083fd73202
Calling the placement version of ::operator new "implicitly creates objects in the returned region of storage" as per [intro.object]. This allows the returned memory to be used as storage for implicit-lifetime types (including arrays) without additional action by the caller. This is required by the proposed resolution of LWG 3147. libstdc++-v3/ChangeLog: * include/std/memory_resource (memory_resource::allocate): Implicitly create objects in the returned storage.
841 lines
25 KiB
C++
841 lines
25 KiB
C++
// <memory_resource> -*- C++ -*-
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// Copyright (C) 2018-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file include/memory_resource
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* This is a Standard C++ Library header.
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*/
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#ifndef _GLIBCXX_MEMORY_RESOURCE
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#define _GLIBCXX_MEMORY_RESOURCE 1
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#pragma GCC system_header
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#if __cplusplus >= 201703L
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#include <new>
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#include <vector> // vector
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#include <cstddef> // size_t, max_align_t, byte
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#include <shared_mutex> // shared_mutex
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#include <bits/align.h> // align
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#include <bits/functexcept.h> // __throw_bad_array_new_length
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#include <bits/uses_allocator.h> // allocator_arg_t, __use_alloc
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#include <bits/uses_allocator_args.h> // uninitialized_construct_using_alloc
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#include <ext/numeric_traits.h>
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#include <debug/assertions.h>
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#if ! __cpp_lib_make_obj_using_allocator
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# include <bits/utility.h> // index_sequence
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# include <tuple> // tuple, forward_as_tuple
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#endif
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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namespace pmr
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{
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#ifdef _GLIBCXX_HAS_GTHREADS
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// Header and all contents are present.
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# define __cpp_lib_memory_resource 201603L
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#else
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// The pmr::synchronized_pool_resource type is missing.
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# define __cpp_lib_memory_resource 1
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#endif
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class memory_resource;
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#if __cplusplus == 201703L
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template<typename _Tp>
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class polymorphic_allocator;
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#else // C++20
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# define __cpp_lib_polymorphic_allocator 201902L
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template<typename _Tp = std::byte>
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class polymorphic_allocator;
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#endif
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// Global memory resources
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memory_resource* new_delete_resource() noexcept;
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memory_resource* null_memory_resource() noexcept;
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memory_resource* set_default_resource(memory_resource* __r) noexcept;
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memory_resource* get_default_resource() noexcept
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__attribute__((__returns_nonnull__));
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// Pool resource classes
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struct pool_options;
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#ifdef _GLIBCXX_HAS_GTHREADS
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class synchronized_pool_resource;
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#endif
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class unsynchronized_pool_resource;
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class monotonic_buffer_resource;
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/// Class memory_resource
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class memory_resource
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{
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static constexpr size_t _S_max_align = alignof(max_align_t);
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public:
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memory_resource() = default;
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memory_resource(const memory_resource&) = default;
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virtual ~memory_resource(); // key function
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memory_resource& operator=(const memory_resource&) = default;
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[[nodiscard]]
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void*
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allocate(size_t __bytes, size_t __alignment = _S_max_align)
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__attribute__((__returns_nonnull__,__alloc_size__(2),__alloc_align__(3)))
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{ return ::operator new(__bytes, do_allocate(__bytes, __alignment)); }
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void
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deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
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__attribute__((__nonnull__))
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{ return do_deallocate(__p, __bytes, __alignment); }
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bool
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is_equal(const memory_resource& __other) const noexcept
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{ return do_is_equal(__other); }
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private:
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virtual void*
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do_allocate(size_t __bytes, size_t __alignment) = 0;
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virtual void
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do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
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virtual bool
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do_is_equal(const memory_resource& __other) const noexcept = 0;
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};
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inline bool
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operator==(const memory_resource& __a, const memory_resource& __b) noexcept
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{ return &__a == &__b || __a.is_equal(__b); }
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#if __cpp_impl_three_way_comparison < 201907L
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inline bool
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operator!=(const memory_resource& __a, const memory_resource& __b) noexcept
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{ return !(__a == __b); }
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#endif
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// C++17 23.12.3 Class template polymorphic_allocator
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template<typename _Tp>
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class polymorphic_allocator
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2975. Missing case for pair construction in polymorphic allocators
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template<typename _Up>
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struct __not_pair { using type = void; };
