| // Allocator traits -*- C++ -*- |
| |
| // Copyright (C) 2011-2025 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file bits/alloc_traits.h |
| * This is an internal header file, included by other library headers. |
| * Do not attempt to use it directly. @headername{memory} |
| */ |
| |
| #ifndef _ALLOC_TRAITS_H |
| #define _ALLOC_TRAITS_H 1 |
| |
| #include <bits/stl_construct.h> |
| #include <bits/memoryfwd.h> |
| #if __cplusplus >= 201103L |
| # include <bits/ptr_traits.h> |
| # include <ext/numeric_traits.h> |
| # if _GLIBCXX_HOSTED |
| # include <bits/allocator.h> |
| # endif |
| # if __cpp_exceptions |
| # include <bits/stl_iterator.h> // __make_move_if_noexcept_iterator |
| # endif |
| #endif |
| |
| namespace std _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| #if __cplusplus >= 201103L |
| |
| #pragma GCC diagnostic push |
| #pragma GCC diagnostic ignored "-Wc++14-extensions" // for variable templates |
| #pragma GCC diagnostic ignored "-Wc++17-extensions" // for if-constexpr |
| |
| /// @cond undocumented |
| struct __allocator_traits_base |
| { |
| #if __cpp_concepts |
| template<typename _Tp, typename _Up> |
| #else |
| template<typename _Tp, typename _Up, typename = void> |
| #endif |
| struct __rebind : __replace_first_arg<_Tp, _Up> |
| { |
| static_assert(is_same< |
| typename __replace_first_arg<_Tp, typename _Tp::value_type>::type, |
| _Tp>::value, |
| "allocator_traits<A>::rebind_alloc<A::value_type> must be A"); |
| }; |
| |
| template<typename _Tp, typename _Up> |
| #if __cpp_concepts |
| requires requires { typename _Tp::template rebind<_Up>::other; } |
| struct __rebind<_Tp, _Up> |
| #else |
| struct __rebind<_Tp, _Up, |
| __void_t<typename _Tp::template rebind<_Up>::other>> |
| #endif |
| { |
| using type = typename _Tp::template rebind<_Up>::other; |
| |
| static_assert(is_same< |
| typename _Tp::template rebind<typename _Tp::value_type>::other, |
| _Tp>::value, |
| "allocator_traits<A>::rebind_alloc<A::value_type> must be A"); |
| }; |
| |
| protected: |
| template<typename _Tp> |
| using __pointer = typename _Tp::pointer; |
| template<typename _Tp> |
| using __c_pointer = typename _Tp::const_pointer; |
| template<typename _Tp> |
| using __v_pointer = typename _Tp::void_pointer; |
| template<typename _Tp> |
| using __cv_pointer = typename _Tp::const_void_pointer; |
| template<typename _Tp> |
| using __pocca = typename _Tp::propagate_on_container_copy_assignment; |
| template<typename _Tp> |
| using __pocma = typename _Tp::propagate_on_container_move_assignment; |
| template<typename _Tp> |
| using __pocs = typename _Tp::propagate_on_container_swap; |
| template<typename _Tp> |
| using __equal = __type_identity<typename _Tp::is_always_equal>; |
| |
| // __has_allocate_hint is true if a.allocate(n, hint) is well-formed. |
| #if __cpp_concepts |
| template<typename _Alloc, typename _Sz, typename _Vp> |
| static constexpr bool __has_allocate_hint |
| = requires (_Alloc& __a, _Sz __n, _Vp __hint) { |
| __a.allocate(__n, __hint); |
| }; |
| #else |
| template<typename _Alloc, typename _Sz, typename _Vp> |
| using __allocate_hint_t |
| = decltype(std::declval<_Alloc&>() |
| .allocate(std::declval<_Sz>(), std::declval<_Vp>())); |
| template<typename _Alloc, typename _Sz, typename _Vp, typename = void> |
| static constexpr bool __has_allocate_hint = false; |
| template<typename _Alloc, typename _Sz, typename _Vp> |
| static constexpr bool |
| __has_allocate_hint<_Alloc, _Sz, _Vp, |
| __void_t<__allocate_hint_t<_Alloc, _Sz, _Vp>>> |
| = true; |
| #endif |
| |
| // __has_construct is true if a.construct(p, args...) is well-formed. |
| // __can_construct is true if either __has_construct is true, or if |
| // a placement new-expression for T(args...) is well-formed. We use this |
| // to constrain allocator_traits::construct, as a libstdc++ extension. |
| #if __cpp_concepts |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| static constexpr bool __has_construct |
| = requires (_Alloc& __a, _Tp* __p, _Args&&... __args) { |
| __a.construct(__p, std::forward<_Args>(__args)...); |
| }; |
| template<typename _Tp, typename... _Args> |
| static constexpr bool __can_construct_at |
| = requires (_Tp* __p, _Args&&... __args) { |
| #if __cpp_constexpr_dynamic_alloc |
| std::construct_at(__p, std::forward<_Args>(__args)...); |
| #else |
| ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); |
| #endif |
| }; |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| static constexpr bool __can_construct |
| = __has_construct<_Alloc, _Tp, _Args...> |
| || __can_construct_at<_Tp, _Args...>; |
| #else |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| using __construct_t |
