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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___CXX03___MEMORY_ALLOCATOR_H11#define _LIBCPP___CXX03___MEMORY_ALLOCATOR_H12 13#include <__cxx03/__config>14#include <__cxx03/__memory/addressof.h>15#include <__cxx03/__memory/allocate_at_least.h>16#include <__cxx03/__memory/allocator_traits.h>17#include <__cxx03/__type_traits/is_const.h>18#include <__cxx03/__type_traits/is_constant_evaluated.h>19#include <__cxx03/__type_traits/is_same.h>20#include <__cxx03/__type_traits/is_void.h>21#include <__cxx03/__type_traits/is_volatile.h>22#include <__cxx03/__utility/forward.h>23#include <__cxx03/cstddef>24#include <__cxx03/new>25 26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)27# pragma GCC system_header28#endif29 30_LIBCPP_BEGIN_NAMESPACE_STD31 32template <class _Tp>33class allocator;34 35template <>36class _LIBCPP_TEMPLATE_VIS allocator<void> {37public:38 typedef void* pointer;39 typedef const void* const_pointer;40 typedef void value_type;41 42 template <class _Up>43 struct rebind {44 typedef allocator<_Up> other;45 };46};47 48// TODO(LLVM 20): Remove the escape hatch49#ifdef _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST50template <>51class _LIBCPP_TEMPLATE_VIS allocator<const void> {52public:53 typedef const void* pointer;54 typedef const void* const_pointer;55 typedef const void value_type;56 57 template <class _Up>58 struct rebind {59 typedef allocator<_Up> other;60 };61};62#endif // _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST63 64// This class provides a non-trivial default constructor to the class that derives from it65// if the condition is satisfied.66//67// The second template parameter exists to allow giving a unique type to __non_trivial_if,68// which makes it possible to avoid breaking the ABI when making this a base class of an69// existing class. Without that, imagine we have classes D1 and D2, both of which used to70// have no base classes, but which now derive from __non_trivial_if. The layout of a class71// that inherits from both D1 and D2 will change because the two __non_trivial_if base72// classes are not allowed to share the same address.73//74// By making those __non_trivial_if base classes unique, we work around this problem and75// it is safe to start deriving from __non_trivial_if in existing classes.76template <bool _Cond, class _Unique>77struct __non_trivial_if {};78 79template <class _Unique>80struct __non_trivial_if<true, _Unique> {81 _LIBCPP_HIDE_FROM_ABI __non_trivial_if() _NOEXCEPT {}82};83 84// allocator85//86// Note: For ABI compatibility between C++20 and previous standards, we make87// allocator<void> trivial in C++20.88 89template <class _Tp>90class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > {91 static_assert(!is_const<_Tp>::value, "std::allocator does not support const types");92 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");93 94public:95 typedef size_t size_type;96 typedef ptrdiff_t difference_type;97 typedef _Tp value_type;98 typedef true_type propagate_on_container_move_assignment;99 typedef true_type is_always_equal;100 101 _LIBCPP_HIDE_FROM_ABI allocator() _NOEXCEPT = default;102 103 template <class _Up>104 _LIBCPP_HIDE_FROM_ABI allocator(const allocator<_Up>&) _NOEXCEPT {}105 106 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _Tp* allocate(size_t __n) {107 if (__n > allocator_traits<allocator>::max_size(*this))108 __throw_bad_array_new_length();109 if (__libcpp_is_constant_evaluated()) {110 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));111 } else {112 return static_cast<_Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));113 }114 }115 116 _LIBCPP_HIDE_FROM_ABI void deallocate(_Tp* __p, size_t __n) _NOEXCEPT {117 if (__libcpp_is_constant_evaluated()) {118 ::operator delete(__p);119 } else {120 std::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));121 }122 }123 124 // C++20 Removed members125 typedef _Tp* pointer;126 typedef const _Tp* const_pointer;127 typedef _Tp& reference;128 typedef const _Tp& const_reference;129 130 template <class _Up>131 struct rebind {132 typedef allocator<_Up> other;133 };134 135 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT { return std::addressof(__x); }136 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT { return std::addressof(__x); }137 138 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _Tp* allocate(size_t __n, const void*) { return allocate(__n); }139 140 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return size_type(~0) / sizeof(_Tp); }141 142 template <class _Up, class... _Args>143 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) {144 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...);145 }146 147 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }148};149 150template <class _Tp, class _Up>151inline _LIBCPP_HIDE_FROM_ABI bool operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {152 return true;153}154 155template <class _Tp, class _Up>156inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {157 return false;158}159 160_LIBCPP_END_NAMESPACE_STD161 162#endif // _LIBCPP___CXX03___MEMORY_ALLOCATOR_H163