// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_SYNCSTREAM
#define _LIBCPP_SYNCSTREAM
/*
syncstream synopsis
#include <ostream> // see [ostream.syn]
namespace std {
template<class charT, class traits, class Allocator>
class basic_syncbuf;
// [syncstream.syncbuf.special], specialized algorithms
template<class charT, class traits, class Allocator>
void swap(basic_syncbuf<charT, traits, Allocator>&,
basic_syncbuf<charT, traits, Allocator>&);
using syncbuf = basic_syncbuf<char>;
using wsyncbuf = basic_syncbuf<wchar_t>;
template<class charT, class traits, class Allocator>
class basic_osyncstream;
using osyncstream = basic_osyncstream<char>;
using wosyncstream = basic_osyncstream<wchar_t>;
template<class charT, class traits, class Allocator>
class basic_syncbuf : public basic_streambuf<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 = Allocator;
using streambuf_type = basic_streambuf<charT, traits>;
// [syncstream.syncbuf.cons], construction and destruction
basic_syncbuf()
: basic_syncbuf(nullptr) {}
explicit basic_syncbuf(streambuf_type* obuf)
: basic_syncbuf(obuf, Allocator()) {}
basic_syncbuf(streambuf_type*, const Allocator&);
basic_syncbuf(basic_syncbuf&&);
~basic_syncbuf();
// [syncstream.syncbuf.assign], assignment and swap
basic_syncbuf& operator=(basic_syncbuf&&);
void swap(basic_syncbuf&);
// [syncstream.syncbuf.members], member functions
bool emit();
streambuf_type* get_wrapped() const noexcept;
allocator_type get_allocator() const noexcept;
void set_emit_on_sync(bool) noexcept;
protected:
// [syncstream.syncbuf.virtuals], overridden virtual functions
int sync() override;
private:
streambuf_type* wrapped; // exposition only
bool emit_on_sync{}; // exposition only
};
// [syncstream.syncbuf.special], specialized algorithms
template<class charT, class traits, class Allocator>
void swap(basic_syncbuf<charT, traits, Allocator>&,
basic_syncbuf<charT, traits, Allocator>&);
template<class charT, class traits, class Allocator>
class basic_osyncstream : public basic_ostream<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 = Allocator;
using streambuf_type = basic_streambuf<charT, traits>;
using syncbuf_type = basic_syncbuf<charT, traits, Allocator>;
// [syncstream.osyncstream.cons], construction and destruction
basic_osyncstream(streambuf_type*, const Allocator&);
explicit basic_osyncstream(streambuf_type* obuf)
: basic_osyncstream(obuf, Allocator()) {}
basic_osyncstream(basic_ostream<charT, traits>& os, const Allocator& allocator)
: basic_osyncstream(os.rdbuf(), allocator) {}
explicit basic_osyncstream(basic_ostream<charT, traits>& os)
: basic_osyncstream(os, Allocator()) {}
basic_osyncstream(basic_osyncstream&&) noexcept;
~basic_osyncstream();
// [syncstream.osyncstream.assign], assignment
basic_osyncstream& operator=(basic_osyncstream&&);
// [syncstream.osyncstream.members], member functions
void emit();
streambuf_type* get_wrapped() const noexcept;
syncbuf_type* rdbuf() const noexcept { return const_cast<syncbuf_type*>(addressof(sb)); }
private:
syncbuf_type sb; // exposition only
};
}
*/
#include <__config>
#include <__utility/move.h>
#include <ios>
#include <iosfwd> // required for declaration of default arguments
#include <streambuf>
#include <string>
#ifndef _LIBCPP_HAS_NO_THREADS
# include <map>
# include <mutex>
# include <shared_mutex>
#endif
// standard-mandated includes
// [syncstream.syn]
#include <ostream>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
// [syncstream.syncbuf.overview]/1
// Class template basic_syncbuf stores character data written to it,
// known as the associated output, into internal buffers allocated
// using the object's allocator. The associated output is transferred
// to the wrapped stream buffer object *wrapped when emit() is called
// or when the basic_syncbuf object is destroyed. Such transfers are
// atomic with respect to transfers by other basic_syncbuf objects
// with the same wrapped stream buffer object.
