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// 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