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template<typename _Up1, typename _Up2>
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struct __not_pair<pair<_Up1, _Up2>> { };
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public:
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using value_type = _Tp;
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polymorphic_allocator() noexcept
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: _M_resource(get_default_resource())
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{ }
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polymorphic_allocator(memory_resource* __r) noexcept
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__attribute__((__nonnull__))
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: _M_resource(__r)
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{ _GLIBCXX_DEBUG_ASSERT(__r); }
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polymorphic_allocator(const polymorphic_allocator& __other) = default;
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template<typename _Up>
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polymorphic_allocator(const polymorphic_allocator<_Up>& __x) noexcept
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: _M_resource(__x.resource())
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{ }
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polymorphic_allocator&
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operator=(const polymorphic_allocator&) = delete;
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[[nodiscard]]
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_Tp*
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allocate(size_t __n)
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__attribute__((__returns_nonnull__))
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{
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if ((__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Tp)) < __n)
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std::__throw_bad_array_new_length();
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return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
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alignof(_Tp)));
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}
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void
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deallocate(_Tp* __p, size_t __n) noexcept
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__attribute__((__nonnull__))
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{ _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
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#if __cplusplus > 201703L
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[[nodiscard]] void*
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allocate_bytes(size_t __nbytes,
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size_t __alignment = alignof(max_align_t))
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{ return _M_resource->allocate(__nbytes, __alignment); }
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void
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deallocate_bytes(void* __p, size_t __nbytes,
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size_t __alignment = alignof(max_align_t))
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{ _M_resource->deallocate(__p, __nbytes, __alignment); }
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template<typename _Up>
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[[nodiscard]] _Up*
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allocate_object(size_t __n = 1)
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{
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if ((__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Up)) < __n)
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std::__throw_bad_array_new_length();
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return static_cast<_Up*>(allocate_bytes(__n * sizeof(_Up),
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alignof(_Up)));
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}
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template<typename _Up>
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void
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deallocate_object(_Up* __p, size_t __n = 1)
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{ deallocate_bytes(__p, __n * sizeof(_Up), alignof(_Up)); }
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template<typename _Up, typename... _CtorArgs>
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[[nodiscard]] _Up*
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new_object(_CtorArgs&&... __ctor_args)
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{
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_Up* __p = allocate_object<_Up>();
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__try
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{
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construct(__p, std::forward<_CtorArgs>(__ctor_args)...);
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}
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__catch (...)
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{
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deallocate_object(__p);
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__throw_exception_again;
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}
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return __p;
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}
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template<typename _Up>
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void
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delete_object(_Up* __p)
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{
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__p->~_Up();
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deallocate_object(__p);
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}
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#endif // C++2a
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#if ! __cpp_lib_make_obj_using_allocator
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template<typename _Tp1, typename... _Args>
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__attribute__((__nonnull__))
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typename __not_pair<_Tp1>::type
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construct(_Tp1* __p, _Args&&... __args)
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2969. polymorphic_allocator::construct() shouldn't pass resource()
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using __use_tag
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= std::__uses_alloc_t<_Tp1, polymorphic_allocator, _Args...>;
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if constexpr (is_base_of_v<__uses_alloc0, __use_tag>)
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::new(__p) _Tp1(std::forward<_Args>(__args)...);
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else if constexpr (is_base_of_v<__uses_alloc1_, __use_tag>)
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::new(__p) _Tp1(allocator_arg, *this,
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std::forward<_Args>(__args)...);
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else
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::new(__p) _Tp1(std::forward<_Args>(__args)..., *this);
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}
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template<typename _Tp1, typename _Tp2,
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typename... _Args1, typename... _Args2>
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__attribute__((__nonnull__))
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void
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construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
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tuple<_Args1...> __x, tuple<_Args2...> __y)
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{
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auto __x_tag =
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__use_alloc<_Tp1, polymorphic_allocator, _Args1...>(*this);
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auto __y_tag =
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__use_alloc<_Tp2, polymorphic_allocator, _Args2...>(*this);
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index_sequence_for<_Args1...> __x_i;
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index_sequence_for<_Args2...> __y_i;
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::new(__p) pair<_Tp1, _Tp2>(piecewise_construct,