| = decltype(std::declval<_Alloc&>().construct(std::declval<_Tp*>(), |
| std::declval<_Args>()...)); |
| template<typename _Alloc, typename _Tp, typename, typename... _Args> |
| static constexpr bool __has_construct_impl = false; |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| static constexpr bool |
| __has_construct_impl<_Alloc, _Tp, |
| __void_t<__construct_t<_Alloc, _Tp, _Args...>>, |
| _Args...> |
| = true; |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| static constexpr bool __has_construct |
| = __has_construct_impl<_Alloc, _Tp, void, _Args...>; |
| template<typename _Tp, typename... _Args> |
| using __new_expr_t |
| = decltype(::new((void*)0) _Tp(std::declval<_Args>()...)); |
| template<typename _Tp, typename, typename... _Args> |
| static constexpr bool __has_new_expr = false; |
| template<typename _Tp, typename... _Args> |
| static constexpr bool |
| __has_new_expr<_Tp, __void_t<__new_expr_t<_Tp, _Args...>>, _Args...> |
| = true; |
| template<typename _Alloc, typename _Tp, typename... _Args> |
| static constexpr bool __can_construct |
| = __has_construct<_Alloc, _Tp, _Args...> |
| || __has_new_expr<_Tp, void, _Args...>; |
| #endif |
| |
| // __has_destroy is true if a.destroy(p) is well-formed. |
| #if __cpp_concepts |
| template<typename _Alloc, typename _Tp> |
| static constexpr bool __has_destroy = requires (_Alloc& __a, _Tp* __p) { |
| __a.destroy(__p); |
| }; |
| #else |
| template<typename _Alloc, typename _Tp> |
| using __destroy_t |
| = decltype(std::declval<_Alloc&>().destroy(std::declval<_Tp*>())); |
| template<typename _Alloc, typename _Tp, typename = void> |
| static constexpr bool __has_destroy = false; |
| template<typename _Alloc, typename _Tp> |
| static constexpr bool __has_destroy<_Alloc, _Tp, |
| __void_t<__destroy_t<_Alloc, _Tp>>> |
| = true; |
| #endif |
| |
| // __has_max_size is true if a.max_size() is well-formed. |
| #if __cpp_concepts |
| template<typename _Alloc> |
| static constexpr bool __has_max_size = requires (const _Alloc& __a) { |
| __a.max_size(); |
| }; |
| #else |
| template<typename _Alloc> |
| using __max_size_t = decltype(std::declval<const _Alloc&>().max_size()); |
| template<typename _Alloc, typename = void> |
| static constexpr bool __has_max_size = false; |
| template<typename _Alloc> |
| static constexpr bool __has_max_size<_Alloc, |
| __void_t<__max_size_t<_Alloc>>> |
| = true; |
| #endif |
| |
| // __has_soccc is true if a.select_on_container_copy_construction() |
| // is well-formed. |
| #if __cpp_concepts |
| template<typename _Alloc> |
| static constexpr bool __has_soccc = requires (const _Alloc& __a) { |
| __a.select_on_container_copy_construction(); |
| }; |
| #else |
| template<typename _Alloc> |
| using __soccc_t |
| = decltype(std::declval<const _Alloc&>() |
| .select_on_container_copy_construction()); |
| template<typename _Alloc, typename = void> |
| static constexpr bool __has_soccc = false; |
| template<typename _Alloc> |
| static constexpr bool __has_soccc<_Alloc, __void_t<__soccc_t<_Alloc>>> |
| = true; |
| #endif |
| }; |
| |
| template<typename _Alloc, typename _Up> |
| using __alloc_rebind |
| = typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type; |
| /// @endcond |
| |
| /** |
| * @brief Uniform interface to all allocator types. |
| * @headerfile memory |
| * @ingroup allocators |
| * @since C++11 |
| */ |
| template<typename _Alloc> |
| struct allocator_traits : __allocator_traits_base |
| { |
| /// The allocator type |
| typedef _Alloc allocator_type; |
| /// The allocated type |
| typedef typename _Alloc::value_type value_type; |
| |
| /** |
| * @brief The allocator's pointer type. |
| * |
| * @c Alloc::pointer if that type exists, otherwise @c value_type* |
| */ |
| using pointer = __detected_or_t<value_type*, __pointer, _Alloc>; |
| |
| private: |
| // Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp> |
| template<template<typename> class _Func, typename _Tp, typename = void> |
| struct _Ptr |
| { |
| using type = typename pointer_traits<pointer>::template rebind<_Tp>; |
| }; |
| |
| template<template<typename> class _Func, typename _Tp> |
| struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>> |
| { |
| using type = _Func<_Alloc>; |
| }; |
| |
| // Select _A2::difference_type or pointer_traits<_Ptr>::difference_type |
| template<typename _A2, typename _PtrT, typename = void> |
| struct _Diff |
| { using type = typename pointer_traits<_PtrT>::difference_type; }; |
| |
| template<typename _A2, typename _PtrT> |
| struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>> |
| { using type = typename _A2::difference_type; }; |
