locale/generic/codecvt_members.cc

// std::codecvt implementation details, generic version -*- C++ -*-

// Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

//
// ISO C++ 14882: 22.2.1.5 - Template class codecvt
//

// Written by Benjamin Kosnik <bkoz@redhat.com>

#include <locale>
#include <cstdlib>  // For MB_CUR_MAX
#include <climits>  // For MB_LEN_MAX
#include <cstring>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // Specializations.
#ifdef _GLIBCXX_USE_WCHAR_T
  codecvt_base::result
  codecvt<wchar_t, char, mbstate_t>::
  do_out(state_type& __state, const intern_type* __from,
           const intern_type* __from_end, const intern_type*& __from_next,
           extern_type* __to, extern_type* __to_end,
           extern_type*& __to_next) const
  {
    result __ret = ok;
    // The conversion must be done using a temporary destination buffer
    // since it is not possible to pass the size of the buffer to wcrtomb
    state_type __tmp_state(__state);

    // The conversion must be done by calling wcrtomb in a loop rather
    // than using wcsrtombs because wcsrtombs assumes that the input is
    // zero-terminated.

    // Either we can upper bound the total number of external characters to
    // something smaller than __to_end - __to or the conversion must be done
    // using a temporary destination buffer since it is not possible to
    // pass the size of the buffer to wcrtomb
    if (MB_CUR_MAX * (__from_end - __from) - (__to_end - __to) <= 0)
      while (__from < __from_end)
          {
            const size_t __conv = wcrtomb(__to, *__from, &__tmp_state);
            if (__conv == static_cast<size_t>(-1))
              {
                __ret = error;
                break;
              }
            __state = __tmp_state;
            __to += __conv;
            __from++;
          }
    else
      {
          extern_type __buf[MB_LEN_MAX];
          while (__from < __from_end && __to < __to_end)
            {
              const size_t __conv = wcrtomb(__buf, *__from, &__tmp_state);
              if (__conv == static_cast<size_t>(-1))
                {
                    __ret = error;
                    break;
                }
              else if (__conv > static_cast<size_t>(__to_end - __to))
                {
                    __ret = partial;
                    break;
                }

              memcpy(__to, __buf, __conv);
              __state = __tmp_state;
              __to += __conv;
              __from++;
            }
      }

    if (__ret == ok && __from < __from_end)
      __ret = partial;

    __from_next = __from;
    __to_next = __to;
    return __ret;
  }

  codecvt_base::result
  codecvt<wchar_t, char, mbstate_t>::
  do_in(state_type& __state, const extern_type* __from,
          const extern_type* __from_end, const extern_type*& __from_next,
          intern_type* __to, intern_type* __to_end,
          intern_type*& __to_next) const
  {
    result __ret = ok;
    // This temporary state object is neccessary so __state won't be modified
    // if [__from, __from_end) is a partial multibyte character.
    state_type __tmp_state(__state);

    // Conversion must be done by calling mbrtowc in a loop rather than
    // by calling mbsrtowcs because mbsrtowcs assumes that the input
    // sequence is zero-terminated.
    while (__from < __from_end && __to < __to_end)
      {
          size_t __conv = mbrtowc(__to, __from, __from_end - __from,
                                        &__tmp_state);
          if (__conv == static_cast<size_t>(-1))
            {
              __ret = error;
              break;
            }
          else if (__conv == static_cast<size_t>(-2))
            {
              // It is unclear what to return in this case (see DR 382).
              __ret = partial;
              break;
            }
          else if (__conv == 0)
            {
              // XXX Probably wrong for stateful encodings
              __conv = 1;
              *__to = L'\0';
            }

          __state = __tmp_state;
          __to++;
          __from += __conv;
      }

    // It is not clear that __from < __from_end implies __ret != ok
    // (see DR 382).
    if (__ret == ok && __from < __from_end)
      __ret = partial;

    __from_next = __from;
    __to_next = __to;
    return __ret;
  }

  int
  codecvt<wchar_t, char, mbstate_t>::
  do_encoding() const throw()
  {
    // XXX This implementation assumes that the encoding is
    // stateless and is either single-byte or variable-width.
    int __ret = 0;
    if (MB_CUR_MAX == 1)
      __ret = 1;
    return __ret;
  }

  int
  codecvt<wchar_t, char, mbstate_t>::
  do_max_length() const throw()
  {
    // XXX Probably wrong for stateful encodings.
    int __ret = MB_CUR_MAX;
    return __ret;
  }

  int
  codecvt<wchar_t, char, mbstate_t>::
  do_length(state_type& __state, const extern_type* __from,
              const extern_type* __end, size_t __max) const
  {
    int __ret = 0;
    state_type __tmp_state(__state);

    while (__from < __end && __max)
      {
          size_t __conv = mbrtowc(0, __from, __end - __from, &__tmp_state);
          if (__conv == static_cast<size_t>(-1))
            {
              // Invalid source character
              break;
            }
          else if (__conv == static_cast<size_t>(-2))
            {
              // Remainder of input does not form a complete destination
              // character.
              break;
            }
          else if (__conv == 0)
            {
              // XXX Probably wrong for stateful encodings
              __conv = 1;
            }

          __state = __tmp_state;
          __from += __conv;
          __ret += __conv;
          __max--;
      }

    return __ret;
  }
#endif

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace