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

// Copyright (C) 2002, 2003 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 2, 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.

// You should have received a copy of the GNU General Public License along

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

//

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

//

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

#include <locale>

#include <bits/c++locale_internal.h>

namespace std

{

  // 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;

    state_type __tmp_state(__state);

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __c_locale __old = __uselocale(_M_c_locale_codecvt);

#endif

    // wcsnrtombs is *very* fast but stops if encounters NUL characters:

    // in case we fall back to wcrtomb and then continue, in a loop.

    // NB: wcsnrtombs is a GNU extension

    for (__from_next = __from, __to_next = __to;

         __from_next < __from_end && __to_next < __to_end

         && __ret == ok;)

      {

        const intern_type* __from_chunk_end = wmemchr(__from_next, L'\0',

                                                      __from_end - __from_next);

        if (!__from_chunk_end)

          __from_chunk_end = __from_end;

        __from = __from_next;

        const size_t __conv = wcsnrtombs(__to_next, &__from_next,

                                         __from_chunk_end - __from_next,

                                         __to_end - __to_next, &__state);

        if (__conv == static_cast<size_t>(-1))

          {

            // In case of error, in order to stop at the exact place we

            // have to start again from the beginning with a series of

            // wcrtomb.

            for (; __from < __from_next; ++__from)

              __to_next += wcrtomb(__to_next, *__from, &__tmp_state);

            __state = __tmp_state;

            __ret = error;

          }

        else if (__from_next && __from_next < __from_chunk_end)

          {

            __to_next += __conv;

            __ret = partial;

          }

        else

          {

            __from_next = __from_chunk_end;

            __to_next += __conv;

          }

        if (__from_next < __from_end && __ret == ok)

          {

            extern_type __buf[MB_LEN_MAX];

            __tmp_state = __state;

            const size_t __conv = wcrtomb(__buf, *__from_next, &__tmp_state);

            if (__conv > static_cast<size_t>(__to_end - __to_next))

              __ret = partial;

            else

              {

                memcpy(__to_next, __buf, __conv);

                __state = __tmp_state;

                __to_next += __conv;

                ++__from_next;

              }

          }

      }

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __uselocale(__old);

#endif

    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;

    state_type __tmp_state(__state);

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __c_locale __old = __uselocale(_M_c_locale_codecvt);

#endif

    // mbsnrtowcs is *very* fast but stops if encounters NUL characters:

    // in case we store a L'\0' and then continue, in a loop.

    // NB: mbsnrtowcs is a GNU extension

    for (__from_next = __from, __to_next = __to;

         __from_next < __from_end && __to_next < __to_end

         && __ret == ok;)

      {

        const extern_type* __from_chunk_end;

        __from_chunk_end = static_cast<const extern_type*>(memchr(__from_next, '\0',

                                                                  __from_end

                                                                  - __from_next));

        if (!__from_chunk_end)

          __from_chunk_end = __from_end;

        __from = __from_next;

        size_t __conv = mbsnrtowcs(__to_next, &__from_next,

                                   __from_chunk_end - __from_next,

                                   __to_end - __to_next, &__state);

        if (__conv == static_cast<size_t>(-1))

          {

            // In case of error, in order to stop at the exact place we

            // have to start again from the beginning with a series of

            // mbrtowc.

            for (;; ++__to_next, __from += __conv)

              {

                __conv = mbrtowc(__to_next, __from, __from_end - __from,

                                 &__tmp_state);

                if (__conv == static_cast<size_t>(-1)

                    || __conv == static_cast<size_t>(-2))

                  break;

              }

            __from_next = __from;

            __state = __tmp_state;

            __ret = error;

          }

        else if (__from_next && __from_next < __from_chunk_end)

          {

            // It is unclear what to return in this case (see DR 382). 

            __to_next += __conv;

            __ret = partial;

          }

        else

          {

            __from_next = __from_chunk_end;

            __to_next += __conv;

          }

        if (__from_next < __from_end && __ret == ok)

          {

            if (__to_next < __to_end)

              {

                // XXX Probably wrong for stateful encodings

                __tmp_state = __state;

                ++__from_next;

                *__to_next++ = L'\0';

              }

            else

              __ret = partial;

          }

      }

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __uselocale(__old);

#endif

    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 __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __c_locale __old = __uselocale(_M_c_locale_codecvt);

#endif

    if (MB_CUR_MAX == 1)

      __ret = 1;

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __uselocale(__old);

#endif

    return __ret;

  }

  int

  codecvt<wchar_t, char, mbstate_t>::

  do_max_length() const throw()

  {

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __c_locale __old = __uselocale(_M_c_locale_codecvt);

#endif

    // XXX Probably wrong for stateful encodings.

    int __ret = MB_CUR_MAX;

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __uselocale(__old);

#endif

    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);

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __c_locale __old = __uselocale(_M_c_locale_codecvt);

#endif

    // mbsnrtowcs is *very* fast but stops if encounters NUL characters:

    // in case we advance past it and then continue, in a loop.

    // NB: mbsnrtowcs is a GNU extension

    // A dummy internal buffer is needed in order for mbsnrtocws to consider

    // its fourth parameter (it wouldn't with NULL as first parameter).

    wchar_t* __to = static_cast<wchar_t*>(__builtin_alloca(sizeof(wchar_t)

                                                           * __max));

    while (__from < __end && __max)

      {

        const extern_type* __from_chunk_end;

        __from_chunk_end = static_cast<const extern_type*>(memchr(__from, '\0',

                                                                  __end

                                                                  - __from));

        if (!__from_chunk_end)

          __from_chunk_end = __end;

        const extern_type* __tmp_from = __from;

        size_t __conv = mbsnrtowcs(__to, &__from,

                                   __from_chunk_end - __from,

                                   __max, &__state);

        if (__conv == static_cast<size_t>(-1))

          {

            // In case of error, in order to stop at the exact place we

            // have to start again from the beginning with a series of

            // mbrtowc.

            for (__from = __tmp_from;; __from += __conv)

              {

                __conv = mbrtowc(NULL, __from, __end - __from,

                                 &__tmp_state);

                if (__conv == static_cast<size_t>(-1)

                    || __conv == static_cast<size_t>(-2))

                  break;

              }

            __state = __tmp_state;

            __ret += __from - __tmp_from;

            break;

          }

        if (!__from)

          __from = __from_chunk_end;

        __ret += __from - __tmp_from;

        __max -= __conv;

        if (__from < __end && __max)

          {

            // XXX Probably wrong for stateful encodings

            __tmp_state = __state;

            ++__from;

            ++__ret;

            --__max;

          }

      }

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)

    __uselocale(__old);

#endif

    return __ret;

  }

#endif

}