| |
| // Select _A2::size_type or make_unsigned<_DiffT>::type |
| template<typename _A2, typename _DiffT, typename = void> |
| struct _Size : make_unsigned<_DiffT> { }; |
| |
| template<typename _A2, typename _DiffT> |
| struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>> |
| { using type = typename _A2::size_type; }; |
| |
| public: |
| /** |
| * @brief The allocator's const pointer type. |
| * |
| * @c Alloc::const_pointer if that type exists, otherwise |
| * <tt> pointer_traits<pointer>::rebind<const value_type> </tt> |
| */ |
| using const_pointer = typename _Ptr<__c_pointer, const value_type>::type; |
| |
| /** |
| * @brief The allocator's void pointer type. |
| * |
| * @c Alloc::void_pointer if that type exists, otherwise |
| * <tt> pointer_traits<pointer>::rebind<void> </tt> |
| */ |
| using void_pointer = typename _Ptr<__v_pointer, void>::type; |
| |
| /** |
| * @brief The allocator's const void pointer type. |
| * |
| * @c Alloc::const_void_pointer if that type exists, otherwise |
| * <tt> pointer_traits<pointer>::rebind<const void> </tt> |
| */ |
| using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type; |
| |
| /** |
| * @brief The allocator's difference type |
| * |
| * @c Alloc::difference_type if that type exists, otherwise |
| * <tt> pointer_traits<pointer>::difference_type </tt> |
| */ |
| using difference_type = typename _Diff<_Alloc, pointer>::type; |
| |
| /** |
| * @brief The allocator's size type |
| * |
| * @c Alloc::size_type if that type exists, otherwise |
| * <tt> make_unsigned<difference_type>::type </tt> |
| */ |
| using size_type = typename _Size<_Alloc, difference_type>::type; |
| |
| /** |
| * @brief How the allocator is propagated on copy assignment |
| * |
| * @c Alloc::propagate_on_container_copy_assignment if that type exists, |
| * otherwise @c false_type |
| */ |
| using propagate_on_container_copy_assignment |
| = __detected_or_t<false_type, __pocca, _Alloc>; |
| |
| /** |
| * @brief How the allocator is propagated on move assignment |
| * |
| * @c Alloc::propagate_on_container_move_assignment if that type exists, |
| * otherwise @c false_type |
| */ |
| using propagate_on_container_move_assignment |
| = __detected_or_t<false_type, __pocma, _Alloc>; |
| |
| /** |
| * @brief How the allocator is propagated on swap |
| * |
| * @c Alloc::propagate_on_container_swap if that type exists, |
| * otherwise @c false_type |
| */ |
| using propagate_on_container_swap |
| = __detected_or_t<false_type, __pocs, _Alloc>; |
| |
| /** |
| * @brief Whether all instances of the allocator type compare equal. |
| * |
| * @c Alloc::is_always_equal if that type exists, |
| * otherwise @c is_empty<Alloc>::type |
| */ |
| using is_always_equal |
| = typename __detected_or_t<is_empty<_Alloc>, __equal, _Alloc>::type; |
| |
| template<typename _Tp> |
| using rebind_alloc = __alloc_rebind<_Alloc, _Tp>; |
| template<typename _Tp> |
| using rebind_traits = allocator_traits<rebind_alloc<_Tp>>; |
| |
| /** |
| * @brief Allocate memory. |
| * @param __a An allocator. |
| * @param __n The number of objects to allocate space for. |
| * |
| * Calls @c a.allocate(n) |
| */ |
| _GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer |
| allocate(_Alloc& __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> if that expression is |
| * well-formed, otherwise returns @c a.allocate(n) |
| */ |
| _GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer |
| allocate(_Alloc& __a, size_type __n, const_void_pointer __hint) |
| { |
| if constexpr (__has_allocate_hint<_Alloc, size_type, const_void_pointer>) |
| return __a.allocate(__n, __hint); |
| else |
| return __a.allocate(__n); |
| } |
| |
| /** |
| * @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> |
| */ |
| static _GLIBCXX20_CONSTEXPR void |
| deallocate(_Alloc& __a, pointer __p, size_type __n) |
| { __a.deallocate(__p, __n); } |
| |
| /** |
| * @brief Construct an object of type `_Tp` |
| * @param __a An allocator. |
| * @param __p Pointer to memory of suitable size and alignment for Tp |
| * @param __args Constructor arguments. |
| * |
| * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt> |
| * if that expression is well-formed, otherwise uses placement-new |
| * to construct an object of type @a _Tp at location @a __p from the |
| * arguments @a __args... |
| */ |
| template<typename _Tp, typename... _Args> |
| #if __cpp_concepts && __cpp_constexpr_dynamic_alloc |
| requires __can_construct<_Alloc, _Tp, _Args...> |
| static constexpr void |
| #else |
| 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 |
| } |
| |
| /** |
| * @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 |