//
// This helper singleton is used to implement the required
// synchronisation guarantees.
# ifndef _LIBCPP_HAS_NO_THREADS
class __wrapped_streambuf_mutex {
_LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex() = default;
public:
__wrapped_streambuf_mutex(const __wrapped_streambuf_mutex&) = delete;
__wrapped_streambuf_mutex& operator=(const __wrapped_streambuf_mutex&) = delete;
_LIBCPP_HIDE_FROM_ABI void __inc_reference([[maybe_unused]] void* __ptr) {
_LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
unique_lock __lock{__mutex_};
++__lut_[reinterpret_cast<uintptr_t>(__ptr)].__count;
}
// pre: __ptr is in __lut_
_LIBCPP_HIDE_FROM_ABI void __dec_reference([[maybe_unused]] void* __ptr) noexcept {
unique_lock __lock{__mutex_};
auto __it = __get_it(__ptr);
if (__it->second.__count == 1)
__lut_.erase(__it);
else
--__it->second.__count;
}
// TODO
// This function causes emit() aquire two mutexes:
// - __mutex_ shared
// _ __get_it(__ptr)->second.__mutex exclusive
//
// Instead store a pointer to __get_it(__ptr)->second.__mutex when
// calling __inc_reference.
//
// pre: __ptr is in __lut_
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI lock_guard<mutex> __get_lock([[maybe_unused]] void* __ptr) noexcept {
shared_lock __lock{__mutex_};
return lock_guard{__get_it(__ptr)->second.__mutex};
}
// This function is used for testing.
//
// It is allowed to call this function with a non-registered pointer.
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI size_t __get_count([[maybe_unused]] void* __ptr) noexcept {
_LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
shared_lock __lock{__mutex_};
auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
return __it != __lut_.end() ? __it->second.__count : 0;
}
[[nodiscard]] static _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex& __instance() noexcept {
static __wrapped_streambuf_mutex __result;
return __result;
}
private:
struct __value {
mutex __mutex;
size_t __count{0};
};
shared_mutex __mutex_;
map<uintptr_t, __value> __lut_;
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI map<uintptr_t, __value>::iterator __get_it(void* __ptr) noexcept {
_LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
_LIBCPP_ASSERT_INTERNAL(__it != __lut_.end(), "using a wrapped streambuf that has not been registered");
_LIBCPP_ASSERT_INTERNAL(__it->second.__count >= 1, "found an inactive streambuf wrapper");
return __it;
}
};
# endif // _LIBCPP_HAS_NO_THREADS
// basic_syncbuf
// The class uses a basic_string<_CharT, _Traits, _Allocator> as
// internal buffer. Per [syncstream.syncbuf.cons]/4
// Remarks: A copy of allocator is used to allocate memory for
// internal buffers holding the associated output.
//
// Therefore the allocator used in the constructor is passed to the
// basic_string. The class does not keep a copy of this allocator.
