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Implement proposals adopted for C++23: P0401R6, "Providing size feedback in the Allocator interface" P2652R2, "Disallow User Specialization of allocator_traits". This is the minimal conforming implementation, i.e. without the useful parts. Useful parts, to come in future patches, would include giving access to any extra storage reserved, and use of it in vector, string, and other contiguous containers. libstdc++-v3/ChangeLog: PR libstdc++/118030 * include/bits/alloc_traits.h (allocate_at_least (2x)): Define. * include/bits/allocator.h (allocate_at_least): Define. * include/std/memory (__glibcxx_want_allocate_at_least): Define. * include/bits/memoryfwd.h (allocation_result): Define, #include <bits/version.h> first so that will work. * include/bits/version.def (allocate_at_least): Add. * include/bits/version.h: Regenerate. * testsuite/20_util/allocator/allocate_at_least.cc: New test. * testsuite/20_util/allocator/allocate_at_least_neg.cc: New test.
1094 lines
35 KiB
C++
1094 lines
35 KiB
C++
// Allocator traits -*- C++ -*-
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// Copyright (C) 2011-2026 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 bits/alloc_traits.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{memory}
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*/
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#ifndef _ALLOC_TRAITS_H
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#define _ALLOC_TRAITS_H 1
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#include <bits/stl_construct.h>
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#include <bits/memoryfwd.h>
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#if __cplusplus >= 201103L
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# include <bits/ptr_traits.h>
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# include <ext/numeric_traits.h>
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# if _GLIBCXX_HOSTED
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# include <bits/allocator.h>
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# endif
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# if __cpp_exceptions
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# include <bits/stl_iterator.h> // __make_move_if_noexcept_iterator
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# endif
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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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#if __cplusplus >= 201103L
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wc++14-extensions" // for variable templates
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#pragma GCC diagnostic ignored "-Wc++17-extensions" // for if-constexpr
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/// @cond undocumented
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struct __allocator_traits_base
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{
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#if __cpp_concepts
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template<typename _Tp, typename _Up>
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#else
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template<typename _Tp, typename _Up, typename = void>
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#endif
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struct __rebind : __replace_first_arg<_Tp, _Up>
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{
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static_assert(is_same<
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typename __replace_first_arg<_Tp, typename _Tp::value_type>::type,
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_Tp>::value,
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"allocator_traits<A>::rebind_alloc<A::value_type> must be A");
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};
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template<typename _Tp, typename _Up>
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#if __cpp_concepts
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requires requires { typename _Tp::template rebind<_Up>::other; }
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struct __rebind<_Tp, _Up>
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#else
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struct __rebind<_Tp, _Up,
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__void_t<typename _Tp::template rebind<_Up>::other>>
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#endif
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{
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using type = typename _Tp::template rebind<_Up>::other;
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static_assert(is_same<
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typename _Tp::template rebind<typename _Tp::value_type>::other,
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_Tp>::value,
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"allocator_traits<A>::rebind_alloc<A::value_type> must be A");
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};
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protected:
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template<typename _Tp>
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using __pointer = typename _Tp::pointer;
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template<typename _Tp>
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using __c_pointer = typename _Tp::const_pointer;
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template<typename _Tp>
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using __v_pointer = typename _Tp::void_pointer;
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template<typename _Tp>
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using __cv_pointer = typename _Tp::const_void_pointer;
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template<typename _Tp>
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using __pocca = typename _Tp::propagate_on_container_copy_assignment;
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template<typename _Tp>
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using __pocma = typename _Tp::propagate_on_container_move_assignment;
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template<typename _Tp>
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using __pocs = typename _Tp::propagate_on_container_swap;
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template<typename _Tp>
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using __equal = __type_identity<typename _Tp::is_always_equal>;
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// __has_allocate_hint is true if a.allocate(n, hint) is well-formed.
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#if __cpp_concepts
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template<typename _Alloc, typename _Sz, typename _Vp>
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static constexpr bool __has_allocate_hint
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= requires (_Alloc& __a, _Sz __n, _Vp __hint) {
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__a.allocate(__n, __hint);
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};
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#else
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template<typename _Alloc, typename _Sz, typename _Vp>
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using __allocate_hint_t
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= decltype(std::declval<_Alloc&>()
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.allocate(std::declval<_Sz>(), std::declval<_Vp>()));
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template<typename _Alloc, typename _Sz, typename _Vp, typename = void>
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static constexpr bool __has_allocate_hint = false;
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template<typename _Alloc, typename _Sz, typename _Vp>
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static constexpr bool
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__has_allocate_hint<_Alloc, _Sz, _Vp,
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__void_t<__allocate_hint_t<_Alloc, _Sz, _Vp>>>
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= true;
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#endif
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// __has_construct is true if a.construct(p, args...) is well-formed.
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// __can_construct is true if either __has_construct is true, or if
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// a placement new-expression for T(args...) is well-formed. We use this
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// to constrain allocator_traits::construct, as a libstdc++ extension.
