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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___MEMORY_ALLOCATOR_H11#define _LIBCPP___MEMORY_ALLOCATOR_H12 13#include <__config>14#include <__cstddef/ptrdiff_t.h>15#include <__cstddef/size_t.h>16#include <__memory/addressof.h>17#include <__memory/allocate_at_least.h>18#include <__memory/allocator_traits.h>19#include <__new/allocate.h>20#include <__new/exceptions.h>21#include <__type_traits/is_const.h>22#include <__type_traits/is_constant_evaluated.h>23#include <__type_traits/is_same.h>24#include <__type_traits/is_void.h>25#include <__type_traits/is_volatile.h>26#include <__utility/forward.h>27 28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)29# pragma GCC system_header30#endif31 32_LIBCPP_BEGIN_NAMESPACE_STD33 34template <class _Tp>35class allocator;36 37#if _LIBCPP_STD_VER <= 1738// These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17.39// Specializing allocator<void> is deprecated, but not using it.40template <>41class allocator<void> {42public:43 _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer;44 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;45 _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type;46 47 template <class _Up>48 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {49 typedef allocator<_Up> other;50 };51};52#endif // _LIBCPP_STD_VER <= 1753 54// This class provides a non-trivial default constructor to the class that derives from it55// if the condition is satisfied.56//57// The second template parameter exists to allow giving a unique type to __non_trivial_if,58// which makes it possible to avoid breaking the ABI when making this a base class of an59// existing class. Without that, imagine we have classes D1 and D2, both of which used to60// have no base classes, but which now derive from __non_trivial_if. The layout of a class61// that inherits from both D1 and D2 will change because the two __non_trivial_if base62// classes are not allowed to share the same address.63//64// By making those __non_trivial_if base classes unique, we work around this problem and65// it is safe to start deriving from __non_trivial_if in existing classes.66template <bool _Cond, class _Unique>67struct __non_trivial_if {};68 69template <class _Unique>70struct __non_trivial_if<true, _Unique> {71 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT {}72};73 74// allocator75//76// Note: For ABI compatibility between C++20 and previous standards, we make77// allocator<void> trivial in C++20.78 79template <class _Tp>80class allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > {81 static_assert(!is_const<_Tp>::value, "std::allocator does not support const types");82 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");83 84public:85 typedef size_t size_type;86 typedef ptrdiff_t difference_type;87 typedef _Tp value_type;88 typedef true_type propagate_on_container_move_assignment;89#if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)90 _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;91#endif92 93 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;94 95 template <class _Up>96 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {}97 98 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* allocate(size_t __n) {99 static_assert(sizeof(_Tp) >= 0, "cannot allocate memory for an incomplete type");100 if (__n > allocator_traits<allocator>::max_size(*this))101 std::__throw_bad_array_new_length();102 if (__libcpp_is_constant_evaluated()) {103 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));104 } else {105 return std::__libcpp_allocate<_Tp>(__element_count(__n));106 }107 }108 109#if _LIBCPP_STD_VER >= 23110 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<_Tp*> allocate_at_least(size_t __n) {111 static_assert(sizeof(_Tp) >= 0, "cannot allocate memory for an incomplete type");112 return {allocate(__n), __n};113 }114#endif115 116 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT {117 if (__libcpp_is_constant_evaluated()) {118 ::operator delete(__p);119 } else {120 std::__libcpp_deallocate<_Tp>(__p, __element_count(__n));121 }122 }123 124 // C++20 Removed members125#if _LIBCPP_STD_VER <= 17126 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer;127 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;128 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference;129 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference;130 131 template <class _Up>132 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {133 typedef allocator<_Up> other;134 };135 136 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT {137 return std::addressof(__x);138 }139 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {140 return std::addressof(__x);141 }142 143 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp* allocate(size_t __n, const void*) {144 return allocate(__n);145 }146 147 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {148 return size_type(~0) / sizeof(_Tp);149 }150 151 template <class _Up, class... _Args>152 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) {153 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...);154 }155 156 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }157#endif158};159 160template <class _Tp, class _Up>161inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool162operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {163 return true;164}165 166#if _LIBCPP_STD_VER <= 17167 168template <class _Tp, class _Up>169inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {170 return false;171}172 173#endif174 175_LIBCPP_END_NAMESPACE_STD176 177#endif // _LIBCPP___MEMORY_ALLOCATOR_H178