syncstream
Go to the documentation of this file.
// <syncstream> -*- C++ -*-
// Copyright (C) 2020-2024 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 include/syncstream
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_SYNCSTREAM
#define _GLIBCXX_SYNCSTREAM 1
#pragma GCC system_header
#include <bits/requires_hosted.h> // iostreams
#include <bits/c++config.h>
#define __glibcxx_want_syncbuf
#include <bits/version.h>
#ifdef __cpp_lib_syncbuf // C++ >= 20 && HOSTED && CXX11ABI
#include <sstream>
#include <bits/alloc_traits.h>
#include <bits/allocator.h>
#include <bits/functexcept.h>
#include <bits/functional_hash.h>
#include <bits/std_mutex.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits, typename _Alloc>
class basic_syncbuf : public __syncbuf_base<_CharT, _Traits>
{
public:
using char_type = _CharT;
using int_type = typename _Traits::int_type;
using pos_type = typename _Traits::pos_type;
using off_type = typename _Traits::off_type;
using traits_type = _Traits;
using allocator_type = _Alloc;
using streambuf_type = basic_streambuf<_CharT, _Traits>;
basic_syncbuf()
: basic_syncbuf(nullptr, allocator_type{})
{ }
explicit
basic_syncbuf(streambuf_type* __obuf)
: basic_syncbuf(__obuf, allocator_type{})
{ }
basic_syncbuf(streambuf_type* __obuf, const allocator_type& __alloc)
: __syncbuf_base<_CharT, _Traits>(__obuf)
, _M_impl(__alloc)
, _M_mtx(__obuf)
{ }
basic_syncbuf(basic_syncbuf&& __other)
: __syncbuf_base<_CharT, _Traits>(__other._M_wrapped)
, _M_impl(std::move(__other._M_impl))
, _M_mtx(std::move(__other._M_mtx))
{
this->_M_emit_on_sync = __other._M_emit_on_sync;
this->_M_needs_sync = __other._M_needs_sync;
__other._M_wrapped = nullptr;
}
~basic_syncbuf()
{
__try
{
emit();
}
__catch (...)
{ }
}
basic_syncbuf&
operator=(basic_syncbuf&& __other)
{
emit();
_M_impl = std::move(__other._M_impl);
this->_M_emit_on_sync = __other._M_emit_on_sync;
this->_M_needs_sync = __other._M_needs_sync;
this->_M_wrapped = __other._M_wrapped;
__other._M_wrapped = nullptr;
_M_mtx = std::move(__other._M_mtx);
return *this;
}
void
swap(basic_syncbuf& __other)
{
using _ATr = allocator_traits<_Alloc>;
if constexpr (!_ATr::propagate_on_container_swap::value)
__glibcxx_assert(get_allocator() == __other.get_allocator());
std::swap(_M_impl, __other._M_impl);
std::swap(this->_M_emit_on_sync, __other._M_emit_on_sync);
std::swap(this->_M_needs_sync, __other._M_needs_sync);
std::swap(this->_M_wrapped, __other._M_wrapped);
std::swap(_M_mtx, __other._M_mtx);
}
bool
emit()
{
if (!this->_M_wrapped)
return false;
auto __s = std::move(_M_impl).str();
const lock_guard<__mutex> __l(_M_mtx);
if (auto __size = __s.size())
{
auto __n = this->_M_wrapped->sputn(__s.data(), __size);
if (__n != __size)
{
__s.erase(0, __n);
_M_impl.str(std::move(__s));
return false;
}
}
if (this->_M_needs_sync)
{
this->_M_needs_sync = false;
if (this->_M_wrapped->pubsync() != 0)
return false;
}
return true;
}
streambuf_type*
get_wrapped() const noexcept
{ return this->_M_wrapped; }
allocator_type
get_allocator() const noexcept
{ return _M_impl.get_allocator(); }
void
set_emit_on_sync(bool __b) noexcept
{ this->_M_emit_on_sync = __b; }
protected:
int
sync() override
{
this->_M_needs_sync = true;
if (this->_M_emit_on_sync && !emit())
return -1;
return 0;
}
int_type
overflow(int_type __c) override
{
int_type __eof = traits_type::eof();
if (__builtin_expect(!traits_type::eq_int_type(__c, __eof), true))
return _M_impl.sputc(__c);
return __eof;
}
streamsize