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#if __cpp_concepts
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template<typename _Alloc, typename _Tp, typename... _Args>
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static constexpr bool __has_construct
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= requires (_Alloc& __a, _Tp* __p, _Args&&... __args) {
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__a.construct(__p, std::forward<_Args>(__args)...);
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};
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template<typename _Tp, typename... _Args>
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static constexpr bool __can_construct_at
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= requires (_Tp* __p, _Args&&... __args) {
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#if __cpp_constexpr_dynamic_alloc
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std::construct_at(__p, std::forward<_Args>(__args)...);
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#else
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::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
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#endif
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};
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template<typename _Alloc, typename _Tp, typename... _Args>
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static constexpr bool __can_construct
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= __has_construct<_Alloc, _Tp, _Args...>
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|| __can_construct_at<_Tp, _Args...>;
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#else
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template<typename _Alloc, typename _Tp, typename... _Args>
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using __construct_t
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= decltype(std::declval<_Alloc&>().construct(std::declval<_Tp*>(),
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std::declval<_Args>()...));
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template<typename _Alloc, typename _Tp, typename, typename... _Args>
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static constexpr bool __has_construct_impl = false;
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template<typename _Alloc, typename _Tp, typename... _Args>
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static constexpr bool
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__has_construct_impl<_Alloc, _Tp,
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__void_t<__construct_t<_Alloc, _Tp, _Args...>>,
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_Args...>
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= true;
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template<typename _Alloc, typename _Tp, typename... _Args>
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static constexpr bool __has_construct
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= __has_construct_impl<_Alloc, _Tp, void, _Args...>;
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template<typename _Tp, typename... _Args>
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using __new_expr_t
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= decltype(::new((void*)0) _Tp(std::declval<_Args>()...));
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template<typename _Tp, typename, typename... _Args>
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static constexpr bool __has_new_expr = false;
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template<typename _Tp, typename... _Args>
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static constexpr bool
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__has_new_expr<_Tp, __void_t<__new_expr_t<_Tp, _Args...>>, _Args...>
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= true;
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template<typename _Alloc, typename _Tp, typename... _Args>
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static constexpr bool __can_construct
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= __has_construct<_Alloc, _Tp, _Args...>
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|| __has_new_expr<_Tp, void, _Args...>;
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#endif
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// __has_destroy is true if a.destroy(p) is well-formed.
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#if __cpp_concepts
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template<typename _Alloc, typename _Tp>
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static constexpr bool __has_destroy = requires (_Alloc& __a, _Tp* __p) {
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__a.destroy(__p);
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};
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#else
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template<typename _Alloc, typename _Tp>
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using __destroy_t
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= decltype(std::declval<_Alloc&>().destroy(std::declval<_Tp*>()));
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template<typename _Alloc, typename _Tp, typename = void>
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static constexpr bool __has_destroy = false;
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template<typename _Alloc, typename _Tp>
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static constexpr bool __has_destroy<_Alloc, _Tp,
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__void_t<__destroy_t<_Alloc, _Tp>>>
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= true;
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#endif
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// __has_max_size is true if a.max_size() is well-formed.
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#if __cpp_concepts
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template<typename _Alloc>
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static constexpr bool __has_max_size = requires (const _Alloc& __a) {
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__a.max_size();
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};
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#else
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template<typename _Alloc>
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using __max_size_t = decltype(std::declval<const _Alloc&>().max_size());
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template<typename _Alloc, typename = void>
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static constexpr bool __has_max_size = false;
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template<typename _Alloc>
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static constexpr bool __has_max_size<_Alloc,
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__void_t<__max_size_t<_Alloc>>>
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= true;
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#endif
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// __has_soccc is true if a.select_on_container_copy_construction()
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// is well-formed.
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#if __cpp_concepts
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template<typename _Alloc>
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static constexpr bool __has_soccc = requires (const _Alloc& __a) {
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__a.select_on_container_copy_construction();
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};
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#else
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template<typename _Alloc>
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using __soccc_t
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= decltype(std::declval<const _Alloc&>()
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.select_on_container_copy_construction());
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template<typename _Alloc, typename = void>
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static constexpr bool __has_soccc = false;
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template<typename _Alloc>
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static constexpr bool __has_soccc<_Alloc, __void_t<__soccc_t<_Alloc>>>
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= true;
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#endif
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};
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template<typename _Alloc, typename _Up>
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using __alloc_rebind
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= typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type;
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/// @endcond
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/**
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* @brief Uniform interface to all allocator types.
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* @headerfile memory
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* @ingroup allocators
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* @since C++11
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*/
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template<typename _Alloc>
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struct allocator_traits : __allocator_traits_base
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{
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/// The allocator type
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typedef _Alloc allocator_type;
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/// The allocated type
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typedef typename _Alloc::value_type value_type;
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/**
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* @brief The allocator's pointer type.
