source: Daodan/MSYS2/mingw32/include/c++/11.2.0/bits/streambuf.tcc

// Stream buffer classes -*- C++ -*-

// Copyright (C) 1997-2021 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/>.

/** @file bits/streambuf.tcc
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{streambuf}
 */

//
// ISO C++ 14882: 27.5  Stream buffers
//

#ifndef _STREAMBUF_TCC
#define _STREAMBUF_TCC 1

#pragma GCC system_header

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  template<typename _CharT, typename _Traits>
    streamsize
    basic_streambuf<_CharT, _Traits>::
    xsgetn(char_type* __s, streamsize __n)
    {
      streamsize __ret = 0;
      while (__ret < __n)
        {
          const streamsize __buf_len = this->egptr() - this->gptr();
          if (__buf_len)
            {
              const streamsize __remaining = __n - __ret;
              const streamsize __len = std::min(__buf_len, __remaining);
              traits_type::copy(__s, this->gptr(), __len);
              __ret += __len;
              __s += __len;
              this->__safe_gbump(__len);
            }

          if (__ret < __n)
            {
              const int_type __c = this->uflow();
              if (!traits_type::eq_int_type(__c, traits_type::eof()))
                {
                  traits_type::assign(*__s++, traits_type::to_char_type(__c));
                  ++__ret;
                }
              else
                break;
            }
        }
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    streamsize
    basic_streambuf<_CharT, _Traits>::
    xsputn(const char_type* __s, streamsize __n)
    {
      streamsize __ret = 0;
      while (__ret < __n)
        {
          const streamsize __buf_len = this->epptr() - this->pptr();
          if (__buf_len)
            {
              const streamsize __remaining = __n - __ret;
              const streamsize __len = std::min(__buf_len, __remaining);
              traits_type::copy(this->pptr(), __s, __len);
              __ret += __len;
              __s += __len;
              this->__safe_pbump(__len);
            }

          if (__ret < __n)
            {
              int_type __c = this->overflow(traits_type::to_int_type(*__s));
              if (!traits_type::eq_int_type(__c, traits_type::eof()))
                {
                  ++__ret;
                  ++__s;
                }
              else
                break;
            }
        }
      return __ret;
    }

  // Conceivably, this could be used to implement buffer-to-buffer
  // copies, if this was ever desired in an un-ambiguous way by the
  // standard.
  template<typename _CharT, typename _Traits>
    streamsize
    __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>* __sbin,
                          basic_streambuf<_CharT, _Traits>* __sbout,
                          bool& __ineof)
    {
      streamsize __ret = 0;
      __ineof = true;
      typename _Traits::int_type __c = __sbin->sgetc();
      while (!_Traits::eq_int_type(__c, _Traits::eof()))
        {
          __c = __sbout->sputc(_Traits::to_char_type(__c));
          if (_Traits::eq_int_type(__c, _Traits::eof()))
            {
              __ineof = false;
              break;
            }
          ++__ret;
          __c = __sbin->snextc();
        }
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    inline streamsize
    __copy_streambufs(basic_streambuf<_CharT, _Traits>* __sbin,
                      basic_streambuf<_CharT, _Traits>* __sbout)
    {
      bool __ineof;
      return __copy_streambufs_eof(__sbin, __sbout, __ineof);
    }

  // Inhibit implicit instantiations for required instantiations,
  // which are defined via explicit instantiations elsewhere.
#if _GLIBCXX_EXTERN_TEMPLATE
  extern template class basic_streambuf<char>;
  extern template
    streamsize
    __copy_streambufs(basic_streambuf<char>*,
                      basic_streambuf<char>*);
  extern template
    streamsize
    __copy_streambufs_eof(basic_streambuf<char>*,
                          basic_streambuf<char>*, bool&);

#ifdef _GLIBCXX_USE_WCHAR_T
  extern template class basic_streambuf<wchar_t>;
  extern template
    streamsize
    __copy_streambufs(basic_streambuf<wchar_t>*,
                      basic_streambuf<wchar_t>*);
  extern template
    streamsize
    __copy_streambufs_eof(basic_streambuf<wchar_t>*,
                          basic_streambuf<wchar_t>*, bool&);
#endif
#endif

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif