streambuf.tcc
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// Stream buffer classes -*- C++ -*-
// Copyright (C) 1997-2026 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
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wc++11-extensions" // extern template
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>*);
#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>*);
#endif
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#pragma GCC diagnostic pop
#endif
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:232
std
ISO C++ entities toplevel namespace is std.
std::streamsize
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition postypes.h:73
std::basic_streambuf
The actual work of input and output (interface).
Definition streambuf:127
std::basic_streambuf::int_type
traits_type::int_type int_type
Definition streambuf:137
std::basic_streambuf::epptr
char_type * epptr() const
Access to the put area.
Definition streambuf:549
std::basic_streambuf::overflow
virtual int_type overflow(int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition streambuf:782
std::basic_streambuf::xsputn
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition streambuf.tcc:85
std::basic_streambuf::pptr
char_type * pptr() const
Access to the put area.
Definition streambuf:546
std::basic_streambuf::char_type
_CharT char_type
Definition streambuf:135
std::basic_streambuf::uflow
virtual int_type uflow()
Fetches more data from the controlled sequence.
Definition streambuf:714
std::basic_streambuf::egptr
char_type * egptr() const
Access to the get area.
Definition streambuf:501
std::basic_streambuf::gptr
char_type * gptr() const
Access to the get area.
Definition streambuf:498
std::basic_streambuf::xsgetn
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition streambuf.tcc:51
std::basic_streambuf::snextc
int_type snextc()
Getting the next character.
Definition streambuf:307
std::basic_streambuf::sgetc
int_type sgetc()
Getting the next character.
Definition streambuf:347
std::basic_streambuf::sputc
int_type sputc(char_type __c)
Entry point for all single-character output functions.
Definition streambuf:433