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*
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* @c Alloc::pointer if that type exists, otherwise @c value_type*
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*/
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using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;
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private:
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// Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp>
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template<template<typename> class _Func, typename _Tp, typename = void>
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struct _Ptr
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{
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using type = typename pointer_traits<pointer>::template rebind<_Tp>;
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};
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template<template<typename> class _Func, typename _Tp>
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struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>>
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{
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using type = _Func<_Alloc>;
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};
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// Select _A2::difference_type or pointer_traits<_Ptr>::difference_type
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template<typename _A2, typename _PtrT, typename = void>
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struct _Diff
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{ using type = typename pointer_traits<_PtrT>::difference_type; };
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template<typename _A2, typename _PtrT>
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struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>>
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{ using type = typename _A2::difference_type; };
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// Select _A2::size_type or make_unsigned<_DiffT>::type
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template<typename _A2, typename _DiffT, typename = void>
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struct _Size : make_unsigned<_DiffT> { };
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template<typename _A2, typename _DiffT>
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struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>>
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{ using type = typename _A2::size_type; };
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public:
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/**
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* @brief The allocator's const pointer type.
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*
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* @c Alloc::const_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
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*/
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using const_pointer = typename _Ptr<__c_pointer, const value_type>::type;
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/**
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* @brief The allocator's void pointer type.
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*
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* @c Alloc::void_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<void> </tt>
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*/
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using void_pointer = typename _Ptr<__v_pointer, void>::type;
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/**
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* @brief The allocator's const void pointer type.
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*
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* @c Alloc::const_void_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<const void> </tt>
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*/
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using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type;
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/**
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* @brief The allocator's difference type
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*
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* @c Alloc::difference_type if that type exists, otherwise
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* <tt> pointer_traits<pointer>::difference_type </tt>
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*/
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using difference_type = typename _Diff<_Alloc, pointer>::type;
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/**
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* @brief The allocator's size type
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*
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* @c Alloc::size_type if that type exists, otherwise
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* <tt> make_unsigned<difference_type>::type </tt>
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*/
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using size_type = typename _Size<_Alloc, difference_type>::type;
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/**
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* @brief How the allocator is propagated on copy assignment
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*
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* @c Alloc::propagate_on_container_copy_assignment if that type exists,
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* otherwise @c false_type
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*/
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using propagate_on_container_copy_assignment
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= __detected_or_t<false_type, __pocca, _Alloc>;
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/**
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* @brief How the allocator is propagated on move assignment
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*
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* @c Alloc::propagate_on_container_move_assignment if that type exists,
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* otherwise @c false_type
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*/
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using propagate_on_container_move_assignment
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= __detected_or_t<false_type, __pocma, _Alloc>;
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/**
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* @brief How the allocator is propagated on swap
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*
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* @c Alloc::propagate_on_container_swap if that type exists,
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* otherwise @c false_type
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*/
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using propagate_on_container_swap
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= __detected_or_t<false_type, __pocs, _Alloc>;
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/**
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* @brief Whether all instances of the allocator type compare equal.
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*
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* @c Alloc::is_always_equal if that type exists,
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* otherwise @c is_empty<Alloc>::type
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*/
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using is_always_equal
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= typename __detected_or_t<is_empty<_Alloc>, __equal, _Alloc>::type;
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template<typename _Tp>
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using rebind_alloc = __alloc_rebind<_Alloc, _Tp>;
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template<typename _Tp>
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using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
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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 @c a.allocate(n)
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*/
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_GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer
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allocate(_Alloc& __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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* @param __hint Aid to locality.
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* @return Memory of suitable size and alignment for @a n objects
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* of type @c value_type
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*
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* Returns <tt> a.allocate(n, hint) </tt> if that expression is
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* well-formed, otherwise returns @c a.allocate(n)
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*/
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_GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer
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allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
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{
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if constexpr (__has_allocate_hint<_Alloc, size_type, const_void_pointer>)
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return __a.allocate(__n, __hint);
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else
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return __a.allocate(__n);
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}
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#ifdef __glibcxx_allocate_at_least // C++23
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/**
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* @brief Allocate memory, generously.
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* @param __a An allocator.
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* @param __n The minimum number of objects to allocate space for.
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* @return Memory of suitable size and alignment for `n` or more
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* contiguous objects of type `value_type`.
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*
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* Returns `a.allocate_at_least(n)` if that expression is
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* well-formed, else `{ a.allocate(n), n }`. When an allocator
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* is obliged to reserve more space than required for the cited
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* `n` objects, it may deliver the extra space to the caller.
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*/
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[[nodiscard]] static constexpr auto
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allocate_at_least(_Alloc& __a, size_type __n)
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-> allocation_result<pointer, size_type>
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{
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if constexpr (requires { __a.allocate_at_least(__n); })
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return __a.allocate_at_least(__n);
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else
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return { __a.allocate(__n), __n };
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}
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#endif
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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 <tt> a.deallocate(p, n) </tt>
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*/
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static _GLIBCXX20_CONSTEXPR void
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deallocate(_Alloc& __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 `_Tp`
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* @param __a An allocator.
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* @param __p Pointer to memory of suitable size and alignment for Tp
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* @param __args Constructor arguments.
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*
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* Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
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* if that expression is well-formed, otherwise uses placement-new
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* to construct an object of type @a _Tp at location @a __p from the
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* arguments @a __args...
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*/
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template<typename _Tp, typename... _Args>
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#if __cpp_concepts && __cpp_constexpr_dynamic_alloc
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requires __can_construct<_Alloc, _Tp, _Args...>
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static constexpr void
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#else
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|
static __enable_if_t<__can_construct<_Alloc, _Tp, _Args...>>
|
|
#endif
|
|
construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
|
|
noexcept(_S_nothrow_construct<_Tp, _Args...>())
|
|
{
|
|
if constexpr (__has_construct<_Alloc, _Tp, _Args...>)
|
|
__a.construct(__p, std::forward<_Args>(__args)...);
|
|
else
|
|
std::_Construct(__p, std::forward<_Args>(__args)...);
|
|
}
|
|
|
|
/**
|
|
* @brief Destroy an object of type @a _Tp
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to the object to destroy
|
|
*
|
|
* Calls @c __a.destroy(__p) if that expression is well-formed,
|
|
* otherwise calls @c __p->~_Tp()
|
|
*/
|
|
template<typename _Tp>
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
destroy(_Alloc& __a, _Tp* __p)
|
|
noexcept(_S_nothrow_destroy<_Tp>())
|
|
{
|
|
if constexpr (__has_destroy<_Alloc, _Tp>)
|
|
__a.destroy(__p);
|
|
else
|
|
std::_Destroy(__p);
|
|
}
|
|
|
|
/**
|
|
* @brief The maximum supported allocation size
|
|
* @param __a An allocator.
|
|
* @return @c __a.max_size() or @c numeric_limits<size_type>::max()
|
|
*
|
|
* Returns @c __a.max_size() if that expression is well-formed,
|
|
* otherwise returns @c numeric_limits<size_type>::max()
|
|
*/
|
|
static _GLIBCXX20_CONSTEXPR size_type
|
|
max_size(const _Alloc& __a) noexcept
|
|
{
|
|
if constexpr (__has_max_size<_Alloc>)
|
|
return __a.max_size();
|
|
else
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2466. allocator_traits::max_size() default behavior is incorrect
|
|
return __gnu_cxx::__numeric_traits<size_type>::__max
|
|
/ sizeof(value_type);
|
|
}
|
|
|
|
/**
|
|
* @brief Obtain an allocator to use when copying a container.
|
|
* @param __rhs An allocator.
|
|
* @return @c __rhs.select_on_container_copy_construction() or @a __rhs
|
|
*
|
|
* Returns @c __rhs.select_on_container_copy_construction() if that
|
|
* expression is well-formed, otherwise returns @a __rhs
|
|
*/
|
|
static _GLIBCXX20_CONSTEXPR _Alloc
|
|
select_on_container_copy_construction(const _Alloc& __rhs)
|
|
{
|
|
if constexpr (__has_soccc<_Alloc>)
|
|
return __rhs.select_on_container_copy_construction();
|
|
else
|
|
return __rhs;
|
|
}
|
|
|
|
private:
|
|
#if __cpp_constexpr >= 201304 // >= C++14
|
|
template<typename _Tp, typename... _Args>
|
|
static constexpr bool
|
|
_S_nothrow_construct(_Alloc* __a = nullptr, _Tp* __p = nullptr)
|
|
{
|
|
if constexpr (__has_construct<_Alloc, _Tp, _Args...>)
|
|
return noexcept(__a->construct(__p, std::declval<_Args>()...));
|
|
else
|
|
return __is_nothrow_new_constructible<_Tp, _Args...>;
|
|
}
|
|
|
|
template<typename _Tp>
|
|
static constexpr bool
|
|
_S_nothrow_destroy(_Alloc* __a = nullptr, _Tp* __p = nullptr)
|
|
{
|
|
if constexpr (__has_destroy<_Alloc, _Tp>)
|
|
return noexcept(__a->destroy(__p));
|
|
else
|
|
return is_nothrow_destructible<_Tp>::value;
|
|
}
|
|
#else
|
|
template<typename _Tp, typename... _Args>
