src/json/elements.inl

/******************************************************************************

Copyright (c) 2009-2010, Terry Caton
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      may be used to endorse or promote products derived from this software 
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#include "visitor.h"
#include "reader.h"
#include <cassert>
#include <algorithm>
#include <map>

/*  

TODO:
* better documentation

*/

namespace json
{


inline Exception::Exception(const std::string& sMessage) :
   std::runtime_error(sMessage) {}


/////////////////////////
// UnknownElement members

class UnknownElement::Imp
{
public:
   virtual ~Imp() {}
   virtual Imp* Clone() const = 0;

   virtual bool Compare(const Imp& imp) const = 0;

   virtual void Accept(ConstVisitor& visitor) const = 0;
   virtual void Accept(Visitor& visitor) = 0;
};


template <typename ElementTypeT>
class UnknownElement::Imp_T : public UnknownElement::Imp
{
public:
   Imp_T(const ElementTypeT& element) : m_Element(element) {}
   virtual Imp* Clone() const { return new Imp_T<ElementTypeT>(*this); }

   virtual void Accept(ConstVisitor& visitor) const { visitor.Visit(m_Element); }
   virtual void Accept(Visitor& visitor) { visitor.Visit(m_Element); }

   virtual bool Compare(const Imp& imp) const
   {
      ConstCastVisitor_T<ElementTypeT> castVisitor;
      imp.Accept(castVisitor);
      return castVisitor.m_pElement &&
             m_Element == *castVisitor.m_pElement;
   }

private:
   ElementTypeT m_Element;
};


class UnknownElement::ConstCastVisitor : public ConstVisitor
{
   virtual void Visit(const Array& array) {}
   virtual void Visit(const Object& object) {}
   virtual void Visit(const Number& number) {}
   virtual void Visit(const String& string) {}
   virtual void Visit(const Boolean& boolean) {}
   virtual void Visit(const Null& null) {}
};

template <typename ElementTypeT>
class UnknownElement::ConstCastVisitor_T : public ConstCastVisitor
{
public:
   ConstCastVisitor_T() : m_pElement(0) {}
   virtual void Visit(const ElementTypeT& element) { m_pElement = &element; } // we don't know what this is, but it overrides one of the base's no-op functions
   const ElementTypeT* m_pElement;
};


class UnknownElement::CastVisitor : public Visitor
{
   virtual void Visit(Array& array) {}
   virtual void Visit(Object& object) {}
   virtual void Visit(Number& number) {}
   virtual void Visit(String& string) {}
   virtual void Visit(Boolean& boolean) {}
   virtual void Visit(Null& null) {}
};

template <typename ElementTypeT>
class UnknownElement::CastVisitor_T : public CastVisitor
{
public:
   CastVisitor_T() : m_pElement(0) {}
   virtual void Visit(ElementTypeT& element) { m_pElement = &element; } // we don't know what this is, but it overrides one of the base's no-op functions
   ElementTypeT* m_pElement;
};




inline UnknownElement::UnknownElement() :                               m_pImp( new Imp_T<Null>( Null() ) ) {}
inline UnknownElement::UnknownElement(const UnknownElement& unknown) :  m_pImp( unknown.m_pImp->Clone()) {}
inline UnknownElement::UnknownElement(const Object& object) :           m_pImp( new Imp_T<Object>(object) ) {}
inline UnknownElement::UnknownElement(const Array& array) :             m_pImp( new Imp_T<Array>(array) ) {}
inline UnknownElement::UnknownElement(const Number& number) :           m_pImp( new Imp_T<Number>(number) ) {}
inline UnknownElement::UnknownElement(const Boolean& boolean) :         m_pImp( new Imp_T<Boolean>(boolean) ) {}
inline UnknownElement::UnknownElement(const String& string) :           m_pImp( new Imp_T<String>(string) ) {}
inline UnknownElement::UnknownElement(const Null& null) :               m_pImp( new Imp_T<Null>(null) ) {}

