string_capabilities
            else if (details::is_string_node(branch[0]))
            {
               lodge_assignment(e_st_string,branch[0]);
               return synthesize_expression<assignment_string_node_t,2>(operation, branch);
            }
            else if (details::is_string_range_node(branch[0]))
            {
               lodge_assignment(e_st_string,branch[0]);
               return synthesize_expression<assignment_string_range_node_t,2>(operation, branch);
            }
            #endif
            else if (details::is_vector_node(branch[0]))
            {
               lodge_assignment(e_st_vector,branch[0]);

               if (details::is_ivector_node(branch[1]))
                  return synthesize_expression<assignment_vecvec_node_t,2>(operation, branch);
               else
                  return synthesize_expression<assignment_vec_node_t,2>(operation, branch);
            }
            else if (details::is_literal_node(branch[0]))
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR266 - Cannot assign value to const variable",
                  exprtk_error_location));

               return error_node();
            }
            else
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR267 - Invalid branches for assignment operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }
         }

         inline expression_node_ptr synthesize_assignment_operation_expression(const details::operator_type& operation,
                                                                               expression_node_ptr (&branch)[2])
         {
            if (assign_immutable_symbol(branch[0]))
            {
               return error_node();
            }

            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (details::is_variable_node(branch[0]))
            {
               lodge_assignment(e_st_variable,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                 \
                  case op0 : result = node_allocator_->                                                       \
                                template allocate_rrr<typename details::assignment_op_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                         \
                             node_name = "assignment_op_node";                                                \
                             break;                                                                           \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_vector_elem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                           \
                  case op0 : result = node_allocator_->                                                                 \
                                 template allocate_rrr<typename details::assignment_vec_elem_op_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                  \
                             node_name = "assignment_vec_elem_op_node";                                                 \
                             break;                                                                                     \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_vector_elem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                               \
                  case op0 : result = node_allocator_->                                                                     \
                                 template allocate_rrr<typename details::assignment_vec_elem_op_rtc_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                      \
                             node_name = "assignment_vec_elem_op_rtc_node";                                                 \
                             break;                                                                                         \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_vector_celem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                                \
                  case op0 : result = node_allocator_->                                                                      \
                                 template allocate_rrr<typename details::assignment_vec_celem_op_rtc_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                       \
                             node_name = "assignment_vec_celem_op_rtc_node";                                                 \
                             break;                                                                                          \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_rebasevector_elem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                                 \
                  case op0 : result = node_allocator_->                                                                       \
                                 template allocate_rrr<typename details::assignment_rebasevec_elem_op_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                        \
                             node_name = "assignment_rebasevec_elem_op_node";                                                 \
                             break;                                                                                           \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_rebasevector_celem_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                                  \
                  case op0 : result = node_allocator_->                                                                        \
                                 template allocate_rrr<typename details::assignment_rebasevec_celem_op_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                         \
                             node_name = "assignment_rebasevec_celem_op_node";                                                 \
                             break;                                                                                            \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_rebasevector_elem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                                     \
                  case op0 : result = node_allocator_->                                                                           \
                                 template allocate_rrr<typename details::assignment_rebasevec_elem_op_rtc_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                            \
                             node_name = "assignment_rebasevec_elem_op_rtc_node";                                                 \
                             break;                                                                                               \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_rebasevector_celem_rtc_node(branch[0]))
            {
               lodge_assignment(e_st_vecelem,branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                                      \
                  case op0 : result = node_allocator_->                                                                            \
                                 template allocate_rrr<typename details::assignment_rebasevec_celem_op_rtc_node<Type,op1<Type> > > \
                                    (operation, branch[0], branch[1]);                                                             \
                             node_name = "assignment_rebasevec_celem_op_rtc_node";                                                 \
                             break;                                                                                                \

                  case_stmt(details::e_addass , details::add_op)
                  case_stmt(details::e_subass , details::sub_op)
                  case_stmt(details::e_mulass , details::mul_op)
                  case_stmt(details::e_divass , details::div_op)
                  case_stmt(details::e_modass , details::mod_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (details::is_vector_node(branch[0]))
            {
               lodge_assignment(e_st_vector,branch[0]);

               if (details::is_ivector_node(branch[1]))
               {
                  switch (operation)
                  {
                     #define case_stmt(op0, op1)                                                                        \
                     case op0 : result = node_allocator_->                                                              \
                                   template allocate_rrr<typename details::assignment_vecvec_op_node<Type,op1<Type> > > \
                                      (operation, branch[0], branch[1]);                                                \
                                node_name = "assignment_rebasevec_celem_op_node";                                       \
                                break;                                                                                  \

                     case_stmt(details::e_addass , details::add_op)
                     case_stmt(details::e_subass , details::sub_op)
                     case_stmt(details::e_mulass , details::mul_op)
                     case_stmt(details::e_divass , details::div_op)
                     case_stmt(details::e_modass , details::mod_op)
                     #undef case_stmt
                     default : return error_node();
                  }
               }
               else
               {
                  switch (operation)
                  {
                     #define case_stmt(op0, op1)                                                                     \
                     case op0 : result = node_allocator_->                                                           \
                                   template allocate_rrr<typename details::assignment_vec_op_node<Type,op1<Type> > > \
                                      (operation, branch[0], branch[1]);                                             \
                                node_name = "assignment_vec_op_node";                                                \
                                break;                                                                               \

                     case_stmt(details::e_addass , details::add_op)
                     case_stmt(details::e_subass , details::sub_op)
                     case_stmt(details::e_mulass , details::mul_op)
                     case_stmt(details::e_divass , details::div_op)
                     case_stmt(details::e_modass , details::mod_op)
                     #undef case_stmt
                     default : return error_node();
                  }
               }
            }
            #ifndef exprtk_disable_string_capabilities
            else if (
                      (details::e_addass == operation) &&
                      details::is_string_node(branch[0])
                    )
            {
               typedef details::assignment_string_node<T,details::asn_addassignment> addass_t;

               lodge_assignment(e_st_string,branch[0]);

               result = synthesize_expression<addass_t,2>(operation,branch);
               node_name = "assignment_string_node<T,details::asn_addassignment>";
            }
            #endif
            else
            {
               parser_->set_error(parser_error::make_error(
                  parser_error::e_syntax,
                  parser_->current_state().token,
                  "ERR268 - Invalid branches for assignment operator '" + details::to_str(operation) + "'",
                  exprtk_error_location));

               return error_node();
            }

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR269 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();
         }

         inline expression_node_ptr synthesize_veceqineqlogic_operation_expression(const details::operator_type& operation,
                                                                                   expression_node_ptr (&branch)[2])
         {
            const bool is_b0_ivec = details::is_ivector_node(branch[0]);
            const bool is_b1_ivec = details::is_ivector_node(branch[1]);

            #define batch_eqineq_logic_case                 \
            case_stmt(details::e_lt    , details::lt_op   ) \
            case_stmt(details::e_lte   , details::lte_op  ) \
            case_stmt(details::e_gt    , details::gt_op   ) \
            case_stmt(details::e_gte   , details::gte_op  ) \
            case_stmt(details::e_eq    , details::eq_op   ) \
            case_stmt(details::e_ne    , details::ne_op   ) \
            case_stmt(details::e_equal , details::equal_op) \
            case_stmt(details::e_and   , details::and_op  ) \
            case_stmt(details::e_nand  , details::nand_op ) \
            case_stmt(details::e_or    , details::or_op   ) \
            case_stmt(details::e_nor   , details::nor_op  ) \
            case_stmt(details::e_xor   , details::xor_op  ) \
            case_stmt(details::e_xnor  , details::xnor_op ) \

            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (is_b0_ivec && is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_vecvec_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_vecvec_node";                                                \
                             break;                                                                              \

                  batch_eqineq_logic_case
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (is_b0_ivec && !is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_vecval_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_vecval_node";                                                \
                             break;                                                                              \

                  batch_eqineq_logic_case
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (!is_b0_ivec && is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_valvec_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_valvec_node";                                                \
                             break;                                                                              \

                  batch_eqineq_logic_case
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else
               return error_node();

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR270 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();

            #undef batch_eqineq_logic_case
         }

         inline expression_node_ptr synthesize_vecarithmetic_operation_expression(const details::operator_type& operation,
                                                                                  expression_node_ptr (&branch)[2])
         {
            const bool is_b0_ivec = details::is_ivector_node(branch[0]);
            const bool is_b1_ivec = details::is_ivector_node(branch[1]);

            #define vector_ops                          \
            case_stmt(details::e_add , details::add_op) \
            case_stmt(details::e_sub , details::sub_op) \
            case_stmt(details::e_mul , details::mul_op) \
            case_stmt(details::e_div , details::div_op) \
            case_stmt(details::e_mod , details::mod_op) \

            expression_node_ptr result = error_node();
            std::string node_name = "Unknown";

            if (is_b0_ivec && is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_vecvec_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_vecvec_node";                                                \
                             break;                                                                              \

                  vector_ops
                  case_stmt(details::e_pow,details:: pow_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (is_b0_ivec && !is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_vecval_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_vecval_node(b0ivec,!b1ivec)";                                \
                             break;                                                                              \

                  vector_ops
                  case_stmt(details::e_pow,details:: pow_op)
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else if (!is_b0_ivec && is_b1_ivec)
            {
               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                                    \
                  case op0 : result = node_allocator_->                                                          \
                                template allocate_rrr<typename details::vec_binop_valvec_node<Type,op1<Type> > > \
                                   (operation, branch[0], branch[1]);                                            \
                             node_name = "vec_binop_vecval_node(!b0ivec,b1ivec)";                                \
                             break;                                                                              \

                  vector_ops
                  #undef case_stmt
                  default : return error_node();
               }
            }
            else
               return error_node();

            if (result && result->valid())
            {
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR271 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();

            #undef vector_ops
         }

         inline expression_node_ptr synthesize_swap_expression(expression_node_ptr (&branch)[2])
         {
            const bool v0_is_ivar = details::is_ivariable_node(branch[0]);
            const bool v1_is_ivar = details::is_ivariable_node(branch[1]);

            const bool v0_is_ivec = details::is_ivector_node  (branch[0]);
            const bool v1_is_ivec = details::is_ivector_node  (branch[1]);

            #ifndef exprtk_disable_string_capabilities
            const bool v0_is_str = details::is_generally_string_node(branch[0]);
            const bool v1_is_str = details::is_generally_string_node(branch[1]);
            #endif

            expression_node_ptr result = error_node();
            std::string node_name      = "Unknown";

            if (v0_is_ivar && v1_is_ivar)
            {
               typedef details::variable_node<T>* variable_node_ptr;

               variable_node_ptr v0 = variable_node_ptr(0);
               variable_node_ptr v1 = variable_node_ptr(0);

               if (
                    (0 != (v0 = dynamic_cast<variable_node_ptr>(branch[0]))) &&
                    (0 != (v1 = dynamic_cast<variable_node_ptr>(branch[1])))
                  )
               {
                  result    = node_allocator_->allocate<details::swap_node<T> >(v0,v1);
                  node_name = "swap_node";
               }
               else
               {
                  result    = node_allocator_->allocate<details::swap_generic_node<T> >(branch[0],branch[1]);
                  node_name = "swap_generic_node";
               }
            }
            else if (v0_is_ivec && v1_is_ivec)
            {
               result    = node_allocator_->allocate<details::swap_vecvec_node<T> >(branch[0],branch[1]);
               node_name = "swap_vecvec_node";
            }
            #ifndef exprtk_disable_string_capabilities
            else if (v0_is_str && v1_is_str)
            {
               if (is_string_node(branch[0]) && is_string_node(branch[1]))
               {
                  result = node_allocator_->allocate<details::swap_string_node<T> >
                                               (branch[0], branch[1]);
                  node_name = "swap_string_node";
               }
               else
               {
                  result = node_allocator_->allocate<details::swap_genstrings_node<T> >
                                               (branch[0], branch[1]);
                  node_name = "swap_genstrings_node";
               }
            }
            #endif
            else
            {
               parser_->set_synthesis_error("Only variables, strings, vectors or vector elements can be swapped");
               return error_node();
            }

            if (result && result->valid())
            {
               parser_->state_.activate_side_effect("synthesize_swap_expression()");
               return result;
            }

            parser_->set_error(parser_error::make_error(
               parser_error::e_synthesis,
               token_t(),
               "ERR272 - Failed to synthesize node: " + node_name,
               exprtk_error_location));

            details::free_node(*node_allocator_, result);
            return error_node();
         }

         #ifndef exprtk_disable_sc_andor
         inline expression_node_ptr synthesize_shortcircuit_expression(const details::operator_type& operation, expression_node_ptr (&branch)[2])
         {
            expression_node_ptr result = error_node();

            if (details::is_constant_node(branch[0]))
            {
               if (
                    (details::e_scand == operation) &&
                    std::equal_to<T>()(T(0),branch[0]->value())
                  )
                  result = node_allocator_->allocate_c<literal_node_t>(T(0));
               else if (
                         (details::e_scor == operation) &&
                         std::not_equal_to<T>()(T(0),branch[0]->value())
                       )
                  result = node_allocator_->allocate_c<literal_node_t>(T(1));
            }

            if (details::is_constant_node(branch[1]) && (0 == result))
            {
               if (
                    (details::e_scand == operation) &&
                    std::equal_to<T>()(T(0),branch[1]->value())
                  )
                  result = node_allocator_->allocate_c<literal_node_t>(T(0));
               else if (
                         (details::e_scor == operation) &&
                         std::not_equal_to<T>()(T(0),branch[1]->value())
                       )
                  result = node_allocator_->allocate_c<literal_node_t>(T(1));
            }

            if (result)
            {
               details::free_node(*node_allocator_, branch[0]);
               details::free_node(*node_allocator_, branch[1]);

               return result;
            }
            else if (details::e_scand == operation)
            {
               return synthesize_expression<scand_node_t,2>(operation, branch);
            }
            else if (details::e_scor == operation)
            {
               return synthesize_expression<scor_node_t,2>(operation, branch);
            }
            else
               return error_node();
         }
         #else
         inline expression_node_ptr synthesize_shortcircuit_expression(const details::operator_type&, expression_node_ptr (&)[2])
         {
            return error_node();
         }
         #endif

         #define basic_opr_switch_statements         \
         case_stmt(details::e_add , details::add_op) \
         case_stmt(details::e_sub , details::sub_op) \
         case_stmt(details::e_mul , details::mul_op) \
         case_stmt(details::e_div , details::div_op) \
         case_stmt(details::e_mod , details::mod_op) \
         case_stmt(details::e_pow , details::pow_op) \

         #define extended_opr_switch_statements        \
         case_stmt(details::e_lt   , details::lt_op  ) \
         case_stmt(details::e_lte  , details::lte_op ) \
         case_stmt(details::e_gt   , details::gt_op  ) \
         case_stmt(details::e_gte  , details::gte_op ) \
         case_stmt(details::e_eq   , details::eq_op  ) \
         case_stmt(details::e_ne   , details::ne_op  ) \
         case_stmt(details::e_and  , details::and_op ) \
         case_stmt(details::e_nand , details::nand_op) \
         case_stmt(details::e_or   , details::or_op  ) \
         case_stmt(details::e_nor  , details::nor_op ) \
         case_stmt(details::e_xor  , details::xor_op ) \
         case_stmt(details::e_xnor , details::xnor_op) \

         #ifndef exprtk_disable_cardinal_pow_optimisation
         template <typename TType, template <typename, typename> class IPowNode>
         inline expression_node_ptr cardinal_pow_optimisation_impl(const TType& v, const unsigned int& p)
         {
            switch (p)
            {
               #define case_stmt(cp)                                                     \
               case cp : return node_allocator_->                                        \
                            allocate<IPowNode<T,details::numeric::fast_exp<T,cp> > >(v); \

               case_stmt( 1) case_stmt( 2) case_stmt( 3) case_stmt( 4)
               case_stmt( 5) case_stmt( 6) case_stmt( 7) case_stmt( 8)
               case_stmt( 9) case_stmt(10) case_stmt(11) case_stmt(12)
               case_stmt(13) case_stmt(14) case_stmt(15) case_stmt(16)
               case_stmt(17) case_stmt(18) case_stmt(19) case_stmt(20)
               case_stmt(21) case_stmt(22) case_stmt(23) case_stmt(24)
               case_stmt(25) case_stmt(26) case_stmt(27) case_stmt(28)
               case_stmt(29) case_stmt(30) case_stmt(31) case_stmt(32)
               case_stmt(33) case_stmt(34) case_stmt(35) case_stmt(36)
               case_stmt(37) case_stmt(38) case_stmt(39) case_stmt(40)
               case_stmt(41) case_stmt(42) case_stmt(43) case_stmt(44)
               case_stmt(45) case_stmt(46) case_stmt(47) case_stmt(48)
               case_stmt(49) case_stmt(50) case_stmt(51) case_stmt(52)
               case_stmt(53) case_stmt(54) case_stmt(55) case_stmt(56)
               case_stmt(57) case_stmt(58) case_stmt(59) case_stmt(60)
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr cardinal_pow_optimisation(const T& v, const T& c)
         {
            const bool not_recipricol = (c >= T(0));
            const unsigned int p = static_cast<unsigned int>(details::numeric::to_int32(details::numeric::abs(c)));

            if (0 == p)
               return node_allocator_->allocate_c<literal_node_t>(T(1));
            else if (std::equal_to<T>()(T(2),c))
            {
               return node_allocator_->
                  template allocate_rr<typename details::vov_node<Type,details::mul_op<Type> > >(v,v);
            }
            else
            {
               if (not_recipricol)
                  return cardinal_pow_optimisation_impl<T,details::ipow_node>(v,p);
               else
                  return cardinal_pow_optimisation_impl<T,details::ipowinv_node>(v,p);
            }
         }

         inline bool cardinal_pow_optimisable(const details::operator_type& operation, const T& c) const
         {
            return (details::e_pow == operation) && (details::numeric::abs(c) <= T(60)) && details::numeric::is_integer(c);
         }

         inline expression_node_ptr cardinal_pow_optimisation(expression_node_ptr (&branch)[2])
         {
            const Type c = static_cast<details::literal_node<Type>*>(branch[1])->value();
            const bool not_recipricol = (c >= T(0));
            const unsigned int p = static_cast<unsigned int>(details::numeric::to_int32(details::numeric::abs(c)));

            node_allocator_->free(branch[1]);

            if (0 == p)
            {
               details::free_all_nodes(*node_allocator_, branch);

               return node_allocator_->allocate_c<literal_node_t>(T(1));
            }
            else if (not_recipricol)
               return cardinal_pow_optimisation_impl<expression_node_ptr,details::bipow_node>(branch[0],p);
            else
               return cardinal_pow_optimisation_impl<expression_node_ptr,details::bipowinv_node>(branch[0],p);
         }
         #else
         inline expression_node_ptr cardinal_pow_optimisation(T&, const T&)
         {
            return error_node();
         }

         inline bool cardinal_pow_optimisable(const details::operator_type&, const T&)
         {
            return false;
         }

         inline expression_node_ptr cardinal_pow_optimisation(expression_node_ptr(&)[2])
         {
            return error_node();
         }
         #endif

         struct synthesize_binary_ext_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const bool left_neg  = is_neg_unary_node(branch[0]);
               const bool right_neg = is_neg_unary_node(branch[1]);

               if (left_neg && right_neg)
               {
                  if (
                       (details::e_add == operation) ||
                       (details::e_sub == operation) ||
                       (details::e_mul == operation) ||
                       (details::e_div == operation)
                     )
                  {
                     if (
                          !expr_gen.parser_->simplify_unary_negation_branch(branch[0]) ||
                          !expr_gen.parser_->simplify_unary_negation_branch(branch[1])
                        )
                     {
                        details::free_all_nodes(*expr_gen.node_allocator_,branch);

                        return error_node();
                     }
                  }

                  switch (operation)
                  {
                                           // -f(x + 1) + -g(y + 1) --> -(f(x + 1) + g(y + 1))
                     case details::e_add : return expr_gen(details::e_neg,
                                              expr_gen.node_allocator_->
                                                 template allocate<typename details::binary_ext_node<Type,details::add_op<Type> > >
                                                    (branch[0],branch[1]));

                                           // -f(x + 1) - -g(y + 1) --> g(y + 1) - f(x + 1)
                     case details::e_sub : return expr_gen.node_allocator_->
                                              template allocate<typename details::binary_ext_node<Type,details::sub_op<Type> > >
                                                 (branch[1],branch[0]);

                     default             : break;
                  }
               }
               else if (left_neg && !right_neg)
               {
                  if (
                       (details::e_add == operation) ||
                       (details::e_sub == operation) ||
                       (details::e_mul == operation) ||
                       (details::e_div == operation)
                     )
                  {
                     if (!expr_gen.parser_->simplify_unary_negation_branch(branch[0]))
                     {
                        details::free_all_nodes(*expr_gen.node_allocator_,branch);

                        return error_node();
                     }

                     switch (operation)
                     {
                                              // -f(x + 1) + g(y + 1) --> g(y + 1) - f(x + 1)
                        case details::e_add : return expr_gen.node_allocator_->
                                                 template allocate<typename details::binary_ext_node<Type,details::sub_op<Type> > >
                                                   (branch[1], branch[0]);

                                              // -f(x + 1) - g(y + 1) --> -(f(x + 1) + g(y + 1))
                        case details::e_sub : return expr_gen(details::e_neg,
                                                 expr_gen.node_allocator_->
                                                    template allocate<typename details::binary_ext_node<Type,details::add_op<Type> > >
                                                       (branch[0], branch[1]));

                                              // -f(x + 1) * g(y + 1) --> -(f(x + 1) * g(y + 1))
                        case details::e_mul : return expr_gen(details::e_neg,
                                                 expr_gen.node_allocator_->
                                                    template allocate<typename details::binary_ext_node<Type,details::mul_op<Type> > >
                                                       (branch[0], branch[1]));

                                              // -f(x + 1) / g(y + 1) --> -(f(x + 1) / g(y + 1))
                        case details::e_div : return expr_gen(details::e_neg,
                                                 expr_gen.node_allocator_->
                                                    template allocate<typename details::binary_ext_node<Type,details::div_op<Type> > >
                                                       (branch[0], branch[1]));

                        default             : return error_node();
                     }
                  }
               }
               else if (!left_neg && right_neg)
               {
                  if (
                       (details::e_add == operation) ||
                       (details::e_sub == operation) ||
                       (details::e_mul == operation) ||
                       (details::e_div == operation)
                     )
                  {
                     if (!expr_gen.parser_->simplify_unary_negation_branch(branch[1]))
                     {
                        details::free_all_nodes(*expr_gen.node_allocator_,branch);

                        return error_node();
                     }

                     switch (operation)
                     {
                                              // f(x + 1) + -g(y + 1) --> f(x + 1) - g(y + 1)
                        case details::e_add : return expr_gen.node_allocator_->
                                                 template allocate<typename details::binary_ext_node<Type,details::sub_op<Type> > >
                                                   (branch[0], branch[1]);

                                              // f(x + 1) - - g(y + 1) --> f(x + 1) + g(y + 1)
                        case details::e_sub : return expr_gen.node_allocator_->
                                                 template allocate<typename details::binary_ext_node<Type,details::add_op<Type> > >
                                                   (branch[0], branch[1]);

                                              // f(x + 1) * -g(y + 1) --> -(f(x + 1) * g(y + 1))
                        case details::e_mul : return expr_gen(details::e_neg,
                                                 expr_gen.node_allocator_->
                                                    template allocate<typename details::binary_ext_node<Type,details::mul_op<Type> > >
                                                       (branch[0], branch[1]));

                                              // f(x + 1) / -g(y + 1) --> -(f(x + 1) / g(y + 1))
                        case details::e_div : return expr_gen(details::e_neg,
                                                 expr_gen.node_allocator_->
                                                    template allocate<typename details::binary_ext_node<Type,details::div_op<Type> > >
                                                       (branch[0], branch[1]));

                        default             : return error_node();
                     }
                  }
               }

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                          \
                  case op0 : return expr_gen.node_allocator_->                                         \
                                template allocate<typename details::binary_ext_node<Type,op1<Type> > > \
                                   (branch[0], branch[1]);                                             \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_vob_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type& v = static_cast<details::variable_node<Type>*>(branch[0])->ref();

               #ifndef exprtk_disable_enhanced_features
               if (details::is_sf3ext_node(branch[1]))
               {
                  expression_node_ptr result = error_node();

                  const bool synthesis_result =
                     synthesize_sf4ext_expression::template compile_right<vtype>
                        (expr_gen, v, operation, branch[1], result);

                  if (synthesis_result)
                  {
                     details::free_node(*expr_gen.node_allocator_,branch[1]);
                     return result;
                  }
               }
               #endif

               if (
                    (details::e_mul == operation) ||
                    (details::e_div == operation)
                  )
               {
                  if (details::is_uv_node(branch[1]))
                  {
                     typedef details::uv_base_node<Type>* uvbn_ptr_t;

                     details::operator_type o = static_cast<uvbn_ptr_t>(branch[1])->operation();

                     if (details::e_neg == o)
                     {
                        const Type& v1 = static_cast<uvbn_ptr_t>(branch[1])->v();

                        details::free_node(*expr_gen.node_allocator_,branch[1]);

                        switch (operation)
                        {
                           case details::e_mul : return expr_gen(details::e_neg,
                                                    expr_gen.node_allocator_->
                                                       template allocate_rr<typename details::
                                                          vov_node<Type,details::mul_op<Type> > >(v,v1));

                           case details::e_div : return expr_gen(details::e_neg,
                                                    expr_gen.node_allocator_->
                                                       template allocate_rr<typename details::
                                                          vov_node<Type,details::div_op<Type> > >(v,v1));

                           default             : break;
                        }
                     }
                  }
               }

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_rc<typename details::vob_node<Type,op1<Type> > > \
                                   (v, branch[1]);                                                 \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_bov_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type& v = static_cast<details::variable_node<Type>*>(branch[1])->ref();

               #ifndef exprtk_disable_enhanced_features
               if (details::is_sf3ext_node(branch[0]))
               {
                  expression_node_ptr result = error_node();

                  const bool synthesis_result =
                     synthesize_sf4ext_expression::template compile_left<vtype>
                        (expr_gen, v, operation, branch[0], result);

                  if (synthesis_result)
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);

                     return result;
                  }
               }
               #endif

               if (
                    (details::e_add == operation) ||
                    (details::e_sub == operation) ||
                    (details::e_mul == operation) ||
                    (details::e_div == operation)
                  )
               {
                  if (details::is_uv_node(branch[0]))
                  {
                     typedef details::uv_base_node<Type>* uvbn_ptr_t;

                     details::operator_type o = static_cast<uvbn_ptr_t>(branch[0])->operation();

                     if (details::e_neg == o)
                     {
                        const Type& v0 = static_cast<uvbn_ptr_t>(branch[0])->v();

                        details::free_node(*expr_gen.node_allocator_,branch[0]);

                        switch (operation)
                        {
                           case details::e_add : return expr_gen.node_allocator_->
                                                    template allocate_rr<typename details::
                                                       vov_node<Type,details::sub_op<Type> > >(v,v0);

                           case details::e_sub : return expr_gen(details::e_neg,
                                                    expr_gen.node_allocator_->
                                                       template allocate_rr<typename details::
                                                          vov_node<Type,details::add_op<Type> > >(v0,v));

                           case details::e_mul : return expr_gen(details::e_neg,
                                                    expr_gen.node_allocator_->
                                                       template allocate_rr<typename details::
                                                          vov_node<Type,details::mul_op<Type> > >(v0,v));

                           case details::e_div : return expr_gen(details::e_neg,
                                                    expr_gen.node_allocator_->
                                                       template allocate_rr<typename details::
                                                          vov_node<Type,details::div_op<Type> > >(v0,v));
                           default : break;
                        }
                     }
                  }
               }

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_cr<typename details::bov_node<Type,op1<Type> > > \
                                   (branch[0], v);                                                 \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_cob_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type c = static_cast<details::literal_node<Type>*>(branch[0])->value();

               details::free_node(*expr_gen.node_allocator_,branch[0]);

               if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
               {
                  details::free_node(*expr_gen.node_allocator_,branch[1]);

                  return expr_gen(T(0));
               }
               else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
               {
                  details::free_node(*expr_gen.node_allocator_, branch[1]);

                  return expr_gen(T(0));
               }
               else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  return branch[1];
               else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  return branch[1];

               if (details::is_cob_node(branch[1]))
               {
                  // Simplify expressions of the form:
                  // 1. (1 * (2 * (3 * (4 * (5 * (6 * (7 * (8 * (9 + x))))))))) --> 40320 * (9 + x)
                  // 2. (1 + (2 + (3 + (4 + (5 + (6 + (7 + (8 + (9 + x))))))))) --> 45 + x
                  if (
                       (details::e_mul == operation) ||
                       (details::e_add == operation)
                     )
                  {
                     details::cob_base_node<Type>* cobnode = static_cast<details::cob_base_node<Type>*>(branch[1]);

                     if (operation == cobnode->operation())
                     {
                        switch (operation)
                        {
                           case details::e_add : cobnode->set_c(c + cobnode->c()); break;
                           case details::e_mul : cobnode->set_c(c * cobnode->c()); break;
                           default             : return error_node();
                        }

                        return cobnode;
                     }
                  }

                  if (operation == details::e_mul)
                  {
                     details::cob_base_node<Type>* cobnode = static_cast<details::cob_base_node<Type>*>(branch[1]);
                     details::operator_type cob_opr = cobnode->operation();

                     if (
                          (details::e_div == cob_opr) ||
                          (details::e_mul == cob_opr)
                        )
                     {
                        switch (cob_opr)
                        {
                           case details::e_div : cobnode->set_c(c * cobnode->c()); break;
                           case details::e_mul : cobnode->set_c(cobnode->c() / c); break;
                           default             : return error_node();
                        }

                        return cobnode;
                     }
                  }
                  else if (operation == details::e_div)
                  {
                     details::cob_base_node<Type>* cobnode = static_cast<details::cob_base_node<Type>*>(branch[1]);
                     details::operator_type cob_opr = cobnode->operation();

                     if (
                          (details::e_div == cob_opr) ||
                          (details::e_mul == cob_opr)
                        )
                     {
                        details::expression_node<Type>* new_cobnode = error_node();