|
|
static constexpr
|
|
__enable_if_t<__has_construct<_Alloc, _Tp, _Args...>, bool>
|
|
_S_nothrow_construct(_Alloc* __a = nullptr, _Tp* __p = nullptr)
|
|
{ return noexcept(__a->construct(__p, std::declval<_Args>()...)); }
|
|
|
|
template<typename _Tp, typename... _Args>
|
|
static constexpr
|
|
__enable_if_t<!__has_construct<_Alloc, _Tp, _Args...>, bool>
|
|
_S_nothrow_construct(_Alloc* = nullptr, _Tp* __p = nullptr)
|
|
{ return __is_nothrow_new_constructible<_Tp, _Args...>; }
|
|
|
|
template<typename _Tp>
|
|
static constexpr
|
|
__enable_if_t<__has_destroy<_Alloc, _Tp>, bool>
|
|
_S_nothrow_destroy(_Alloc* __a = nullptr, _Tp* __p = nullptr)
|
|
{ return noexcept(__a->destroy(__p)); }
|
|
|
|
template<typename _Tp>
|
|
static constexpr
|
|
__enable_if_t<!__has_destroy<_Alloc, _Tp>, bool>
|
|
_S_nothrow_destroy(_Alloc* = nullptr, _Tp* __p = nullptr)
|
|
{ return is_nothrow_destructible<_Tp>::value; }
|
|
#endif
|
|
};
|
|
#pragma GCC diagnostic pop
|
|
|
|
#if _GLIBCXX_HOSTED
|
|
/**
|
|
* @brief Partial specialization for `std::allocator`
|
|
* @headerfile memory
|
|
* @ingroup allocators
|
|
* @since C++11
|
|
* @see std::allocator_traits
|
|
*/
|
|
template<typename _Tp>
|
|
struct allocator_traits<allocator<_Tp>>
|
|
{
|
|
/// The allocator type
|
|
using allocator_type = allocator<_Tp>;
|
|
|
|
/// The allocated type
|
|
using value_type = _Tp;
|
|
|
|
/// The allocator's pointer type.
|
|
using pointer = _Tp*;
|
|
|
|
/// The allocator's const pointer type.
|
|
using const_pointer = const _Tp*;
|
|
|
|
/// The allocator's void pointer type.
|
|
using void_pointer = void*;
|
|
|
|
/// The allocator's const void pointer type.
|
|
using const_void_pointer = const void*;
|
|
|
|
/// The allocator's difference type
|
|
using difference_type = std::ptrdiff_t;
|
|
|
|
/// The allocator's size type
|
|
using size_type = std::size_t;
|
|
|
|
/// How the allocator is propagated on copy assignment
|
|
using propagate_on_container_copy_assignment = false_type;
|
|
|
|
/// How the allocator is propagated on move assignment
|
|
using propagate_on_container_move_assignment = true_type;
|
|
|
|
/// How the allocator is propagated on swap
|
|
using propagate_on_container_swap = false_type;
|
|
|
|
/// Whether all instances of the allocator type compare equal.
|
|
using is_always_equal = true_type;
|
|
|
|
template<typename _Up>
|
|
using rebind_alloc = allocator<_Up>;
|
|
|
|
template<typename _Up>
|
|
using rebind_traits = allocator_traits<allocator<_Up>>;
|
|
|
|
/**
|
|
* @brief Allocate memory.
|
|
* @param __a An allocator.
|
|
* @param __n The number of objects to allocate space for.
|
|
*
|
|
* Calls @c a.allocate(n)
|
|
*/
|
|
[[__nodiscard__,__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR pointer
|
|
allocate(allocator_type& __a, size_type __n)
|
|
{ return __a.allocate(__n); }
|
|
|
|
/**
|
|
* @brief Allocate memory.
|
|
* @param __a An allocator.
|
|
* @param __n The number of objects to allocate space for.
|
|
* @param __hint Aid to locality.
|
|
* @return Memory of suitable size and alignment for @a n objects
|
|
* of type @c value_type
|
|
*
|
|
* Returns <tt> a.allocate(n, hint) </tt>
|
|
*/
|
|
[[__nodiscard__,__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR pointer
|
|
allocate(allocator_type& __a, size_type __n,
|
|
[[maybe_unused]] const_void_pointer __hint)
|
|
{
|
|
#if __cplusplus <= 201703L
|
|
return __a.allocate(__n, __hint);
|
|
#else
|
|
return __a.allocate(__n);
|
|
#endif
|
|
}
|
|
|
|
#ifdef __glibcxx_allocate_at_least // C++23
|
|
/**
|
|
* @brief Allocate memory, generously.
|
|
* @param __a An allocator.
|
|
* @param __n The minimum number of objects to allocate space for.
|
|
* @return Memory of suitable size and alignment for `n` or more
|
|
* contiguous objects of type `value_type`.
|
|
*
|
|
* Returns `a.allocate_at_least(n)`.
|
|
*/
|
|
[[nodiscard]] static constexpr auto
|
|
allocate_at_least(allocator_type __a, size_type __n)
|
|
-> allocation_result<pointer, size_type>
|
|
{ return __a.allocate_at_least(__n); }
|
|
#endif
|
|
|
|
/**
|
|
* @brief Deallocate memory.