template <class _CharT, class _Traits, class _Allocator>
class _LIBCPP_TEMPLATE_VIS basic_syncbuf : public basic_streambuf<_CharT, _Traits> {
public:
using char_type = _CharT;
using traits_type = _Traits;
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 allocator_type = _Allocator;
using streambuf_type = basic_streambuf<_CharT, _Traits>;
// [syncstream.syncbuf.cons], construction and destruction
_LIBCPP_HIDE_FROM_ABI basic_syncbuf() : basic_syncbuf(nullptr) {}
_LIBCPP_HIDE_FROM_ABI explicit basic_syncbuf(streambuf_type* __obuf) : basic_syncbuf(__obuf, _Allocator()) {}
_LIBCPP_HIDE_FROM_ABI basic_syncbuf(streambuf_type* __obuf, _Allocator const& __alloc)
: __wrapped_(__obuf), __str_(__alloc) {
__inc_reference();
}
_LIBCPP_HIDE_FROM_ABI basic_syncbuf(basic_syncbuf&& __other)
: __wrapped_(__other.get_wrapped()), __str_(std::move(__other.__str_)), __emit_on_sync_(__other.__emit_on_sync_) {
__move_common(__other);
}
_LIBCPP_HIDE_FROM_ABI ~basic_syncbuf() {
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
try {
# endif // _LIBCPP_HAS_NO_EXCEPTIONS
emit();
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
} catch (...) {
}
# endif // _LIBCPP_HAS_NO_EXCEPTIONS
__dec_reference();
}
// [syncstream.syncbuf.assign], assignment and swap
_LIBCPP_HIDE_FROM_ABI basic_syncbuf& operator=(basic_syncbuf&& __other) {
// The function is specified to call emit. This call should
// propagate the exception thrown.
emit();
__dec_reference();
__wrapped_ = __other.get_wrapped();
__str_ = std::move(__other.__str_);
__emit_on_sync_ = __other.__emit_on_sync_;
__move_common(__other);
return *this;
}
_LIBCPP_HIDE_FROM_ABI void swap(basic_syncbuf& __other) {
_LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
allocator_traits<_Allocator>::propagate_on_container_swap::value || get_allocator() == __other.get_allocator(),
"violates the mandated swap precondition");
basic_syncbuf __tmp(std::move(__other));
__other = std::move(*this);
*this = std::move(__tmp);
}
// [syncstream.syncbuf.members], member functions
_LIBCPP_HIDE_FROM_ABI bool emit() { return emit(false); }
_LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __wrapped_; }
_LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const noexcept { return __str_.get_allocator(); }
_LIBCPP_HIDE_FROM_ABI void set_emit_on_sync(bool __b) noexcept { __emit_on_sync_ = __b; }
protected:
// [syncstream.syncbuf.virtuals], overridden virtual functions
_LIBCPP_HIDE_FROM_ABI_VIRTUAL
int sync() override {
if (__emit_on_sync_ && !emit(true))
return -1;
return 0;
}
_LIBCPP_HIDE_FROM_ABI_VIRTUAL
int_type overflow(int_type __c = traits_type::eof()) override {
if (traits_type::eq_int_type(__c, traits_type::eof()))
return traits_type::not_eof(__c);
if (this->pptr() == this->epptr()) {
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
try {
# endif
size_t __size = __str_.size();
__str_.resize(__str_.capacity() + 1);
_LIBCPP_ASSERT_INTERNAL(__str_.size() > __size, "the buffer hasn't grown");
char_type* __p = static_cast<char_type*>(__str_.data());
this->setp(__p, __p + __str_.size());
this->pbump(__size);
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
} catch (...) {
return traits_type::eof();
}
# endif
}
return this->sputc(traits_type::to_char_type(__c));
}
private:
streambuf_type* __wrapped_;
// TODO Use a more generic buffer.
// That buffer should be light with almost no additional headers. Then
// it can be use here, the __retarget_buffer, and place that use
// the now deprecated get_temporary_buffer
basic_string<_CharT, _Traits, _Allocator> __str_;
bool __emit_on_sync_{false};
_LIBCPP_HIDE_FROM_ABI bool emit(bool __flush) {
if (!__wrapped_)
return false;
# ifndef _LIBCPP_HAS_NO_THREADS
lock_guard<mutex> __lock = __wrapped_streambuf_mutex::__instance().__get_lock(__wrapped_);
# endif
bool __result = true;
if (this->pptr() != this->pbase()) {
_LIBCPP_ASSERT_INTERNAL(this->pbase() && this->pptr() && this->epptr(), "all put area pointers shold be valid");
// The __str_ does not know how much of its buffer is used. This
// information is extracted from the information of the base class.