                        switch (cob_opr)
                        {
                           case details::e_div : new_cobnode = expr_gen.node_allocator_->
                                                    template allocate_tt<typename details::cob_node<Type,details::mul_op<Type> > >
                                                       (c / cobnode->c(), cobnode->move_branch(0));
                                                 break;

                           case details::e_mul : new_cobnode = expr_gen.node_allocator_->
                                                    template allocate_tt<typename details::cob_node<Type,details::div_op<Type> > >
                                                       (c / cobnode->c(), cobnode->move_branch(0));
                                                 break;

                           default             : return error_node();
                        }

                        details::free_node(*expr_gen.node_allocator_,branch[1]);

                        return new_cobnode;
                     }
                  }
               }
               #ifndef exprtk_disable_enhanced_features
               else if (details::is_sf3ext_node(branch[1]))
               {
                  expression_node_ptr result = error_node();

                  const bool synthesis_result =
                     synthesize_sf4ext_expression::template compile_right<ctype>
                        (expr_gen, c, operation, branch[1], result);

                  if (synthesis_result)
                  {
                     details::free_node(*expr_gen.node_allocator_,branch[1]);

                     return result;
                  }
               }
               #endif

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_tt<typename details::cob_node<Type,op1<Type> > > \
                                   (c,  branch[1]);                                                \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_boc_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type c = static_cast<details::literal_node<Type>*>(branch[1])->value();

               details::free_node(*(expr_gen.node_allocator_), branch[1]);

               if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
               {
                  details::free_node(*expr_gen.node_allocator_, branch[0]);

                  return expr_gen(T(0));
               }
               else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
               {
                  details::free_node(*expr_gen.node_allocator_, branch[0]);

                  return expr_gen(std::numeric_limits<T>::quiet_NaN());
               }
               else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  return branch[0];
               else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  return branch[0];

               if (details::is_boc_node(branch[0]))
               {
                  // Simplify expressions of the form:
                  // 1. (((((((((x + 9) * 8) * 7) * 6) * 5) * 4) * 3) * 2) * 1) --> (x + 9) * 40320
                  // 2. (((((((((x + 9) + 8) + 7) + 6) + 5) + 4) + 3) + 2) + 1) --> x + 45
                  if (
                       (details::e_mul == operation) ||
                       (details::e_add == operation)
                     )
                  {
                     details::boc_base_node<Type>* bocnode = static_cast<details::boc_base_node<Type>*>(branch[0]);

                     if (operation == bocnode->operation())
                     {
                        switch (operation)
                        {
                           case details::e_add : bocnode->set_c(c + bocnode->c()); break;
                           case details::e_mul : bocnode->set_c(c * bocnode->c()); break;
                           default             : return error_node();
                        }

                        return bocnode;
                     }
                  }
                  else if (operation == details::e_div)
                  {
                     details::boc_base_node<Type>* bocnode = static_cast<details::boc_base_node<Type>*>(branch[0]);
                     details::operator_type        boc_opr = bocnode->operation();

                     if (
                          (details::e_div == boc_opr) ||
                          (details::e_mul == boc_opr)
                        )
                     {
                        switch (boc_opr)
                        {
                           case details::e_div : bocnode->set_c(c * bocnode->c()); break;
                           case details::e_mul : bocnode->set_c(bocnode->c() / c); break;
                           default             : return error_node();
                        }

                        return bocnode;
                     }
                  }
                  else if (operation == details::e_pow)
                  {
                     // (v ^ c0) ^ c1 --> v ^(c0 * c1)
                     details::boc_base_node<Type>* bocnode = static_cast<details::boc_base_node<Type>*>(branch[0]);
                     details::operator_type        boc_opr = bocnode->operation();

                     if (details::e_pow == boc_opr)
                     {
                        bocnode->set_c(bocnode->c() * c);

                        return bocnode;
                     }
                  }
               }

               #ifndef exprtk_disable_enhanced_features
               if (details::is_sf3ext_node(branch[0]))
               {
                  expression_node_ptr result = error_node();

                  const bool synthesis_result =
                     synthesize_sf4ext_expression::template compile_left<ctype>
                        (expr_gen, c, operation, branch[0], result);

                  if (synthesis_result)
                  {
                     free_node(*expr_gen.node_allocator_, branch[0]);

                     return result;
                  }
               }
               #endif

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_cr<typename details::boc_node<Type,op1<Type> > > \
                                   (branch[0], c);                                                 \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_cocob_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               expression_node_ptr result = error_node();

               // (cob) o c --> cob
               if (details::is_cob_node(branch[0]))
               {
                  details::cob_base_node<Type>* cobnode = static_cast<details::cob_base_node<Type>*>(branch[0]);

                  const Type c = static_cast<details::literal_node<Type>*>(branch[1])->value();

                  if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return expr_gen(T(0));
                  }
                  else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return expr_gen(T(std::numeric_limits<T>::quiet_NaN()));
                  }
                  else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return branch[0];
                  }
                  else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return branch[0];
                  }
                  else if (std::equal_to<T>()(T(1),c) && (details::e_div == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return branch[0];
                  }

                  const bool op_addsub = (details::e_add == cobnode->operation()) ||
                                         (details::e_sub == cobnode->operation()) ;

                  if (op_addsub)
                  {
                     switch (operation)
                     {
                        case details::e_add : cobnode->set_c(cobnode->c() + c); break;
                        case details::e_sub : cobnode->set_c(cobnode->c() - c); break;
                        default             : return error_node();
                     }

                     result = cobnode;
                  }
                  else if (details::e_mul == cobnode->operation())
                  {
                     switch (operation)
                     {
                        case details::e_mul : cobnode->set_c(cobnode->c() * c); break;
                        case details::e_div : cobnode->set_c(cobnode->c() / c); break;
                        default             : return error_node();
                     }

                     result = cobnode;
                  }
                  else if (details::e_div == cobnode->operation())
                  {
                     if (details::e_mul == operation)
                     {
                        cobnode->set_c(cobnode->c() * c);
                        result = cobnode;
                     }
                     else if (details::e_div == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::div_op<Type> > >
                                       (cobnode->c() / c, cobnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_, branch[0]);
                     }
                  }

                  if (result)
                  {
                     details::free_node(*expr_gen.node_allocator_,branch[1]);
                  }
               }

               // c o (cob) --> cob
               else if (details::is_cob_node(branch[1]))
               {
                  details::cob_base_node<Type>* cobnode = static_cast<details::cob_base_node<Type>*>(branch[1]);

                  const Type c = static_cast<details::literal_node<Type>*>(branch[0])->value();

                  if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return expr_gen(T(0));
                  }
                  else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);
                     details::free_node(*expr_gen.node_allocator_, branch[1]);

                     return expr_gen(T(0));
                  }
                  else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);

                     return branch[1];
                  }
                  else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[0]);

                     return branch[1];
                  }

                  if (details::e_add == cobnode->operation())
                  {
                     if (details::e_add == operation)
                     {
                        cobnode->set_c(c + cobnode->c());
                        result = cobnode;
                     }
                     else if (details::e_sub == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::sub_op<Type> > >
                                       (c - cobnode->c(), cobnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_sub == cobnode->operation())
                  {
                     if (details::e_add == operation)
                     {
                        cobnode->set_c(c + cobnode->c());
                        result = cobnode;
                     }
                     else if (details::e_sub == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::add_op<Type> > >
                                       (c - cobnode->c(), cobnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_mul == cobnode->operation())
                  {
                     if (details::e_mul == operation)
                     {
                        cobnode->set_c(c * cobnode->c());
                        result = cobnode;
                     }
                     else if (details::e_div == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::div_op<Type> > >
                                       (c / cobnode->c(), cobnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_div == cobnode->operation())
                  {
                     if (details::e_mul == operation)
                     {
                        cobnode->set_c(c * cobnode->c());
                        result = cobnode;
                     }
                     else if (details::e_div == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::mul_op<Type> > >
                                       (c / cobnode->c(), cobnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }

                  if (result)
                  {
                     details::free_node(*expr_gen.node_allocator_,branch[0]);
                  }
               }

               return result;
            }
         };

         struct synthesize_coboc_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               expression_node_ptr result = error_node();

               // (boc) o c --> boc
               if (details::is_boc_node(branch[0]))
               {
                  details::boc_base_node<Type>* bocnode = static_cast<details::boc_base_node<Type>*>(branch[0]);

                  const Type c = static_cast<details::literal_node<Type>*>(branch[1])->value();

                  if (details::e_add == bocnode->operation())
                  {
                     switch (operation)
                     {
                        case details::e_add : bocnode->set_c(bocnode->c() + c); break;
                        case details::e_sub : bocnode->set_c(bocnode->c() - c); break;
                        default             : return error_node();
                     }

                     result = bocnode;
                  }
                  else if (details::e_mul == bocnode->operation())
                  {
                     switch (operation)
                     {
                        case details::e_mul : bocnode->set_c(bocnode->c() * c); break;
                        case details::e_div : bocnode->set_c(bocnode->c() / c); break;
                        default             : return error_node();
                     }

                     result = bocnode;
                  }
                  else if (details::e_sub == bocnode->operation())
                  {
                     if (details::e_add == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::boc_node<Type,details::add_op<Type> > >
                                       (bocnode->move_branch(0), c - bocnode->c());

                        details::free_node(*expr_gen.node_allocator_,branch[0]);
                     }
                     else if (details::e_sub == operation)
                     {
                        bocnode->set_c(bocnode->c() + c);
                        result = bocnode;
                     }
                  }
                  else if (details::e_div == bocnode->operation())
                  {
                     switch (operation)
                     {
                        case details::e_div : bocnode->set_c(bocnode->c() * c); break;
                        case details::e_mul : bocnode->set_c(bocnode->c() / c); break;
                        default             : return error_node();
                     }

                     result = bocnode;
                  }

                  if (result)
                  {
                     details::free_node(*expr_gen.node_allocator_, branch[1]);
                  }
               }

               // c o (boc) --> boc
               else if (details::is_boc_node(branch[1]))
               {
                  details::boc_base_node<Type>* bocnode = static_cast<details::boc_base_node<Type>*>(branch[1]);

                  const Type c = static_cast<details::literal_node<Type>*>(branch[0])->value();

                  if (details::e_add == bocnode->operation())
                  {
                     if (details::e_add == operation)
                     {
                        bocnode->set_c(c + bocnode->c());
                        result = bocnode;
                     }
                     else if (details::e_sub == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::sub_op<Type> > >
                                       (c - bocnode->c(), bocnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_sub == bocnode->operation())
                  {
                     if (details::e_add == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::boc_node<Type,details::add_op<Type> > >
                                       (bocnode->move_branch(0), c - bocnode->c());

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                     else if (details::e_sub == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::sub_op<Type> > >
                                       (c + bocnode->c(), bocnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_mul == bocnode->operation())
                  {
                     if (details::e_mul == operation)
                     {
                        bocnode->set_c(c * bocnode->c());
                        result = bocnode;
                     }
                     else if (details::e_div == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::div_op<Type> > >
                                       (c / bocnode->c(), bocnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }
                  else if (details::e_div == bocnode->operation())
                  {
                     if (details::e_mul == operation)
                     {
                        bocnode->set_c(bocnode->c() / c);
                        result = bocnode;
                     }
                     else if (details::e_div == operation)
                     {
                        result = expr_gen.node_allocator_->
                                    template allocate_tt<typename details::cob_node<Type,details::div_op<Type> > >
                                       (c * bocnode->c(), bocnode->move_branch(0));

                        details::free_node(*expr_gen.node_allocator_,branch[1]);
                     }
                  }

                  if (result)
                  {
                     details::free_node(*expr_gen.node_allocator_,branch[0]);
                  }
               }

               return result;
            }
         };

         #ifndef exprtk_disable_enhanced_features
         inline bool synthesize_expression(const details::operator_type& operation,
                                           expression_node_ptr (&branch)[2],
                                           expression_node_ptr& result)
         {
            result = error_node();

            if (!operation_optimisable(operation))
               return false;

            const std::string node_id = branch_to_id(branch);

            const typename synthesize_map_t::iterator itr = synthesize_map_.find(node_id);

            if (synthesize_map_.end() != itr)
            {
               result = itr->second((*this), operation, branch);

               return true;
            }
            else
               return false;
         }

         struct synthesize_vov_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_rr<typename details::vov_node<Type,op1<Type> > > \
                                   (v1, v2);                                                       \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_cov_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type  c = static_cast<details::literal_node<Type>*> (branch[0])->value();
               const Type& v = static_cast<details::variable_node<Type>*>(branch[1])->ref  ();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
                  return expr_gen(T(0));
               else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
                  return expr_gen(T(0));
               else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  return static_cast<details::variable_node<Type>*>(branch[1]);
               else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  return static_cast<details::variable_node<Type>*>(branch[1]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_cr<typename details::cov_node<Type,op1<Type> > > \
                                   (c, v);                                                         \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_voc_expression
         {
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               const Type& v = static_cast<details::variable_node<Type>*>(branch[0])->ref  ();
               const Type  c = static_cast<details::literal_node<Type>*> (branch[1])->value();

               details::free_node(*(expr_gen.node_allocator_), branch[1]);

               if (expr_gen.cardinal_pow_optimisable(operation,c))
               {
                  if (std::equal_to<T>()(T(1),c))
                     return branch[0];
                  else
                     return expr_gen.cardinal_pow_optimisation(v,c);
               }
               else if (std::equal_to<T>()(T(0),c) && (details::e_mul == operation))
                  return expr_gen(T(0));
               else if (std::equal_to<T>()(T(0),c) && (details::e_div == operation))
                  return expr_gen(std::numeric_limits<T>::quiet_NaN());
               else if (std::equal_to<T>()(T(0),c) && (details::e_add == operation))
                  return static_cast<details::variable_node<Type>*>(branch[0]);
               else if (std::equal_to<T>()(T(1),c) && (details::e_mul == operation))
                  return static_cast<details::variable_node<Type>*>(branch[0]);
               else if (std::equal_to<T>()(T(1),c) && (details::e_div == operation))
                  return static_cast<details::variable_node<Type>*>(branch[0]);

               switch (operation)
               {
                  #define case_stmt(op0, op1)                                                      \
                  case op0 : return expr_gen.node_allocator_->                                     \
                                template allocate_rc<typename details::voc_node<Type,op1<Type> > > \
                                   (v, c);                                                         \

                  basic_opr_switch_statements
                  extended_opr_switch_statements
                  #undef case_stmt
                  default : return error_node();
               }
            }
         };

         struct synthesize_sf3ext_expression
         {
            template <typename T0, typename T1, typename T2>
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& sf3opr,
                                                      T0 t0, T1 t1, T2 t2)
            {
               switch (sf3opr)
               {
                  #define case_stmt(op)                                                                              \
                  case details::e_sf##op : return details::T0oT1oT2_sf3ext<T,T0,T1,T2,details::sf##op##_op<Type> >:: \
                                allocate(*(expr_gen.node_allocator_), t0, t1, t2);                                   \

                  case_stmt(00) case_stmt(01) case_stmt(02) case_stmt(03)
                  case_stmt(04) case_stmt(05) case_stmt(06) case_stmt(07)
                  case_stmt(08) case_stmt(09) case_stmt(10) case_stmt(11)
                  case_stmt(12) case_stmt(13) case_stmt(14) case_stmt(15)
                  case_stmt(16) case_stmt(17) case_stmt(18) case_stmt(19)
                  case_stmt(20) case_stmt(21) case_stmt(22) case_stmt(23)
                  case_stmt(24) case_stmt(25) case_stmt(26) case_stmt(27)
                  case_stmt(28) case_stmt(29) case_stmt(30)
                  #undef case_stmt
                  default : return error_node();
               }
            }

            template <typename T0, typename T1, typename T2>
            static inline bool compile(expression_generator<Type>& expr_gen, const std::string& id,
                                       T0 t0, T1 t1, T2 t2,
                                       expression_node_ptr& result)
            {
               details::operator_type sf3opr;

               if (!expr_gen.sf3_optimisable(id,sf3opr))
                  return false;
               else
                  result = synthesize_sf3ext_expression::template process<T0, T1, T2>
                              (expr_gen, sf3opr, t0, t1, t2);

               return true;
            }
         };

         struct synthesize_sf4ext_expression
         {
            template <typename T0, typename T1, typename T2, typename T3>
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& sf4opr,
                                                      T0 t0, T1 t1, T2 t2, T3 t3)
            {
               switch (sf4opr)
               {
                  #define case_stmt0(op)                                                                                      \
                  case details::e_sf##op : return details::T0oT1oT2oT3_sf4ext<Type,T0,T1,T2,T3,details::sf##op##_op<Type> >:: \
                                allocate(*(expr_gen.node_allocator_), t0, t1, t2, t3);                                        \

                  #define case_stmt1(op)                                                                                             \
                  case details::e_sf4ext##op : return details::T0oT1oT2oT3_sf4ext<Type,T0,T1,T2,T3,details::sfext##op##_op<Type> >:: \
                                allocate(*(expr_gen.node_allocator_), t0, t1, t2, t3);                                               \

                  case_stmt0(48) case_stmt0(49) case_stmt0(50) case_stmt0(51)
                  case_stmt0(52) case_stmt0(53) case_stmt0(54) case_stmt0(55)
                  case_stmt0(56) case_stmt0(57) case_stmt0(58) case_stmt0(59)
                  case_stmt0(60) case_stmt0(61) case_stmt0(62) case_stmt0(63)
                  case_stmt0(64) case_stmt0(65) case_stmt0(66) case_stmt0(67)
                  case_stmt0(68) case_stmt0(69) case_stmt0(70) case_stmt0(71)
                  case_stmt0(72) case_stmt0(73) case_stmt0(74) case_stmt0(75)
                  case_stmt0(76) case_stmt0(77) case_stmt0(78) case_stmt0(79)
                  case_stmt0(80) case_stmt0(81) case_stmt0(82) case_stmt0(83)

                  case_stmt1(00) case_stmt1(01) case_stmt1(02) case_stmt1(03)
                  case_stmt1(04) case_stmt1(05) case_stmt1(06) case_stmt1(07)
                  case_stmt1(08) case_stmt1(09) case_stmt1(10) case_stmt1(11)
                  case_stmt1(12) case_stmt1(13) case_stmt1(14) case_stmt1(15)
                  case_stmt1(16) case_stmt1(17) case_stmt1(18) case_stmt1(19)
                  case_stmt1(20) case_stmt1(21) case_stmt1(22) case_stmt1(23)
                  case_stmt1(24) case_stmt1(25) case_stmt1(26) case_stmt1(27)
                  case_stmt1(28) case_stmt1(29) case_stmt1(30) case_stmt1(31)
                  case_stmt1(32) case_stmt1(33) case_stmt1(34) case_stmt1(35)
                  case_stmt1(36) case_stmt1(37) case_stmt1(38) case_stmt1(39)
                  case_stmt1(40) case_stmt1(41) case_stmt1(42) case_stmt1(43)
                  case_stmt1(44) case_stmt1(45) case_stmt1(46) case_stmt1(47)
                  case_stmt1(48) case_stmt1(49) case_stmt1(50) case_stmt1(51)
                  case_stmt1(52) case_stmt1(53) case_stmt1(54) case_stmt1(55)
                  case_stmt1(56) case_stmt1(57) case_stmt1(58) case_stmt1(59)
                  case_stmt1(60) case_stmt1(61)

                  #undef case_stmt0
                  #undef case_stmt1
                  default : return error_node();
               }
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline bool compile(expression_generator<Type>& expr_gen, const std::string& id,
                                       T0 t0, T1 t1, T2 t2, T3 t3,
                                       expression_node_ptr& result)
            {
               details::operator_type sf4opr;

               if (!expr_gen.sf4_optimisable(id,sf4opr))
                  return false;
               else
                  result = synthesize_sf4ext_expression::template process<T0, T1, T2, T3>
                              (expr_gen, sf4opr, t0, t1, t2, t3);

               return true;
            }

            // T o (sf3ext)
            template <typename ExternalType>
            static inline bool compile_right(expression_generator<Type>& expr_gen,
                                             ExternalType t,
                                             const details::operator_type& operation,
                                             expression_node_ptr& sf3node,
                                             expression_node_ptr& result)
            {
               if (!details::is_sf3ext_node(sf3node))
                  return false;

               typedef details::T0oT1oT2_base_node<Type>* sf3ext_base_ptr;

               sf3ext_base_ptr n = static_cast<sf3ext_base_ptr>(sf3node);
               const std::string id = "t" + expr_gen.to_str(operation) + "(" + n->type_id() + ")";

               switch (n->type())
               {
                  case details::expression_node<Type>::e_covoc : return compile_right_impl
                                                                    <typename covoc_t::sf3_type_node,ExternalType, ctype, vtype, ctype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_covov : return compile_right_impl
                                                                    <typename covov_t::sf3_type_node,ExternalType, ctype, vtype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vocov : return compile_right_impl
                                                                    <typename vocov_t::sf3_type_node,ExternalType, vtype, ctype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vovoc : return compile_right_impl
                                                                    <typename vovoc_t::sf3_type_node,ExternalType, vtype, vtype, ctype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vovov : return compile_right_impl
                                                                    <typename vovov_t::sf3_type_node,ExternalType, vtype, vtype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  default                                      : return false;
               }
            }

            // (sf3ext) o T
            template <typename ExternalType>
            static inline bool compile_left(expression_generator<Type>& expr_gen,
                                            ExternalType t,
                                            const details::operator_type& operation,
                                            expression_node_ptr& sf3node,
                                            expression_node_ptr& result)
            {
               if (!details::is_sf3ext_node(sf3node))
                  return false;

               typedef details::T0oT1oT2_base_node<Type>* sf3ext_base_ptr;

               sf3ext_base_ptr n = static_cast<sf3ext_base_ptr>(sf3node);

               const std::string id = "(" + n->type_id() + ")" + expr_gen.to_str(operation) + "t";

               switch (n->type())
               {
                  case details::expression_node<Type>::e_covoc : return compile_left_impl
                                                                    <typename covoc_t::sf3_type_node,ExternalType, ctype, vtype, ctype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_covov : return compile_left_impl
                                                                    <typename covov_t::sf3_type_node,ExternalType, ctype, vtype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vocov : return compile_left_impl
                                                                    <typename vocov_t::sf3_type_node,ExternalType, vtype, ctype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vovoc : return compile_left_impl
                                                                    <typename vovoc_t::sf3_type_node,ExternalType, vtype, vtype, ctype>
                                                                       (expr_gen, id, t, sf3node, result);

                  case details::expression_node<Type>::e_vovov : return compile_left_impl
                                                                    <typename vovov_t::sf3_type_node,ExternalType, vtype, vtype, vtype>
                                                                       (expr_gen, id, t, sf3node, result);

                  default                                      : return false;
               }
            }

            template <typename SF3TypeNode, typename ExternalType, typename T0, typename T1, typename T2>
            static inline bool compile_right_impl(expression_generator<Type>& expr_gen,
                                                  const std::string& id,
                                                  ExternalType t,
                                                  expression_node_ptr& node,
                                                  expression_node_ptr& result)
            {
               SF3TypeNode* n = dynamic_cast<SF3TypeNode*>(node);

               if (n)
               {
                  T0 t0 = n->t0();
                  T1 t1 = n->t1();
                  T2 t2 = n->t2();

                  return synthesize_sf4ext_expression::template compile<ExternalType, T0, T1, T2>
                            (expr_gen, id, t, t0, t1, t2, result);
               }
               else
                  return false;
            }

            template <typename SF3TypeNode, typename ExternalType, typename T0, typename T1, typename T2>
            static inline bool compile_left_impl(expression_generator<Type>& expr_gen,
                                                 const std::string& id,
                                                 ExternalType t,
                                                 expression_node_ptr& node,
                                                 expression_node_ptr& result)
            {
               SF3TypeNode* n = dynamic_cast<SF3TypeNode*>(node);

               if (n)
               {
                  T0 t0 = n->t0();
                  T1 t1 = n->t1();
                  T2 t2 = n->t2();

                  return synthesize_sf4ext_expression::template compile<T0, T1, T2, ExternalType>
                            (expr_gen, id, t0, t1, t2, t, result);
               }
               else
                  return false;
            }
         };

         struct synthesize_vovov_expression0
         {
            typedef typename vovov_t::type0 node_type;
            typedef typename vovov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 v1) o1 (v2)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[0]);
               const Type& v0 = vov->v0();
               const Type& v1 = vov->v1();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = vov->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / v1) / v2 --> (vovov) v0 / (v1 * v2)
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, vtype>(expr_gen, "t/(t*t)", v0, v1, v2, result);

                     exprtk_debug(("(v0 / v1) / v2 --> (vovov) v0 / (v1 * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, vtype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), v0, v1, v2, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_vovov_expression1
         {
            typedef typename vovov_t::type1 node_type;
            typedef typename vovov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0) o0 (v1 o1 v2)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vov->v0();
               const Type& v2 = vov->v1();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = vov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // v0 / (v1 / v2) --> (vovov) (v0 * v2) / v1
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, vtype>(expr_gen, "(t*t)/t", v0, v2, v1, result);

                     exprtk_debug(("v0 / (v1 / v2) --> (vovov) (v0 * v2) / v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, vtype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), v0, v1, v2, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_vovoc_expression0
         {
            typedef typename vovoc_t::type0 node_type;
            typedef typename vovoc_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 v1) o1 (c)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[0]);
               const Type& v0 = vov->v0();
               const Type& v1 = vov->v1();
               const Type   c = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = vov->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / v1) / c --> (vovoc) v0 / (v1 * c)
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, "t/(t*t)", v0, v1, c, result);

                     exprtk_debug(("(v0 / v1) / c --> (vovoc) v0 / (v1 * c)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, vtype, ctype>
                     (expr_gen, id(expr_gen, o0, o1), v0, v1, c, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_vovoc_expression1
         {
            typedef typename vovoc_t::type1 node_type;
            typedef typename vovoc_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0) o0 (v1 o1 c)
               const details::voc_base_node<Type>* voc = static_cast<const details::voc_base_node<Type>*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = voc->v();
               const Type   c = voc->c();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = voc->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // v0 / (v1 / c) --> (vocov) (v0 * c) / v1
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, ctype, vtype>(expr_gen, "(t*t)/t", v0, c, v1, result);

                     exprtk_debug(("v0 / (v1 / c) --> (vocov) (v0 * c) / v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, vtype, ctype>
                     (expr_gen, id(expr_gen, o0, o1), v0, v1, c, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_vocov_expression0
         {
            typedef typename vocov_t::type0 node_type;
            typedef typename vocov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 c) o1 (v1)
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[0]);
               const Type& v0 = voc->v();
               const Type   c = voc->c();
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = voc->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / c) / v1 --> (vovoc) v0 / (v1 * c)
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, "t/(t*t)", v0, v1, c, result);

                     exprtk_debug(("(v0 / c) / v1 --> (vovoc) v0 / (v1 * c)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, ctype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), v0, c, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_vocov_expression1
         {
            typedef typename vocov_t::type1 node_type;
            typedef typename vocov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0) o0 (c o1 v1)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type   c = cov->c();
               const Type& v1 = cov->v();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = cov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // v0 / (c / v1) --> (vovoc) (v0 * v1) / c
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, "(t*t)/t", v0, v1, c, result);

                     exprtk_debug(("v0 / (c / v1) --> (vovoc) (v0 * v1) / c\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, ctype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), v0, c, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_covov_expression0
         {
            typedef typename covov_t::type0 node_type;
            typedef typename covov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c o0 v0) o1 (v1)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[0]);
               const Type   c = cov->c();
               const Type& v0 = cov->v();
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = cov->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c / v0) / v1 --> (covov) c / (v0 * v1)
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t/(t*t)", c, v0, v1, result);

                     exprtk_debug(("(c / v0) / v1 --> (covov) c / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<ctype, vtype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), c, v0, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_covov_expression1
         {
            typedef typename covov_t::type1 node_type;
            typedef typename covov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c) o0 (v0 o1 v1)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[1]);
               const Type   c = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vov->v0();
               const Type& v1 = vov->v1();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = vov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // c / (v0 / v1) --> (covov) (c * v1) / v0
                  if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", c, v1, v0, result);