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to the memory to deallocate.
|
|
* @param __n The number of objects space was allocated for.
|
|
*
|
|
* Calls <tt> a.deallocate(p, n) </tt>
|
|
*/
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
deallocate(allocator_type& __a, pointer __p, size_type __n)
|
|
{ __a.deallocate(__p, __n); }
|
|
|
|
/**
|
|
* @brief Construct an object of type `_Up`
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to memory of suitable size and alignment for
|
|
* an object of type `_Up`.
|
|
* @param __args Constructor arguments.
|
|
*
|
|
* Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
|
|
* in C++11, C++14 and C++17. Changed in C++20 to call
|
|
* `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
|
|
*/
|
|
template<typename _Up, typename... _Args>
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
construct(allocator_type& __a __attribute__((__unused__)),
|
|
_Up* __p, _Args&&... __args)
|
|
#if __cplusplus <= 201703L
|
|
noexcept(noexcept(__a.construct(__p, std::forward<_Args>(__args)...)))
|
|
#else
|
|
noexcept(__is_nothrow_new_constructible<_Up, _Args...>)
|
|
#endif
|
|
{
|
|
#if __cplusplus <= 201703L
|
|
__a.construct(__p, std::forward<_Args>(__args)...);
|
|
#elif __cpp_constexpr_dynamic_alloc // >= C++20
|
|
std::construct_at(__p, std::forward<_Args>(__args)...);
|
|
#else
|
|
std::_Construct(__p, std::forward<_Args>(__args)...);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* @brief Destroy an object of type @a _Up
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to the object to destroy
|
|
*
|
|
* Calls @c __a.destroy(__p).
|
|
*/
|
|
template<typename _Up>
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
destroy(allocator_type& __a __attribute__((__unused__)), _Up* __p)
|
|
noexcept(is_nothrow_destructible<_Up>::value)
|
|
{
|
|
#if __cplusplus <= 201703L
|
|
__a.destroy(__p);
|
|
#else
|
|
std::destroy_at(__p);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* @brief The maximum supported allocation size
|
|
* @param __a An allocator.
|
|
* @return @c __a.max_size()
|
|
*/
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR size_type
|
|
max_size(const allocator_type& __a __attribute__((__unused__))) noexcept
|
|
{
|
|
#if __cplusplus <= 201703L
|
|
return __a.max_size();
|
|
#else
|
|
return size_t(-1) / sizeof(value_type);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* @brief Obtain an allocator to use when copying a container.
|
|
* @param __rhs An allocator.
|
|
* @return @c __rhs
|
|
*/
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR allocator_type
|
|
select_on_container_copy_construction(const allocator_type& __rhs)
|
|
{ return __rhs; }
|
|
};
|
|
|
|
/**
|
|
* @brief Explicit specialization for `std::allocator<void>`
|
|
* @headerfile memory
|
|
* @ingroup allocators
|
|
* @since C++11
|
|
* @see std::allocator_traits
|
|
*/
|
|
template<>
|
|
struct allocator_traits<allocator<void>>
|
|
{
|
|
/// The allocator type
|
|
using allocator_type = allocator<void>;
|
|
|
|
/// The allocated type
|
|
using value_type = void;
|
|
|
|
/// The allocator's pointer type.
|
|
using pointer = void*;
|
|
|
|
/// The allocator's const pointer type.
|
|
using const_pointer = const void*;
|
|
|
|
/// The allocator's void pointer type.
|
|
using void_pointer = void*;
|
|
|
|
/// The allocator's const void pointer type.
|
|
using const_void_pointer = const void*;
|
|
|
|
/// The allocator's difference type
|
|
using difference_type = std::ptrdiff_t;
|
|
|
|
/// The allocator's size type
|
|
using size_type = std::size_t;
|
|
|
|
/// How the allocator is propagated on copy assignment
|
|
using propagate_on_container_copy_assignment = false_type;
|
|
|
|
/// How the allocator is propagated on move assignment
|
|
using propagate_on_container_move_assignment = true_type;
|
|
|
|
/// How the allocator is propagated on swap
|
|
using propagate_on_container_swap = false_type;
|
|
|
|
/// Whether all instances of the allocator type compare equal.
|
|
using is_always_equal = true_type;
|
|
|
|
template<typename _Up>
|
|
using rebind_alloc = allocator<_Up>;
|
|
|
|
template<typename _Up>
|
|
using rebind_traits = allocator_traits<allocator<_Up>>;
|
|
|
|
/// allocate is ill-formed for allocator<void>
|
|
static void*
|
|
allocate(allocator_type&, size_type, const void* = nullptr) = delete;
|
|
|
|
/// deallocate is ill-formed for allocator<void>
|
|
static void
|
|
deallocate(allocator_type&, void*, size_type) = delete;
|
|
|
|
/**
|
|
* @brief Construct an object of type `_Up`
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to memory of suitable size and alignment for
|
|
* an object of type `_Up`.
|
|
* @param __args Constructor arguments.