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_S_construct_p(__x_tag, __x_i, __x),
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_S_construct_p(__y_tag, __y_i, __y));
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}
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template<typename _Tp1, typename _Tp2>
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__attribute__((__nonnull__))
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void
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construct(pair<_Tp1, _Tp2>* __p)
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{ this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
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template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
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__attribute__((__nonnull__))
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void
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construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y)
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{
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this->construct(__p, piecewise_construct,
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std::forward_as_tuple(std::forward<_Up>(__x)),
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std::forward_as_tuple(std::forward<_Vp>(__y)));
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}
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template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
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__attribute__((__nonnull__))
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void
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construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
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{
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this->construct(__p, piecewise_construct,
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std::forward_as_tuple(__pr.first),
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std::forward_as_tuple(__pr.second));
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}
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template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
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__attribute__((__nonnull__))
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void
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construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr)
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{
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this->construct(__p, piecewise_construct,
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std::forward_as_tuple(std::forward<_Up>(__pr.first)),
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std::forward_as_tuple(std::forward<_Vp>(__pr.second)));
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}
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#else // make_obj_using_allocator
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template<typename _Tp1, typename... _Args>
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__attribute__((__nonnull__))
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void
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construct(_Tp1* __p, _Args&&... __args)
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{
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std::uninitialized_construct_using_allocator(__p, *this,
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std::forward<_Args>(__args)...);
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}
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#endif
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template<typename _Up>
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_GLIBCXX20_DEPRECATED_SUGGEST("allocator_traits::destroy")
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__attribute__((__nonnull__))
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void
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destroy(_Up* __p)
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{ __p->~_Up(); }
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polymorphic_allocator
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select_on_container_copy_construction() const noexcept
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{ return polymorphic_allocator(); }
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memory_resource*
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resource() const noexcept
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__attribute__((__returns_nonnull__))
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{ return _M_resource; }
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private:
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#if ! __cpp_lib_make_obj_using_allocator
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using __uses_alloc1_ = __uses_alloc1<polymorphic_allocator>;
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using __uses_alloc2_ = __uses_alloc2<polymorphic_allocator>;
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template<typename _Ind, typename... _Args>
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static tuple<_Args&&...>
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_S_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
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{ return std::move(__t); }
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template<size_t... _Ind, typename... _Args>
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static tuple<allocator_arg_t, polymorphic_allocator, _Args&&...>
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_S_construct_p(__uses_alloc1_ __ua, index_sequence<_Ind...>,
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tuple<_Args...>& __t)
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{
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return {
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allocator_arg, *__ua._M_a, std::get<_Ind>(std::move(__t))...
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};
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}
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template<size_t... _Ind, typename... _Args>
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static tuple<_Args&&..., polymorphic_allocator>
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_S_construct_p(__uses_alloc2_ __ua, index_sequence<_Ind...>,
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tuple<_Args...>& __t)
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{ return { std::get<_Ind>(std::move(__t))..., *__ua._M_a }; }
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#endif
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memory_resource* _M_resource;
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};
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template<typename _Tp1, typename _Tp2>
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inline bool
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operator==(const polymorphic_allocator<_Tp1>& __a,
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const polymorphic_allocator<_Tp2>& __b) noexcept
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{ return *__a.resource() == *__b.resource(); }
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#if __cpp_impl_three_way_comparison < 201907L
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template<typename _Tp1, typename _Tp2>
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inline bool
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operator!=(const polymorphic_allocator<_Tp1>& __a,
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const polymorphic_allocator<_Tp2>& __b) noexcept
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{ return !(__a == __b); }
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#endif
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} // namespace pmr
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/// Partial specialization for std::pmr::polymorphic_allocator
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template<typename _Tp>
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struct allocator_traits<pmr::polymorphic_allocator<_Tp>>
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{
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/// The allocator type
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using allocator_type = pmr::polymorphic_allocator<_Tp>;
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/// The allocated type
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using value_type = _Tp;
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/// The allocator's pointer type.