                     exprtk_debug(("c / (v0 / v1) --> (covov) (c * v1) / v0\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<ctype, vtype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), c, v0, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_covoc_expression0
         {
            typedef typename covoc_t::type0 node_type;
            typedef typename covoc_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c0 o0 v) o1 (c1)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[0]);
               const Type  c0 = cov->c();
               const Type&  v = cov->v();
               const Type  c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = cov->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c0 + v) + c1 --> (cov) (c0 + c1) + v
                  if ((details::e_add == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0 + v) + c1 --> (cov) (c0 + c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 + c1, v);
                  }
                  // (c0 + v) - c1 --> (cov) (c0 - c1) + v
                  else if ((details::e_add == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0 + v) - c1 --> (cov) (c0 - c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 - c1, v);
                  }
                  // (c0 - v) + c1 --> (cov) (c0 + c1) - v
                  else if ((details::e_sub == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0 - v) + c1 --> (cov) (c0 + c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 + c1, v);
                  }
                  // (c0 - v) - c1 --> (cov) (c0 - c1) - v
                  else if ((details::e_sub == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0 - v) - c1 --> (cov) (c0 - c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 - c1, v);
                  }
                  // (c0 * v) * c1 --> (cov) (c0 * c1) * v
                  else if ((details::e_mul == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0 * v) * c1 --> (cov) (c0 * c1) * v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 * c1, v);
                  }
                  // (c0 * v) / c1 --> (cov) (c0 / c1) * v
                  else if ((details::e_mul == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0 * v) / c1 --> (cov) (c0 / c1) * v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 / c1, v);
                  }
                  // (c0 / v) * c1 --> (cov) (c0 * c1) / v
                  else if ((details::e_div == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0 / v) * c1 --> (cov) (c0 * c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 * c1, v);
                  }
                  // (c0 / v) / c1 --> (cov) (c0 / c1) / v
                  else if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0 / v) / c1 --> (cov) (c0 / c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 / c1, v);
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<ctype, vtype, ctype>
                     (expr_gen, id(expr_gen, o0, o1), c0, v, c1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c0, v, c1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_covoc_expression1
         {
            typedef typename covoc_t::type1 node_type;
            typedef typename covoc_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c0) o0 (v o1 c1)
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type&  v = voc->v();
               const Type  c1 = voc->c();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = voc->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c0) + (v + c1) --> (cov) (c0 + c1) + v
                  if ((details::e_add == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0) + (v + c1) --> (cov) (c0 + c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 + c1, v);
                  }
                  // (c0) + (v - c1) --> (cov) (c0 - c1) + v
                  else if ((details::e_add == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0) + (v - c1) --> (cov) (c0 - c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 - c1, v);
                  }
                  // (c0) - (v + c1) --> (cov) (c0 - c1) - v
                  else if ((details::e_sub == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0) - (v + c1) --> (cov) (c0 - c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 - c1, v);
                  }
                  // (c0) - (v - c1) --> (cov) (c0 + c1) - v
                  else if ((details::e_sub == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0) - (v - c1) --> (cov) (c0 + c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 + c1, v);
                  }
                  // (c0) * (v * c1) --> (voc) v * (c0 * c1)
                  else if ((details::e_mul == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0) * (v * c1) --> (voc) v * (c0 * c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 * c1, v);
                  }
                  // (c0) * (v / c1) --> (cov) (c0 / c1) * v
                  else if ((details::e_mul == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0) * (v / c1) --> (cov) (c0 / c1) * v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 / c1, v);
                  }
                  // (c0) / (v * c1) --> (cov) (c0 / c1) / v
                  else if ((details::e_div == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0) / (v * c1) --> (cov) (c0 / c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 / c1, v);
                  }
                  // (c0) / (v / c1) --> (cov) (c0 * c1) / v
                  else if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0) / (v / c1) --> (cov) (c0 * c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 * c1, v);
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<ctype, vtype, ctype>
                     (expr_gen, id(expr_gen, o0, o1), c0, v, c1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c0, v, c1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_cocov_expression0
         {
            typedef typename cocov_t::type0 node_type;
            static inline expression_node_ptr process(expression_generator<Type>&,
                                                      const details::operator_type&,
                                                      expression_node_ptr (&)[2])
            {
               // (c0 o0 c1) o1 (v) - Not possible.
               return error_node();
            }
         };

         struct synthesize_cocov_expression1
         {
            typedef typename cocov_t::type1 node_type;
            typedef typename cocov_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c0) o0 (c1 o1 v)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type  c1 = cov->c();
               const Type&  v = cov->v();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = cov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c0) + (c1 + v) --> (cov) (c0 + c1) + v
                  if ((details::e_add == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0) + (c1 + v) --> (cov) (c0 + c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 + c1, v);
                  }
                  // (c0) + (c1 - v) --> (cov) (c0 + c1) - v
                  else if ((details::e_add == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0) + (c1 - v) --> (cov) (c0 + c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 + c1, v);
                  }
                  // (c0) - (c1 + v) --> (cov) (c0 - c1) - v
                  else if ((details::e_sub == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(c0) - (c1 + v) --> (cov) (c0 - c1) - v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::sub_op<Type> > >(c0 - c1, v);
                  }
                  // (c0) - (c1 - v) --> (cov) (c0 - c1) + v
                  else if ((details::e_sub == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(c0) - (c1 - v) --> (cov) (c0 - c1) + v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::add_op<Type> > >(c0 - c1, v);
                  }
                  // (c0) * (c1 * v) --> (cov) (c0 * c1) * v
                  else if ((details::e_mul == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0) * (c1 * v) --> (cov) (c0 * c1) * v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 * c1, v);
                  }
                  // (c0) * (c1 / v) --> (cov) (c0 * c1) / v
                  else if ((details::e_mul == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0) * (c1 / v) --> (cov) (c0 * c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 * c1, v);
                  }
                  // (c0) / (c1 * v) --> (cov) (c0 / c1) / v
                  else if ((details::e_div == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(c0) / (c1 * v) --> (cov) (c0 / c1) / v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::div_op<Type> > >(c0 / c1, v);
                  }
                  // (c0) / (c1 / v) --> (cov) (c0 / c1) * v
                  else if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(c0) / (c1 / v) --> (cov) (c0 / c1) * v\n"));

                     return expr_gen.node_allocator_->
                               template allocate_cr<typename details::cov_node<Type,details::mul_op<Type> > >(c0 / c1, v);
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<ctype, ctype, vtype>
                     (expr_gen, id(expr_gen, o0, o1), c0, c1, v, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c0, c1, v, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)";
            }
         };

         struct synthesize_vococ_expression0
         {
            typedef typename vococ_t::type0 node_type;
            typedef typename vococ_t::sf3_type sf3_type;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v o0 c0) o1 (c1)
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[0]);
               const Type&  v = voc->v();
               const Type& c0 = voc->c();
               const Type& c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = voc->operation();
               const details::operator_type o1 = operation;

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v + c0) + c1 --> (voc) v + (c0 + c1)
                  if ((details::e_add == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(v + c0) + c1 --> (voc) v + (c0 + c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::add_op<Type> > >(v, c0 + c1);
                  }
                  // (v + c0) - c1 --> (voc) v + (c0 - c1)
                  else if ((details::e_add == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(v + c0) - c1 --> (voc) v + (c0 - c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::add_op<Type> > >(v, c0 - c1);
                  }
                  // (v - c0) + c1 --> (voc) v - (c0 + c1)
                  else if ((details::e_sub == o0) && (details::e_add == o1))
                  {
                     exprtk_debug(("(v - c0) + c1 --> (voc) v - (c0 + c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::add_op<Type> > >(v, c1 - c0);
                  }
                  // (v - c0) - c1 --> (voc) v - (c0 + c1)
                  else if ((details::e_sub == o0) && (details::e_sub == o1))
                  {
                     exprtk_debug(("(v - c0) - c1 --> (voc) v - (c0 + c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::sub_op<Type> > >(v, c0 + c1);
                  }
                  // (v * c0) * c1 --> (voc) v * (c0 * c1)
                  else if ((details::e_mul == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(v * c0) * c1 --> (voc) v * (c0 * c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::mul_op<Type> > >(v, c0 * c1);
                  }
                  // (v * c0) / c1 --> (voc) v * (c0 / c1)
                  else if ((details::e_mul == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(v * c0) / c1 --> (voc) v * (c0 / c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::mul_op<Type> > >(v, c0 / c1);
                  }
                  // (v / c0) * c1 --> (voc) v * (c1 / c0)
                  else if ((details::e_div == o0) && (details::e_mul == o1))
                  {
                     exprtk_debug(("(v / c0) * c1 --> (voc) v * (c1 / c0)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::mul_op<Type> > >(v, c1 / c0);
                  }
                  // (v / c0) / c1 --> (voc) v / (c0 * c1)
                  else if ((details::e_div == o0) && (details::e_div == o1))
                  {
                     exprtk_debug(("(v / c0) / c1 --> (voc) v / (c0 * c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::div_op<Type> > >(v, c0 * c1);
                  }
                  // (v ^ c0) ^ c1 --> (voc) v ^ (c0 * c1)
                  else if ((details::e_pow == o0) && (details::e_pow == o1))
                  {
                     exprtk_debug(("(v ^ c0) ^ c1 --> (voc) v ^ (c0 * c1)\n"));

                     return expr_gen.node_allocator_->
                               template allocate_rc<typename details::voc_node<Type,details::pow_op<Type> > >(v, c0 * c1);
                  }
               }

               const bool synthesis_result =
                  synthesize_sf3ext_expression::template compile<vtype, ctype, ctype>
                     (expr_gen, id(expr_gen, o0, o1), v, c0, c1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v, c0, c1, f0, f1);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "t";
            }
         };

         struct synthesize_vococ_expression1
         {
            typedef typename vococ_t::type0 node_type;

            static inline expression_node_ptr process(expression_generator<Type>&,
                                                      const details::operator_type&,
                                                      expression_node_ptr (&)[2])
            {
               // (v) o0 (c0 o1 c1) - Not possible.
               exprtk_debug(("(v) o0 (c0 o1 c1) - Not possible.\n"));
               return error_node();
            }
         };

         struct synthesize_vovovov_expression0
         {
            typedef typename vovovov_t::type0 node_type;
            typedef typename vovovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 v1) o1 (v2 o2 v3)
               const details::vov_base_node<Type>* vov0 = static_cast<details::vov_base_node<Type>*>(branch[0]);
               const details::vov_base_node<Type>* vov1 = static_cast<details::vov_base_node<Type>*>(branch[1]);
               const Type& v0 = vov0->v0();
               const Type& v1 = vov0->v1();
               const Type& v2 = vov1->v0();
               const Type& v3 = vov1->v1();
               const details::operator_type o0 = vov0->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = vov1->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / v1) * (v2 / v3) --> (vovovov) (v0 * v2) / (v1 * v3)
                  if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", v0, v2, v1, v3, result);

                     exprtk_debug(("(v0 / v1) * (v2 / v3) --> (vovovov) (v0 * v2) / (v1 * v3)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / v1) / (v2 / v3) --> (vovovov) (v0 * v3) / (v1 * v2)
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", v0, v3, v1, v2, result);

                     exprtk_debug(("(v0 / v1) / (v2 / v3) --> (vovovov) (v0 * v3) / (v1 * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 + v1) / (v2 / v3) --> (vovovov) (v0 + v1) * (v3 / v2)
                  else if ((details::e_add == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, vtype>(expr_gen, "(t+t)*(t/t)", v0, v1, v3, v2, result);

                     exprtk_debug(("(v0 + v1) / (v2 / v3) --> (vovovov) (v0 + v1) * (v3 / v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 - v1) / (v2 / v3) --> (vovovov) (v0 + v1) * (v3 / v2)
                  else if ((details::e_sub == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, vtype>(expr_gen, "(t-t)*(t/t)", v0, v1, v3, v2, result);

                     exprtk_debug(("(v0 - v1) / (v2 / v3) --> (vovovov) (v0 - v1) * (v3 / v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * v1) / (v2 / v3) --> (vovovov) ((v0 * v1) * v3) / v2
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, vtype>(expr_gen, "((t*t)*t)/t", v0, v1, v3, v2, result);

                     exprtk_debug(("(v0 * v1) / (v2 / v3) --> (vovovov) ((v0 * v1) * v3) / v2\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, v3, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, v3, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vovovoc_expression0
         {
            typedef typename vovovoc_t::type0 node_type;
            typedef typename vovovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 v1) o1 (v2 o2 c)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[0]);
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[1]);
               const Type& v0 = vov->v0();
               const Type& v1 = vov->v1();
               const Type& v2 = voc->v ();
               const Type   c = voc->c ();
               const details::operator_type o0 = vov->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = voc->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / v1) * (v2 / c) --> (vovovoc) (v0 * v2) / (v1 * c)
                  if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, ctype>(expr_gen, "(t*t)/(t*t)", v0, v2, v1, c, result);

                     exprtk_debug(("(v0 / v1) * (v2 / c) --> (vovovoc) (v0 * v2) / (v1 * c)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / v1) / (v2 / c) --> (vocovov) (v0 * c) / (v1 * v2)
                  if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, ctype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", v0, c, v1, v2, result);

                     exprtk_debug(("(v0 / v1) / (v2 / c) --> (vocovov) (v0 * c) / (v1 * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, c, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, c, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vovocov_expression0
         {
            typedef typename vovocov_t::type0 node_type;
            typedef typename vovocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 v1) o1 (c o2 v2)
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[0]);
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[1]);
               const Type& v0 = vov->v0();
               const Type& v1 = vov->v1();
               const Type& v2 = cov->v ();
               const Type   c = cov->c ();
               const details::operator_type o0 = vov->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = cov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / v1) * (c / v2) --> (vocovov) (v0 * c) / (v1 * v2)
                  if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, ctype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", v0, c, v1, v2, result);

                     exprtk_debug(("(v0 / v1) * (c / v2) --> (vocovov) (v0 * c) / (v1 * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / v1) / (c / v2) --> (vovovoc) (v0 * v2) / (v1 * c)
                  if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, vtype, ctype>(expr_gen, "(t*t)/(t*t)", v0, v2, v1, c, result);

                     exprtk_debug(("(v0 / v1) / (c / v2) --> (vovovoc) (v0 * v2) / (v1 * c)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, c, v2, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vocovov_expression0
         {
            typedef typename vocovov_t::type0 node_type;
            typedef typename vocovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 c) o1 (v1 o2 v2)
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[0]);
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[1]);
               const Type   c = voc->c ();
               const Type& v0 = voc->v ();
               const Type& v1 = vov->v0();
               const Type& v2 = vov->v1();
               const details::operator_type o0 = voc->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = vov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 / c) * (v1 / v2) --> (vovocov) (v0 * v1) / (c * v2)
                  if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, ctype, vtype>(expr_gen, "(t*t)/(t*t)", v0, v1, c, v2, result);

                     exprtk_debug(("(v0 / c) * (v1 / v2) --> (vovocov) (v0 * v1) / (c * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c) / (v1 / v2) --> (vovocov) (v0 * v2) / (c * v1)
                  if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, vtype, ctype, vtype>(expr_gen, "(t*t)/(t*t)", v0, v2, c, v1, result);

                     exprtk_debug(("(v0 / c) / (v1 / v2) --> (vovocov) (v0 * v2) / (c * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c, v1, v2, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_covovov_expression0
         {
            typedef typename covovov_t::type0 node_type;
            typedef typename covovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c o0 v0) o1 (v1 o2 v2)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[0]);
               const details::vov_base_node<Type>* vov = static_cast<details::vov_base_node<Type>*>(branch[1]);
               const Type   c = cov->c ();
               const Type& v0 = cov->v ();
               const Type& v1 = vov->v0();
               const Type& v2 = vov->v1();
               const details::operator_type o0 = cov->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = vov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c / v0) * (v1 / v2) --> (covovov) (c * v1) / (v0 * v2)
                  if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<ctype, vtype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", c, v1, v0, v2, result);

                     exprtk_debug(("(c / v0) * (v1 / v2) --> (covovov) (c * v1) / (v0 * v2)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c / v0) / (v1 / v2) --> (covovov) (c * v2) / (v0 * v1)
                  if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<ctype, vtype, vtype, vtype>(expr_gen, "(t*t)/(t*t)", c, v2, v0, v1, result);

                     exprtk_debug(("(c / v0) / (v1 / v2) --> (covovov) (c * v2) / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c, v0, v1, v2, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_covocov_expression0
         {
            typedef typename covocov_t::type0 node_type;
            typedef typename covocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c0 o0 v0) o1 (c1 o2 v1)
               const details::cov_base_node<Type>* cov0 = static_cast<details::cov_base_node<Type>*>(branch[0]);
               const details::cov_base_node<Type>* cov1 = static_cast<details::cov_base_node<Type>*>(branch[1]);
               const Type  c0 = cov0->c();
               const Type& v0 = cov0->v();
               const Type  c1 = cov1->c();
               const Type& v1 = cov1->v();
               const details::operator_type o0 = cov0->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = cov1->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c0 + v0) + (c1 + v1) --> (covov) (c0 + c1) + v0 + v1
                  if ((details::e_add == o0) && (details::e_add == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)+t", (c0 + c1), v0, v1, result);

                     exprtk_debug(("(c0 + v0) + (c1 + v1) --> (covov) (c0 + c1) + v0 + v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 + v0) - (c1 + v1) --> (covov) (c0 - c1) + v0 - v1
                  else if ((details::e_add == o0) && (details::e_sub == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)-t", (c0 - c1), v0, v1, result);

                     exprtk_debug(("(c0 + v0) - (c1 + v1) --> (covov) (c0 - c1) + v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 - v0) - (c1 - v1) --> (covov) (c0 - c1) - v0 + v1
                  else if ((details::e_sub == o0) && (details::e_sub == o1) && (details::e_sub == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t-t)+t", (c0 - c1), v0, v1, result);

                     exprtk_debug(("(c0 - v0) - (c1 - v1) --> (covov) (c0 - c1) - v0 + v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) * (c1 * v1) --> (covov) (c0 * c1) * v0 * v1
                  else if ((details::e_mul == o0) && (details::e_mul == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) * (c1 * v1) --> (covov) (c0 * c1) * v0 * v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) / (c1 * v1) --> (covov) (c0 / c1) * (v0 / v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) / (c1 * v1) --> (covov) (c0 / c1) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) * (c1 / v1) --> (covov) (c0 * c1) / (v0 * v1)
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t/(t*t)", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(c0 / v0) * (c1 / v1) --> (covov) (c0 * c1) / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) / (c1 / v1) --> (covov) ((c0 / c1) * v1) / v0
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 / c1), v1, v0, result);

                     exprtk_debug(("(c0 / v0) / (c1 / v1) --> (covov) ((c0 / c1) * v1) / v0\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) / (c1 / v1) --> (covov) (c0 / c1) * (v0 * v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t*(t*t)", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) / (c1 / v1) --> (covov) (c0 / c1) * (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) / (c1 * v1) --> (covov) (c0 / c1) / (v0 * v1)
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t/(t*t)", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(c0 / v0) / (c1 * v1) --> (covov) (c0 / c1) / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c * v0) +/- (c * v1) --> (covov) c * (v0 +/- v1)
                  else if (
                            (std::equal_to<T>()(c0,c1)) &&
                            (details::e_mul == o0)      &&
                            (details::e_mul == o2)      &&
                            (
                              (details::e_add == o1) ||
                              (details::e_sub == o1)
                            )
                          )
                  {
                     std::string specfunc;

                     switch (o1)
                     {
                        case details::e_add : specfunc = "t*(t+t)"; break;
                        case details::e_sub : specfunc = "t*(t-t)"; break;
                        default             : return error_node();
                     }

                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, specfunc, c0, v0, v1, result);

                     exprtk_debug(("(c * v0) +/- (c * v1) --> (covov) c * (v0 +/- v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, c1, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vocovoc_expression0
         {
            typedef typename vocovoc_t::type0 node_type;
            typedef typename vocovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 c0) o1 (v1 o2 c1)
               const details::voc_base_node<Type>* voc0 = static_cast<details::voc_base_node<Type>*>(branch[0]);
               const details::voc_base_node<Type>* voc1 = static_cast<details::voc_base_node<Type>*>(branch[1]);
               const Type  c0 = voc0->c();
               const Type& v0 = voc0->v();
               const Type  c1 = voc1->c();
               const Type& v1 = voc1->v();
               const details::operator_type o0 = voc0->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = voc1->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 + c0) + (v1 + c1) --> (covov) (c0 + c1) + v0 + v1
                  if ((details::e_add == o0) && (details::e_add == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)+t", (c0 + c1), v0, v1, result);

                     exprtk_debug(("(v0 + c0) + (v1 + c1) --> (covov) (c0 + c1) + v0 + v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 + c0) - (v1 + c1) --> (covov) (c0 - c1) + v0 - v1
                  else if ((details::e_add == o0) && (details::e_sub == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)-t", (c0 - c1), v0, v1, result);

                     exprtk_debug(("(v0 + c0) - (v1 + c1) --> (covov) (c0 - c1) + v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 - c0) - (v1 - c1) --> (covov) (c1 - c0) + v0 - v1
                  else if ((details::e_sub == o0) && (details::e_sub == o1) && (details::e_sub == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)-t", (c1 - c0), v0, v1, result);

                     exprtk_debug(("(v0 - c0) - (v1 - c1) --> (covov) (c1 - c0) + v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) * (v1 * c1) --> (covov) (c0 * c1) * v0 * v1
                  else if ((details::e_mul == o0) && (details::e_mul == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) * (v1 * c1) --> (covov) (c0 * c1) * v0 * v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) / (v1 * c1) --> (covov) (c0 / c1) * (v0 / v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) / (v1 * c1) --> (covov) (c0 / c1) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) * (v1 / c1) --> (covov) (1 / (c0 * c1)) * v0 * v1
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", Type(1) / (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 / c0) * (v1 / c1) --> (covov) (1 / (c0 * c1)) * v0 * v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) / (v1 / c1) --> (covov) ((c1 / c0) * v0) / v1
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c1 / c0), v0, v1, result);

                     exprtk_debug(("(v0 / c0) / (v1 / c1) --> (covov) ((c1 / c0) * v0) / v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) / (v1 / c1) --> (covov) (c0 * c1) * (v0 / v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t*(t/t)", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) / (v1 / c1) --> (covov) (c0 * c1) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) / (v1 * c1) --> (covov) (1 / (c0 * c1)) * v0 / v1
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t*(t/t)", Type(1) / (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 / c0) / (v1 * c1) --> (covov) (1 / (c0 * c1)) * v0 / v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) * (v1 + c1) --> (vocovoc) (v0 * (1 / c0)) * (v1 + c1)
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, ctype, vtype, ctype>(expr_gen, "(t*t)*(t+t)", v0, T(1) / c0, v1, c1, result);

                     exprtk_debug(("(v0 / c0) * (v1 + c1) --> (vocovoc) (v0 * (1 / c0)) * (v1 + c1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) * (v1 - c1) --> (vocovoc) (v0 * (1 / c0)) * (v1 - c1)
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_sub == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf4ext_expression::
                           template compile<vtype, ctype, vtype, ctype>(expr_gen, "(t*t)*(t-t)", v0, T(1) / c0, v1, c1, result);

                     exprtk_debug(("(v0 / c0) * (v1 - c1) --> (vocovoc) (v0 * (1 / c0)) * (v1 - c1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c) +/- (v1 * c) --> (covov) c * (v0 +/- v1)
                  else if (
                            (std::equal_to<T>()(c0,c1)) &&
                            (details::e_mul == o0)      &&
                            (details::e_mul == o2)      &&
                            (
                              (details::e_add == o1) ||
                              (details::e_sub == o1)
                            )
                          )
                  {
                     std::string specfunc;

                     switch (o1)
                     {
                        case details::e_add : specfunc = "t*(t+t)"; break;
                        case details::e_sub : specfunc = "t*(t-t)"; break;
                        default             : return error_node();
                     }

                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, specfunc, c0, v0, v1, result);

                     exprtk_debug(("(v0 * c) +/- (v1 * c) --> (covov) c * (v0 +/- v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c) +/- (v1 / c) --> (vovoc) (v0 +/- v1) / c
                  else if (
                            (std::equal_to<T>()(c0,c1)) &&
                            (details::e_div == o0)      &&
                            (details::e_div == o2)      &&
                            (
                              (details::e_add == o1) ||
                              (details::e_sub == o1)
                            )
                          )
                  {
                     std::string specfunc;

                     switch (o1)
                     {
                        case details::e_add : specfunc = "(t+t)/t"; break;
                        case details::e_sub : specfunc = "(t-t)/t"; break;
                        default             : return error_node();
                     }

                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, specfunc, v0, v1, c0, result);

                     exprtk_debug(("(v0 / c) +/- (v1 / c) --> (vovoc) (v0 +/- v1) / c\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, v1, c1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_covovoc_expression0
         {
            typedef typename covovoc_t::type0 node_type;
            typedef typename covovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (c0 o0 v0) o1 (v1 o2 c1)
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[0]);
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[1]);
               const Type  c0 = cov->c();
               const Type& v0 = cov->v();
               const Type  c1 = voc->c();
               const Type& v1 = voc->v();
               const details::operator_type o0 = cov->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = voc->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (c0 + v0) + (v1 + c1) --> (covov) (c0 + c1) + v0 + v1
                  if ((details::e_add == o0) && (details::e_add == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)+t", (c0 + c1), v0, v1, result);

                     exprtk_debug(("(c0 + v0) + (v1 + c1) --> (covov) (c0 + c1) + v0 + v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 + v0) - (v1 + c1) --> (covov) (c0 - c1) + v0 - v1
                  else if ((details::e_add == o0) && (details::e_sub == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)-t", (c0 - c1), v0, v1, result);

                     exprtk_debug(("(c0 + v0) - (v1 + c1) --> (covov) (c0 - c1) + v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 - v0) - (v1 - c1) --> (covov) (c0 + c1) - v0 - v1
                  else if ((details::e_sub == o0) && (details::e_sub == o1) && (details::e_sub == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t-(t+t)", (c0 + c1), v0, v1, result);

                     exprtk_debug(("(c0 - v0) - (v1 - c1) --> (covov) (c0 + c1) - v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) * (v1 * c1) --> (covov) (c0 * c1) * v0 * v1
                  else if ((details::e_mul == o0) && (details::e_mul == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) * (v1 * c1) --> (covov) (c0 * c1) * v0 * v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) / (v1 * c1) --> (covov) (c0 / c1) * (v0 / v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) / (v1 * c1) --> (covov) (c0 / c1) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) * (v1 / c1) --> (covov) (c0 / c1) * (v1 / v0)
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t*(t/t)", (c0 / c1), v1, v0, result);

                     exprtk_debug(("(c0 / v0) * (v1 / c1) --> (covov) (c0 / c1) * (v1 / v0)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) / (v1 / c1) --> (covov) (c0 * c1) / (v0 * v1)
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t/(t*t)", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(c0 / v0) / (v1 / c1) --> (covov) (c0 * c1) / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 * v0) / (v1 / c1) --> (covov) (c0 * c1) * (v0 / v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(c0 * v0) / (v1 / c1) --> (covov) (c0 * c1) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c0 / v0) / (v1 * c1) --> (covov) (c0 / c1) / (v0 * v1)
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "t/(t*t)", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(c0 / v0) / (v1 * c1) --> (covov) (c0 / c1) / (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (c * v0) +/- (v1 * c) --> (covov) c * (v0 +/- v1)
                  else if (
                            (std::equal_to<T>()(c0,c1)) &&
                            (details::e_mul == o0)      &&
                            (details::e_mul == o2)      &&
                            (
                              (details::e_add == o1) ||
                              (details::e_sub == o1)
                            )
                          )
                  {
                     std::string specfunc;

                     switch (o1)
                     {
                        case details::e_add : specfunc = "t*(t+t)"; break;
                        case details::e_sub : specfunc = "t*(t-t)"; break;
                        default             : return error_node();
                     }

                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, specfunc, c0, v0, v1, result);

                     exprtk_debug(("(c * v0) +/- (v1 * c) --> (covov) c * (v0 +/- v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, v1, c1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vococov_expression0
         {
            typedef typename vococov_t::type0 node_type;
            typedef typename vococov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 c0) o1 (c1 o2 v1)
               const details::voc_base_node<Type>* voc = static_cast<details::voc_base_node<Type>*>(branch[0]);
               const details::cov_base_node<Type>* cov = static_cast<details::cov_base_node<Type>*>(branch[1]);
               const Type  c0 = voc->c();
               const Type& v0 = voc->v();
               const Type  c1 = cov->c();
               const Type& v1 = cov->v();
               const details::operator_type o0 = voc->operation();
               const details::operator_type o1 = operation;
               const details::operator_type o2 = cov->operation();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               if (expr_gen.parser_->settings_.strength_reduction_enabled())
               {
                  // (v0 + c0) + (c1 + v1) --> (covov) (c0 + c1) + v0 + v1
                  if ((details::e_add == o0) && (details::e_add == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)+t", (c0 + c1), v0, v1, result);

                     exprtk_debug(("(v0 + c0) + (c1 + v1) --> (covov) (c0 + c1) + v0 + v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 + c0) - (c1 + v1) --> (covov) (c0 - c1) + v0 - v1
                  else if ((details::e_add == o0) && (details::e_sub == o1) && (details::e_add == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t+t)-t", (c0 - c1), v0, v1, result);

                     exprtk_debug(("(v0 + c0) - (c1 + v1) --> (covov) (c0 - c1) + v0 - v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 - c0) - (c1 - v1) --> (vovoc) v0 + v1 - (c1 + c0)
                  else if ((details::e_sub == o0) && (details::e_sub == o1) && (details::e_sub == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, "(t+t)-t", v0, v1, (c1 + c0), result);

                     exprtk_debug(("(v0 - c0) - (c1 - v1) --> (vovoc) v0 + v1 - (c1 + c0)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) * (c1 * v1) --> (covov) (c0 * c1) * v0 * v1
                  else if ((details::e_mul == o0) && (details::e_mul == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) * (c1 * v1) --> (covov) (c0 * c1) * v0 * v1\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) / (c1 * v1) --> (covov) (c0 / c1) * (v0 * v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) / (c1 * v1) --> (covov) (c0 / c1) * (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) * (c1 / v1) --> (covov) (c1 / c0) * (v0 / v1)
                  else if ((details::e_div == o0) && (details::e_mul == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", (c1 / c0), v0, v1, result);

                     exprtk_debug(("(v0 / c0) * (c1 / v1) --> (covov) (c1 / c0) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c0) / (c1 / v1) --> (covov) (c0 / c1) * (v0 * v1)
                  else if ((details::e_mul == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)*t", (c0 / c1), v0, v1, result);

                     exprtk_debug(("(v0 * c0) / (c1 / v1) --> (covov) (c0 / c1) * (v0 * v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) / (c1 * v1) --> (covov) (1 / (c0 * c1)) * (v0 / v1)
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_mul == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, "(t*t)/t", Type(1) / (c0 * c1), v0, v1, result);

                     exprtk_debug(("(v0 / c0) / (c1 * v1) --> (covov) (1 / (c0 * c1)) * (v0 / v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 / c0) / (c1 / v1) --> (vovoc) (v0 * v1) * (1 / (c0 * c1))
                  else if ((details::e_div == o0) && (details::e_div == o1) && (details::e_div == o2))
                  {
                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<vtype, vtype, ctype>(expr_gen, "(t*t)*t", v0, v1, Type(1) / (c0 * c1), result);

                     exprtk_debug(("(v0 / c0) / (c1 / v1) --> (vovoc) (v0 * v1) * (1 / (c0 * c1))\n"));

                     return (synthesis_result) ? result : error_node();
                  }
                  // (v0 * c) +/- (c * v1) --> (covov) c * (v0 +/- v1)
                  else if (
                            (std::equal_to<T>()(c0,c1)) &&
                            (details::e_mul == o0)      &&
                            (details::e_mul == o2)      &&
                            (
                              (details::e_add == o1) || (details::e_sub == o1)
                            )
                          )
                  {
                     std::string specfunc;

                     switch (o1)
                     {
                        case details::e_add : specfunc = "t*(t+t)"; break;
                        case details::e_sub : specfunc = "t*(t-t)"; break;
                        default             : return error_node();
                     }

                     const bool synthesis_result =
                        synthesize_sf3ext_expression::
                           template compile<ctype, vtype, vtype>(expr_gen, specfunc, c0, v0, v1, result);

                     exprtk_debug(("(v0 * c) +/- (c * v1) --> (covov) c * (v0 +/- v1)\n"));

                     return (synthesis_result) ? result : error_node();
                  }
               }

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, c1, v1, result);

               if (synthesis_result)
                  return result;

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();
               else if (!expr_gen.valid_operator(o1,f1))
                  return error_node();
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();
               else
                  return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "t)" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vovovov_expression1
         {
            typedef typename vovovov_t::type1 node_type;
            typedef typename vovovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (v1 o1 (v2 o2 v3))
               typedef typename synthesize_vovov_expression1::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vovov->t0();
               const Type& v2 = vovov->t1();
               const Type& v3 = vovov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovov->f0();
               binary_functor_t f2 = vovov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen,id(expr_gen, o0, o1, o2), v0, v1, v2, v3, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (v1 o1 (v2 o2 v3))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, v3, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vovovoc_expression1
         {
            typedef typename vovovoc_t::type1 node_type;
            typedef typename vovovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (v1 o1 (v2 o2 c))
               typedef typename synthesize_vovoc_expression1::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vovoc->t0();
               const Type& v2 = vovoc->t1();
               const Type   c = vovoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovoc->f0();
               binary_functor_t f2 = vovoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, c, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (v1 o1 (v2 o2 c))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, c, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vovocov_expression1
         {
            typedef typename vovocov_t::type1 node_type;
            typedef typename vovocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (v1 o1 (c o2 v2))
               typedef typename synthesize_vocov_expression1::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vocov->t0();
               const Type   c = vocov->t1();
               const Type& v2 = vocov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vocov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vocov->f0();
               binary_functor_t f2 = vocov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, c, v2, result);

               if (synthesis_result)
                  return result;
               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (v1 o1 (c o2 v2))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vocovov_expression1
         {
            typedef typename vocovov_t::type1 node_type;
            typedef typename vocovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (c o1 (v1 o2 v2))
               typedef typename synthesize_covov_expression1::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type   c = covov->t0();
               const Type& v1 = covov->t1();
               const Type& v2 = covov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(covov->f0());
               const details::operator_type o2 = expr_gen.get_operator(covov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = covov->f0();
               binary_functor_t f2 = covov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (c o1 (v1 o2 v2))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_covovov_expression1
         {
            typedef typename covovov_t::type1 node_type;
            typedef typename covovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c o0 (v0 o1 (v1 o2 v2))
               typedef typename synthesize_vovov_expression1::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[1]);
               const Type   c = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovov->f0();
               binary_functor_t f2 = vovov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c, v0, v1, v2, result);

               if (synthesis_result)
                  return result;
               if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c o0 (v0 o1 (v1 o2 v2))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_covocov_expression1
         {
            typedef typename covocov_t::type1 node_type;
            typedef typename covocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c0 o0 (v0 o1 (c1 o2 v1))
               typedef typename synthesize_vocov_expression1::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vocov->t0();
               const Type  c1 = vocov->t1();
               const Type& v1 = vocov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vocov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vocov->f0();
               binary_functor_t f2 = vocov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c0 o0 (v0 o1 (c1 o2 v1))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vocovoc_expression1
         {
            typedef typename vocovoc_t::type1 node_type;
            typedef typename vocovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (c0 o1 (v1 o2 c2))
               typedef typename synthesize_covoc_expression1::node_type lcl_covoc_t;

               const lcl_covoc_t* covoc = static_cast<const lcl_covoc_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type  c0 = covoc->t0();
               const Type& v1 = covoc->t1();
               const Type  c1 = covoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(covoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(covoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = covoc->f0();
               binary_functor_t f2 = covoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (c0 o1 (v1 o2 c2))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_covovoc_expression1
         {
            typedef typename covovoc_t::type1 node_type;
            typedef typename covovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;
            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c0 o0 (v0 o1 (v1 o2 c1))
               typedef typename synthesize_vovoc_expression1::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vovoc->t0();
               const Type& v1 = vovoc->t1();
               const Type  c1 = vovoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovoc->f0();
               binary_functor_t f2 = vovoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c0 o0 (v0 o1 (v1 o2 c1))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vococov_expression1
         {
            typedef typename vococov_t::type1 node_type;
            typedef typename vococov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 (c0 o1 (c1 o2 v1))
               typedef typename synthesize_cocov_expression1::node_type lcl_cocov_t;

               const lcl_cocov_t* cocov = static_cast<const lcl_cocov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type  c0 = cocov->t0();
               const Type  c1 = cocov->t1();
               const Type& v1 = cocov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(cocov->f0());
               const details::operator_type o2 = expr_gen.get_operator(cocov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = cocov->f0();
               binary_functor_t f2 = cocov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 (c0 o1 (c1 o2 v1))\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"  << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "(t" << expr_gen.to_str(o2)
                  << "t))";
            }
         };

         struct synthesize_vovovov_expression2
         {
            typedef typename vovovov_t::type2 node_type;
            typedef typename vovovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 ((v1 o1 v2) o2 v3)
               typedef typename synthesize_vovov_expression0::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vovov->t0();
               const Type& v2 = vovov->t1();
               const Type& v3 = vovov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovov->f0();
               binary_functor_t f2 = vovov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, v3, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 ((v1 o1 v2) o2 v3)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, v3, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vovovoc_expression2
         {
            typedef typename vovovoc_t::type2 node_type;
            typedef typename vovovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 ((v1 o1 v2) o2 c)
               typedef typename synthesize_vovoc_expression0::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vovoc->t0();
               const Type& v2 = vovoc->t1();
               const Type   c = vovoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovoc->f0();
               binary_functor_t f2 = vovoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, c, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 ((v1 o1 v2) o2 c)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, c, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vovocov_expression2
         {
            typedef typename vovocov_t::type2 node_type;
            typedef typename vovocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 ((v1 o1 c) o2 v2)
               typedef typename synthesize_vocov_expression0::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type& v1 = vocov->t0();
               const Type   c = vocov->t1();
               const Type& v2 = vocov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vocov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vocov->f0();
               binary_functor_t f2 = vocov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, c, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 ((v1 o1 c) o2 v2)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vocovov_expression2
         {
            typedef typename vocovov_t::type2 node_type;
            typedef typename vocovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 ((c o1 v1) o2 v2)
               typedef typename synthesize_covov_expression0::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type   c = covov->t0();
               const Type& v1 = covov->t1();
               const Type& v2 = covov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(covov->f0());
               const details::operator_type o2 = expr_gen.get_operator(covov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = covov->f0();
               binary_functor_t f2 = covov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 ((c o1 v1) o2 v2)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_covovov_expression2
         {
            typedef typename covovov_t::type2 node_type;
            typedef typename covovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c o0 ((v1 o1 v2) o2 v3)
               typedef typename synthesize_vovov_expression0::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[1]);
               const Type   c = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovov->f0();
               binary_functor_t f2 = vovov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c, v0, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c o0 ((v1 o1 v2) o2 v3)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
        };

         struct synthesize_covocov_expression2
         {
            typedef typename covocov_t::type2 node_type;
            typedef typename covocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c0 o0 ((v0 o1 c1) o2 v1)
               typedef typename synthesize_vocov_expression0::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vocov->t0();
               const Type  c1 = vocov->t1();
               const Type& v1 = vocov->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o2 = expr_gen.get_operator(vocov->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vocov->f0();
               binary_functor_t f2 = vocov->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c0 o0 ((v0 o1 c1) o2 v1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vocovoc_expression2
         {
            typedef typename vocovoc_t::type2 node_type;
            typedef typename vocovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // v0 o0 ((c0 o1 v1) o2 c1)
               typedef typename synthesize_covoc_expression0::node_type lcl_covoc_t;

               const lcl_covoc_t* covoc = static_cast<const lcl_covoc_t*>(branch[1]);
               const Type& v0 = static_cast<details::variable_node<Type>*>(branch[0])->ref();
               const Type  c0 = covoc->t0();
               const Type& v1 = covoc->t1();
               const Type  c1 = covoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(covoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(covoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = covoc->f0();
               binary_functor_t f2 = covoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("v0 o0 ((c0 o1 v1) o2 c1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_covovoc_expression2
         {
            typedef typename covovoc_t::type2 node_type;
            typedef typename covovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // c0 o0 ((v0 o1 v1) o2 c1)
               typedef typename synthesize_vovoc_expression0::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[1]);
               const Type  c0 = static_cast<details::literal_node<Type>*>(branch[0])->value();
               const Type& v0 = vovoc->t0();
               const Type& v1 = vovoc->t1();
               const Type  c1 = vovoc->t2();
               const details::operator_type o0 = operation;
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o2 = expr_gen.get_operator(vovoc->f1());

               binary_functor_t f0 = reinterpret_cast<binary_functor_t>(0);
               binary_functor_t f1 = vovoc->f0();
               binary_functor_t f2 = vovoc->f1();

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o0,f0))
                  return error_node();

               exprtk_debug(("c0 o0 ((v0 o1 v1) o2 c1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "t"   << expr_gen.to_str(o0)
                  << "((t" << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t)";
            }
         };

         struct synthesize_vococov_expression2
         {
            typedef typename vococov_t::type2 node_type;
            static inline expression_node_ptr process(expression_generator<Type>&,
                                                      const details::operator_type&,
                                                      expression_node_ptr (&)[2])
            {
               // v0 o0 ((c0 o1 c1) o2 v1) - Not possible
               exprtk_debug(("v0 o0 ((c0 o1 c1) o2 v1) - Not possible\n"));
               return error_node();
            }

            static inline std::string id(expression_generator<Type>&,
                                         const details::operator_type,
                                         const details::operator_type,
                                         const details::operator_type)
            {
               return "INVALID";
            }
         };

         struct synthesize_vovovov_expression3
         {
            typedef typename vovovov_t::type3 node_type;
            typedef typename vovovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 v1) o1 v2) o2 v3
               typedef typename synthesize_vovov_expression0::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[0]);
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const Type& v3 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovov->f0();
               binary_functor_t f1 = vovov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, v3, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 v1) o1 v2) o2 v3\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, v3, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vovovoc_expression3
         {
            typedef typename vovovoc_t::type3 node_type;
            typedef typename vovovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 v1) o1 v2) o2 c
               typedef typename synthesize_vovov_expression0::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[0]);
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const Type   c = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovov->f0();
               binary_functor_t f1 = vovov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, c, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 v1) o1 v2) o2 c\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, c, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vovocov_expression3
         {
            typedef typename vovocov_t::type3 node_type;
            typedef typename vovocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 v1) o1 c) o2 v2
               typedef typename synthesize_vovoc_expression0::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[0]);
               const Type& v0 = vovoc->t0();
               const Type& v1 = vovoc->t1();
               const Type   c = vovoc->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovoc->f0();
               binary_functor_t f1 = vovoc->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, c, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 v1) o1 c) o2 v2\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vocovov_expression3
         {
            typedef typename vocovov_t::type3 node_type;
            typedef typename vocovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 c) o1 v1) o2 v2
               typedef typename synthesize_vocov_expression0::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[0]);
               const Type& v0 = vocov->t0();
               const Type   c = vocov->t1();
               const Type& v1 = vocov->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vocov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vocov->f0();
               binary_functor_t f1 = vocov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 c) o1 v1) o2 v2\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covovov_expression3
         {
            typedef typename covovov_t::type3 node_type;
            typedef typename covovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c o0 v0) o1 v1) o2 v2
               typedef typename synthesize_covov_expression0::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[0]);
               const Type   c = covov->t0();
               const Type& v0 = covov->t1();
               const Type& v1 = covov->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(covov->f0());
               const details::operator_type o1 = expr_gen.get_operator(covov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covov->f0();
               binary_functor_t f1 = covov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c, v0, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c o0 v0) o1 v1) o2 v2\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covocov_expression3
         {
            typedef typename covocov_t::type3 node_type;
            typedef typename covocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c0 o0 v0) o1 c1) o2 v1
               typedef typename synthesize_covoc_expression0::node_type lcl_covoc_t;

               const lcl_covoc_t* covoc = static_cast<const lcl_covoc_t*>(branch[0]);
               const Type  c0 = covoc->t0();
               const Type& v0 = covoc->t1();
               const Type  c1 = covoc->t2();
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(covoc->f0());
               const details::operator_type o1 = expr_gen.get_operator(covoc->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covoc->f0();
               binary_functor_t f1 = covoc->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c0 o0 v0) o1 c1) o2 v1\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vocovoc_expression3
         {
            typedef typename vocovoc_t::type3 node_type;
            typedef typename vocovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 c0) o1 v1) o2 c1
               typedef typename synthesize_vocov_expression0::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[0]);
               const Type& v0 = vocov->t0();
               const Type  c0 = vocov->t1();
               const Type& v1 = vocov->t2();
               const Type  c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vocov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vocov->f0();
               binary_functor_t f1 = vocov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 c0) o1 v1) o2 c1\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covovoc_expression3
         {
            typedef typename covovoc_t::type3 node_type;
            typedef typename covovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c0 o0 v0) o1 v1) o2 c1
               typedef typename synthesize_covov_expression0::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[0]);
               const Type  c0 = covov->t0();
               const Type& v0 = covov->t1();
               const Type& v1 = covov->t2();
               const Type  c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(covov->f0());
               const details::operator_type o1 = expr_gen.get_operator(covov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covov->f0();
               binary_functor_t f1 = covov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c0 o0 v0) o1 v1) o2 c1\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vococov_expression3
         {
            typedef typename vococov_t::type3 node_type;
            typedef typename vococov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 c0) o1 c1) o2 v1
               typedef typename synthesize_vococ_expression0::node_type lcl_vococ_t;

               const lcl_vococ_t* vococ = static_cast<const lcl_vococ_t*>(branch[0]);
               const Type& v0 = vococ->t0();
               const Type  c0 = vococ->t1();
               const Type  c1 = vococ->t2();
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vococ->f0());
               const details::operator_type o1 = expr_gen.get_operator(vococ->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vococ->f0();
               binary_functor_t f1 = vococ->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 c0) o1 c1) o2 v1\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "((t" << expr_gen.to_str(o0)
                  << "t)"  << expr_gen.to_str(o1)
                  << "t)"  << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vovovov_expression4
         {
            typedef typename vovovov_t::type4 node_type;
            typedef typename vovovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // (v0 o0 (v1 o1 v2)) o2 v3
               typedef typename synthesize_vovov_expression1::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[0]);
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const Type& v3 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovov->f0();
               binary_functor_t f1 = vovov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, v3, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("(v0 o0 (v1 o1 v2)) o2 v3\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, v3, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vovovoc_expression4
         {
            typedef typename vovovoc_t::type4 node_type;
            typedef typename vovovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 (v1 o1 v2)) o2 c)
               typedef typename synthesize_vovov_expression1::node_type lcl_vovov_t;

               const lcl_vovov_t* vovov = static_cast<const lcl_vovov_t*>(branch[0]);
               const Type& v0 = vovov->t0();
               const Type& v1 = vovov->t1();
               const Type& v2 = vovov->t2();
               const Type   c = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(vovov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovov->f0();
               binary_functor_t f1 = vovov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, v2, c, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 (v1 o1 v2)) o2 c)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, v2, c, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vovocov_expression4
         {
            typedef typename vovocov_t::type4 node_type;
            typedef typename vovocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 (v1 o1 c)) o2 v1)
               typedef typename synthesize_vovoc_expression1::node_type lcl_vovoc_t;

               const lcl_vovoc_t* vovoc = static_cast<const lcl_vovoc_t*>(branch[0]);
               const Type& v0 = vovoc->t0();
               const Type& v1 = vovoc->t1();
               const Type   c = vovoc->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vovoc->f0());
               const details::operator_type o1 = expr_gen.get_operator(vovoc->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vovoc->f0();
               binary_functor_t f1 = vovoc->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, v1, c, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 (v1 o1 c)) o2 v1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, v1, c, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vocovov_expression4
         {
            typedef typename vocovov_t::type4 node_type;
            typedef typename vocovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 (c o1 v1)) o2 v2)
               typedef typename synthesize_vocov_expression1::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[0]);
               const Type& v0 = vocov->t0();
               const Type   c = vocov->t1();
               const Type& v1 = vocov->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vocov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vocov->f0();
               binary_functor_t f1 = vocov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 (c o1 v1)) o2 v2)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covovov_expression4
         {
            typedef typename covovov_t::type4 node_type;
            typedef typename covovov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c o0 (v0 o1 v1)) o2 v2)
               typedef typename synthesize_covov_expression1::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[0]);
               const Type   c = covov->t0();
               const Type& v0 = covov->t1();
               const Type& v1 = covov->t2();
               const Type& v2 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(covov->f0());
               const details::operator_type o1 = expr_gen.get_operator(covov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covov->f0();
               binary_functor_t f1 = covov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c, v0, v1, v2, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c o0 (v0 o1 v1)) o2 v2)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c, v0, v1, v2, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covocov_expression4
         {
            typedef typename covocov_t::type4 node_type;
            typedef typename covocov_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c0 o0 (v0 o1 c1)) o2 v1)
               typedef typename synthesize_covoc_expression1::node_type lcl_covoc_t;

               const lcl_covoc_t* covoc = static_cast<const lcl_covoc_t*>(branch[0]);
               const Type  c0 = covoc->t0();
               const Type& v0 = covoc->t1();
               const Type  c1 = covoc->t2();
               const Type& v1 = static_cast<details::variable_node<Type>*>(branch[1])->ref();
               const details::operator_type o0 = expr_gen.get_operator(covoc->f0());
               const details::operator_type o1 = expr_gen.get_operator(covoc->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covoc->f0();
               binary_functor_t f1 = covoc->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, c1, v1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c0 o0 (v0 o1 c1)) o2 v1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, c1, v1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vocovoc_expression4
         {
            typedef typename vocovoc_t::type4 node_type;
            typedef typename vocovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((v0 o0 (c0 o1 v1)) o2 c1)
               typedef typename synthesize_vocov_expression1::node_type lcl_vocov_t;

               const lcl_vocov_t* vocov = static_cast<const lcl_vocov_t*>(branch[0]);
               const Type& v0 = vocov->t0();
               const Type  c0 = vocov->t1();
               const Type& v1 = vocov->t2();
               const Type  c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(vocov->f0());
               const details::operator_type o1 = expr_gen.get_operator(vocov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = vocov->f0();
               binary_functor_t f1 = vocov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), v0, c0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((v0 o0 (c0 o1 v1)) o2 c1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), v0, c0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_covovoc_expression4
         {
            typedef typename covovoc_t::type4 node_type;
            typedef typename covovoc_t::sf4_type sf4_type;
            typedef typename node_type::T0 T0;
            typedef typename node_type::T1 T1;
            typedef typename node_type::T2 T2;
            typedef typename node_type::T3 T3;

            static inline expression_node_ptr process(expression_generator<Type>& expr_gen,
                                                      const details::operator_type& operation,
                                                      expression_node_ptr (&branch)[2])
            {
               // ((c0 o0 (v0 o1 v1)) o2 c1)
               typedef typename synthesize_covov_expression1::node_type lcl_covov_t;

               const lcl_covov_t* covov = static_cast<const lcl_covov_t*>(branch[0]);
               const Type  c0 = covov->t0();
               const Type& v0 = covov->t1();
               const Type& v1 = covov->t2();
               const Type  c1 = static_cast<details::literal_node<Type>*>(branch[1])->value();
               const details::operator_type o0 = expr_gen.get_operator(covov->f0());
               const details::operator_type o1 = expr_gen.get_operator(covov->f1());
               const details::operator_type o2 = operation;

               binary_functor_t f0 = covov->f0();
               binary_functor_t f1 = covov->f1();
               binary_functor_t f2 = reinterpret_cast<binary_functor_t>(0);

               details::free_node(*(expr_gen.node_allocator_),branch[0]);
               details::free_node(*(expr_gen.node_allocator_),branch[1]);

               expression_node_ptr result = error_node();

               const bool synthesis_result =
                  synthesize_sf4ext_expression::template compile<T0, T1, T2, T3>
                     (expr_gen, id(expr_gen, o0, o1, o2), c0, v0, v1, c1, result);

               if (synthesis_result)
                  return result;
               else if (!expr_gen.valid_operator(o2,f2))
                  return error_node();

               exprtk_debug(("((c0 o0 (v0 o1 v1)) o2 c1)\n"));

               return node_type::allocate(*(expr_gen.node_allocator_), c0, v0, v1, c1, f0, f1, f2);
            }

            static inline std::string id(expression_generator<Type>& expr_gen,
                                         const details::operator_type o0,
                                         const details::operator_type o1,
                                         const details::operator_type o2)
            {
               return details::build_string()
                  << "(t" << expr_gen.to_str(o0)
                  << "(t" << expr_gen.to_str(o1)
                  << "t)" << expr_gen.to_str(o2)
                  << "t";
            }
         };

         struct synthesize_vococov_expression4
         {
            typedef typename vococov_t::type4 node_type;
            static inline expression_node_ptr process(expression_generator<Type>&,
                                                      const details::operator_type&,
                                                      expression_node_ptr (&)[2])
            {
               // ((v0 o0 (c0 o1 c1)) o2 v1) - Not possible
               exprtk_debug(("((v0 o0 (c0 o1 c1)) o2 v1) - Not possible\n"));
               return error_node();
            }

            static inline std::string id(expression_generator<Type>&,
                                         const details::operator_type,
                                         const details::operator_type,
                                         const details::operator_type)
            {
               return "INVALID";
            }
         };
         #endif

         inline expression_node_ptr synthesize_uvouv_expression(const details::operator_type& operation, expression_node_ptr (&branch)[2])
         {
            // Definition: uv o uv
            details::operator_type o0 = static_cast<details::uv_base_node<Type>*>(branch[0])->operation();
            details::operator_type o1 = static_cast<details::uv_base_node<Type>*>(branch[1])->operation();
            const Type& v0 = static_cast<details::uv_base_node<Type>*>(branch[0])->v();
            const Type& v1 = static_cast<details::uv_base_node<Type>*>(branch[1])->v();
            unary_functor_t u0 = reinterpret_cast<unary_functor_t> (0);
            unary_functor_t u1 = reinterpret_cast<unary_functor_t> (0);
            binary_functor_t f = reinterpret_cast<binary_functor_t>(0);

            if (!valid_operator(o0,u0))
               return error_node();
            else if (!valid_operator(o1,u1))
               return error_node();
            else if (!valid_operator(operation,f))
               return error_node();

            expression_node_ptr result = error_node();

            if (
                 (details::e_neg == o0) &&
                 (details::e_neg == o1)
               )
            {
               switch (operation)
               {
                  // (-v0 + -v1) --> -(v0 + v1)
                  case details::e_add : result = (*this)(details::e_neg,
                                                    node_allocator_->
                                                       allocate_rr<typename details::
                                                          vov_node<Type,details::add_op<Type> > >(v0, v1));
                                        exprtk_debug(("(-v0 + -v1) --> -(v0 + v1)\n"));
                                        break;

                  // (-v0 - -v1) --> (v1 - v0)
                  case details::e_sub : result = node_allocator_->
                                                    allocate_rr<typename details::
                                                       vov_node<Type,details::sub_op<Type> > >(v1, v0);
                                        exprtk_debug(("(-v0 - -v1) --> (v1 - v0)\n"));
                                        break;

                  // (-v0 * -v1) --> (v0 * v1)
                  case details::e_mul : result = node_allocator_->
                                                    allocate_rr<typename details::
                                                       vov_node<Type,details::mul_op<Type> > >(v0, v1);
                                        exprtk_debug(("(-v0 * -v1) --> (v0 * v1)\n"));
                                        break;

                  // (-v0 / -v1) --> (v0 / v1)
                  case details::e_div : result = node_allocator_->
                                                    allocate_rr<typename details::
                                                       vov_node<Type,details::div_op<Type> > >(v0, v1);
                                        exprtk_debug(("(-v0 / -v1) --> (v0 / v1)\n"));
                                        break;

                  default             : break;
               }
            }

            if (0 == result)
            {
               result = node_allocator_->
                            allocate_rrrrr<typename details::uvouv_node<Type> >(v0, v1, u0, u1, f);
            }

            details::free_all_nodes(*node_allocator_,branch);
            return result;
         }

         #undef basic_opr_switch_statements
         #undef extended_opr_switch_statements
         #undef unary_opr_switch_statements

         #ifndef exprtk_disable_string_capabilities

         #define string_opr_switch_statements            \
         case_stmt(details::e_lt    , details::lt_op   ) \
         case_stmt(details::e_lte   , details::lte_op  ) \
         case_stmt(details::e_gt    , details::gt_op   ) \
         case_stmt(details::e_gte   , details::gte_op  ) \
         case_stmt(details::e_eq    , details::eq_op   ) \
         case_stmt(details::e_ne    , details::ne_op   ) \
         case_stmt(details::e_in    , details::in_op   ) \
         case_stmt(details::e_like  , details::like_op ) \
         case_stmt(details::e_ilike , details::ilike_op) \

         template <typename T0, typename T1>
         inline expression_node_ptr synthesize_str_xrox_expression_impl(const details::operator_type& opr,
                                                                        T0 s0, T1 s1,
                                                                        range_t rp0)
         {
            switch (opr)
            {
               #define case_stmt(op0, op1)                                                                      \
               case op0 : return node_allocator_->                                                              \
                             allocate_ttt<typename details::str_xrox_node<Type,T0,T1,range_t,op1<Type> >,T0,T1> \
                                (s0, s1, rp0);                                                                  \

               string_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         template <typename T0, typename T1>
         inline expression_node_ptr synthesize_str_xoxr_expression_impl(const details::operator_type& opr,
                                                                        T0 s0, T1 s1,
                                                                        range_t rp1)
         {
            switch (opr)
            {
               #define case_stmt(op0, op1)                                                                      \
               case op0 : return node_allocator_->                                                              \
                             allocate_ttt<typename details::str_xoxr_node<Type,T0,T1,range_t,op1<Type> >,T0,T1> \
                                (s0, s1, rp1);                                                                  \

               string_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         template <typename T0, typename T1>
         inline expression_node_ptr synthesize_str_xroxr_expression_impl(const details::operator_type& opr,
                                                                         T0 s0, T1 s1,
                                                                         range_t rp0, range_t rp1)
         {
            switch (opr)
            {
               #define case_stmt(op0, op1)                                                                        \
               case op0 : return node_allocator_->                                                                \
                             allocate_tttt<typename details::str_xroxr_node<Type,T0,T1,range_t,op1<Type> >,T0,T1> \
                                (s0, s1, rp0, rp1);                                                               \

               string_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         template <typename T0, typename T1>
         inline expression_node_ptr synthesize_sos_expression_impl(const details::operator_type& opr, T0 s0, T1 s1)
         {
            switch (opr)
            {
               #define case_stmt(op0, op1)                                                                 \
               case op0 : return node_allocator_->                                                         \
                             allocate_tt<typename details::sos_node<Type,T0,T1,op1<Type> >,T0,T1>(s0, s1); \

               string_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         inline expression_node_ptr synthesize_sos_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string& s0 = static_cast<details::stringvar_node<Type>*>(branch[0])->ref();
            std::string& s1 = static_cast<details::stringvar_node<Type>*>(branch[1])->ref();

            return synthesize_sos_expression_impl<std::string&,std::string&>(opr, s0, s1);
         }

         inline expression_node_ptr synthesize_sros_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::string_range_node<Type>*>(branch[0])->ref  ();
            std::string&  s1 = static_cast<details::stringvar_node<Type>*>   (branch[1])->ref  ();
            range_t      rp0 = static_cast<details::string_range_node<Type>*>(branch[0])->range();

            static_cast<details::string_range_node<Type>*>(branch[0])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);

            return synthesize_str_xrox_expression_impl<std::string&,std::string&>(opr, s0, s1, rp0);
         }

         inline expression_node_ptr synthesize_sosr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::stringvar_node<Type>*>   (branch[0])->ref  ();
            std::string&  s1 = static_cast<details::string_range_node<Type>*>(branch[1])->ref  ();
            range_t      rp1 = static_cast<details::string_range_node<Type>*>(branch[1])->range();

            static_cast<details::string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xoxr_expression_impl<std::string&,std::string&>(opr, s0, s1, rp1);
         }

         inline expression_node_ptr synthesize_socsr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::stringvar_node<Type>*>         (branch[0])->ref  ();
            std::string   s1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->str  ();
            range_t      rp1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xoxr_expression_impl<std::string&, const std::string>(opr, s0, s1, rp1);
         }

         inline expression_node_ptr synthesize_srosr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::string_range_node<Type>*>(branch[0])->ref  ();
            std::string&  s1 = static_cast<details::string_range_node<Type>*>(branch[1])->ref  ();
            range_t      rp0 = static_cast<details::string_range_node<Type>*>(branch[0])->range();
            range_t      rp1 = static_cast<details::string_range_node<Type>*>(branch[1])->range();

            static_cast<details::string_range_node<Type>*>(branch[0])->range_ref().clear();
            static_cast<details::string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xroxr_expression_impl<std::string&,std::string&>(opr, s0, s1, rp0, rp1);
         }

         inline expression_node_ptr synthesize_socs_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string& s0 = static_cast<     details::stringvar_node<Type>*>(branch[0])->ref();
            std::string  s1 = static_cast<details::string_literal_node<Type>*>(branch[1])->str();

            details::free_node(*node_allocator_,branch[1]);

            return synthesize_sos_expression_impl<std::string&, const std::string>(opr, s0, s1);
         }

         inline expression_node_ptr synthesize_csos_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string  s0 = static_cast<details::string_literal_node<Type>*>(branch[0])->str();
            std::string& s1 = static_cast<details::stringvar_node<Type>*     >(branch[1])->ref();

            details::free_node(*node_allocator_,branch[0]);

            return synthesize_sos_expression_impl<const std::string,std::string&>(opr, s0, s1);
         }