|
|
*
|
|
* Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
|
|
* in C++11, C++14 and C++17. Changed in C++20 to call
|
|
* `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
|
|
*/
|
|
template<typename _Up, typename... _Args>
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
construct(allocator_type&, _Up* __p, _Args&&... __args)
|
|
noexcept(__is_nothrow_new_constructible<_Up, _Args...>)
|
|
{ std::_Construct(__p, std::forward<_Args>(__args)...); }
|
|
|
|
/**
|
|
* @brief Destroy an object of type `_Up`
|
|
* @param __a An allocator.
|
|
* @param __p Pointer to the object to destroy
|
|
*
|
|
* Invokes the destructor for `*__p`.
|
|
*/
|
|
template<typename _Up>
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR void
|
|
destroy(allocator_type&, _Up* __p)
|
|
noexcept(is_nothrow_destructible<_Up>::value)
|
|
{ std::_Destroy(__p); }
|
|
|
|
/// max_size is ill-formed for allocator<void>
|
|
static size_type
|
|
max_size(const allocator_type&) = delete;
|
|
|
|
/**
|
|
* @brief Obtain an allocator to use when copying a container.
|
|
* @param __rhs An allocator.
|
|
* @return `__rhs`
|
|
*/
|
|
[[__gnu__::__always_inline__]]
|
|
static _GLIBCXX20_CONSTEXPR allocator_type
|
|
select_on_container_copy_construction(const allocator_type& __rhs)
|
|
{ return __rhs; }
|
|
};
|
|
#endif
|
|
|
|
/// @cond undocumented
|
|
#pragma GCC diagnostic push
|
|
#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
|
|
template<typename _Alloc>
|
|
[[__gnu__::__always_inline__]]
|
|
_GLIBCXX14_CONSTEXPR inline void
|
|
__alloc_on_copy(_Alloc& __one, const _Alloc& __two)
|
|
{
|
|
using __traits = allocator_traits<_Alloc>;
|
|
using __pocca =
|
|
typename __traits::propagate_on_container_copy_assignment::type;
|
|
if constexpr (__pocca::value)
|
|
__one = __two;
|
|
}
|
|
|
|
template<typename _Alloc>
|
|
[[__gnu__::__always_inline__]]
|
|
constexpr _Alloc
|
|
__alloc_on_copy(const _Alloc& __a)
|
|
{
|
|
typedef allocator_traits<_Alloc> __traits;
|
|
return __traits::select_on_container_copy_construction(__a);
|
|
}
|
|
|
|
template<typename _Alloc>
|
|
[[__gnu__::__always_inline__]]
|
|
_GLIBCXX14_CONSTEXPR inline void
|
|
__alloc_on_move(_Alloc& __one, _Alloc& __two)
|
|
{
|
|
using __traits = allocator_traits<_Alloc>;
|
|
using __pocma
|
|
= typename __traits::propagate_on_container_move_assignment::type;
|
|
if constexpr (__pocma::value)
|
|
__one = std::move(__two);
|
|
}
|
|
|
|
template<typename _Alloc>
|
|
[[__gnu__::__always_inline__]]
|
|
_GLIBCXX14_CONSTEXPR inline void
|
|
__alloc_on_swap(_Alloc& __one, _Alloc& __two)
|
|
{
|
|
using __traits = allocator_traits<_Alloc>;
|
|
using __pocs = typename __traits::propagate_on_container_swap::type;
|
|
if constexpr (__pocs::value)
|
|
{
|
|
using std::swap;
|
|
swap(__one, __two);
|
|
}
|
|
}
|
|
#pragma GCC diagnostic pop
|
|
|
|
template<typename _Alloc, typename _Tp,
|
|
typename _ValueT = __remove_cvref_t<typename _Alloc::value_type>,
|
|
typename = void>
|
|
struct __is_alloc_insertable_impl
|
|
: false_type
|
|
{ };
|
|
|
|
template<typename _Alloc, typename _Tp, typename _ValueT>
|
|
struct __is_alloc_insertable_impl<_Alloc, _Tp, _ValueT,
|
|
__void_t<decltype(allocator_traits<_Alloc>::construct(
|
|
std::declval<_Alloc&>(), std::declval<_ValueT*>(),
|
|
std::declval<_Tp>()))>>
|
|
: true_type
|
|
{ };
|
|
|
|
// true if _Alloc::value_type is CopyInsertable into containers using _Alloc
|
|
// (might be wrong if _Alloc::construct exists but is not constrained,
|
|
// i.e. actually trying to use it would still be invalid. Use with caution.)
|
|
template<typename _Alloc>
|
|
struct __is_copy_insertable
|
|
: __is_alloc_insertable_impl<_Alloc,
|
|
typename _Alloc::value_type const&>::type
|
|
{ };
|
|
|
|
#if _GLIBCXX_HOSTED
|
|
// std::allocator<_Tp> just requires CopyConstructible
|
|
template<typename _Tp>
|
|
struct __is_copy_insertable<allocator<_Tp>>
|
|
: is_copy_constructible<_Tp>
|
|
{ };
|
|
#endif
|
|
|
|
// true if _Alloc::value_type is MoveInsertable into containers using _Alloc
|
|
// (might be wrong if _Alloc::construct exists but is not constrained,
|
|
// i.e. actually trying to use it would still be invalid. Use with caution.)