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using pointer = _Tp*;
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/// The allocator's const pointer type.
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using const_pointer = const _Tp*;
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/// The allocator's void pointer type.
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using void_pointer = void*;
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/// The allocator's const void pointer type.
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using const_void_pointer = const void*;
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/// The allocator's difference type
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using difference_type = std::ptrdiff_t;
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/// The allocator's size type
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using size_type = std::size_t;
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/** @{
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* A `polymorphic_allocator` does not propagate when a
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* container is copied, moved, or swapped.
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*/
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using propagate_on_container_copy_assignment = false_type;
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using propagate_on_container_move_assignment = false_type;
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using propagate_on_container_swap = false_type;
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static allocator_type
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select_on_container_copy_construction(const allocator_type&) noexcept
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{ return allocator_type(); }
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/// @}
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/// Whether all instances of the allocator type compare equal.
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using is_always_equal = false_type;
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template<typename _Up>
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using rebind_alloc = pmr::polymorphic_allocator<_Up>;
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template<typename _Up>
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using rebind_traits = allocator_traits<pmr::polymorphic_allocator<_Up>>;
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/**
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* @brief Allocate memory.
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* @param __a An allocator.
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* @param __n The number of objects to allocate space for.
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*
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* Calls `a.allocate(n)`.
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*/
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[[nodiscard]] static pointer
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allocate(allocator_type& __a, size_type __n)
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{ return __a.allocate(__n); }
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/**
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* @brief Allocate memory.
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* @param __a An allocator.
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* @param __n The number of objects to allocate space for.
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* @return Memory of suitable size and alignment for `n` objects
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* of type `value_type`.
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*
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* The third parameter is ignored..
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*
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* Returns `a.allocate(n)`.
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*/
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[[nodiscard]] static pointer
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allocate(allocator_type& __a, size_type __n, const_void_pointer)
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{ return __a.allocate(__n); }
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/**
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* @brief Deallocate memory.
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* @param __a An allocator.
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* @param __p Pointer to the memory to deallocate.
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* @param __n The number of objects space was allocated for.
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*
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* Calls `a.deallocate(p, n)`.
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*/
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static void
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deallocate(allocator_type& __a, pointer __p, size_type __n)
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{ __a.deallocate(__p, __n); }
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/**
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* @brief Construct an object of type `_Up`
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* @param __a An allocator.
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* @param __p Pointer to memory of suitable size and alignment for
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* an object of type `_Up`.
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* @param __args Constructor arguments.
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*
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* Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
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* in C++11, C++14 and C++17. Changed in C++20 to call
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* `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
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*/
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template<typename _Up, typename... _Args>
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static void
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construct(allocator_type& __a, _Up* __p, _Args&&... __args)
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{ __a.construct(__p, std::forward<_Args>(__args)...); }
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/**
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* @brief Destroy an object of type `_Up`
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* @param __a An allocator.
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* @param __p Pointer to the object to destroy
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|
*
|
|
* Calls `p->_Up()`.
|
|
*/
|
|
template<typename _Up>
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
destroy(allocator_type&, _Up* __p)
|
|
noexcept(is_nothrow_destructible<_Up>::value)
|
|
{ __p->~_Up(); }
|
|
|
|
/**
|
|
* @brief The maximum supported allocation size
|
|
* @return `numeric_limits<size_t>::max() / sizeof(value_type)`
|
|
*/
|
|
static _GLIBCXX20_CONSTEXPR size_type
|
|
max_size(const allocator_type&) noexcept
|
|
{ return size_t(-1) / sizeof(value_type); }
|
|
};
|
|
|
|
namespace pmr
|
|
{
|
|
/// Parameters for tuning a pool resource's behaviour.
|
|
struct pool_options
|
|
{
|
|
/** @brief Upper limit on number of blocks in a chunk.
