uses_allocator_args.h
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// Utility functions for uses-allocator construction -*- C++ -*-
// Copyright (C) 2019-2022 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/bits/uses_allocator_args.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _USES_ALLOCATOR_ARGS
#define _USES_ALLOCATOR_ARGS 1
#pragma GCC system_header
#if __cplusplus > 201703L && __cpp_concepts
#include <new> // for placement operator new
#include <tuple> // for tuple, make_tuple, make_from_tuple
#include <bits/stl_construct.h> // construct_at
#include <bits/stl_pair.h> // pair
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
concept _Std_pair = __is_pair<_Tp>;
/** @addtogroup allocators
* @{
*/
// Not specified by C++20, used internally
#define __cpp_lib_make_obj_using_allocator 201811L
template<typename _Tp, typename _Alloc, typename... _Args>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a,
_Args&&... __args) noexcept
requires (! _Std_pair<_Tp>)
{
if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
{
if constexpr (is_constructible_v<_Tp, allocator_arg_t,
const _Alloc&, _Args...>)
{
return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
allocator_arg, __a, std::forward<_Args>(__args)...);
}
else
{
static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
"construction with an allocator must be possible"
" if uses_allocator is true");
return tuple<_Args&&..., const _Alloc&>(
std::forward<_Args>(__args)..., __a);
}
}
else
{
static_assert(is_constructible_v<_Tp, _Args...>);
return tuple<_Args&&...>(std::forward<_Args>(__args)...);
}
}
template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
_Tuple1&& __x, _Tuple2&& __y) noexcept;
template<_Std_pair _Tp, typename _Alloc>
constexpr auto
uses_allocator_construction_args(const _Alloc&) noexcept;
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc&,
const pair<_Up, _Vp>&) noexcept;
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
_Tuple1&& __x, _Tuple2&& __y) noexcept
{
using _Tp1 = typename _Tp::first_type;
using _Tp2 = typename _Tp::second_type;
return std::make_tuple(piecewise_construct,
std::apply([&__a](auto&&... __args1) {
return std::uses_allocator_construction_args<_Tp1>(
__a, std::forward<decltype(__args1)>(__args1)...);
}, std::forward<_Tuple1>(__x)),
std::apply([&__a](auto&&... __args2) {
return std::uses_allocator_construction_args<_Tp2>(
__a, std::forward<decltype(__args2)>(__args2)...);
}, std::forward<_Tuple2>(__y)));
}
template<_Std_pair _Tp, typename _Alloc>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a) noexcept
{
using _Tp1 = typename _Tp::first_type;
using _Tp2 = typename _Tp::second_type;
return std::make_tuple(piecewise_construct,
std::uses_allocator_construction_args<_Tp1>(__a),
std::uses_allocator_construction_args<_Tp2>(__a));
}
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
noexcept
{
using _Tp1 = typename _Tp::first_type;
using _Tp2 = typename _Tp::second_type;
return std::make_tuple(piecewise_construct,
std::uses_allocator_construction_args<_Tp1>(__a,
std::forward<_Up>(__u)),
std::uses_allocator_construction_args<_Tp2>(__a,
std::forward<_Vp>(__v)));
}
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a,
const pair<_Up, _Vp>& __pr) noexcept
{
using _Tp1 = typename _Tp::first_type;
using _Tp2 = typename _Tp::second_type;
return std::make_tuple(piecewise_construct,
std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
}
template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
constexpr auto
uses_allocator_construction_args(const _Alloc& __a,
pair<_Up, _Vp>&& __pr) noexcept
{
using _Tp1 = typename _Tp::first_type;
using _Tp2 = typename _Tp::second_type;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3527. uses_allocator_construction_args handles rvalue pairs
// of rvalue references incorrectly
return std::make_tuple(piecewise_construct,
std::uses_allocator_construction_args<_Tp1>(__a,
std::get<0>(std::move(__pr))),
std::uses_allocator_construction_args<_Tp2>(__a,
std::get<1>(std::move(__pr))));
}
template<typename _Tp, typename _Alloc, typename... _Args>
constexpr _Tp
make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
{
return std::make_from_tuple<_Tp>(
std::uses_allocator_construction_args<_Tp>(__a,
std::forward<_Args>(__args)...));
}
template<typename _Tp, typename _Alloc, typename... _Args>
constexpr _Tp*
uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
_Args&&... __args)
{
return std::apply([&](auto&&... __xs) {
return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
}, std::uses_allocator_construction_args<_Tp>(__a,
std::forward<_Args>(__args)...));
}
/// @}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++20
#endif // _USES_ALLOCATOR_ARGS
new
stl_construct.h
stl_pair.h
std::piecewise_construct
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:83
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
std
ISO C++ entities toplevel namespace is std.
tuple