inline UnknownElement::~UnknownElement()   { delete m_pImp; }

inline UnknownElement::operator const Object& () const    { return CastTo<Object>(); }
inline UnknownElement::operator const Array& () const     { return CastTo<Array>(); }
inline UnknownElement::operator const Number& () const    { return CastTo<Number>(); }
inline UnknownElement::operator const Boolean& () const   { return CastTo<Boolean>(); }
inline UnknownElement::operator const String& () const    { return CastTo<String>(); }
inline UnknownElement::operator const Null& () const      { return CastTo<Null>(); }

inline UnknownElement::operator Object& ()    { return ConvertTo<Object>(); }
inline UnknownElement::operator Array& ()     { return ConvertTo<Array>(); }
inline UnknownElement::operator Number& ()    { return ConvertTo<Number>(); }
inline UnknownElement::operator Boolean& ()   { return ConvertTo<Boolean>(); }
inline UnknownElement::operator String& ()    { return ConvertTo<String>(); }
inline UnknownElement::operator Null& ()      { return ConvertTo<Null>(); }

inline UnknownElement& UnknownElement::operator = (const UnknownElement& unknown) 
{
   // always check for this
   if (&unknown != this)
   {
      // we might be copying from a subtree of ourselves. delete the old imp
      //  only after the clone operation is complete. yes, this could be made 
      //  more efficient, but isn't worth the complexity
      Imp* pOldImp = m_pImp;
      m_pImp = unknown.m_pImp->Clone();
      delete pOldImp;
   }

   return *this;
}

inline UnknownElement& UnknownElement::operator[] (const std::string& key)
{
   // the people want an object. make us one if we aren't already
   Object& object = ConvertTo<Object>();
   return object[key];
}

inline const UnknownElement& UnknownElement::operator[] (const std::string& key) const
{
   // throws if we aren't an object
   const Object& object = CastTo<Object>();
   return object[key];
}

inline UnknownElement& UnknownElement::operator[] (size_t index)
{
   // the people want an array. make us one if we aren't already
   Array& array = ConvertTo<Array>();
   return array[index];
}

inline const UnknownElement& UnknownElement::operator[] (size_t index) const
{
   // throws if we aren't an array
   const Array& array = CastTo<Array>();
   return array[index];
}


template <typename ElementTypeT>
const ElementTypeT& UnknownElement::CastTo() const
{
   ConstCastVisitor_T<ElementTypeT> castVisitor;
   m_pImp->Accept(castVisitor);
   if (castVisitor.m_pElement == 0)
      throw Exception("Bad cast");
   return *castVisitor.m_pElement;
}



template <typename ElementTypeT>
ElementTypeT& UnknownElement::ConvertTo() 
{
   CastVisitor_T<ElementTypeT> castVisitor;
   m_pImp->Accept(castVisitor);
   if (castVisitor.m_pElement == 0)
   {
      // we're not the right type. fix it & try again
      *this = ElementTypeT();
      m_pImp->Accept(castVisitor);
   }

   return *castVisitor.m_pElement;
}


inline void UnknownElement::Accept(ConstVisitor& visitor) const { m_pImp->Accept(visitor); }
inline void UnknownElement::Accept(Visitor& visitor)            { m_pImp->Accept(visitor); }


inline bool UnknownElement::operator == (const UnknownElement& element) const
{
   return m_pImp->Compare(*element.m_pImp);
}



//////////////////
// Object members


inline Object::Member::Member(const std::string& nameIn, const UnknownElement& elementIn) :
   name(nameIn), element(elementIn) {}

inline bool Object::Member::operator == (const Member& member) const 
{
   return name == member.name &&
          element == member.element;
}

class Object::Finder : public std::unary_function<Object::Member, bool>
{
public:
   Finder(const std::string& name) : m_name(name) {}
   bool operator () (const Object::Member& member) {
      return member.name == m_name;
   }

private:
   std::string m_name;
};



inline Object::iterator Object::Begin() { return m_Members.begin(); }
inline Object::iterator Object::End() { return m_Members.end(); }
inline Object::const_iterator Object::Begin() const { return m_Members.begin(); }
inline Object::const_iterator Object::End() const { return m_Members.end(); }

inline size_t Object::Size() const { return m_Members.size(); }
inline bool Object::Empty() const { return m_Members.empty(); }

inline Object::iterator Object::Find(const std::string& name) 
{
   return std::find_if(m_Members.begin(), m_Members.end(), Finder(name));
}

inline Object::const_iterator Object::Find(const std::string& name) const 
{
   return std::find_if(m_Members.begin(), m_Members.end(), Finder(name));
}

inline Object::iterator Object::Insert(const Member& member)
{
   return Insert(member, End());
}

inline Object::iterator Object::Insert(const Member& member, iterator itWhere)
{
   iterator it = Find(member.name);
   if (it != m_Members.end())
      throw Exception(std::string("Object member already exists: ") + member.name);

   it = m_Members.insert(itWhere, member);
   return it;
}

inline Object::iterator Object::Erase(iterator itWhere) 
{
   return m_Members.erase(itWhere);
}

inline UnknownElement& Object::operator [](const std::string& name)
{

   iterator it = Find(name);
   if (it == m_Members.end())
   {
      Member member(name);
      it = Insert(member, End());
   }
   return it->element;      
}

inline const UnknownElement& Object::operator [](const std::string& name) const 
{
   const_iterator it = Find(name);
   if (it == End())
      throw Exception(std::string("Object member not found: ") + name);
   return it->element;
}

inline void Object::Clear() 
{
   m_Members.clear(); 
}

inline bool Object::operator == (const Object& object) const 
{
   return m_Members == object.m_Members;
}


/////////////////
// Array members

inline Array::iterator Array::Begin()  { return m_Elements.begin(); }
inline Array::iterator Array::End()    { return m_Elements.end(); }
inline Array::const_iterator Array::Begin() const  { return m_Elements.begin(); }
inline Array::const_iterator Array::End() const    { return m_Elements.end(); }

inline Array::iterator Array::Insert(const UnknownElement& element, iterator itWhere)
{ 
   return m_Elements.insert(itWhere, element);
}

inline Array::iterator Array::Insert(const UnknownElement& element)
{
   return Insert(element, End());
}

inline Array::iterator Array::Erase(iterator itWhere)
{ 
   return m_Elements.erase(itWhere);
}

inline void Array::Resize(size_t newSize)
{
   m_Elements.resize(newSize);
}

inline size_t Array::Size() const  { return m_Elements.size(); }
inline bool Array::Empty() const   { return m_Elements.empty(); }

inline UnknownElement& Array::operator[] (size_t index)
{
   size_t nMinSize = index + 1; // zero indexed
   if (m_Elements.size() < nMinSize)
      m_Elements.resize(nMinSize);
   return m_Elements[index]; 
}

inline const UnknownElement& Array::operator[] (size_t index) const 
{
   if (index >= m_Elements.size())
      throw Exception("Array out of bounds");
   return m_Elements[index]; 
}

inline void Array::Clear() {
   m_Elements.clear();
}

inline bool Array::operator == (const Array& array) const
{
   return m_Elements == array.m_Elements;
}


////////////////////////
// TrivialType_T members

template <typename DataTypeT>
TrivialType_T<DataTypeT>::TrivialType_T(const DataTypeT& t) :
   m_tValue(t) {}

template <typename DataTypeT>
TrivialType_T<DataTypeT>::operator DataTypeT&()
{
   return Value(); 
}

template <typename DataTypeT>
TrivialType_T<DataTypeT>::operator const DataTypeT&() const
{
   return Value(); 
}

template <typename DataTypeT>
DataTypeT& TrivialType_T<DataTypeT>::Value()
{
   return m_tValue; 
}

template <typename DataTypeT>
const DataTypeT& TrivialType_T<DataTypeT>::Value() const
{
   return m_tValue; 
}

template <typename DataTypeT>
bool TrivialType_T<DataTypeT>::operator == (const TrivialType_T<DataTypeT>& trivial) const
{
   return m_tValue == trivial.m_tValue;
}



//////////////////
// Null members

inline bool Null::operator == (const Null& trivial) const
{
   return true;
}



} // End namespace