swoc++/src/TextView.cc

/** @file

    Class for handling "views" of a buffer. Views presume the memory for the
    buffer is managed elsewhere and allow efficient access to segments of the
    buffer without copies. Views are read only as the view doesn't own the
    memory. Along with generic buffer methods are specialized methods to support
    better string parsing, particularly token based parsing.
*/

/*  Licensed to the Apache Software Foundation (ASF) under one or more
    contributor license agreements.  See the NOTICE file distributed with this
    work for additional information regarding copyright ownership.  The ASF
    licenses this file to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    License for the specific language governing permissions and limitations under
    the License.
*/
#include "swoc/TextView.h"
#include <cctype>
#include <sstream>

int
memcmp(std::string_view const &lhs, std::string_view const &rhs)
{
  int zret = 0;
  size_t n = rhs.size();

  // Seems a bit ugly but size comparisons must be done anyway to get the memcmp args.
  if (lhs.size() < rhs.size()) {
    zret = 1;
    n    = lhs.size();
  } else if (lhs.size() > rhs.size()) {
    zret = -1;
  } else if (lhs.data() == rhs.data()) { // same memory, obviously equal.
    return 0;
  }

  int r = ::memcmp(lhs.data(), rhs.data(), n);
  return r ? r : zret;
}

int
strcasecmp(const std::string_view &lhs, const std::string_view &rhs)
{
  int zret = 0;
  size_t n = rhs.size();

  // Seems a bit ugly but size comparisons must be done anyway to get the @c strncasecmp args.
  if (lhs.size() < rhs.size()) {
    zret = 1;
    n    = lhs.size();
  } else if (lhs.size() > rhs.size()) {
    zret = -1;
  } else if (lhs.data() == rhs.data()) { // the same memory, obviously equal.
    return 0;
  }

  int r = ::strncasecmp(lhs.data(), rhs.data(), n);

  return r ? r : zret;
}

/// @cond INTERNAL_DETAIL
const int8_t swoc::svtoi_convert[256] = {
  /* [can't do this nicely because clang format won't allow exdented comments]
   0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
  */
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20
  0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  -1, -1, -1, -1, -1, -1, // 30
  -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 40
  25, 26, 27, 28, 20, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1, // 50
  -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 60
  25, 26, 27, 28, 20, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1, // 70
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 80
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 90
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // A0
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // B0
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // C0
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // D0
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // E0
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // F0
};
/// @endcond

intmax_t
swoc::svtoi(TextView src, TextView *out, int base)
{
  intmax_t zret = 0;

  if (src.ltrim_if(&isspace) && src) {
    TextView parsed;
    const char *start = src.data();
    bool neg          = false;
    if ('-' == *src) {
      ++src;
      neg = true;
    } else if ('+' == *src) {
      ++src;
    }
    zret = intmax_t(svtou(src, &parsed, base));
    if (!parsed.empty()) {
      if (out) {
        out->assign(start, parsed.data_end());
      }
      if (neg) {
        zret = -zret;
      }
    }
  }
  return zret;
}

uintmax_t
swoc::svtou(TextView src, TextView *out, int base)
{
  uintmax_t zret = 0;

  if (out) {
    out->clear();
  }
  if (!(0 <= base && base <= 36)) {
    return 0;
  }
  if (src.ltrim_if(&isspace).size()) {
    auto origin = src.data();
    int8_t v;
    // If base is 0, it wasn't specified - check for standard base prefixes
    if (0 == base) {
      base = 10;
      if ('0' == *src) {
        ++src;
        base = 8;
        if (src && ('x' == *src || 'X' == *src)) {
          ++src;
          base = 16;
        }
      }
    }

    // For performance in common cases, use the templated conversion.
    switch (base) {
    case 8:
      zret = svto_radix<8>(src);
      break;
    case 10:
      zret = svto_radix<10>(src);
      break;
    case 16:
      zret = svto_radix<16>(src);
      break;
    default:
      while (src.size() && (0 <= (v = svtoi_convert[static_cast<unsigned char>(*src)])) && v < base) {
        auto n = zret * base + v;
        if (n < zret) {
          zret = std::numeric_limits<uintmax_t>::max();
          break; // overflow, stop parsing.
        }
        zret = n;
        ++src;
      }
      break;
    }

    if (out) {
      out->assign(origin, src.data());
    }
  }
  return zret;
}

// Do the template instantions.
template std::ostream &swoc::TextView::stream_write(std::ostream &, const swoc::TextView &) const;

namespace std
{
ostream &
operator<<(ostream &os, const swoc::TextView &b)
{
  if (os.good()) {
    b.stream_write<ostream>(os, b);
    os.width(0);
  }
  return os;
}
} // namespace std