|
|
template<typename _Alloc>
|
|
struct __is_move_insertable
|
|
: __is_alloc_insertable_impl<_Alloc, typename _Alloc::value_type>::type
|
|
{ };
|
|
|
|
#if _GLIBCXX_HOSTED
|
|
// std::allocator<_Tp> just requires MoveConstructible
|
|
template<typename _Tp>
|
|
struct __is_move_insertable<allocator<_Tp>>
|
|
: is_move_constructible<_Tp>
|
|
{ };
|
|
#endif
|
|
|
|
// Trait to detect Allocator-like types.
|
|
template<typename _Alloc, typename = void>
|
|
struct __is_allocator : false_type { };
|
|
|
|
template<typename _Alloc>
|
|
struct __is_allocator<_Alloc,
|
|
__void_t<typename _Alloc::value_type,
|
|
decltype(std::declval<_Alloc&>().allocate(size_t{}))>>
|
|
: true_type { };
|
|
|
|
template<typename _Alloc>
|
|
using _RequireAllocator
|
|
= typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;
|
|
|
|
template<typename _Alloc>
|
|
using _RequireNotAllocator
|
|
= typename enable_if<!__is_allocator<_Alloc>::value, _Alloc>::type;
|
|
|
|
#if __cpp_concepts >= 201907L
|
|
template<typename _Alloc>
|
|
concept __allocator_like = requires (_Alloc& __a) {
|
|
typename _Alloc::value_type;
|
|
__a.deallocate(__a.allocate(1u), 1u);
|
|
};
|
|
|
|
template<typename _Alloc>
|
|
concept __not_allocator_like = !__allocator_like<_Alloc>;
|
|
#endif
|
|
/// @endcond
|
|
#endif // C++11
|
|
|
|
/// @cond undocumented
|
|
|
|
// To implement Option 3 of DR 431.
|
|
template<typename _Alloc, bool = __is_empty(_Alloc)>
|
|
struct __alloc_swap
|
|
{ static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
|
|
|
|
template<typename _Alloc>
|
|
struct __alloc_swap<_Alloc, false>
|
|
{
|
|
static void
|
|
_S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
|
|
{
|
|
// Precondition: swappable allocators.
|
|
if (__one != __two)
|
|
swap(__one, __two);
|
|
}
|
|
};
|
|
|
|
#if __cplusplus >= 201103L
|
|
template<typename _Tp, bool
|
|
= __or_<is_copy_constructible<typename _Tp::value_type>,
|
|
is_nothrow_move_constructible<typename _Tp::value_type>>::value>
|
|
struct __shrink_to_fit_aux
|
|
{ static bool _S_do_it(_Tp&) noexcept { return false; } };
|
|
|
|
template<typename _Tp>
|
|
struct __shrink_to_fit_aux<_Tp, true>
|
|
{
|
|
_GLIBCXX20_CONSTEXPR
|
|
static bool
|
|
_S_do_it(_Tp& __c) noexcept
|
|
{
|
|
#if __cpp_exceptions
|
|
try
|
|
{
|
|
_Tp(__make_move_if_noexcept_iterator(__c.begin()),
|
|
__make_move_if_noexcept_iterator(__c.end()),
|
|
__c.get_allocator()).swap(__c);
|
|
return true;
|
|
}
|
|
catch(...)
|
|
{ return false; }
|
|
#else
|
|
return false;
|
|
#endif
|
|
}
|
|
};
|
|
#endif
|
|
|
|
/**
|
|
* Destroy a range of objects using the supplied allocator. For
|
|
* non-default allocators we do not optimize away invocation of
|
|
* destroy() even if _Tp has a trivial destructor.
|
|
*/
|
|
|
|
template<typename _ForwardIterator, typename _Allocator>
|
|
_GLIBCXX20_CONSTEXPR
|
|
void
|
|
_Destroy(_ForwardIterator __first, _ForwardIterator __last,
|
|
_Allocator& __alloc)
|
|
{
|
|
for (; __first != __last; ++__first)
|
|
#if __cplusplus < 201103L
|
|
__alloc.destroy(std::__addressof(*__first));
|
|
#else
|
|
allocator_traits<_Allocator>::destroy(__alloc,
|
|
std::__addressof(*__first));
|
|
#endif
|
|
}
|
|
|
|
#if _GLIBCXX_HOSTED
|
|
template<typename _ForwardIterator, typename _Tp>
|
|
__attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR
|
|
inline void
|
|
_Destroy(_ForwardIterator __first, _ForwardIterator __last,
|
|
allocator<_Tp>&)
|
|
{
|
|
std::_Destroy(__first, __last);
|
|
}
|
|
#endif
|
|
|
|
/// @endcond
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace std
|
|
#endif // _ALLOC_TRAITS_H
|