xsputn(const char_type* __s, streamsize __n) override
{ return _M_impl.sputn(__s, __n); }
private:
basic_stringbuf<char_type, traits_type, allocator_type> _M_impl;
struct __mutex
{
#if _GLIBCXX_HAS_GTHREADS
mutex* _M_mtx;
__mutex(void* __t)
: _M_mtx(__t ? &_S_get_mutex(__t) : nullptr)
{ }
void
swap(__mutex& __other) noexcept
{ std::swap(_M_mtx, __other._M_mtx); }
void
lock()
{
_M_mtx->lock();
}
void
unlock()
{
_M_mtx->unlock();
}
// FIXME: This should be put in the .so
static mutex&
_S_get_mutex(void* __t)
{
const unsigned char __mask = 0xf;
static mutex __m[__mask + 1];
auto __key = _Hash_impl::hash(__t) & __mask;
return __m[__key];
}
#else
__mutex(void*) { }
void swap(__mutex&&) noexcept { }
void lock() { }
void unlock() { }
#endif
__mutex(__mutex&&) = default;
__mutex& operator=(__mutex&&) = default;
};
__mutex _M_mtx;
};
template <typename _CharT, typename _Traits, typename _Alloc>
class basic_osyncstream : public basic_ostream<_CharT, _Traits>
{
using __ostream_type = basic_ostream<_CharT, _Traits>;
public:
// Types:
using char_type = _CharT;
using traits_type = _Traits;
using allocator_type = _Alloc;
using int_type = typename traits_type::int_type;
using pos_type = typename traits_type::pos_type;
using off_type = typename traits_type::off_type;
using syncbuf_type = basic_syncbuf<_CharT, _Traits, _Alloc>;
using streambuf_type = typename syncbuf_type::streambuf_type;
private:
syncbuf_type _M_syncbuf;
public:
basic_osyncstream(streambuf_type* __buf, const allocator_type& __a)
: _M_syncbuf(__buf, __a)
{ this->init(std::__addressof(_M_syncbuf)); }
explicit basic_osyncstream(streambuf_type* __buf)
: _M_syncbuf(__buf)
{ this->init(std::__addressof(_M_syncbuf)); }
basic_osyncstream(basic_ostream<char_type, traits_type>& __os,
const allocator_type& __a)
: basic_osyncstream(__os.rdbuf(), __a)
{ this->init(std::__addressof(_M_syncbuf)); }
explicit basic_osyncstream(basic_ostream<char_type, traits_type>& __os)
: basic_osyncstream(__os.rdbuf())
{ this->init(std::__addressof(_M_syncbuf)); }
basic_osyncstream(basic_osyncstream&& __rhs) noexcept
: __ostream_type(std::move(__rhs)),
_M_syncbuf(std::move(__rhs._M_syncbuf))
{ __ostream_type::set_rdbuf(std::__addressof(_M_syncbuf)); }
~basic_osyncstream() = default;
basic_osyncstream& operator=(basic_osyncstream&&) = default;
syncbuf_type* rdbuf() const noexcept
{ return const_cast<syncbuf_type*>(&_M_syncbuf); }
streambuf_type* get_wrapped() const noexcept
{ return _M_syncbuf.get_wrapped(); }
void emit()
{
if (!_M_syncbuf.emit())
this->setstate(ios_base::failbit);
}
};
template <class _CharT, class _Traits, class _Allocator>
inline void
swap(basic_syncbuf<_CharT, _Traits, _Allocator>& __x,
basic_syncbuf<_CharT, _Traits, _Allocator>& __y) noexcept
{ __x.swap(__y); }
using syncbuf = basic_syncbuf<char>;
using wsyncbuf = basic_syncbuf<wchar_t>;
using osyncstream = basic_osyncstream<char>;
using wosyncstream = basic_osyncstream<wchar_t>;
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // __cpp_lib_syncbuf
#endif /* _GLIBCXX_SYNCSTREAM */
sstream
allocator.h
functexcept.h
version.h
functional_hash.h
std_mutex.h
requires_hosted.h
c++config.h
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:137
std::__addressof
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition move.h:51
std::lock
void lock(_L1 &__l1, _L2 &__l2, _L3 &... __l3)
Generic lock.
Definition mutex:698
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:68
std::basic_ostream
Template class basic_ostream.
Definition ostream:67
alloc_traits.h