         inline expression_node_ptr synthesize_csosr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string  s0  = static_cast<details::string_literal_node<Type>*>(branch[0])->str  ();
            std::string& s1  = static_cast<details::string_range_node<Type>*  >(branch[1])->ref  ();
            range_t      rp1 = static_cast<details::string_range_node<Type>*  >(branch[1])->range();

            static_cast<details::string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xoxr_expression_impl<const std::string,std::string&>(opr, s0, s1, rp1);
         }

         inline expression_node_ptr synthesize_srocs_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::string_range_node<Type>*  >(branch[0])->ref  ();
            std::string   s1 = static_cast<details::string_literal_node<Type>*>(branch[1])->str  ();
            range_t      rp0 = static_cast<details::string_range_node<Type>*  >(branch[0])->range();

            static_cast<details::string_range_node<Type>*>(branch[0])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xrox_expression_impl<std::string&, const std::string>(opr, s0, s1, rp0);
         }

         inline expression_node_ptr synthesize_srocsr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string&  s0 = static_cast<details::string_range_node<Type>*      >(branch[0])->ref  ();
            std::string   s1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->str  ();
            range_t      rp0 = static_cast<details::string_range_node<Type>*      >(branch[0])->range();
            range_t      rp1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->range();

            static_cast<details::string_range_node<Type>*>      (branch[0])->range_ref().clear();
            static_cast<details::const_string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xroxr_expression_impl<std::string&, const std::string>(opr, s0, s1, rp0, rp1);
         }

         inline expression_node_ptr synthesize_csocs_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            const std::string s0 = static_cast<details::string_literal_node<Type>*>(branch[0])->str();
            const std::string s1 = static_cast<details::string_literal_node<Type>*>(branch[1])->str();

            expression_node_ptr result = error_node();

            if (details::e_add == opr)
               result = node_allocator_->allocate_c<details::string_literal_node<Type> >(s0 + s1);
            else if (details::e_in == opr)
               result = node_allocator_->allocate_c<details::literal_node<Type> >(details::in_op   <Type>::process(s0,s1));
            else if (details::e_like == opr)
               result = node_allocator_->allocate_c<details::literal_node<Type> >(details::like_op <Type>::process(s0,s1));
            else if (details::e_ilike == opr)
               result = node_allocator_->allocate_c<details::literal_node<Type> >(details::ilike_op<Type>::process(s0,s1));
            else
            {
               expression_node_ptr temp = synthesize_sos_expression_impl<const std::string, const std::string>(opr, s0, s1);

               const Type v = temp->value();

               details::free_node(*node_allocator_,temp);

               result = node_allocator_->allocate<literal_node_t>(v);
            }

            details::free_all_nodes(*node_allocator_,branch);

            return result;
         }

         inline expression_node_ptr synthesize_csocsr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            const std::string s0 = static_cast<details::string_literal_node<Type>*    >(branch[0])->str  ();
                  std::string s1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->str  ();
            range_t          rp1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xoxr_expression_impl<const std::string, const std::string>(opr, s0, s1, rp1);
         }

         inline expression_node_ptr synthesize_csros_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            std::string   s0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->str  ();
            std::string&  s1 = static_cast<details::stringvar_node<Type>*         >(branch[1])->ref  ();
            range_t      rp0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[0])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);

            return synthesize_str_xrox_expression_impl<const std::string,std::string&>(opr, s0, s1, rp0);
         }

         inline expression_node_ptr synthesize_csrosr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            const std::string  s0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->str  ();
                  std::string& s1 = static_cast<details::string_range_node<Type>*      >(branch[1])->ref  ();
            const range_t     rp0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->range();
            const range_t     rp1 = static_cast<details::string_range_node<Type>*      >(branch[1])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[0])->range_ref().clear();
            static_cast<details::string_range_node<Type>*>      (branch[1])->range_ref().clear();

            details::free_node(*node_allocator_,branch[0]);
            details::free_node(*node_allocator_,branch[1]);

            return synthesize_str_xroxr_expression_impl<const std::string,std::string&>(opr, s0, s1, rp0, rp1);
         }

         inline expression_node_ptr synthesize_csrocs_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            const std::string s0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->str  ();
            const std::string s1 = static_cast<details::string_literal_node<Type>*    >(branch[1])->str  ();
            const range_t    rp0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[0])->range_ref().clear();

            details::free_all_nodes(*node_allocator_,branch);

            return synthesize_str_xrox_expression_impl<const std::string,std::string>(opr, s0, s1, rp0);
         }

         inline expression_node_ptr synthesize_csrocsr_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            const std::string s0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->str  ();
            const std::string s1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->str  ();
            const range_t    rp0 = static_cast<details::const_string_range_node<Type>*>(branch[0])->range();
            const range_t    rp1 = static_cast<details::const_string_range_node<Type>*>(branch[1])->range();

            static_cast<details::const_string_range_node<Type>*>(branch[0])->range_ref().clear();
            static_cast<details::const_string_range_node<Type>*>(branch[1])->range_ref().clear();

            details::free_all_nodes(*node_allocator_,branch);

            return synthesize_str_xroxr_expression_impl<const std::string, const std::string>(opr, s0, s1, rp0, rp1);
         }

         inline expression_node_ptr synthesize_strogen_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            switch (opr)
            {
               #define case_stmt(op0, op1)                                                      \
               case op0 : return node_allocator_->                                              \
                             allocate_ttt<typename details::str_sogens_node<Type,op1<Type> > >  \
                                (opr, branch[0], branch[1]);                                    \

               string_opr_switch_statements
               #undef case_stmt
               default : return error_node();
            }
         }

         #undef string_opr_switch_statements
         #endif

         #ifndef exprtk_disable_string_capabilities
         inline expression_node_ptr synthesize_string_expression(const details::operator_type& opr, expression_node_ptr (&branch)[2])
         {
            if ((0 == branch[0]) || (0 == branch[1]))
            {
               details::free_all_nodes(*node_allocator_,branch);

               return error_node();
            }

            const bool b0_is_s   = details::is_string_node            (branch[0]);
            const bool b0_is_cs  = details::is_const_string_node      (branch[0]);
            const bool b0_is_sr  = details::is_string_range_node      (branch[0]);
            const bool b0_is_csr = details::is_const_string_range_node(branch[0]);

            const bool b1_is_s   = details::is_string_node            (branch[1]);
            const bool b1_is_cs  = details::is_const_string_node      (branch[1]);
            const bool b1_is_sr  = details::is_string_range_node      (branch[1]);
            const bool b1_is_csr = details::is_const_string_range_node(branch[1]);

            const bool b0_is_gen = details::is_string_assignment_node (branch[0]) ||
                                   details::is_genricstring_range_node(branch[0]) ||
                                   details::is_string_concat_node     (branch[0]) ||
                                   details::is_string_function_node   (branch[0]) ||
                                   details::is_string_condition_node  (branch[0]) ||
                                   details::is_string_ccondition_node (branch[0]) ||
                                   details::is_string_vararg_node     (branch[0]) ;

            const bool b1_is_gen = details::is_string_assignment_node (branch[1]) ||
                                   details::is_genricstring_range_node(branch[1]) ||
                                   details::is_string_concat_node     (branch[1]) ||
                                   details::is_string_function_node   (branch[1]) ||
                                   details::is_string_condition_node  (branch[1]) ||
                                   details::is_string_ccondition_node (branch[1]) ||
                                   details::is_string_vararg_node     (branch[1]) ;

            if (details::e_add == opr)
            {
               if (!b0_is_cs || !b1_is_cs)
               {
                  return synthesize_expression<string_concat_node_t,2>(opr,branch);
               }
            }

            if (b0_is_gen || b1_is_gen)
            {
               return synthesize_strogen_expression(opr,branch);
            }
            else if (b0_is_s)
            {
               if      (b1_is_s  ) return synthesize_sos_expression   (opr,branch);
               else if (b1_is_cs ) return synthesize_socs_expression  (opr,branch);
               else if (b1_is_sr ) return synthesize_sosr_expression  (opr,branch);
               else if (b1_is_csr) return synthesize_socsr_expression (opr,branch);
            }
            else if (b0_is_cs)
            {
               if      (b1_is_s  ) return synthesize_csos_expression  (opr,branch);
               else if (b1_is_cs ) return synthesize_csocs_expression (opr,branch);
               else if (b1_is_sr ) return synthesize_csosr_expression (opr,branch);
               else if (b1_is_csr) return synthesize_csocsr_expression(opr,branch);
            }
            else if (b0_is_sr)
            {
               if      (b1_is_s  ) return synthesize_sros_expression  (opr,branch);
               else if (b1_is_sr ) return synthesize_srosr_expression (opr,branch);
               else if (b1_is_cs ) return synthesize_srocs_expression (opr,branch);
               else if (b1_is_csr) return synthesize_srocsr_expression(opr,branch);
            }
            else if (b0_is_csr)
            {
               if      (b1_is_s  ) return synthesize_csros_expression  (opr,branch);
               else if (b1_is_sr ) return synthesize_csrosr_expression (opr,branch);
               else if (b1_is_cs ) return synthesize_csrocs_expression (opr,branch);
               else if (b1_is_csr) return synthesize_csrocsr_expression(opr,branch);
            }

            return error_node();
         }
         #else
         inline expression_node_ptr synthesize_string_expression(const details::operator_type&, expression_node_ptr (&branch)[2])
         {
            details::free_all_nodes(*node_allocator_,branch);
            return error_node();
         }
         #endif

         #ifndef exprtk_disable_string_capabilities
         inline expression_node_ptr synthesize_string_expression(const details::operator_type& opr, expression_node_ptr (&branch)[3])
         {
            if (details::e_inrange != opr)
               return error_node();
            else if ((0 == branch[0]) || (0 == branch[1]) || (0 == branch[2]))
            {
               details::free_all_nodes(*node_allocator_,branch);

               return error_node();
            }
            else if (
                      details::is_const_string_node(branch[0]) &&
                      details::is_const_string_node(branch[1]) &&
                      details::is_const_string_node(branch[2])
                    )
            {
               const std::string s0 = static_cast<details::string_literal_node<Type>*>(branch[0])->str();
               const std::string s1 = static_cast<details::string_literal_node<Type>*>(branch[1])->str();
               const std::string s2 = static_cast<details::string_literal_node<Type>*>(branch[2])->str();

               const Type v = (((s0 <= s1) && (s1 <= s2)) ? Type(1) : Type(0));

               details::free_all_nodes(*node_allocator_,branch);

               return node_allocator_->allocate_c<details::literal_node<Type> >(v);
            }
            else if (
                      details::is_string_node(branch[0]) &&
                      details::is_string_node(branch[1]) &&
                      details::is_string_node(branch[2])
                    )
            {
               std::string& s0 = static_cast<details::stringvar_node<Type>*>(branch[0])->ref();
               std::string& s1 = static_cast<details::stringvar_node<Type>*>(branch[1])->ref();
               std::string& s2 = static_cast<details::stringvar_node<Type>*>(branch[2])->ref();

               typedef typename details::sosos_node<Type, std::string&, std::string&, std::string&, details::inrange_op<Type> > inrange_t;

               return node_allocator_->allocate_type<inrange_t, std::string&, std::string&, std::string&>(s0, s1, s2);
            }
            else if (
                      details::is_const_string_node(branch[0]) &&
                            details::is_string_node(branch[1]) &&
                      details::is_const_string_node(branch[2])
                    )
            {
               std::string  s0 = static_cast<details::string_literal_node<Type>*>(branch[0])->str();
               std::string& s1 = static_cast<details::stringvar_node<Type>*     >(branch[1])->ref();
               std::string  s2 = static_cast<details::string_literal_node<Type>*>(branch[2])->str();

               typedef typename details::sosos_node<Type, std::string, std::string&, std::string, details::inrange_op<Type> > inrange_t;

               details::free_node(*node_allocator_,branch[0]);
               details::free_node(*node_allocator_,branch[2]);

               return node_allocator_->allocate_type<inrange_t, std::string, std::string&, std::string>(s0, s1, s2);
            }
            else if (
                            details::is_string_node(branch[0]) &&
                      details::is_const_string_node(branch[1]) &&
                            details::is_string_node(branch[2])
                    )
            {
               std::string&  s0 = static_cast<details::stringvar_node<Type>*     >(branch[0])->ref();
               std::string   s1 = static_cast<details::string_literal_node<Type>*>(branch[1])->str();
               std::string&  s2 = static_cast<details::stringvar_node<Type>*     >(branch[2])->ref();

               typedef typename details::sosos_node<Type, std::string&, std::string, std::string&, details::inrange_op<Type> > inrange_t;

               details::free_node(*node_allocator_,branch[1]);

               return node_allocator_->allocate_type<inrange_t, std::string&, std::string, std::string&>(s0, s1, s2);
            }
            else if (
                      details::is_string_node(branch[0]) &&
                      details::is_string_node(branch[1]) &&
                      details::is_const_string_node(branch[2])
                    )
            {
               std::string& s0 = static_cast<details::stringvar_node<Type>*     >(branch[0])->ref();
               std::string& s1 = static_cast<details::stringvar_node<Type>*     >(branch[1])->ref();
               std::string  s2 = static_cast<details::string_literal_node<Type>*>(branch[2])->str();

               typedef typename details::sosos_node<Type, std::string&, std::string&, std::string, details::inrange_op<Type> > inrange_t;

               details::free_node(*node_allocator_,branch[2]);

               return node_allocator_->allocate_type<inrange_t, std::string&, std::string&, std::string>(s0, s1, s2);
            }
            else if (
                      details::is_const_string_node(branch[0]) &&
                      details::      is_string_node(branch[1]) &&
                      details::      is_string_node(branch[2])
                    )
            {
               std::string  s0 = static_cast<details::string_literal_node<Type>*>(branch[0])->str();
               std::string& s1 = static_cast<details::stringvar_node<Type>*     >(branch[1])->ref();
               std::string& s2 = static_cast<details::stringvar_node<Type>*     >(branch[2])->ref();

               typedef typename details::sosos_node<Type, std::string, std::string&, std::string&, details::inrange_op<Type> > inrange_t;

               details::free_node(*node_allocator_,branch[0]);

               return node_allocator_->allocate_type<inrange_t, std::string, std::string&, std::string&>(s0, s1, s2);
            }
            else
               return error_node();
         }
         #else
         inline expression_node_ptr synthesize_string_expression(const details::operator_type&, expression_node_ptr (&branch)[3])
         {
            details::free_all_nodes(*node_allocator_,branch);
            return error_node();
         }
         #endif

         inline expression_node_ptr synthesize_null_expression(const details::operator_type& operation, expression_node_ptr (&branch)[2])
         {
            /*
             Note: The following are the type promotion rules
             that relate to operations that include 'null':
             0. null ==/!=     null --> true false
             1. null operation null --> null
             2. x    ==/!=     null --> true/false
             3. null ==/!=     x    --> true/false
             4. x   operation  null --> x
             5. null operation x    --> x
            */

            typedef typename details::null_eq_node<T> nulleq_node_t;

            const bool b0_null = details::is_null_node(branch[0]);
            const bool b1_null = details::is_null_node(branch[1]);

            if (b0_null && b1_null)
            {
               expression_node_ptr result = error_node();

               if (details::e_eq == operation)
                  result = node_allocator_->allocate_c<literal_node_t>(T(1));
               else if (details::e_ne == operation)
                  result = node_allocator_->allocate_c<literal_node_t>(T(0));

               if (result)
               {
                  details::free_node(*node_allocator_,branch[0]);
                  details::free_node(*node_allocator_,branch[1]);

                  return result;
               }

               details::free_node(*node_allocator_,branch[1]);

               return branch[0];
            }
            else if (details::e_eq == operation)
            {
               expression_node_ptr result = node_allocator_->
                                                allocate_rc<nulleq_node_t>(branch[b0_null ? 0 : 1],true);

               details::free_node(*node_allocator_,branch[b0_null ? 1 : 0]);

               return result;
            }
            else if (details::e_ne == operation)
            {
               expression_node_ptr result = node_allocator_->
                                                allocate_rc<nulleq_node_t>(branch[b0_null ? 0 : 1],false);

               details::free_node(*node_allocator_,branch[b0_null ? 1 : 0]);

               return result;
            }
            else if (b0_null)
            {
               details::free_node(*node_allocator_,branch[0]);
               branch[0] = branch[1];
               branch[1] = error_node();
            }
            else if (b1_null)
            {
               details::free_node(*node_allocator_,branch[1]);
               branch[1] = error_node();
            }

            if (
                 (details::e_add == operation) || (details::e_sub == operation) ||
                 (details::e_mul == operation) || (details::e_div == operation) ||
                 (details::e_mod == operation) || (details::e_pow == operation)
               )
            {
               return branch[0];
            }

            details::free_node(*node_allocator_, branch[0]);

            if (
                 (details::e_lt    == operation) || (details::e_lte  == operation) ||
                 (details::e_gt    == operation) || (details::e_gte  == operation) ||
                 (details::e_and   == operation) || (details::e_nand == operation) ||
                 (details::e_or    == operation) || (details::e_nor  == operation) ||
                 (details::e_xor   == operation) || (details::e_xnor == operation) ||
                 (details::e_in    == operation) || (details::e_like == operation) ||
                 (details::e_ilike == operation)
               )
            {
               return node_allocator_->allocate_c<literal_node_t>(T(0));
            }

            return node_allocator_->allocate<details::null_node<Type> >();
         }

         template <typename NodeType, std::size_t N>
         inline expression_node_ptr synthesize_expression(const details::operator_type& operation, expression_node_ptr (&branch)[N])
         {
            if (
                 (details::e_in    == operation) ||
                 (details::e_like  == operation) ||
                 (details::e_ilike == operation)
               )
            {
               free_all_nodes(*node_allocator_,branch);

               return error_node();
            }
            else if (!details::all_nodes_valid<N>(branch))
            {
               free_all_nodes(*node_allocator_,branch);

               return error_node();
            }
            else if ((details::e_default != operation))
            {
               // Attempt simple constant folding optimisation.
               expression_node_ptr expression_point = node_allocator_->allocate<NodeType>(operation,branch);

               if (is_constant_foldable<N>(branch))
               {
                  const Type v = expression_point->value();
                  details::free_node(*node_allocator_,expression_point);

                  return node_allocator_->allocate<literal_node_t>(v);
               }

               if (expression_point && expression_point->valid())
               {
                  return expression_point;
               }

               parser_->set_error(parser_error::make_error(
                  parser_error::e_parser,
                  token_t(),
                  "ERR273 - Failed to synthesize node: NodeType",
                  exprtk_error_location));

               details::free_node(*node_allocator_, expression_point);
            }

            return error_node();
         }

         template <typename NodeType, std::size_t N>
         inline expression_node_ptr synthesize_expression(F* f, expression_node_ptr (&branch)[N])
         {
            if (!details::all_nodes_valid<N>(branch))
            {
               free_all_nodes(*node_allocator_,branch);

               return error_node();
            }

            typedef typename details::function_N_node<T,ifunction_t,N> function_N_node_t;

            // Attempt simple constant folding optimisation.

            expression_node_ptr expression_point = node_allocator_->allocate<NodeType>(f);
            function_N_node_t* func_node_ptr = dynamic_cast<function_N_node_t*>(expression_point);

            if (0 == func_node_ptr)
            {
               free_all_nodes(*node_allocator_,branch);

               return error_node();
            }
            else
               func_node_ptr->init_branches(branch);

            if (is_constant_foldable<N>(branch) && !f->has_side_effects())
            {
               Type v = expression_point->value();
               details::free_node(*node_allocator_,expression_point);

               return node_allocator_->allocate<literal_node_t>(v);
            }

            parser_->state_.activate_side_effect("synthesize_expression(function<NT,N>)");

            return expression_point;
         }

         bool                     strength_reduction_enabled_;
         details::node_allocator* node_allocator_;
         synthesize_map_t         synthesize_map_;
         unary_op_map_t*          unary_op_map_;
         binary_op_map_t*         binary_op_map_;
         inv_binary_op_map_t*     inv_binary_op_map_;
         sf3_map_t*               sf3_map_;
         sf4_map_t*               sf4_map_;
         parser_t*                parser_;
      }; // class expression_generator

      inline void set_error(const parser_error::type& error_type)
      {
         error_list_.push_back(error_type);
      }

      inline void remove_last_error()
      {
         if (!error_list_.empty())
         {
            error_list_.pop_back();
         }
      }

      inline void set_synthesis_error(const std::string& synthesis_error_message)
      {
         if (synthesis_error_.empty())
         {
            synthesis_error_ = synthesis_error_message;
         }
      }

      inline void register_local_vars(expression<T>& e)
      {
         for (std::size_t i = 0; i < sem_.size(); ++i)
         {
            scope_element& se = sem_.get_element(i);

            exprtk_debug(("register_local_vars() - se[%s]\n", se.name.c_str()));

            if (
                 (scope_element::e_variable == se.type) ||
                 (scope_element::e_literal  == se.type) ||
                 (scope_element::e_vecelem  == se.type)
               )
            {
               if (se.var_node)
               {
                  e.register_local_var(se.var_node);
               }

               if (se.data)
               {
                  e.register_local_data(se.data, 1, 0);
               }
            }
            else if (scope_element::e_vector == se.type)
            {
               if (se.vec_node)
               {
                  e.register_local_var(se.vec_node);
               }

               if (se.data)
               {
                  e.register_local_data(se.data, se.size, 1);
               }
            }
            #ifndef exprtk_disable_string_capabilities
            else if (scope_element::e_string == se.type)
            {
               if (se.str_node)
               {
                  e.register_local_var(se.str_node);
               }

               if (se.data)
               {
                  e.register_local_data(se.data, se.size, 2);
               }
            }
            #endif

            se.var_node  = 0;
            se.vec_node  = 0;
            #ifndef exprtk_disable_string_capabilities
            se.str_node  = 0;
            #endif
            se.data      = 0;
            se.ref_count = 0;
            se.active    = false;
         }
      }

      inline void register_return_results(expression<T>& e)
      {
         e.register_return_results(results_context_);
         results_context_ = 0;
      }

      inline void load_unary_operations_map(unary_op_map_t& m)
      {
         #define register_unary_op(Op, UnaryFunctor)            \
         m.insert(std::make_pair(Op,UnaryFunctor<T>::process)); \

         register_unary_op(details::e_abs   , details::abs_op  )
         register_unary_op(details::e_acos  , details::acos_op )
         register_unary_op(details::e_acosh , details::acosh_op)
         register_unary_op(details::e_asin  , details::asin_op )
         register_unary_op(details::e_asinh , details::asinh_op)
         register_unary_op(details::e_atanh , details::atanh_op)
         register_unary_op(details::e_ceil  , details::ceil_op )
         register_unary_op(details::e_cos   , details::cos_op  )
         register_unary_op(details::e_cosh  , details::cosh_op )
         register_unary_op(details::e_exp   , details::exp_op  )
         register_unary_op(details::e_expm1 , details::expm1_op)
         register_unary_op(details::e_floor , details::floor_op)
         register_unary_op(details::e_log   , details::log_op  )
         register_unary_op(details::e_log10 , details::log10_op)
         register_unary_op(details::e_log2  , details::log2_op )
         register_unary_op(details::e_log1p , details::log1p_op)
         register_unary_op(details::e_neg   , details::neg_op  )
         register_unary_op(details::e_pos   , details::pos_op  )
         register_unary_op(details::e_round , details::round_op)
         register_unary_op(details::e_sin   , details::sin_op  )
         register_unary_op(details::e_sinc  , details::sinc_op )
         register_unary_op(details::e_sinh  , details::sinh_op )
         register_unary_op(details::e_sqrt  , details::sqrt_op )
         register_unary_op(details::e_tan   , details::tan_op  )
         register_unary_op(details::e_tanh  , details::tanh_op )
         register_unary_op(details::e_cot   , details::cot_op  )
         register_unary_op(details::e_sec   , details::sec_op  )
         register_unary_op(details::e_csc   , details::csc_op  )
         register_unary_op(details::e_r2d   , details::r2d_op  )
         register_unary_op(details::e_d2r   , details::d2r_op  )
         register_unary_op(details::e_d2g   , details::d2g_op  )
         register_unary_op(details::e_g2d   , details::g2d_op  )
         register_unary_op(details::e_notl  , details::notl_op )
         register_unary_op(details::e_sgn   , details::sgn_op  )
         register_unary_op(details::e_erf   , details::erf_op  )
         register_unary_op(details::e_erfc  , details::erfc_op )
         register_unary_op(details::e_ncdf  , details::ncdf_op )
         register_unary_op(details::e_frac  , details::frac_op )
         register_unary_op(details::e_trunc , details::trunc_op)
         #undef register_unary_op
      }

      inline void load_binary_operations_map(binary_op_map_t& m)
      {
         typedef typename binary_op_map_t::value_type value_type;

         #define register_binary_op(Op, BinaryFunctor)       \
         m.insert(value_type(Op,BinaryFunctor<T>::process)); \

         register_binary_op(details::e_add  , details::add_op )
         register_binary_op(details::e_sub  , details::sub_op )
         register_binary_op(details::e_mul  , details::mul_op )
         register_binary_op(details::e_div  , details::div_op )
         register_binary_op(details::e_mod  , details::mod_op )
         register_binary_op(details::e_pow  , details::pow_op )
         register_binary_op(details::e_lt   , details::lt_op  )
         register_binary_op(details::e_lte  , details::lte_op )
         register_binary_op(details::e_gt   , details::gt_op  )
         register_binary_op(details::e_gte  , details::gte_op )
         register_binary_op(details::e_eq   , details::eq_op  )
         register_binary_op(details::e_ne   , details::ne_op  )
         register_binary_op(details::e_and  , details::and_op )
         register_binary_op(details::e_nand , details::nand_op)
         register_binary_op(details::e_or   , details::or_op  )
         register_binary_op(details::e_nor  , details::nor_op )
         register_binary_op(details::e_xor  , details::xor_op )
         register_binary_op(details::e_xnor , details::xnor_op)
         #undef register_binary_op
      }

      inline void load_inv_binary_operations_map(inv_binary_op_map_t& m)
      {
         typedef typename inv_binary_op_map_t::value_type value_type;

         #define register_binary_op(Op, BinaryFunctor)       \
         m.insert(value_type(BinaryFunctor<T>::process,Op)); \

         register_binary_op(details::e_add  , details::add_op )
         register_binary_op(details::e_sub  , details::sub_op )
         register_binary_op(details::e_mul  , details::mul_op )
         register_binary_op(details::e_div  , details::div_op )
         register_binary_op(details::e_mod  , details::mod_op )
         register_binary_op(details::e_pow  , details::pow_op )
         register_binary_op(details::e_lt   , details::lt_op  )
         register_binary_op(details::e_lte  , details::lte_op )
         register_binary_op(details::e_gt   , details::gt_op  )
         register_binary_op(details::e_gte  , details::gte_op )
         register_binary_op(details::e_eq   , details::eq_op  )
         register_binary_op(details::e_ne   , details::ne_op  )
         register_binary_op(details::e_and  , details::and_op )
         register_binary_op(details::e_nand , details::nand_op)
         register_binary_op(details::e_or   , details::or_op  )
         register_binary_op(details::e_nor  , details::nor_op )
         register_binary_op(details::e_xor  , details::xor_op )
         register_binary_op(details::e_xnor , details::xnor_op)
         #undef register_binary_op
      }

      inline void load_sf3_map(sf3_map_t& sf3_map)
      {
         typedef std::pair<trinary_functor_t,details::operator_type> pair_t;

         #define register_sf3(Op)                                                                             \
         sf3_map[details::sf##Op##_op<T>::id()] = pair_t(details::sf##Op##_op<T>::process,details::e_sf##Op); \

         register_sf3(00) register_sf3(01) register_sf3(02) register_sf3(03)
         register_sf3(04) register_sf3(05) register_sf3(06) register_sf3(07)
         register_sf3(08) register_sf3(09) register_sf3(10) register_sf3(11)
         register_sf3(12) register_sf3(13) register_sf3(14) register_sf3(15)
         register_sf3(16) register_sf3(17) register_sf3(18) register_sf3(19)
         register_sf3(20) register_sf3(21) register_sf3(22) register_sf3(23)
         register_sf3(24) register_sf3(25) register_sf3(26) register_sf3(27)
         register_sf3(28) register_sf3(29) register_sf3(30)
         #undef register_sf3

         #define register_sf3_extid(Id, Op)                                        \
         sf3_map[Id] = pair_t(details::sf##Op##_op<T>::process,details::e_sf##Op); \

         register_sf3_extid("(t-t)-t",23)  // (t-t)-t --> t-(t+t)
         #undef register_sf3_extid
      }

      inline void load_sf4_map(sf4_map_t& sf4_map)
      {
         typedef std::pair<quaternary_functor_t,details::operator_type> pair_t;

         #define register_sf4(Op)                                                                             \
         sf4_map[details::sf##Op##_op<T>::id()] = pair_t(details::sf##Op##_op<T>::process,details::e_sf##Op); \

         register_sf4(48) register_sf4(49) register_sf4(50) register_sf4(51)
         register_sf4(52) register_sf4(53) register_sf4(54) register_sf4(55)
         register_sf4(56) register_sf4(57) register_sf4(58) register_sf4(59)
         register_sf4(60) register_sf4(61) register_sf4(62) register_sf4(63)
         register_sf4(64) register_sf4(65) register_sf4(66) register_sf4(67)
         register_sf4(68) register_sf4(69) register_sf4(70) register_sf4(71)
         register_sf4(72) register_sf4(73) register_sf4(74) register_sf4(75)
         register_sf4(76) register_sf4(77) register_sf4(78) register_sf4(79)
         register_sf4(80) register_sf4(81) register_sf4(82) register_sf4(83)
         #undef register_sf4

         #define register_sf4ext(Op)                                                                                    \
         sf4_map[details::sfext##Op##_op<T>::id()] = pair_t(details::sfext##Op##_op<T>::process,details::e_sf4ext##Op); \

         register_sf4ext(00) register_sf4ext(01) register_sf4ext(02) register_sf4ext(03)
         register_sf4ext(04) register_sf4ext(05) register_sf4ext(06) register_sf4ext(07)
         register_sf4ext(08) register_sf4ext(09) register_sf4ext(10) register_sf4ext(11)
         register_sf4ext(12) register_sf4ext(13) register_sf4ext(14) register_sf4ext(15)
         register_sf4ext(16) register_sf4ext(17) register_sf4ext(18) register_sf4ext(19)
         register_sf4ext(20) register_sf4ext(21) register_sf4ext(22) register_sf4ext(23)
         register_sf4ext(24) register_sf4ext(25) register_sf4ext(26) register_sf4ext(27)
         register_sf4ext(28) register_sf4ext(29) register_sf4ext(30) register_sf4ext(31)
         register_sf4ext(32) register_sf4ext(33) register_sf4ext(34) register_sf4ext(35)
         register_sf4ext(36) register_sf4ext(36) register_sf4ext(38) register_sf4ext(39)
         register_sf4ext(40) register_sf4ext(41) register_sf4ext(42) register_sf4ext(43)
         register_sf4ext(44) register_sf4ext(45) register_sf4ext(46) register_sf4ext(47)
         register_sf4ext(48) register_sf4ext(49) register_sf4ext(50) register_sf4ext(51)
         register_sf4ext(52) register_sf4ext(53) register_sf4ext(54) register_sf4ext(55)
         register_sf4ext(56) register_sf4ext(57) register_sf4ext(58) register_sf4ext(59)
         register_sf4ext(60) register_sf4ext(61)
         #undef register_sf4ext
      }

      inline results_context_t& results_ctx()
      {
         if (0 == results_context_)
         {
            results_context_ = new results_context_t();
         }

         return (*results_context_);
      }

      inline void return_cleanup()
      {
         #ifndef exprtk_disable_return_statement
         if (results_context_)
         {
            delete results_context_;
            results_context_ = 0;
         }

         state_.return_stmt_present = false;
         #endif
      }

   private:

      parser(const parser<T>&) exprtk_delete;
      parser<T>& operator=(const parser<T>&) exprtk_delete;

      settings_store settings_;
      expression_generator<T> expression_generator_;
      details::node_allocator node_allocator_;
      symtab_store symtab_store_;
      dependent_entity_collector dec_;
      std::deque<parser_error::type> error_list_;
      std::deque<bool> brkcnt_list_;
      parser_state state_;
      bool resolve_unknown_symbol_;
      results_context_t* results_context_;
      unknown_symbol_resolver* unknown_symbol_resolver_;
      unknown_symbol_resolver default_usr_;
      base_ops_map_t base_ops_map_;
      unary_op_map_t unary_op_map_;
      binary_op_map_t binary_op_map_;
      inv_binary_op_map_t inv_binary_op_map_;
      sf3_map_t sf3_map_;
      sf4_map_t sf4_map_;
      std::string synthesis_error_;
      scope_element_manager sem_;
      std::vector<state_t> current_state_stack_;

      immutable_memory_map_t immutable_memory_map_;
      immutable_symtok_map_t immutable_symtok_map_;

      lexer::helper::helper_assembly helper_assembly_;

      lexer::helper::commutative_inserter       commutative_inserter_;
      lexer::helper::operator_joiner            operator_joiner_2_;
      lexer::helper::operator_joiner            operator_joiner_3_;
      lexer::helper::symbol_replacer            symbol_replacer_;
      lexer::helper::bracket_checker            bracket_checker_;
      lexer::helper::numeric_checker<T>         numeric_checker_;
      lexer::helper::sequence_validator         sequence_validator_;
      lexer::helper::sequence_validator_3tokens sequence_validator_3tkns_;

      loop_runtime_check_ptr          loop_runtime_check_;
      vector_access_runtime_check_ptr vector_access_runtime_check_;
      compilation_check_ptr           compilation_check_ptr_;
      assert_check_ptr                assert_check_;
      std::set<std::string>           assert_ids_;

      template <typename ParserType>
      friend void details::disable_type_checking(ParserType& p);
   }; // class parser

   namespace details
   {
      template <typename T>
      struct collector_helper
      {
         typedef exprtk::symbol_table<T> symbol_table_t;
         typedef exprtk::expression<T>   expression_t;
         typedef exprtk::parser<T>       parser_t;
         typedef typename parser_t::dependent_entity_collector::symbol_t symbol_t;
         typedef typename parser_t::unknown_symbol_resolver usr_t;

         struct resolve_as_vector : public usr_t
         {
            typedef exprtk::parser<T> parser_t;

            using usr_t::process;

            resolve_as_vector()
            : usr_t(usr_t::e_usrmode_extended)
            {}

            virtual bool process(const std::string& unknown_symbol,
                                 symbol_table_t& symbol_table,
                                 std::string&) exprtk_override
            {
               static T v[1];
               symbol_table.add_vector(unknown_symbol,v);
               return true;
            }
         };

         static inline bool collection_pass(const std::string& expression_string,
                                            std::set<std::string>& symbol_set,
                                            const bool collect_variables,
                                            const bool collect_functions,
                                            const bool vector_pass,
                                            symbol_table_t& ext_symbol_table)
         {
            symbol_table_t symbol_table;
            expression_t   expression;
            parser_t       parser;

            resolve_as_vector vect_resolver;

            expression.register_symbol_table(symbol_table    );
            expression.register_symbol_table(ext_symbol_table);

            if (vector_pass)
               parser.enable_unknown_symbol_resolver(&vect_resolver);
            else
               parser.enable_unknown_symbol_resolver();

            if (collect_variables)
               parser.dec().collect_variables() = true;

            if (collect_functions)
               parser.dec().collect_functions() = true;

            bool pass_result = false;

            details::disable_type_checking(parser);

            if (parser.compile(expression_string, expression))
            {
               pass_result = true;

               std::deque<symbol_t> symb_list;
               parser.dec().symbols(symb_list);

               for (std::size_t i = 0; i < symb_list.size(); ++i)
               {
                  symbol_set.insert(symb_list[i].first);
               }
            }

            return pass_result;
         }
      };
   }

   template <typename Allocator,
             template <typename, typename> class Sequence>
   inline bool collect_variables(const std::string& expression,
                                 Sequence<std::string, Allocator>& symbol_list)
   {
      typedef double T;
      typedef details::collector_helper<T> collect_t;

      collect_t::symbol_table_t null_symbol_table;

      std::set<std::string> symbol_set;

      const bool variable_pass = collect_t::collection_pass
                                    (expression, symbol_set, true, false, false, null_symbol_table);
      const bool vector_pass   = collect_t::collection_pass
                                    (expression, symbol_set, true, false,  true, null_symbol_table);

      if (!variable_pass && !vector_pass)
         return false;

      std::set<std::string>::iterator itr = symbol_set.begin();

      while (symbol_set.end() != itr)
      {
         symbol_list.push_back(*itr);
         ++itr;
      }

      return true;
   }

   template <typename T,
             typename Allocator,
             template <typename, typename> class Sequence>
   inline bool collect_variables(const std::string& expression,
                                 exprtk::symbol_table<T>& extrnl_symbol_table,
                                 Sequence<std::string, Allocator>& symbol_list)
   {
      typedef details::collector_helper<T> collect_t;

      std::set<std::string> symbol_set;

      const bool variable_pass = collect_t::collection_pass
                                    (expression, symbol_set, true, false, false, extrnl_symbol_table);
      const bool vector_pass   = collect_t::collection_pass
                                    (expression, symbol_set, true, false,  true, extrnl_symbol_table);

      if (!variable_pass && !vector_pass)
         return false;

      std::set<std::string>::iterator itr = symbol_set.begin();

      while (symbol_set.end() != itr)
      {
         symbol_list.push_back(*itr);
         ++itr;
      }

      return true;
   }

   template <typename Allocator,
             template <typename, typename> class Sequence>
   inline bool collect_functions(const std::string& expression,
                                 Sequence<std::string, Allocator>& symbol_list)
   {
      typedef double T;
      typedef details::collector_helper<T> collect_t;

      collect_t::symbol_table_t null_symbol_table;

      std::set<std::string> symbol_set;

      const bool variable_pass = collect_t::collection_pass
                                    (expression, symbol_set, false, true, false, null_symbol_table);
      const bool vector_pass   = collect_t::collection_pass
                                    (expression, symbol_set, false, true,  true, null_symbol_table);

      if (!variable_pass && !vector_pass)
         return false;

      std::set<std::string>::iterator itr = symbol_set.begin();

      while (symbol_set.end() != itr)
      {
         symbol_list.push_back(*itr);
         ++itr;
      }

      return true;
   }

   template <typename T,
             typename Allocator,
             template <typename, typename> class Sequence>
   inline bool collect_functions(const std::string& expression,
                                 exprtk::symbol_table<T>& extrnl_symbol_table,
                                 Sequence<std::string, Allocator>& symbol_list)
   {
      typedef details::collector_helper<T> collect_t;

      std::set<std::string> symbol_set;

      const bool variable_pass = collect_t::collection_pass
                                    (expression, symbol_set, false, true, false, extrnl_symbol_table);
      const bool vector_pass   = collect_t::collection_pass
                                    (expression, symbol_set, false, true,  true, extrnl_symbol_table);

      if (!variable_pass && !vector_pass)
         return false;

      std::set<std::string>::iterator itr = symbol_set.begin();

      while (symbol_set.end() != itr)
      {
         symbol_list.push_back(*itr);
         ++itr;
      }

      return true;
   }

   template <typename T>
   inline T integrate(const expression<T>& e,
                      T& x,
                      const T& r0, const T& r1,
                      const std::size_t number_of_intervals = 1000000)
   {
      if (r0 > r1)
         return T(0);

      const T h = (r1 - r0) / (T(2) * number_of_intervals);
      T total_area = T(0);

      for (std::size_t i = 0; i < number_of_intervals; ++i)
      {
         x = r0 + T(2) * i * h;
         const T y0 = e.value(); x += h;
         const T y1 = e.value(); x += h;
         const T y2 = e.value(); x += h;
         total_area += h * (y0 + T(4) * y1 + y2) / T(3);
      }

      return total_area;
   }

   template <typename T>
   inline T integrate(const expression<T>& e,
                      const std::string& variable_name,
                      const T& r0, const T& r1,
                      const std::size_t number_of_intervals = 1000000)
   {
      const symbol_table<T>& sym_table = e.get_symbol_table();

      if (!sym_table.valid())
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      details::variable_node<T>* var = sym_table.get_variable(variable_name);

      if (var)
      {
         T& x = var->ref();
         const T x_original = x;
         const T result = integrate(e, x, r0, r1, number_of_intervals);
         x = x_original;

         return result;
      }

      return std::numeric_limits<T>::quiet_NaN();
   }

   template <typename T>
   inline T derivative(const expression<T>& e,
                       T& x,
                       const T& h = T(0.00000001))
   {
      const T x_init = x;
      const T _2h    = T(2) * h;

      x = x_init + _2h;
      const T y0 = e.value();
      x = x_init + h;
      const T y1 = e.value();
      x = x_init - h;
      const T y2 = e.value();
      x = x_init - _2h;
      const T y3 = e.value();
      x = x_init;

      return (-y0 + T(8) * (y1 - y2) + y3) / (T(12) * h);
   }

   template <typename T>
   inline T second_derivative(const expression<T>& e,
                              T& x,
                              const T& h = T(0.00001))
   {
      const T x_init = x;
      const T _2h    = T(2) * h;

      const T y = e.value();
      x = x_init + _2h;
      const T y0 = e.value();
      x = x_init + h;
      const T y1 = e.value();
      x = x_init - h;
      const T y2 = e.value();
      x = x_init - _2h;
      const T y3 = e.value();
      x = x_init;

      return (-y0 + T(16) * (y1 + y2) - T(30) * y - y3) / (T(12) * h * h);
   }

   template <typename T>
   inline T third_derivative(const expression<T>& e,
                             T& x,
                             const T& h = T(0.0001))
   {
      const T x_init = x;
      const T _2h    = T(2) * h;

      x = x_init + _2h;
      const T y0 = e.value();
      x = x_init + h;
      const T y1 = e.value();
      x = x_init - h;
      const T y2 = e.value();
      x = x_init - _2h;
      const T y3 = e.value();
      x = x_init;

      return (y0 + T(2) * (y2 - y1) - y3) / (T(2) * h * h * h);
   }

   template <typename T>
   inline T derivative(const expression<T>& e,
                       const std::string& variable_name,
                       const T& h = T(0.00000001))
   {
      const symbol_table<T>& sym_table = e.get_symbol_table();

      if (!sym_table.valid())
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      details::variable_node<T>* var = sym_table.get_variable(variable_name);

      if (var)
      {
         T& x = var->ref();
         const T x_original = x;
         const T result = derivative(e, x, h);
         x = x_original;

         return result;
      }

      return std::numeric_limits<T>::quiet_NaN();
   }

   template <typename T>
   inline T second_derivative(const expression<T>& e,
                              const std::string& variable_name,
                              const T& h = T(0.00001))
   {
      const symbol_table<T>& sym_table = e.get_symbol_table();

      if (!sym_table.valid())
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      details::variable_node<T>* var = sym_table.get_variable(variable_name);

      if (var)
      {
         T& x = var->ref();
         const T x_original = x;
         const T result = second_derivative(e, x, h);
         x = x_original;

         return result;
      }

      return std::numeric_limits<T>::quiet_NaN();
   }

   template <typename T>
   inline T third_derivative(const expression<T>& e,
                             const std::string& variable_name,
                             const T& h = T(0.0001))
   {
      const symbol_table<T>& sym_table = e.get_symbol_table();

      if (!sym_table.valid())
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      details::variable_node<T>* var = sym_table.get_variable(variable_name);

      if (var)
      {
         T& x = var->ref();
         const T x_original = x;
         const T result = third_derivative(e, x, h);
         x = x_original;

         return result;
      }

      return std::numeric_limits<T>::quiet_NaN();
   }

   /*
      Note: The following 'compute' routines are simple helpers,
      for quickly setting up the required pieces of code in order
      to evaluate an expression. By virtue of how they operate
      there will be an overhead with regards to their setup and
      teardown and hence should not be used in time critical
      sections of code.
      Furthermore they only assume a small sub set of variables,
      no string variables or user defined functions.
   */
   template <typename T>
   inline bool compute(const std::string& expression_string, T& result)
   {
      // No variables
      symbol_table<T> symbol_table;
      symbol_table.add_constants();

      expression<T> expression;
      expression.register_symbol_table(symbol_table);

      parser<T> parser;

      if (parser.compile(expression_string,expression))
      {
         result = expression.value();

         return true;
      }
      else
         return false;
   }

   template <typename T>
   inline bool compute(const std::string& expression_string,
                       const T& x,
                       T& result)
   {
      // Only 'x'
      static const std::string x_var("x");

      symbol_table<T> symbol_table;
      symbol_table.add_constants();
      symbol_table.add_constant(x_var,x);

      expression<T> expression;
      expression.register_symbol_table(symbol_table);

      parser<T> parser;

      if (parser.compile(expression_string,expression))
      {
         result = expression.value();

         return true;
      }
      else
         return false;
   }

   template <typename T>
   inline bool compute(const std::string& expression_string,
                       const T&x, const T& y,
                       T& result)
   {
      // Only 'x' and 'y'
      static const std::string x_var("x");
      static const std::string y_var("y");

      symbol_table<T> symbol_table;
      symbol_table.add_constants();
      symbol_table.add_constant(x_var,x);
      symbol_table.add_constant(y_var,y);

      expression<T> expression;
      expression.register_symbol_table(symbol_table);

      parser<T> parser;

      if (parser.compile(expression_string,expression))
      {
         result = expression.value();

         return true;
      }
      else
         return false;
   }

   template <typename T>
   inline bool compute(const std::string& expression_string,
                       const T& x, const T& y, const T& z,
                       T& result)
   {
      // Only 'x', 'y' or 'z'
      static const std::string x_var("x");
      static const std::string y_var("y");
      static const std::string z_var("z");

      symbol_table<T> symbol_table;
      symbol_table.add_constants();
      symbol_table.add_constant(x_var,x);
      symbol_table.add_constant(y_var,y);
      symbol_table.add_constant(z_var,z);

      expression<T> expression;
      expression.register_symbol_table(symbol_table);

      parser<T> parser;

      if (parser.compile(expression_string,expression))
      {
         result = expression.value();

         return true;
      }
      else
         return false;
   }

   template <typename T, std::size_t N>
   class polynomial : public ifunction<T>
   {
   private:

      template <typename Type, std::size_t NumberOfCoefficients>
      struct poly_impl { };

      template <typename Type>
      struct poly_impl <Type,12>
      {
         static inline T evaluate(const Type x,
                                  const Type c12, const Type c11, const Type c10, const Type c9, const Type c8,
                                  const Type  c7, const Type  c6, const Type  c5, const Type c4, const Type c3,
                                  const Type  c2, const Type  c1, const Type  c0)
         {
            // p(x) = c_12x^12 + c_11x^11 + c_10x^10 + c_9x^9 + c_8x^8 + c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return ((((((((((((c12 * x + c11) * x + c10) * x + c9) * x + c8) * x + c7) * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,11>
      {
         static inline T evaluate(const Type x,
                                  const Type c11, const Type c10, const Type c9, const Type c8, const Type c7,
                                  const Type c6,  const Type  c5, const Type c4, const Type c3, const Type c2,
                                  const Type c1,  const Type  c0)
         {
            // p(x) = c_11x^11 + c_10x^10 + c_9x^9 + c_8x^8 + c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return (((((((((((c11 * x + c10) * x + c9) * x + c8) * x + c7) * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,10>
      {
         static inline T evaluate(const Type x,
                                  const Type c10, const Type c9, const Type c8, const Type c7, const Type c6,
                                  const Type c5,  const Type c4, const Type c3, const Type c2, const Type c1,
                                  const Type c0)
         {
            // p(x) = c_10x^10 + c_9x^9 + c_8x^8 + c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return ((((((((((c10 * x + c9) * x + c8) * x + c7) * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,9>
      {
         static inline T evaluate(const Type x,
                                  const Type c9, const Type c8, const Type c7, const Type c6, const Type c5,
                                  const Type c4, const Type c3, const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_9x^9 + c_8x^8 + c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return (((((((((c9 * x + c8) * x + c7) * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,8>
      {
         static inline T evaluate(const Type x,
                                  const Type c8, const Type c7, const Type c6, const Type c5, const Type c4,
                                  const Type c3, const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_8x^8 + c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return ((((((((c8 * x + c7) * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,7>
      {
         static inline T evaluate(const Type x,
                                  const Type c7, const Type c6, const Type c5, const Type c4, const Type c3,
                                  const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_7x^7 + c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return (((((((c7 * x + c6) * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,6>
      {
         static inline T evaluate(const Type x,
                                  const Type c6, const Type c5, const Type c4, const Type c3, const Type c2,
                                  const Type c1, const Type c0)
         {
            // p(x) = c_6x^6 + c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return ((((((c6 * x + c5) * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,5>
      {
         static inline T evaluate(const Type x,
                                  const Type c5, const Type c4, const Type c3, const Type c2,
                                  const Type c1, const Type c0)
         {
            // p(x) = c_5x^5 + c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return (((((c5 * x + c4) * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,4>
      {
         static inline T evaluate(const Type x, const Type c4, const Type c3, const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_4x^4 + c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return ((((c4 * x + c3) * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,3>
      {
         static inline T evaluate(const Type x, const Type c3, const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_3x^3 + c_2x^2 + c_1x^1 + c_0x^0
            return (((c3 * x + c2) * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,2>
      {
         static inline T evaluate(const Type x, const Type c2, const Type c1, const Type c0)
         {
            // p(x) = c_2x^2 + c_1x^1 + c_0x^0
            return ((c2 * x + c1) * x + c0);
         }
      };

      template <typename Type>
      struct poly_impl <Type,1>
      {
         static inline T evaluate(const Type x, const Type c1, const Type c0)
         {
            // p(x) = c_1x^1 + c_0x^0
            return (c1 * x + c0);
         }
      };

   public:

      using ifunction<T>::operator();

      polynomial()
      : ifunction<T>((N+2 <= 20) ? (N + 2) : std::numeric_limits<std::size_t>::max())
      {
         disable_has_side_effects(*this);
      }

      virtual ~polynomial()
      {}

      #define poly_rtrn(NN) \
      return (NN != N) ? std::numeric_limits<T>::quiet_NaN() :

      inline virtual T operator() (const T& x, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(1) (poly_impl<T,1>::evaluate(x, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(2) (poly_impl<T,2>::evaluate(x, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c3, const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(3) (poly_impl<T,3>::evaluate(x, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c4, const T& c3, const T& c2, const T& c1,
                                   const T& c0) exprtk_override
      {
         poly_rtrn(4) (poly_impl<T,4>::evaluate(x, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c5, const T& c4, const T& c3, const T& c2,
                                   const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(5) (poly_impl<T,5>::evaluate(x, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c6, const T& c5, const T& c4, const T& c3,
                                   const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(6) (poly_impl<T,6>::evaluate(x, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c7, const T& c6, const T& c5, const T& c4,
                                   const T& c3, const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(7) (poly_impl<T,7>::evaluate(x, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c8, const T& c7, const T& c6, const T& c5,
                                   const T& c4, const T& c3, const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(8) (poly_impl<T,8>::evaluate(x, c8, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c9, const T& c8, const T& c7, const T& c6,
                                   const T& c5, const T& c4, const T& c3, const T& c2, const T& c1,
                                   const T& c0) exprtk_override
      {
         poly_rtrn(9) (poly_impl<T,9>::evaluate(x, c9, c8, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c10, const T& c9, const T& c8, const T& c7,
                                   const T& c6, const T& c5, const T& c4, const T& c3, const T& c2,
                                   const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(10) (poly_impl<T,10>::evaluate(x, c10, c9, c8, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c11, const T& c10, const T& c9, const T& c8,
                                   const T& c7, const T& c6, const T& c5, const T& c4, const T& c3,
                                   const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(11) (poly_impl<T,11>::evaluate(x, c11, c10, c9, c8, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      inline virtual T operator() (const T& x, const T& c12, const T& c11, const T& c10, const T& c9,
                                   const T& c8, const T& c7, const T& c6, const T& c5, const T& c4,
                                   const T& c3, const T& c2, const T& c1, const T& c0) exprtk_override
      {
         poly_rtrn(12) (poly_impl<T,12>::evaluate(x, c12, c11, c10, c9, c8, c7, c6, c5, c4, c3, c2, c1, c0));
      }

      #undef poly_rtrn

      inline virtual T operator() () exprtk_override
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator() (const T&) exprtk_override
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator() (const T&, const T&) exprtk_override
      {
         return std::numeric_limits<T>::quiet_NaN();
      }
   };

   template <typename T>
   class function_compositor
   {
   public:

      typedef exprtk::expression<T>             expression_t;
      typedef exprtk::symbol_table<T>           symbol_table_t;
      typedef exprtk::parser<T>                 parser_t;
      typedef typename parser_t::settings_store settings_t;

      struct function
      {
         function()
         {}

         function(const std::string& n)
         : name_(n)
         {}

         function(const std::string& name,
                  const std::string& expression)
         : name_(name)
         , expression_(expression)
         {}

         function(const std::string& name,
                  const std::string& expression,
                  const std::string& v0)
         : name_(name)
         , expression_(expression)
         {
            v_.push_back(v0);
         }

         function(const std::string& name,
                  const std::string& expression,
                  const std::string& v0, const std::string& v1)
         : name_(name)
         , expression_(expression)
         {
            v_.push_back(v0); v_.push_back(v1);
         }

         function(const std::string& name,
                  const std::string& expression,
                  const std::string& v0, const std::string& v1,
                  const std::string& v2)
         : name_(name)
         , expression_(expression)
         {
            v_.push_back(v0); v_.push_back(v1);
            v_.push_back(v2);
         }

         function(const std::string& name,
                  const std::string& expression,
                  const std::string& v0, const std::string& v1,
                  const std::string& v2, const std::string& v3)
         : name_(name)
         , expression_(expression)
         {
            v_.push_back(v0); v_.push_back(v1);
            v_.push_back(v2); v_.push_back(v3);
         }

         function(const std::string& name,
                  const std::string& expression,
                  const std::string& v0, const std::string& v1,
                  const std::string& v2, const std::string& v3,
                  const std::string& v4)
         : name_(name)
         , expression_(expression)
         {
            v_.push_back(v0); v_.push_back(v1);
            v_.push_back(v2); v_.push_back(v3);
            v_.push_back(v4);
         }

         inline function& name(const std::string& n)
         {
            name_ = n;
            return (*this);
         }

         inline function& expression(const std::string& e)
         {
            expression_ = e;
            return (*this);
         }

         inline function& var(const std::string& v)
         {
            v_.push_back(v);
            return (*this);
         }

         inline function& vars(const std::string& v0,
                               const std::string& v1)
         {
            v_.push_back(v0);
            v_.push_back(v1);
            return (*this);
         }

         inline function& vars(const std::string& v0,
                               const std::string& v1,
                               const std::string& v2)
         {
            v_.push_back(v0);
            v_.push_back(v1);
            v_.push_back(v2);
            return (*this);
         }

         inline function& vars(const std::string& v0,
                               const std::string& v1,
                               const std::string& v2,
                               const std::string& v3)
         {
            v_.push_back(v0);
            v_.push_back(v1);
            v_.push_back(v2);
            v_.push_back(v3);
            return (*this);
         }

         inline function& vars(const std::string& v0,
                               const std::string& v1,
                               const std::string& v2,
                               const std::string& v3,
                               const std::string& v4)
         {
            v_.push_back(v0);
            v_.push_back(v1);
            v_.push_back(v2);
            v_.push_back(v3);
            v_.push_back(v4);
            return (*this);
         }

         std::string name_;
         std::string expression_;
         std::deque<std::string> v_;
      };

   private:

      struct base_func : public exprtk::ifunction<T>
      {
         typedef const T&                  type;
         typedef exprtk::ifunction<T>      function_t;
         typedef std::vector<T*>           varref_t;
         typedef std::vector<T>            var_t;
         typedef std::vector<std::string>  str_t;
         typedef std::pair<T*,std::size_t> lvarref_t;
         typedef std::vector<lvarref_t>    lvr_vec_t;
         typedef std::vector<std::string*> lstr_vec_t;

         using exprtk::ifunction<T>::operator();

         base_func(const std::size_t& pc = 0)
         : exprtk::ifunction<T>(pc)
         , local_var_stack_size(0)
         , stack_depth(0)
         {
            v.resize(pc);
         }

         virtual ~base_func()
         {}

         #define exprtk_assign(Index) \
         (*v[Index]) = v##Index;      \

         inline void update(const T& v0)
         {
            exprtk_assign(0)
         }

         inline void update(const T& v0, const T& v1)
         {
            exprtk_assign(0) exprtk_assign(1)
         }

         inline void update(const T& v0, const T& v1, const T& v2)
         {
            exprtk_assign(0) exprtk_assign(1)
            exprtk_assign(2)
         }

         inline void update(const T& v0, const T& v1, const T& v2, const T& v3)
         {
            exprtk_assign(0) exprtk_assign(1)
            exprtk_assign(2) exprtk_assign(3)
         }

         inline void update(const T& v0, const T& v1, const T& v2, const T& v3, const T& v4)
         {
            exprtk_assign(0) exprtk_assign(1)
            exprtk_assign(2) exprtk_assign(3)
            exprtk_assign(4)
         }

         inline void update(const T& v0, const T& v1, const T& v2, const T& v3, const T& v4, const T& v5)
         {
            exprtk_assign(0) exprtk_assign(1)
            exprtk_assign(2) exprtk_assign(3)
            exprtk_assign(4) exprtk_assign(5)
         }