|
|
*
|
|
* A lower value prevents allocating huge chunks that could remain mostly
|
|
* unused, but means pools will need to replenished more frequently.
|
|
*/
|
|
size_t max_blocks_per_chunk = 0;
|
|
|
|
/* @brief Largest block size (in bytes) that should be served from pools.
|
|
*
|
|
* Larger allocations will be served directly by the upstream resource,
|
|
* not from one of the pools managed by the pool resource.
|
|
*/
|
|
size_t largest_required_pool_block = 0;
|
|
};
|
|
|
|
// Common implementation details for un-/synchronized pool resources.
|
|
class __pool_resource
|
|
{
|
|
friend class synchronized_pool_resource;
|
|
friend class unsynchronized_pool_resource;
|
|
|
|
__pool_resource(const pool_options& __opts, memory_resource* __upstream);
|
|
|
|
~__pool_resource();
|
|
|
|
__pool_resource(const __pool_resource&) = delete;
|
|
__pool_resource& operator=(const __pool_resource&) = delete;
|
|
|
|
// Allocate a large unpooled block.
|
|
void*
|
|
allocate(size_t __bytes, size_t __alignment);
|
|
|
|
// Deallocate a large unpooled block.
|
|
void
|
|
deallocate(void* __p, size_t __bytes, size_t __alignment);
|
|
|
|
|
|
// Deallocate unpooled memory.
|
|
void release() noexcept;
|
|
|
|
memory_resource* resource() const noexcept
|
|
{ return _M_unpooled.get_allocator().resource(); }
|
|
|
|
struct _Pool;
|
|
|
|
_Pool* _M_alloc_pools();
|
|
|
|
const pool_options _M_opts;
|
|
|
|
struct _BigBlock;
|
|
// Collection of blocks too big for any pool, sorted by address.
|
|
// This also stores the only copy of the upstream memory resource pointer.
|
|
_GLIBCXX_STD_C::pmr::vector<_BigBlock> _M_unpooled;
|
|
|
|
const int _M_npools;
|
|
};
|
|
|
|
#ifdef _GLIBCXX_HAS_GTHREADS
|
|
/// A thread-safe memory resource that manages pools of fixed-size blocks.
|
|
class synchronized_pool_resource : public memory_resource
|
|
{
|
|
public:
|
|
synchronized_pool_resource(const pool_options& __opts,
|
|
memory_resource* __upstream)
|
|
__attribute__((__nonnull__));
|
|
|
|
synchronized_pool_resource()
|
|
: synchronized_pool_resource(pool_options(), get_default_resource())
|
|
{ }
|
|
|
|
explicit
|
|
synchronized_pool_resource(memory_resource* __upstream)
|
|
__attribute__((__nonnull__))
|
|
: synchronized_pool_resource(pool_options(), __upstream)
|
|
{ }
|
|
|
|
explicit
|
|
synchronized_pool_resource(const pool_options& __opts)
|
|
: synchronized_pool_resource(__opts, get_default_resource()) { }
|
|
|
|
synchronized_pool_resource(const synchronized_pool_resource&) = delete;
|
|
|
|
virtual ~synchronized_pool_resource();
|
|
|
|
synchronized_pool_resource&
|
|
operator=(const synchronized_pool_resource&) = delete;
|
|
|
|
void release();
|
|
|
|
memory_resource*
|
|
upstream_resource() const noexcept
|
|
__attribute__((__returns_nonnull__))
|
|
{ return _M_impl.resource(); }
|
|
|
|
pool_options options() const noexcept { return _M_impl._M_opts; }
|
|
|
|
protected:
|
|
void*
|
|
do_allocate(size_t __bytes, size_t __alignment) override;
|
|
|
|
void
|
|
do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
|
|
|
|
bool
|
|
do_is_equal(const memory_resource& __other) const noexcept override
|
|
{ return this == &__other; }
|
|
|
|
public:
|
|
// Thread-specific pools (only public for access by implementation details)
|
|
struct _TPools;
|
|
|
|
private:
|
|
_TPools* _M_alloc_tpools(lock_guard<shared_mutex>&);
|
|
_TPools* _M_alloc_shared_tpools(lock_guard<shared_mutex>&);
|
|
auto _M_thread_specific_pools() noexcept;
|
|
|
|
__pool_resource _M_impl;
|
|
__gthread_key_t _M_key;
|
|
// Linked list of thread-specific pools. All threads share _M_tpools[0].