__result &= (__wrapped_->sputn(this->pbase(), this->pptr() - this->pbase()) != -1);
// Clears the buffer, but keeps the contents (and) size of the
// internal buffer.
this->setp(this->pbase(), this->epptr());
}
if (__flush)
__result &= (__wrapped_->pubsync() != -1);
return __result;
}
_LIBCPP_HIDE_FROM_ABI void __move_common(basic_syncbuf& __other) {
// Adjust the put area pointers to our buffer.
char_type* __p = static_cast<char_type*>(__str_.data());
this->setp(__p, __p + __str_.size());
this->pbump(__other.pptr() - __other.pbase());
// Clear __other_ so the destructor will act as a NOP.
__other.setp(nullptr, nullptr);
__other.__wrapped_ = nullptr;
}
_LIBCPP_HIDE_FROM_ABI void __inc_reference() {
# ifndef _LIBCPP_HAS_NO_THREADS
if (__wrapped_)
__wrapped_streambuf_mutex::__instance().__inc_reference(__wrapped_);
# endif
}
_LIBCPP_HIDE_FROM_ABI void __dec_reference() noexcept {
# ifndef _LIBCPP_HAS_NO_THREADS
if (__wrapped_)
__wrapped_streambuf_mutex::__instance().__dec_reference(__wrapped_);
# endif
}
};
using std::syncbuf;
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
using std::wsyncbuf;
# endif
// [syncstream.syncbuf.special], specialized algorithms
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI void
swap(basic_syncbuf<_CharT, _Traits, _Allocator>& __lhs, basic_syncbuf<_CharT, _Traits, _Allocator>& __rhs) {
__lhs.swap(__rhs);
}
// basic_osyncstream
template <class _CharT, class _Traits, class _Allocator>
class _LIBCPP_TEMPLATE_VIS basic_osyncstream : public basic_ostream<_CharT, _Traits> {
public:
using char_type = _CharT;
using traits_type = _Traits;
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 allocator_type = _Allocator;
using streambuf_type = basic_streambuf<char_type, traits_type>;
using syncbuf_type = basic_syncbuf<char_type, traits_type, allocator_type>;
// [syncstream.osyncstream.cons], construction and destruction
_LIBCPP_HIDE_FROM_ABI basic_osyncstream(streambuf_type* __obuf, allocator_type const& __alloc)
: basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__obuf, __alloc) {}
_LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(streambuf_type* __obuf)
: basic_osyncstream(__obuf, allocator_type()) {}
_LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_ostream<char_type, traits_type>& __os, allocator_type const& __alloc)
: basic_osyncstream(__os.rdbuf(), __alloc) {}
_LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(basic_ostream<char_type, traits_type>& __os)
: basic_osyncstream(__os, allocator_type()) {}
_LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_osyncstream&& __other) noexcept
: basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(std::move(__other.__sb_)) {
this->set_rdbuf(std::addressof(__sb_));
}
// [syncstream.osyncstream.assign], assignment
_LIBCPP_HIDE_FROM_ABI basic_osyncstream& operator=(basic_osyncstream&& __other) = default;
// [syncstream.osyncstream.members], member functions
_LIBCPP_HIDE_FROM_ABI void emit() {
// The basic_ostream::put places the sentry in a try
// catch, this does not match the wording of the standard
// [ostream.unformatted]
// TODO validate other unformatted output functions.
typename basic_ostream<char_type, traits_type>::sentry __s(*this);
if (__s) {
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
try {
# endif
if (__sb_.emit() == false)
this->setstate(ios::badbit);
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
} catch (...) {
this->__set_badbit_and_consider_rethrow();
}
# endif
}
}
_LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __sb_.get_wrapped(); }
_LIBCPP_HIDE_FROM_ABI syncbuf_type* rdbuf() const noexcept {
return const_cast<syncbuf_type*>(std::addressof(__sb_));
}
private:
syncbuf_type __sb_;
};
using std::osyncstream;
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
using std::wosyncstream;
# endif
#endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP_SYNCSTREAM
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