         #ifdef exprtk_assign
         #undef exprtk_assign
         #endif

         inline function_t& setup(expression_t& expr)
         {
            expression = expr;

            typedef typename expression_t::control_block  ctrlblk_t;
            typedef typename ctrlblk_t::local_data_list_t ldl_t;
            typedef typename ctrlblk_t::data_type         data_t;
            typedef typename ldl_t::value_type            ldl_value_type;

            const ldl_t ldl = expr.local_data_list();

            std::vector<std::pair<std::size_t,data_t> > index_list;

            for (std::size_t i = 0; i < ldl.size(); ++i)
            {
               exprtk_debug(("base_func::setup() - element[%02d] type: %s size: %d\n",
                             static_cast<int>(i),
                             expression_t::control_block::to_str(ldl[i].type).c_str(),
                             static_cast<int>(ldl[i].size)));

               switch (ldl[i].type)
               {
                  case ctrlblk_t::e_unknown   : continue;
                  case ctrlblk_t::e_expr      : continue;
                  case ctrlblk_t::e_vecholder : continue;
                  default                     : break;
               }

               if (ldl[i].size)
               {
                  index_list.push_back(std::make_pair(i,ldl[i].type));
               }
            }

            std::size_t input_param_count = 0;

            for (std::size_t i = 0; i < index_list.size(); ++i)
            {
               const std::size_t index         = index_list[i].first;
               const ldl_value_type& local_var = ldl[index];

               assert(local_var.pointer);

               if (i < (index_list.size() - v.size()))
               {
                  if (local_var.type == ctrlblk_t::e_string)
                  {
                     local_str_vars.push_back(
                        reinterpret_cast<std::string*>(local_var.pointer));
                  }
                  else if (
                            (local_var.type == ctrlblk_t::e_data   ) ||
                            (local_var.type == ctrlblk_t::e_vecdata)
                          )
                  {
                     local_vars.push_back(std::make_pair(
                        reinterpret_cast<T*>(local_var.pointer),
                        local_var.size));

                     local_var_stack_size += local_var.size;
                  }
               }
               else
               {
                  v[input_param_count++] = reinterpret_cast<T*>(local_var.pointer);
               }
            }

            clear_stack();

            return (*this);
         }

         inline void pre()
         {
            if (stack_depth++)
            {
               if (!v.empty())
               {
                  var_t var_stack(v.size(),T(0));
                  copy(v,var_stack);
                  input_params_stack.push_back(var_stack);
               }

               if (!local_vars.empty())
               {
                  var_t local_vec_frame(local_var_stack_size,T(0));
                  copy(local_vars,local_vec_frame);
                  local_var_stack.push_back(local_vec_frame);
               }

               if (!local_str_vars.empty())
               {
                  str_t local_str_frame(local_str_vars.size());
                  copy(local_str_vars,local_str_frame);
                  local_str_stack.push_back(local_str_frame);
               }
            }
         }

         inline void post()
         {
            if (--stack_depth)
            {
               if (!v.empty())
               {
                  copy(input_params_stack.back(), v);
                  input_params_stack.pop_back();
               }

               if (!local_vars.empty())
               {
                  copy(local_var_stack.back(), local_vars);
                  local_var_stack.pop_back();
               }

               if (!local_str_vars.empty())
               {
                  copy(local_str_stack.back(), local_str_vars);
                  local_str_stack.pop_back();
               }
            }
         }

         void copy(const varref_t& src_v, var_t& dest_v)
         {
            for (std::size_t i = 0; i < src_v.size(); ++i)
            {
               dest_v[i] = (*src_v[i]);
            }
         }

         void copy(const lstr_vec_t& src_v, str_t& dest_v)
         {
            for (std::size_t i = 0; i < src_v.size(); ++i)
            {
               dest_v[i] = (*src_v[i]);
            }
         }

         void copy(const var_t& src_v, varref_t& dest_v)
         {
            for (std::size_t i = 0; i < src_v.size(); ++i)
            {
               (*dest_v[i]) = src_v[i];
            }
         }

         void copy(const lvr_vec_t& src_v, var_t& dest_v)
         {
            typename var_t::iterator itr = dest_v.begin();
            typedef  typename std::iterator_traits<typename var_t::iterator>::difference_type diff_t;

            for (std::size_t i = 0; i < src_v.size(); ++i)
            {
               lvarref_t vr = src_v[i];

               if (1 == vr.second)
                  *itr++ = (*vr.first);
               else
               {
                  std::copy(vr.first, vr.first + vr.second, itr);
                  itr += static_cast<diff_t>(vr.second);
               }
            }
         }

         void copy(const var_t& src_v, lvr_vec_t& dest_v)
         {
            typename var_t::const_iterator itr = src_v.begin();
            typedef  typename std::iterator_traits<typename var_t::iterator>::difference_type diff_t;

            for (std::size_t i = 0; i < dest_v.size(); ++i)
            {
               lvarref_t& vr = dest_v[i];

               assert(vr.first != 0);
               assert(vr.second > 0);

               if (1 == vr.second)
                  (*vr.first) = *itr++;
               else
               {
                  std::copy(itr, itr + static_cast<diff_t>(vr.second), vr.first);
                  itr += static_cast<diff_t>(vr.second);
               }
            }
         }

         void copy(const str_t& src_str, lstr_vec_t& dest_str)
         {
            assert(src_str.size() == dest_str.size());

            for (std::size_t i = 0; i < dest_str.size(); ++i)
            {
               *dest_str[i] = src_str[i];
            }
         }

         inline void clear_stack()
         {
            for (std::size_t i = 0; i < v.size(); ++i)
            {
               (*v[i]) = 0;
            }
         }

         inline virtual T value(expression_t& e)
         {
            return e.value();
         }

         expression_t      expression;
         varref_t          v;
         lvr_vec_t         local_vars;
         lstr_vec_t        local_str_vars;
         std::size_t       local_var_stack_size;
         std::size_t       stack_depth;
         std::deque<var_t> input_params_stack;
         std::deque<var_t> local_var_stack;
         std::deque<str_t> local_str_stack;
      };

      typedef std::map<std::string,base_func*> funcparam_t;

      typedef const T& type;

      template <typename BaseFuncType>
      struct scoped_bft
      {
         explicit scoped_bft(BaseFuncType& bft)
         : bft_(bft)
         {
            bft_.pre ();
         }

        ~scoped_bft()
         {
            bft_.post();
         }

         BaseFuncType& bft_;

      private:

         scoped_bft(const scoped_bft&) exprtk_delete;
         scoped_bft& operator=(const scoped_bft&) exprtk_delete;
      };

      struct func_0param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_0param() : base_func(0) {}

         inline T operator() () exprtk_override
         {
            scoped_bft<func_0param> sb(*this);
            return this->value(base_func::expression);
         }
      };

      struct func_1param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_1param() : base_func(1) {}

         inline T operator() (type v0) exprtk_override
         {
            scoped_bft<func_1param> sb(*this);
            base_func::update(v0);
            return this->value(base_func::expression);
         }
      };

      struct func_2param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_2param() : base_func(2) {}

         inline T operator() (type v0, type v1) exprtk_override
         {
            scoped_bft<func_2param> sb(*this);
            base_func::update(v0, v1);
            return this->value(base_func::expression);
         }
      };

      struct func_3param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_3param() : base_func(3) {}

         inline T operator() (type v0, type v1, type v2) exprtk_override
         {
            scoped_bft<func_3param> sb(*this);
            base_func::update(v0, v1, v2);
            return this->value(base_func::expression);
         }
      };

      struct func_4param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_4param() : base_func(4) {}

         inline T operator() (type v0, type v1, type v2, type v3) exprtk_override
         {
            scoped_bft<func_4param> sb(*this);
            base_func::update(v0, v1, v2, v3);
            return this->value(base_func::expression);
         }
      };

      struct func_5param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_5param() : base_func(5) {}

         inline T operator() (type v0, type v1, type v2, type v3, type v4) exprtk_override
         {
            scoped_bft<func_5param> sb(*this);
            base_func::update(v0, v1, v2, v3, v4);
            return this->value(base_func::expression);
         }
      };

      struct func_6param : public base_func
      {
         using exprtk::ifunction<T>::operator();

         func_6param() : base_func(6) {}

         inline T operator() (type v0, type v1, type v2, type v3, type v4, type v5) exprtk_override
         {
            scoped_bft<func_6param> sb(*this);
            base_func::update(v0, v1, v2, v3, v4, v5);
            return this->value(base_func::expression);
         }
      };

      static T return_value(expression_t& e)
      {
         typedef exprtk::results_context<T> results_context_t;
         typedef typename results_context_t::type_store_t type_t;
         typedef typename type_t::scalar_view scalar_t;

         const T result = e.value();

         if (e.return_invoked())
         {
            // Due to the post compilation checks, it can be safely
            // assumed that there will be at least one parameter
            // and that the first parameter will always be scalar.
            return scalar_t(e.results()[0])();
         }

         return result;
      }

      #define def_fp_retval(N)                                            \
      struct func_##N##param_retval exprtk_final : public func_##N##param \
      {                                                                   \
         inline T value(expression_t& e) exprtk_override                  \
         {                                                                \
            return return_value(e);                                       \
         }                                                                \
      };                                                                  \

      def_fp_retval(0)
      def_fp_retval(1)
      def_fp_retval(2)
      def_fp_retval(3)
      def_fp_retval(4)
      def_fp_retval(5)
      def_fp_retval(6)

      #undef def_fp_retval

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline bool add(const std::string& name,
                      const std::string& expression,
                      const Sequence<std::string,Allocator>& var_list,
                      const bool override = false)
      {
         const typename std::map<std::string,expression_t>::iterator itr = expr_map_.find(name);

         if (expr_map_.end() != itr)
         {
            if (!override)
            {
               exprtk_debug(("Compositor error(add): function '%s' already defined\n",
                             name.c_str()));

               return false;
            }

            remove(name, var_list.size());
         }

         if (compile_expression(name, expression, var_list))
         {
            const std::size_t n = var_list.size();

            fp_map_[n][name]->setup(expr_map_[name]);

            return true;
         }
         else
         {
            exprtk_debug(("Compositor error(add): Failed to compile function '%s'\n",
                          name.c_str()));

            return false;
         }
      }

   public:

      function_compositor()
      : parser_(settings_t::default_compile_all_opts +
                settings_t::e_disable_zero_return)
      , fp_map_(7)
      , load_variables_(false)
      , load_vectors_(false)
      {}

      explicit function_compositor(const symbol_table_t& st)
      : symbol_table_(st)
      , parser_(settings_t::default_compile_all_opts +
                settings_t::e_disable_zero_return)
      , fp_map_(7)
      , load_variables_(false)
      , load_vectors_(false)
      {}

     ~function_compositor()
      {
         clear();
      }

      inline symbol_table_t& symbol_table()
      {
         return symbol_table_;
      }

      inline const symbol_table_t& symbol_table() const
      {
         return symbol_table_;
      }

      inline void add_auxiliary_symtab(symbol_table_t& symtab)
      {
         auxiliary_symtab_list_.push_back(&symtab);
      }

      void load_variables(const bool load = true)
      {
         load_variables_ = load;
      }

      void load_vectors(const bool load = true)
      {
         load_vectors_ = load;
      }

      inline void register_loop_runtime_check(loop_runtime_check& lrtchk)
      {
         parser_.register_loop_runtime_check(lrtchk);
      }

      inline void register_vector_access_runtime_check(vector_access_runtime_check& vartchk)
      {
         parser_.register_vector_access_runtime_check(vartchk);
      }

      inline void register_compilation_timeout_check(compilation_check& compchk)
      {
         parser_.register_compilation_timeout_check(compchk);
      }

      inline void clear_loop_runtime_check()
      {
         parser_.clear_loop_runtime_check();
      }

      inline void clear_vector_access_runtime_check()
      {
         parser_.clear_vector_access_runtime_check();
      }

      inline void clear_compilation_timeout_check()
      {
         parser_.clear_compilation_timeout_check();
      }

      void clear()
      {
         symbol_table_.clear();
         expr_map_    .clear();

         for (std::size_t i = 0; i < fp_map_.size(); ++i)
         {
            typename funcparam_t::iterator itr = fp_map_[i].begin();
            typename funcparam_t::iterator end = fp_map_[i].end  ();

            while (itr != end)
            {
               delete itr->second;
               ++itr;
            }

            fp_map_[i].clear();
         }

         clear_loop_runtime_check         ();
         clear_vector_access_runtime_check();
         clear_compilation_timeout_check  ();
      }

      inline bool add(const function& f, const bool override = false)
      {
         return add(f.name_, f.expression_, f.v_,override);
      }

      inline std::string error() const
      {
         if (!error_list_.empty())
         {
            return error_list_[0].diagnostic;
         }
         else
            return std::string("No Error");
      }

      inline std::size_t error_count() const
      {
         return error_list_.size();
      }

      inline parser_error::type get_error(const std::size_t& index) const
      {
         if (index < error_list_.size())
         {
            return error_list_[index];
         }

         throw std::invalid_argument("compositor::get_error() - Invalid error index specified");
      }

   private:

      template <typename Allocator,
                template <typename, typename> class Sequence>
      bool compile_expression(const std::string& name,
                              const std::string& expression,
                              const Sequence<std::string,Allocator>& input_var_list,
                              bool  return_present = false)
      {
         expression_t compiled_expression;
         symbol_table_t local_symbol_table;

         local_symbol_table.load_from(symbol_table_);
         local_symbol_table.add_constants();

         if (load_variables_)
         {
            local_symbol_table.load_variables_from(symbol_table_);
         }

         if (load_vectors_)
         {
            local_symbol_table.load_vectors_from(symbol_table_);
         }

         error_list_.clear();

         if (!valid(name,input_var_list.size()))
         {
            parser_error::type error =
               parser_error::make_error(
                  parser_error::e_parser,
                  lexer::token(),
                  "ERR274 - Function '" + name + "' is an invalid overload",
                  exprtk_error_location);

            error_list_.push_back(error);
            return false;
         }

         if (!forward(name,
                      input_var_list.size(),
                      local_symbol_table,
                      return_present))
            return false;

         compiled_expression.register_symbol_table(local_symbol_table);

         for (std::size_t i = 0; i < auxiliary_symtab_list_.size(); ++i)
         {
            compiled_expression.register_symbol_table((*auxiliary_symtab_list_[i]));
         }

         std::string mod_expression;

         for (std::size_t i = 0; i < input_var_list.size(); ++i)
         {
            mod_expression += " var " + input_var_list[i] + "{};\n";
         }

         if (
              ('{' == details::front(expression)) &&
              ('}' == details::back (expression))
            )
            mod_expression += "~" + expression + ";";
         else
            mod_expression += "~{" + expression + "};";

         if (!parser_.compile(mod_expression,compiled_expression))
         {
            exprtk_debug(("Compositor Error: %s\n", parser_.error().c_str()));
            exprtk_debug(("Compositor modified expression: \n%s\n", mod_expression.c_str()));

            remove(name,input_var_list.size());

            for (std::size_t err_index = 0; err_index < parser_.error_count(); ++err_index)
            {
               error_list_.push_back(parser_.get_error(err_index));
            }

            return false;
         }

         if (!return_present && parser_.dec().return_present())
         {
            remove(name,input_var_list.size());
            return compile_expression(name, expression, input_var_list, true);
         }

         // Make sure every return point has a scalar as its first parameter
         if (parser_.dec().return_present())
         {
            typedef std::vector<std::string> str_list_t;

            str_list_t ret_param_list = parser_.dec().return_param_type_list();

            for (std::size_t i = 0; i < ret_param_list.size(); ++i)
            {
               const std::string& params = ret_param_list[i];

               if (params.empty() || ('T' != params[0]))
               {
                  exprtk_debug(("Compositor Error: Return statement in function '%s' is invalid\n",
                                name.c_str()));

                  remove(name,input_var_list.size());

                  return false;
               }
            }
         }

         expr_map_[name] = compiled_expression;

         exprtk::ifunction<T>& ifunc = (*(fp_map_[input_var_list.size()])[name]);

         if (symbol_table_.add_function(name,ifunc))
            return true;
         else
         {
            exprtk_debug(("Compositor Error: Failed to add function '%s' to symbol table\n",
                          name.c_str()));
            return false;
         }
      }

      inline bool symbol_used(const std::string& symbol) const
      {
         return (
                  symbol_table_.is_variable       (symbol) ||
                  symbol_table_.is_stringvar      (symbol) ||
                  symbol_table_.is_function       (symbol) ||
                  symbol_table_.is_vector         (symbol) ||
                  symbol_table_.is_vararg_function(symbol)
                );
      }

      inline bool valid(const std::string& name,
                        const std::size_t& arg_count) const
      {
         if (arg_count > 6)
            return false;
         else if (symbol_used(name))
            return false;
         else if (fp_map_[arg_count].end() != fp_map_[arg_count].find(name))
            return false;
         else
            return true;
      }

      inline bool forward(const std::string& name,
                          const std::size_t& arg_count,
                          symbol_table_t& sym_table,
                          const bool ret_present = false)
      {
         switch (arg_count)
         {
            #define case_stmt(N)                                     \
            case N : (fp_map_[arg_count])[name] =                    \
                     (!ret_present) ? static_cast<base_func*>        \
                                      (new func_##N##param) :        \
                                      static_cast<base_func*>        \
                                      (new func_##N##param_retval) ; \
                     break;                                          \

            case_stmt(0) case_stmt(1) case_stmt(2)
            case_stmt(3) case_stmt(4) case_stmt(5)
            case_stmt(6)
            #undef case_stmt
         }

         exprtk::ifunction<T>& ifunc = (*(fp_map_[arg_count])[name]);

         return sym_table.add_function(name,ifunc);
      }

      inline void remove(const std::string& name, const std::size_t& arg_count)
      {
         if (arg_count > 6)
            return;

         const typename std::map<std::string,expression_t>::iterator em_itr = expr_map_.find(name);

         if (expr_map_.end() != em_itr)
         {
            expr_map_.erase(em_itr);
         }

         const typename funcparam_t::iterator fp_itr = fp_map_[arg_count].find(name);

         if (fp_map_[arg_count].end() != fp_itr)
         {
            delete fp_itr->second;
            fp_map_[arg_count].erase(fp_itr);
         }

         symbol_table_.remove_function(name);
      }

   private:

      symbol_table_t symbol_table_;
      parser_t parser_;
      std::map<std::string,expression_t> expr_map_;
      std::vector<funcparam_t> fp_map_;
      std::vector<symbol_table_t*> auxiliary_symtab_list_;
      std::deque<parser_error::type> error_list_;
      bool load_variables_;
      bool load_vectors_;
   }; // class function_compositor

} // namespace exprtk

#if defined(_MSC_VER) || defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
#   ifndef NOMINMAX
#      define NOMINMAX
#   endif
#   ifndef WIN32_LEAN_AND_MEAN
#      define WIN32_LEAN_AND_MEAN
#   endif
#   include <windows.h>
#   include <ctime>
#else
#   include <ctime>
#   include <sys/time.h>
#   include <sys/types.h>
#endif

namespace exprtk
{
   class timer
   {
   public:

      #if defined(_MSC_VER) || defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
      timer()
      : in_use_(false)
      , start_time_{ 0 }
      , stop_time_ { 0 }
      {
         QueryPerformanceFrequency(&clock_frequency_);
      }

      inline void start()
      {
         in_use_ = true;
         QueryPerformanceCounter(&start_time_);
      }

      inline void stop()
      {
         QueryPerformanceCounter(&stop_time_);
         in_use_ = false;
      }

      inline double time() const
      {
         return (1.0 * (stop_time_.QuadPart - start_time_.QuadPart)) / (1.0 * clock_frequency_.QuadPart);
      }

      #else

      timer()
      : in_use_(false)
      {
         start_time_.tv_sec  = 0;
         start_time_.tv_usec = 0;

         stop_time_.tv_sec   = 0;
         stop_time_.tv_usec  = 0;
      }

      inline void start()
      {
         in_use_ = true;
         gettimeofday(&start_time_,0);
      }

      inline void stop()
      {
         gettimeofday(&stop_time_, 0);
         in_use_ = false;
      }

      inline unsigned long long int usec_time() const
      {
         if (!in_use_)
         {
            if (stop_time_.tv_sec >= start_time_.tv_sec)
            {
               return 1000000LLU * static_cast<details::_uint64_t>(stop_time_.tv_sec  - start_time_.tv_sec ) +
                                   static_cast<details::_uint64_t>(stop_time_.tv_usec - start_time_.tv_usec) ;
            }
            else
               return std::numeric_limits<details::_uint64_t>::max();
         }
         else
            return std::numeric_limits<details::_uint64_t>::max();
      }

      inline double time() const
      {
         return usec_time() * 0.000001;
      }

      #endif

      inline bool in_use() const
      {
         return in_use_;
      }

   private:

      bool in_use_;

      #if defined(_MSC_VER) || defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
         LARGE_INTEGER start_time_;
         LARGE_INTEGER stop_time_;
         LARGE_INTEGER clock_frequency_;
      #else
         struct timeval start_time_;
         struct timeval stop_time_;
      #endif
   };

   template <typename T>
   struct type_defs
   {
      typedef symbol_table<T>         symbol_table_t;
      typedef expression<T>           expression_t;
      typedef parser<T>               parser_t;
      typedef parser_error::type      error_t;
      typedef function_compositor<T>  compositor_t;
      typedef typename compositor_t::function function_t;
   };

} // namespace exprtk

#ifndef exprtk_disable_rtl_io
namespace exprtk
{
   namespace rtl { namespace io { namespace details
   {
      template <typename T>
      inline void print_type(const std::string& fmt,
                             const T v,
                             exprtk::details::numeric::details::real_type_tag)
      {
         #if defined(__clang__)
            #pragma clang diagnostic push
            #pragma clang diagnostic ignored "-Wformat-nonliteral"
         #elif defined(__GNUC__) || defined(__GNUG__)
            #pragma GCC diagnostic push
            #pragma GCC diagnostic ignored "-Wformat-nonliteral"
         #elif defined(_MSC_VER)
         #endif

         printf(fmt.c_str(), v);

         #if defined(__clang__)
            #pragma clang diagnostic pop
         #elif defined(__GNUC__) || defined(__GNUG__)
            #pragma GCC diagnostic pop
         #elif defined(_MSC_VER)
         #endif
      }

      template <typename T>
      struct print_impl
      {
         typedef typename igeneric_function<T>::generic_type generic_type;
         typedef typename igeneric_function<T>::parameter_list_t parameter_list_t;
         typedef typename generic_type::scalar_view scalar_t;
         typedef typename generic_type::vector_view vector_t;
         typedef typename generic_type::string_view string_t;
         typedef typename exprtk::details::numeric::details::number_type<T>::type num_type;

         static void process(const std::string& scalar_format, parameter_list_t parameters)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               generic_type& gt = parameters[i];

               switch (gt.type)
               {
                  case generic_type::e_scalar : print(scalar_format,scalar_t(gt));
                                                break;

                  case generic_type::e_vector : print(scalar_format,vector_t(gt));
                                                break;

                  case generic_type::e_string : print(string_t(gt));
                                                break;

                  default                     : continue;
               }
            }
         }

         static inline void print(const std::string& scalar_format, const scalar_t& s)
         {
            print_type(scalar_format,s(),num_type());
         }

         static inline void print(const std::string& scalar_format, const vector_t& v)
         {
            for (std::size_t i = 0; i < v.size(); ++i)
            {
               print_type(scalar_format,v[i],num_type());

               if ((i + 1) < v.size())
                  printf(" ");
            }
         }

         static inline void print(const string_t& s)
         {
            printf("%s",to_str(s).c_str());
         }
      };

   } // namespace exprtk::rtl::io::details

   template <typename T>
   struct print exprtk_final : public exprtk::igeneric_function<T>
   {
      typedef typename igeneric_function<T>::parameter_list_t parameter_list_t;

      using exprtk::igeneric_function<T>::operator();

      explicit print(const std::string& scalar_format = "%10.5f")
      : scalar_format_(scalar_format)
      {
         exprtk::enable_zero_parameters(*this);
      }

      inline T operator() (parameter_list_t parameters) exprtk_override
      {
         details::print_impl<T>::process(scalar_format_,parameters);
         return T(0);
      }

      std::string scalar_format_;
   };

   template <typename T>
   struct println exprtk_final : public exprtk::igeneric_function<T>
   {
      typedef typename igeneric_function<T>::parameter_list_t parameter_list_t;

      using exprtk::igeneric_function<T>::operator();

      explicit println(const std::string& scalar_format = "%10.5f")
      : scalar_format_(scalar_format)
      {
         exprtk::enable_zero_parameters(*this);
      }

      inline T operator() (parameter_list_t parameters) exprtk_override
      {
         details::print_impl<T>::process(scalar_format_,parameters);
         printf("\n");
         return T(0);
      }

      std::string scalar_format_;
   };

   template <typename T>
   struct package
   {
      print  <T> p;
      println<T> pl;

      bool register_package(exprtk::symbol_table<T>& symtab)
      {
         #define exprtk_register_function(FunctionName, FunctionType)             \
         if (!symtab.add_function(FunctionName,FunctionType))                     \
         {                                                                        \
            exprtk_debug((                                                        \
              "exprtk::rtl::io::register_package - Failed to add function: %s\n", \
              FunctionName));                                                     \
            return false;                                                         \
         }                                                                        \

         exprtk_register_function("print"  , p )
         exprtk_register_function("println", pl)
         #undef exprtk_register_function

         return true;
      }
   };

   } // namespace exprtk::rtl::io
   } // namespace exprtk::rtl
}    // namespace exprtk
#endif

#ifndef exprtk_disable_rtl_io_file
#include <fstream>
namespace exprtk
{
   namespace rtl { namespace io { namespace file { namespace details
   {
      using ::exprtk::details::char_ptr;
      using ::exprtk::details::char_cptr;

      enum file_mode
      {
         e_error = 0,
         e_read  = 1,
         e_write = 2,
         e_rdwrt = 4
      };

      struct file_descriptor
      {
         file_descriptor(const std::string& fname, const std::string& access)
         : stream_ptr(0)
         , mode(get_file_mode(access))
         , file_name(fname)
         {}

         void*       stream_ptr;
         file_mode   mode;
         std::string file_name;

         bool open()
         {
            if (e_read == mode)
            {
               std::ifstream* stream = new std::ifstream(file_name.c_str(),std::ios::binary);

               if (!(*stream))
               {
                  file_name.clear();
                  delete stream;

                  return false;
               }

               stream_ptr = stream;

               return true;
            }
            else if (e_write == mode)
            {
               std::ofstream* stream = new std::ofstream(file_name.c_str(),std::ios::binary);

               if (!(*stream))
               {
                  file_name.clear();
                  delete stream;

                  return false;
               }

               stream_ptr = stream;

               return true;
            }
            else if (e_rdwrt == mode)
            {
               std::fstream* stream = new std::fstream(file_name.c_str(),std::ios::binary);

               if (!(*stream))
               {
                  file_name.clear();
                  delete stream;

                  return false;
               }

               stream_ptr = stream;

               return true;
            }

            return false;
         }

         template <typename Stream, typename Ptr>
         void close(Ptr& p)
         {
            Stream* stream = reinterpret_cast<Stream*>(p);
            stream->close();
            delete stream;
            p = reinterpret_cast<Ptr>(0);
         }

         bool close()
         {
            switch (mode)
            {
               case e_read  : close<std::ifstream>(stream_ptr);
                              break;

               case e_write : close<std::ofstream>(stream_ptr);
                              break;

               case e_rdwrt : close<std::fstream> (stream_ptr);
                              break;

               default      : return false;
            }

            return true;
         }

         template <typename View>
         bool write(const View& view, const std::size_t amount, const std::size_t offset = 0)
         {
            switch (mode)
            {
               case e_write : reinterpret_cast<std::ofstream*>(stream_ptr)->
                                 write(reinterpret_cast<char_cptr>(view.begin() + offset), amount * sizeof(typename View::value_t));
                              break;

               case e_rdwrt : reinterpret_cast<std::fstream*>(stream_ptr)->
                                 write(reinterpret_cast<char_cptr>(view.begin() + offset) , amount * sizeof(typename View::value_t));
                              break;

               default      : return false;
            }

            return true;
         }

         template <typename View>
         bool read(View& view, const std::size_t amount, const std::size_t offset = 0)
         {
            switch (mode)
            {
               case e_read  : reinterpret_cast<std::ifstream*>(stream_ptr)->
                                 read(reinterpret_cast<char_ptr>(view.begin() + offset), amount * sizeof(typename View::value_t));
                              break;

               case e_rdwrt : reinterpret_cast<std::fstream*>(stream_ptr)->
                                 read(reinterpret_cast<char_ptr>(view.begin() + offset) , amount * sizeof(typename View::value_t));
                              break;

               default      : return false;
            }

            return true;
         }

         bool getline(std::string& s)
         {
            switch (mode)
            {
               case e_read  : return (!!std::getline(*reinterpret_cast<std::ifstream*>(stream_ptr),s));
               case e_rdwrt : return (!!std::getline(*reinterpret_cast<std::fstream* >(stream_ptr),s));
               default      : return false;
            }
         }

         bool eof() const
         {
            switch (mode)
            {
               case e_read  : return reinterpret_cast<std::ifstream*>(stream_ptr)->eof();
               case e_write : return reinterpret_cast<std::ofstream*>(stream_ptr)->eof();
               case e_rdwrt : return reinterpret_cast<std::fstream* >(stream_ptr)->eof();
               default      : return true;
            }
         }

         file_mode get_file_mode(const std::string& access) const
         {
            if (access.empty() || access.size() > 2)
               return e_error;

            std::size_t w_cnt = 0;
            std::size_t r_cnt = 0;

            for (std::size_t i = 0; i < access.size(); ++i)
            {
               switch (std::tolower(access[i]))
               {
                  case 'r' : r_cnt++; break;
                  case 'w' : w_cnt++; break;
                  default  : return e_error;
               }
            }

            if ((0 == r_cnt) && (0 == w_cnt))
               return e_error;
            else if ((r_cnt > 1) || (w_cnt > 1))
               return e_error;
            else if ((1 == r_cnt) && (1 == w_cnt))
               return e_rdwrt;
            else if (1 == r_cnt)
               return e_read;
            else
               return e_write;
         }
      };

      template <typename T>
      file_descriptor* make_handle(T v)
      {
         const std::size_t fd_size    = sizeof(details::file_descriptor*);
         details::file_descriptor* fd = reinterpret_cast<file_descriptor*>(0);

         std::memcpy(reinterpret_cast<char_ptr >(&fd),
                     reinterpret_cast<char_cptr>(&v ),
                     fd_size);
         return fd;
      }

      template <typename T>
      void perform_check()
      {
         #ifdef _MSC_VER
         #pragma warning(push)
         #pragma warning(disable: 4127)
         #endif
         if (sizeof(T) < sizeof(void*))
         {
            throw std::runtime_error("exprtk::rtl::io::file - Error - pointer size larger than holder.");
         }
         #ifdef _MSC_VER
         #pragma warning(pop)
         #endif
         assert(sizeof(T) <= sizeof(void*));
      }

   } // namespace exprtk::rtl::io::file::details

   template <typename T>
   class open exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::string_view    string_t;

      using igfun_t::operator();

      open()
      : exprtk::igeneric_function<T>("S|SS")
      { details::perform_check<T>(); }

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const std::string file_name = to_str(string_t(parameters[0]));

         if (file_name.empty())
         {
            return T(0);
         }

         if ((1 == ps_index) && (0 == string_t(parameters[1]).size()))
         {
            return T(0);
         }

         const std::string access =
            (0 == ps_index) ? "r" : to_str(string_t(parameters[1]));

         details::file_descriptor* fd = new details::file_descriptor(file_name,access);

         if (fd->open())
         {
            T t = T(0);

            const std::size_t fd_size = sizeof(details::file_descriptor*);

            std::memcpy(reinterpret_cast<char*>(&t ),
                        reinterpret_cast<char*>(&fd),
                        fd_size);
            return t;
         }
         else
         {
            delete fd;
            return T(0);
         }
      }
   };

   template <typename T>
   struct close exprtk_final : public exprtk::ifunction<T>
   {
      using exprtk::ifunction<T>::operator();

      close()
      : exprtk::ifunction<T>(1)
      { details::perform_check<T>(); }

      inline T operator() (const T& v) exprtk_override
      {
         details::file_descriptor* fd = details::make_handle(v);

         if (!fd->close())
            return T(0);

         delete fd;

         return T(1);
      }
   };

   template <typename T>
   class write exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::string_view    string_t;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      write()
      : igfun_t("TS|TST|TV|TVT")
      { details::perform_check<T>(); }