|
|
_TPools* _M_tpools = nullptr;
|
|
mutable shared_mutex _M_mx;
|
|
};
|
|
#endif
|
|
|
|
/// A non-thread-safe memory resource that manages pools of fixed-size blocks.
|
|
class unsynchronized_pool_resource : public memory_resource
|
|
{
|
|
public:
|
|
[[__gnu__::__nonnull__]]
|
|
unsynchronized_pool_resource(const pool_options& __opts,
|
|
memory_resource* __upstream);
|
|
|
|
unsynchronized_pool_resource()
|
|
: unsynchronized_pool_resource(pool_options(), get_default_resource())
|
|
{ }
|
|
|
|
[[__gnu__::__nonnull__]]
|
|
explicit
|
|
unsynchronized_pool_resource(memory_resource* __upstream)
|
|
: unsynchronized_pool_resource(pool_options(), __upstream)
|
|
{ }
|
|
|
|
explicit
|
|
unsynchronized_pool_resource(const pool_options& __opts)
|
|
: unsynchronized_pool_resource(__opts, get_default_resource()) { }
|
|
|
|
unsynchronized_pool_resource(const unsynchronized_pool_resource&) = delete;
|
|
|
|
virtual ~unsynchronized_pool_resource();
|
|
|
|
unsynchronized_pool_resource&
|
|
operator=(const unsynchronized_pool_resource&) = delete;
|
|
|
|
void release();
|
|
|
|
[[__gnu__::__returns_nonnull__]]
|
|
memory_resource*
|
|
upstream_resource() const noexcept
|
|
{ return _M_impl.resource(); }
|
|
|
|
pool_options options() const noexcept { return _M_impl._M_opts; }
|
|
|
|
protected:
|
|
void*
|
|
do_allocate(size_t __bytes, size_t __alignment) override;
|
|
|
|
void
|
|
do_deallocate(void* __p, size_t __bytes, size_t __alignment) override;
|
|
|
|
bool
|
|
do_is_equal(const memory_resource& __other) const noexcept override
|
|
{ return this == &__other; }
|
|
|
|
private:
|
|
using _Pool = __pool_resource::_Pool;
|
|
|
|
auto _M_find_pool(size_t) noexcept;
|
|
|
|
__pool_resource _M_impl;
|
|
_Pool* _M_pools = nullptr;
|
|
};
|
|
|
|
class monotonic_buffer_resource : public memory_resource
|
|
{
|
|
public:
|
|
explicit
|
|
monotonic_buffer_resource(memory_resource* __upstream) noexcept
|
|
__attribute__((__nonnull__))
|
|
: _M_upstream(__upstream)
|
|
{ _GLIBCXX_DEBUG_ASSERT(__upstream != nullptr); }
|
|
|
|
monotonic_buffer_resource(size_t __initial_size,
|
|
memory_resource* __upstream) noexcept
|
|
__attribute__((__nonnull__))
|
|
: _M_next_bufsiz(__initial_size),
|
|
_M_upstream(__upstream)
|
|
{
|
|
_GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
|
|
_GLIBCXX_DEBUG_ASSERT(__initial_size > 0);
|
|
}
|
|
|
|
monotonic_buffer_resource(void* __buffer, size_t __buffer_size,
|
|
memory_resource* __upstream) noexcept
|
|
__attribute__((__nonnull__(4)))
|
|
: _M_current_buf(__buffer), _M_avail(__buffer_size),
|
|
_M_next_bufsiz(_S_next_bufsize(__buffer_size)),
|
|
_M_upstream(__upstream),
|
|
_M_orig_buf(__buffer), _M_orig_size(__buffer_size)
|
|
{
|
|
_GLIBCXX_DEBUG_ASSERT(__upstream != nullptr);
|
|
_GLIBCXX_DEBUG_ASSERT(__buffer != nullptr || __buffer_size == 0);
|
|
}
|
|
|
|
monotonic_buffer_resource() noexcept
|
|
: monotonic_buffer_resource(get_default_resource())
|
|
{ }
|
|
|
|
explicit
|
|
monotonic_buffer_resource(size_t __initial_size) noexcept
|
|
: monotonic_buffer_resource(__initial_size, get_default_resource())
|
|
{ }
|
|
|
|
monotonic_buffer_resource(void* __buffer, size_t __buffer_size) noexcept
|
|
: monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource())
|
|
{ }
|
|
|
|
monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;
|
|
|
|
virtual ~monotonic_buffer_resource(); // key function
|
|
|
|
monotonic_buffer_resource&
|
|
operator=(const monotonic_buffer_resource&) = delete;
|
|
|
|
void
|
|
release() noexcept
|
|
{
|
|
if (_M_head)
|
|
_M_release_buffers();
|
|
|
|
// reset to initial state at contruction:
|
|
if ((_M_current_buf = _M_orig_buf))
|
|
{
|
|
_M_avail = _M_orig_size;
|
|
_M_next_bufsiz = _S_next_bufsize(_M_orig_size);
|
|
}
|
|
else
|
|
{
|
|
_M_avail = 0;
|
|
_M_next_bufsiz = _M_orig_size;
|
|
}
|
|
}
|
|
|
|
memory_resource*
|
|
upstream_resource() const noexcept
|
|
__attribute__((__returns_nonnull__))
|
|
{ return _M_upstream; }
|
|
|
|
protected:
|
|
void*
|
|
do_allocate(size_t __bytes, size_t __alignment) override
|
|
{
|
|
if (__builtin_expect(__bytes == 0, false))
|
|
__bytes = 1; // Ensures we don't return the same pointer twice.
|
|
|
|
void* __p = std::align(__alignment, __bytes, _M_current_buf, _M_avail);
|
|
if (__builtin_expect(__p == nullptr, false))
|
|
{
|
|
_M_new_buffer(__bytes, __alignment);
|
|
__p = _M_current_buf;
|
|
}
|
|
_M_current_buf = (char*)_M_current_buf + __bytes;
|
|
_M_avail -= __bytes;
|
|
return __p;
|
|
}
|
|
|
|
void
|
|
do_deallocate(void*, size_t, size_t) override
|
|
{ }
|
|
|
|
bool
|
|
do_is_equal(const memory_resource& __other) const noexcept override
|
|
{ return this == &__other; }
|
|
|
|
private:
|
|
// Update _M_current_buf and _M_avail to refer to a new buffer with
|
|
// at least the specified size and alignment, allocated from upstream.
|
|
void
|
|
_M_new_buffer(size_t __bytes, size_t __alignment);
|
|
|
|
// Deallocate all buffers obtained from upstream.
|
|
void
|
|
_M_release_buffers() noexcept;
|
|
|
|
static size_t
|
|
_S_next_bufsize(size_t __buffer_size) noexcept
|
|
{
|
|
if (__builtin_expect(__buffer_size == 0, false))
|
|
__buffer_size = 1;
|
|
return __buffer_size * _S_growth_factor;
|
|
}
|
|
|
|
static constexpr size_t _S_init_bufsize = 128 * sizeof(void*);
|
|
static constexpr float _S_growth_factor = 1.5;
|
|
|
|
void* _M_current_buf = nullptr;
|
|
size_t _M_avail = 0;
|
|
size_t _M_next_bufsiz = _S_init_bufsize;
|
|
|
|
// Initial values set at construction and reused by release():
|
|
memory_resource* const _M_upstream;
|
|
void* const _M_orig_buf = nullptr;
|
|
size_t const _M_orig_size = _M_next_bufsiz;
|
|
|
|
class _Chunk;
|
|
_Chunk* _M_head = nullptr;
|
|
};
|
|
|
|
} // namespace pmr
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace std
|
|
|
|
#endif // C++17
|
|
#endif // _GLIBCXX_MEMORY_RESOURCE
|