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         details::file_descriptor* fd = details::make_handle(scalar_t(parameters[0])());

         switch (ps_index)
         {
            case 0  : {
                         const string_t buffer(parameters[1]);
                         const std::size_t amount = buffer.size();
                         return T(fd->write(buffer, amount) ? 1 : 0);
                      }

            case 1  : {
                         const string_t buffer(parameters[1]);
                         const std::size_t amount =
                                  std::min(buffer.size(),
                                           static_cast<std::size_t>(scalar_t(parameters[2])()));
                         return T(fd->write(buffer, amount) ? 1 : 0);
                      }

            case 2  : {
                         const vector_t vec(parameters[1]);
                         const std::size_t amount = vec.size();
                         return T(fd->write(vec, amount) ? 1 : 0);
                      }

            case 3  : {
                         const vector_t vec(parameters[1]);
                         const std::size_t amount =
                                  std::min(vec.size(),
                                           static_cast<std::size_t>(scalar_t(parameters[2])()));
                         return T(fd->write(vec, amount) ? 1 : 0);
                      }
         }

         return T(0);
      }
   };

   template <typename T>
   class read exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::string_view    string_t;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      read()
      : igfun_t("TS|TST|TV|TVT")
      { details::perform_check<T>(); }

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         details::file_descriptor* fd = details::make_handle(scalar_t(parameters[0])());

         switch (ps_index)
         {
            case 0  : {
                         string_t buffer(parameters[1]);
                         const std::size_t amount = buffer.size();
                         return T(fd->read(buffer,amount) ? 1 : 0);
                      }

            case 1  : {
                         string_t buffer(parameters[1]);
                         const std::size_t amount =
                                  std::min(buffer.size(),
                                           static_cast<std::size_t>(scalar_t(parameters[2])()));
                         return T(fd->read(buffer,amount) ? 1 : 0);
                      }

            case 2  : {
                         vector_t vec(parameters[1]);
                         const std::size_t amount = vec.size();
                         return T(fd->read(vec,amount) ? 1 : 0);
                      }

            case 3  : {
                         vector_t vec(parameters[1]);
                         const std::size_t amount =
                                  std::min(vec.size(),
                                           static_cast<std::size_t>(scalar_t(parameters[2])()));
                         return T(fd->read(vec,amount) ? 1 : 0);
                      }
         }

         return T(0);
      }
   };

   template <typename T>
   class getline exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::string_view    string_t;
      typedef typename generic_type::scalar_view    scalar_t;

      using igfun_t::operator();

      getline()
      : igfun_t("T",igfun_t::e_rtrn_string)
      { details::perform_check<T>(); }

      inline T operator() (std::string& result, parameter_list_t parameters) exprtk_override
      {
         details::file_descriptor* fd = details::make_handle(scalar_t(parameters[0])());
         return T(fd->getline(result) ? 1 : 0);
      }
   };

   template <typename T>
   struct eof exprtk_final : public exprtk::ifunction<T>
   {
      using exprtk::ifunction<T>::operator();

      eof()
      : exprtk::ifunction<T>(1)
      { details::perform_check<T>(); }

      inline T operator() (const T& v) exprtk_override
      {
         details::file_descriptor* fd = details::make_handle(v);
         return (fd->eof() ? T(1) : T(0));
      }
   };

   template <typename T>
   struct package
   {
      open   <T> o;
      close  <T> c;
      write  <T> w;
      read   <T> r;
      getline<T> g;
      eof    <T> e;

      bool register_package(exprtk::symbol_table<T>& symtab)
      {
         #define exprtk_register_function(FunctionName, FunctionType)                   \
         if (!symtab.add_function(FunctionName,FunctionType))                           \
         {                                                                              \
            exprtk_debug((                                                              \
              "exprtk::rtl::io::file::register_package - Failed to add function: %s\n", \
              FunctionName));                                                           \
            return false;                                                               \
         }                                                                              \

         exprtk_register_function("open"    , o)
         exprtk_register_function("close"   , c)
         exprtk_register_function("write"   , w)
         exprtk_register_function("read"    , r)
         exprtk_register_function("getline" , g)
         exprtk_register_function("eof"     , e)
         #undef exprtk_register_function

         return true;
      }
   };

   } // namespace exprtk::rtl::io::file
   } // namespace exprtk::rtl::io
   } // namespace exprtk::rtl
}    // namespace exprtk
#endif

#ifndef exprtk_disable_rtl_vecops
namespace exprtk
{
   namespace rtl { namespace vecops {

   namespace helper
   {
      template <typename Vector>
      inline bool invalid_range(const Vector& v, const std::size_t r0, const std::size_t r1)
      {
         if (r0 > (v.size() - 1))
            return true;
         else if (r1 > (v.size() - 1))
            return true;
         else if (r1 < r0)
            return true;
         else
            return false;
      }

      template <typename T>
      struct load_vector_range
      {
         typedef typename exprtk::igeneric_function<T> igfun_t;
         typedef typename igfun_t::parameter_list_t    parameter_list_t;
         typedef typename igfun_t::generic_type        generic_type;
         typedef typename generic_type::scalar_view    scalar_t;
         typedef typename generic_type::vector_view    vector_t;

         static inline bool process(parameter_list_t& parameters,
                                    std::size_t& r0, std::size_t& r1,
                                    const std::size_t& r0_prmidx,
                                    const std::size_t& r1_prmidx,
                                    const std::size_t vec_idx = 0)
         {
            if (r0_prmidx >= parameters.size())
               return false;

            if (r1_prmidx >= parameters.size())
               return false;

            if (!scalar_t(parameters[r0_prmidx]).to_uint(r0))
               return false;

            if (!scalar_t(parameters[r1_prmidx]).to_uint(r1))
               return false;

            return !invalid_range(vector_t(parameters[vec_idx]), r0, r1);
         }
      };
   }

   namespace details
   {
      template <typename T>
      inline void kahan_sum(T& sum, T& error, const T v)
      {
         const T x = v - error;
         const T y = sum + x;
         error = (y - sum) - x;
         sum = y;
      }

   } // namespace exprtk::rtl::details

   template <typename T>
   class all_true exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      all_true()
      : exprtk::igeneric_function<T>("V|VTT|T*")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
           2. T*  - T....T
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         if (2 == ps_index)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               if (scalar_t(parameters[i])() == T(0))
               {
                  return T(0);
               }
            }
         }
         else
         {
            const vector_t vec(parameters[0]);

            std::size_t r0 = 0;
            std::size_t r1 = vec.size() - 1;

            if (
                 (1 == ps_index) &&
                 !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
               )
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            for (std::size_t i = r0; i <= r1; ++i)
            {
               if (vec[i] == T(0))
               {
                  return T(0);
               }
            }
         }

         return T(1);
      }
   };

   template <typename T>
   class all_false exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      all_false()
      : exprtk::igeneric_function<T>("V|VTT|T*")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
           2. T*  - T....T
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         if (2 == ps_index)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               if (scalar_t(parameters[i])() != T(0))
               {
                  return T(0);
               }
            }
         }
         else
         {
            const vector_t vec(parameters[0]);

            std::size_t r0 = 0;
            std::size_t r1 = vec.size() - 1;

            if (
                 (1 == ps_index) &&
                 !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
               )
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            for (std::size_t i = r0; i <= r1; ++i)
            {
               if (vec[i] != T(0))
               {
                  return T(0);
               }
            }
         }

         return T(1);
      }
   };

   template <typename T>
   class any_true exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      any_true()
      : exprtk::igeneric_function<T>("V|VTT|T*")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
           2. T*  - T....T
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         if (2 == ps_index)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               if (scalar_t(parameters[i])() != T(0))
               {
                  return T(1);
               }
            }
         }
         else
         {
            const vector_t vec(parameters[0]);

            std::size_t r0 = 0;
            std::size_t r1 = vec.size() - 1;

            if (
                 (1 == ps_index) &&
                 !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
               )
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            for (std::size_t i = r0; i <= r1; ++i)
            {
               if (vec[i] != T(0))
               {
                  return T(1);
               }
            }
         }

         return T(0);
      }
   };

   template <typename T>
   class any_false exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      any_false()
      : exprtk::igeneric_function<T>("V|VTT|T*")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
           2. T*  - T....T
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         if (2 == ps_index)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               if (scalar_t(parameters[i])() == T(0))
               {
                  return T(1);
               }
            }
         }
         else
         {
            const vector_t vec(parameters[0]);

            std::size_t r0 = 0;
            std::size_t r1 = vec.size() - 1;

            if (
                 (1 == ps_index) &&
                 !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
               )
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            for (std::size_t i = r0; i <= r1; ++i)
            {
               if (vec[i] == T(0))
               {
                  return T(1);
               }
            }
         }

         return T(0);
      }
   };

   template <typename T>
   class count exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      count()
      : exprtk::igeneric_function<T>("V|VTT|T*")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
           2. T*  - T....T
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         std::size_t cnt = 0;

         if (2 == ps_index)
         {
            for (std::size_t i = 0; i < parameters.size(); ++i)
            {
               if (scalar_t(parameters[i])() != T(0)) ++cnt;
            }
         }
         else
         {
            const vector_t vec(parameters[0]);

            std::size_t r0 = 0;
            std::size_t r1 = vec.size() - 1;

            if (
                 (1 == ps_index) &&
                 !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
               )
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            for (std::size_t i = r0; i <= r1; ++i)
            {
               if (vec[i] != T(0)) ++cnt;
            }
         }

         return T(cnt);
      }
   };

   template <typename T>
   class copy exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      copy()
      : exprtk::igeneric_function<T>("VV|VTTVTT")
        /*
           Overloads:
           0. VV     - x(vector), y(vector)
           1. VTTVTT - x(vector), xr0, xr1, y(vector), yr0, yr1,
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[0]);
               vector_t y(parameters[(0 == ps_index) ? 1 : 3]);

         std::size_t xr0 = 0;
         std::size_t xr1 = x.size() - 1;

         std::size_t yr0 = 0;
         std::size_t yr1 = y.size() - 1;

         if (1 == ps_index)
         {
            if (
                 !helper::load_vector_range<T>::process(parameters, xr0, xr1, 1, 2, 0) ||
                 !helper::load_vector_range<T>::process(parameters, yr0, yr1, 4, 5, 3)
               )
               return T(0);
         }

         const std::size_t n = std::min(xr1 - xr0 + 1, yr1 - yr0 + 1);

         std::copy(
            x.begin() + xr0,
            x.begin() + xr0 + n,
            y.begin() + yr0);

         return T(n);
      }
   };

   template <typename T>
   class rol exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      rol()
      : exprtk::igeneric_function<T>("VT|VTTT")
        /*
           Overloads:
           0. VT   - vector, N
           1. VTTT - vector, N, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t n  = 0;
         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (!scalar_t(parameters[1]).to_uint(n))
            return T(0);

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0)
            )
            return T(0);

         const std::size_t dist  = r1 - r0 + 1;
         const std::size_t shift = n % dist;

         std::rotate(
            vec.begin() + r0,
            vec.begin() + r0 + shift,
            vec.begin() + r1 + 1);

         return T(1);
      }
   };

   template <typename T>
   class ror exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      ror()
      : exprtk::igeneric_function<T>("VT|VTTT")
        /*
           Overloads:
           0. VT   - vector, N
           1. VTTT - vector, N, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t n  = 0;
         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (!scalar_t(parameters[1]).to_uint(n))
            return T(0);

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0)
            )
            return T(0);

         const std::size_t dist  = r1 - r0 + 1;
         const std::size_t shift = (dist - (n % dist)) % dist;

         std::rotate(
            vec.begin() + r0,
            vec.begin() + r0 + shift,
            vec.begin() + r1 + 1);

         return T(1);
      }
   };

   template <typename T>
   class reverse exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      reverse()
      : exprtk::igeneric_function<T>("V|VTT")
        /*
           Overloads:
           0. V   - vector
           1. VTT - vector, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
            )
            return T(0);

         std::reverse(vec.begin() + r0, vec.begin() + r1 + 1);

         return T(1);
      }
   };

   template <typename T>
   class shift_left exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      shift_left()
      : exprtk::igeneric_function<T>("VT|VTTT")
        /*
           Overloads:
           0. VT   - vector, N
           1. VTTT - vector, N, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t n  = 0;
         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (!scalar_t(parameters[1]).to_uint(n))
            return T(0);

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0)
            )
            return T(0);

         const std::size_t dist = r1 - r0 + 1;

         if (n > dist)
            return T(0);

         std::rotate(
            vec.begin() + r0,
            vec.begin() + r0 + n,
            vec.begin() + r1 + 1);

         for (std::size_t i = r1 - n + 1; i <= r1; ++i)
         {
            vec[i] = T(0);
         }

         return T(1);
      }
   };

   template <typename T>
   class shift_right exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      shift_right()
      : exprtk::igeneric_function<T>("VT|VTTT")
        /*
           Overloads:
           0. VT   - vector, N
           1. VTTT - vector, N, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t n  = 0;
         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (!scalar_t(parameters[1]).to_uint(n))
            return T(0);

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0)
            )
            return T(0);

         const std::size_t dist = r1 - r0 + 1;

         if (n > dist)
            return T(0);

         const std::size_t shift = (dist - (n % dist)) % dist;

         std::rotate(
            vec.begin() + r0,
            vec.begin() + r0 + shift,
            vec.begin() + r1 + 1);

         for (std::size_t i = r0; i < r0 + n; ++i)
         {
            vec[i] = T(0);
         }

         return T(1);
      }
   };

   template <typename T>
   class sort exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::string_view    string_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      sort()
      : exprtk::igeneric_function<T>("V|VTT|VS|VSTT")
        /*
           Overloads:
           0. V    - vector
           1. VTT  - vector, r0, r1
           2. VS   - vector, string
           3. VSTT - vector, string, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0))
            return T(0);
         if ((3 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0))
            return T(0);

         bool ascending = true;

         if ((2 == ps_index) || (3 == ps_index))
         {
            if (exprtk::details::imatch(to_str(string_t(parameters[1])),"ascending"))
               ascending = true;
            else if (exprtk::details::imatch(to_str(string_t(parameters[1])),"descending"))
               ascending = false;
            else
               return T(0);
         }

         if (ascending)
            std::sort(
               vec.begin() + r0,
               vec.begin() + r1 + 1,
               std::less<T>());
         else
            std::sort(
               vec.begin() + r0,
               vec.begin() + r1 + 1,
               std::greater<T>());

         return T(1);
      }
   };

   template <typename T>
   class nthelement exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      nthelement()
      : exprtk::igeneric_function<T>("VT|VTTT")
        /*
           Overloads:
           0. VT   - vector, nth-element
           1. VTTT - vector, nth-element, r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         std::size_t n  = 0;
         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (!scalar_t(parameters[1]).to_uint(n))
            return T(0);

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0))
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         std::nth_element(
            vec.begin() + r0,
            vec.begin() + r0 + n ,
            vec.begin() + r1 + 1);

         return T(1);
      }
   };

   template <typename T>
   class assign exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      assign()
      : exprtk::igeneric_function<T>("VT|VTTT|VTTTT")
        /*
           Overloads:
           0. VT    - vector, V
           1. VTTT  - vector, V, r0, r1
           2. VTTTT - vector, V, r0, r1, SS
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         const T assign_value = scalar_t(parameters[1]);

         const std::size_t step_size = (2 != ps_index) ? 1 :
                                       static_cast<std::size_t>(scalar_t(parameters.back())());

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              ((ps_index == 1) || (ps_index == 2)) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0)
            )
         {
            return T(0);
         }

         for (std::size_t i = r0; i <= r1; i += step_size)
         {
            vec[i] = assign_value;
         }

         return T(1);
      }
   };

   template <typename T>
   class iota exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      iota()
      : exprtk::igeneric_function<T>("VTT|VT|VTTTT|VTTT")
        /*
           Overloads:
           0. VTT  - vector, SV, SS
           1. VT   - vector, SV, SS (+1)
           2. VTTT - vector, r0, r1, SV, SS
           3. VTT  - vector, r0, r1, SV, SS (+1)

           Where:
           1. SV - Start value
           2. SS - Step size
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         const T start_value = (ps_index <= 1) ?
                               scalar_t(parameters[1]) :
                               scalar_t(parameters[3]) ;

         const T step_size = ((0 == ps_index) || (2 == ps_index)) ?
                             scalar_t(parameters.back())() :
                             T(1) ;

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              ((ps_index == 2) || (ps_index == 3)) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
            )
         {
            return T(0);
         }

         for (std::size_t i = r0; i <= r1; ++i)
         {
            vec[i] = start_value + ((i - r0) * step_size);
         }

         return T(1);
      }
   };

   template <typename T>
   class sumk exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      sumk()
      : exprtk::igeneric_function<T>("V|VTT|VTTT")
        /*
           Overloads:
           0. V    - vector
           1. VTT  - vector, r0, r1
           2. VTTT - vector, r0, r1, stride
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t vec(parameters[0]);

         const std::size_t stride = (2 != ps_index) ? 1 :
                                    static_cast<std::size_t>(scalar_t(parameters[3])());

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              ((1 == ps_index) || (2 == ps_index)) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
            )
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         T result = T(0);
         T error  = T(0);

         for (std::size_t i = r0; i <= r1; i += stride)
         {
            details::kahan_sum(result, error, vec[i]);
         }

         return result;
      }
   };

   template <typename T>
   class axpy exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpy()
      : exprtk::igeneric_function<T>("TVV|TVVTT")
        /*
           y <- ax + y
           Overloads:
           0. TVV   - a, x(vector), y(vector)
           1. TVVTT - a, x(vector), y(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
               vector_t y(parameters[2]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 3, 4, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();

         for (std::size_t i = r0; i <= r1; ++i)
         {
            y[i] = (a * x[i]) + y[i];
         }

         return T(1);
      }
   };

   template <typename T>
   class axpby exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpby()
      : exprtk::igeneric_function<T>("TVTV|TVTVTT")
        /*
           y <- ax + by
           Overloads:
           0. TVTV   - a, x(vector), b, y(vector)
           1. TVTVTT - a, x(vector), b, y(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
               vector_t y(parameters[3]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 4, 5, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();
         const T b = scalar_t(parameters[2])();

         for (std::size_t i = r0; i <= r1; ++i)
         {
            y[i] = (a * x[i]) + (b * y[i]);
         }

         return T(1);
      }
   };

   template <typename T>
   class axpyz exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpyz()
      : exprtk::igeneric_function<T>("TVVV|TVVVTT")
        /*
           z <- ax + y
           Overloads:
           0. TVVV   - a, x(vector), y(vector), z(vector)
           1. TVVVTT - a, x(vector), y(vector), z(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
         const vector_t y(parameters[2]);
               vector_t z(parameters[3]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 4, 5, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(z, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();

         for (std::size_t i = r0; i <= r1; ++i)
         {
            z[i] = (a * x[i]) + y[i];
         }

         return T(1);
      }
   };

   template <typename T>
   class axpbyz exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpbyz()
      : exprtk::igeneric_function<T>("TVTVV|TVTVVTT")
        /*
           z <- ax + by
           Overloads:
           0. TVTVV   - a, x(vector), b, y(vector), z(vector)
           1. TVTVVTT - a, x(vector), b, y(vector), z(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
         const vector_t y(parameters[3]);
               vector_t z(parameters[4]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 5, 6, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(z, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();
         const T b = scalar_t(parameters[2])();

         for (std::size_t i = r0; i <= r1; ++i)
         {
            z[i] = (a * x[i]) + (b * y[i]);
         }

         return T(1);
      }
   };

   template <typename T>
   class axpbsy exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpbsy()
      : exprtk::igeneric_function<T>("TVTTV|TVTTVTT")
        /*
           y <- ax + by
           Overloads:
           0. TVTVV   - a, x(vector), b, shift, y(vector), z(vector)
           1. TVTVVTT - a, x(vector), b, shift, y(vector), z(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
               vector_t y(parameters[4]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 5, 6, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();
         const T b = scalar_t(parameters[2])();

         const std::size_t s = static_cast<std::size_t>(scalar_t(parameters[3])());

         for (std::size_t i = r0; i <= r1; ++i)
         {
            y[i] = (a * x[i]) + (b * y[i + s]);
         }

         return T(1);
      }
   };

   template <typename T>
   class axpbsyz exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpbsyz()
      : exprtk::igeneric_function<T>("TVTTVV|TVTTVVTT")
        /*
           z <- ax + by
           Overloads:
           0. TVTVV   - a, x(vector), b, shift, y(vector), z(vector)
           1. TVTVVTT - a, x(vector), b, shift, y(vector), z(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
         const vector_t y(parameters[4]);
               vector_t z(parameters[5]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 6, 7, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(z, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();
         const T b = scalar_t(parameters[2])();

         const std::size_t s = static_cast<std::size_t>(scalar_t(parameters[3])());

         for (std::size_t i = r0; i <= r1; ++i)
         {
            z[i] = (a * x[i]) + (b * y[i + s]);
         }

         return T(1);
      }
   };

   template <typename T>
   class axpbz exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      axpbz()
      : exprtk::igeneric_function<T>("TVTV|TVTVTT")
        /*
           z <- ax + b
           Overloads:
           0. TVTV   - a, x(vector), b, z(vector)
           1. TVTVTT - a, x(vector), b, z(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[1]);
               vector_t z(parameters[3]);

         std::size_t r0 = 0;
         std::size_t r1 = x.size() - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 4, 5, 1))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(z, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         const T a = scalar_t(parameters[0])();
         const T b = scalar_t(parameters[2])();

         for (std::size_t i = r0; i <= r1; ++i)
         {
            z[i] = (a * x[i]) + b;
         }

         return T(1);
      }
   };

   template <typename T>
   class diff exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      diff()
      : exprtk::igeneric_function<T>("VV|VVT")
        /*
           x_(i - stride) - x_i
           Overloads:
           0. VV  - x(vector), y(vector)
           1. VVT - x(vector), y(vector), stride
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[0]);
               vector_t y(parameters[1]);

         const std::size_t r0 = 0;
         const std::size_t r1 = std::min(x.size(),y.size()) - 1;

         const std::size_t stride = (1 != ps_index) ? 1 :
                                    std::min(r1,static_cast<std::size_t>(scalar_t(parameters[2])()));

         for (std::size_t i = 0; i < stride; ++i)
         {
            y[i] = std::numeric_limits<T>::quiet_NaN();
         }

         for (std::size_t i = (r0 + stride); i <= r1; ++i)
         {
            y[i] = x[i] - x[i - stride];
         }

         return T(1);
      }
   };

   template <typename T>
   class dot exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      dot()
      : exprtk::igeneric_function<T>("VV|VVTT")
        /*
           Overloads:
           0. VV   - x(vector), y(vector)
           1. VVTT - x(vector), y(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[0]);
         const vector_t y(parameters[1]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         T result = T(0);

         for (std::size_t i = r0; i <= r1; ++i)
         {
            result += (x[i] * y[i]);
         }

         return result;
      }
   };

   template <typename T>
   class dotk exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      dotk()
      : exprtk::igeneric_function<T>("VV|VVTT")
        /*
           Overloads:
           0. VV   - x(vector), y(vector)
           1. VVTT - x(vector), y(vector), r0, r1
        */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         const vector_t x(parameters[0]);
         const vector_t y(parameters[1]);

         std::size_t r0 = 0;
         std::size_t r1 = std::min(x.size(),y.size()) - 1;

         if ((1 == ps_index) && !helper::load_vector_range<T>::process(parameters, r0, r1, 2, 3, 0))
            return std::numeric_limits<T>::quiet_NaN();
         else if (helper::invalid_range(y, r0, r1))
            return std::numeric_limits<T>::quiet_NaN();

         T result = T(0);
         T error  = T(0);

         for (std::size_t i = r0; i <= r1; ++i)
         {
            details::kahan_sum(result, error, (x[i] * y[i]));
         }

         return result;
      }
   };

   template <typename T>
   class threshold_below exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      threshold_below()
      : exprtk::igeneric_function<T>("VTT|VTTTT")
      /*
         Overloads:
         0. VTT   - vector, TV, SV
         1. VTTTT - vector, r0, r1, TV, SV

         Where:
         TV - Threshold value
         SV - Snap-to value
      */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         const T threshold_value = (0 == ps_index) ?
                                   scalar_t(parameters[1]) :
                                   scalar_t(parameters[3]) ;

         const T snap_value = scalar_t(parameters.back());

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
            )
         {
            return T(0);
         }

         for (std::size_t i = r0; i <= r1; ++i)
         {
            if (vec[i] < threshold_value)
            {
               vec[i] = snap_value;
            }
         }

         return T(1);
      }
   };

   template <typename T>
   class threshold_above exprtk_final : public exprtk::igeneric_function<T>
   {
   public:

      typedef typename exprtk::igeneric_function<T> igfun_t;
      typedef typename igfun_t::parameter_list_t    parameter_list_t;
      typedef typename igfun_t::generic_type        generic_type;
      typedef typename generic_type::scalar_view    scalar_t;
      typedef typename generic_type::vector_view    vector_t;

      using igfun_t::operator();

      threshold_above()
      : exprtk::igeneric_function<T>("VTT|VTTTT")
      /*
         Overloads:
         0. VTT   - vector, TV, SV
         1. VTTTT - vector, r0, r1, TV, SV

         Where:
         TV - Threshold value
         SV - Snap-to value
      */
      {}

      inline T operator() (const std::size_t& ps_index, parameter_list_t parameters) exprtk_override
      {
         vector_t vec(parameters[0]);

         const T threshold_value = (0 == ps_index) ?
                                   scalar_t(parameters[1]) :
                                   scalar_t(parameters[3]) ;

         const T snap_value = scalar_t(parameters.back());

         std::size_t r0 = 0;
         std::size_t r1 = vec.size() - 1;

         if (
              (1 == ps_index) &&
              !helper::load_vector_range<T>::process(parameters, r0, r1, 1, 2, 0)
            )
         {
            return T(0);
         }

         for (std::size_t i = r0; i <= r1; ++i)
         {
            if (vec[i] > threshold_value)
            {
               vec[i] = snap_value;
            }
         }

         return T(1);
      }
   };

   template <typename T>
   struct package
   {
      all_true       <T> at;
      all_false      <T> af;
      any_true       <T> nt;
      any_false      <T> nf;
      count          <T>  c;
      copy           <T> cp;
      rol            <T> rl;
      ror            <T> rr;
      reverse        <T> rev;
      shift_left     <T> sl;
      shift_right    <T> sr;
      sort           <T> st;
      nthelement     <T> ne;
      assign         <T> an;
      iota           <T> ia;
      sumk           <T> sk;
      axpy           <T> b1_axpy;
      axpby          <T> b1_axpby;
      axpyz          <T> b1_axpyz;
      axpbyz         <T> b1_axpbyz;
      axpbsy         <T> b1_axpbsy;
      axpbsyz        <T> b1_axpbsyz;
      axpbz          <T> b1_axpbz;
      diff           <T> df;
      dot            <T> dt;
      dotk           <T> dtk;
      threshold_above<T> ta;
      threshold_below<T> tb;

      bool register_package(exprtk::symbol_table<T>& symtab)
      {
         #define exprtk_register_function(FunctionName, FunctionType)                 \
         if (!symtab.add_function(FunctionName,FunctionType))                         \
         {                                                                            \
            exprtk_debug((                                                            \
              "exprtk::rtl::vecops::register_package - Failed to add function: %s\n", \
              FunctionName));                                                         \
            return false;                                                             \
         }                                                                            \

         exprtk_register_function("all_true"        , at        )
         exprtk_register_function("all_false"       , af        )
         exprtk_register_function("any_true"        , nt        )
         exprtk_register_function("any_false"       , nf        )
         exprtk_register_function("count"           , c         )
         exprtk_register_function("copy"            , cp        )
         exprtk_register_function("rotate_left"     , rl        )
         exprtk_register_function("rol"             , rl        )
         exprtk_register_function("rotate_right"    , rr        )
         exprtk_register_function("ror"             , rr        )
         exprtk_register_function("reverse"         , rev       )
         exprtk_register_function("shftl"           , sl        )
         exprtk_register_function("shftr"           , sr        )
         exprtk_register_function("sort"            , st        )
         exprtk_register_function("nth_element"     , ne        )
         exprtk_register_function("assign"          , an        )
         exprtk_register_function("iota"            , ia        )
         exprtk_register_function("sumk"            , sk        )
         exprtk_register_function("axpy"            , b1_axpy   )
         exprtk_register_function("axpby"           , b1_axpby  )
         exprtk_register_function("axpyz"           , b1_axpyz  )
         exprtk_register_function("axpbyz"          , b1_axpbyz )
         exprtk_register_function("axpbsy"          , b1_axpbsy )
         exprtk_register_function("axpbsyz"         , b1_axpbsyz)
         exprtk_register_function("axpbz"           , b1_axpbz  )
         exprtk_register_function("diff"            , df        )
         exprtk_register_function("dot"             , dt        )
         exprtk_register_function("dotk"            , dtk       )
         exprtk_register_function("threshold_above" , ta        )
         exprtk_register_function("threshold_below" , tb        )
         #undef exprtk_register_function

         return true;
      }
   };

   } // namespace exprtk::rtl::vecops
   } // namespace exprtk::rtl
}    // namespace exprtk
#endif

namespace exprtk
{
   namespace information
   {
      using ::exprtk::details::char_cptr;

      static char_cptr library = "Mathematical Expression Toolkit";
      static char_cptr version = "2.71828182845904523536028747135266249775"
                                 "7247093699959574966967627724076630353547"
                                 "5945713821785251664274274663919320030599"
                                 "2181741359662904357290033429526059563073";
      static char_cptr date    = "20240101";
      static char_cptr min_cpp = "199711L";

      static inline std::string data()
      {
         static const std::string info_str = std::string(library) +
                                             std::string(" v") + std::string(version) +
                                             std::string(" (") + date + std::string(")") +
                                             std::string(" (") + min_cpp + std::string(")");
         return info_str;
      }

   } // namespace information

   #ifdef exprtk_debug
   #undef exprtk_debug
   #endif

   #ifdef exprtk_error_location
   #undef exprtk_error_location
   #endif

   #ifdef exprtk_fallthrough
   #undef exprtk_fallthrough
   #endif

   #ifdef exprtk_override
   #undef exprtk_override
   #endif

   #ifdef exprtk_final
   #undef exprtk_final
   #endif

   #ifdef exprtk_delete
   #undef exprtk_delete
   #endif

} // namespace exprtk

#endif