1 // Uses-allocator Construction -*- C++ -*- 2 3 // Copyright (C) 2010-2024 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file include/bits/uses_allocator_args.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{memory} 28 */ 29 30 #ifndef _USES_ALLOCATOR_H 31 #define _USES_ALLOCATOR_H 1 32 33 #if __cplusplus < 201103L 34 # include <bits/c++0x_warning.h> 35 #else 36 37 #include <type_traits> 38 #include <bits/move.h> 39 40 namespace std _GLIBCXX_VISIBILITY(default) 41 { 42 _GLIBCXX_BEGIN_NAMESPACE_VERSION 43 /// @cond undocumented 44 45 // This is used for std::experimental::erased_type from Library Fundamentals. 46 struct __erased_type { }; 47 48 // This also supports the "type-erased allocator" protocol from the 49 // Library Fundamentals TS, where allocator_type is erased_type. 50 // The second condition will always be false for types not using the TS. 51 template<typename _Alloc, typename _Tp> 52 using __is_erased_or_convertible 53 = __or_<is_convertible<_Alloc, _Tp>, is_same<_Tp, __erased_type>>; 54 55 /// [allocator.tag] 56 struct allocator_arg_t { explicit allocator_arg_t() = default; }; 57 58 _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg = 59 allocator_arg_t(); 60 61 template<typename _Tp, typename _Alloc, typename = __void_t<>> 62 struct __uses_allocator_helper 63 : false_type { }; 64 65 template<typename _Tp, typename _Alloc> 66 struct __uses_allocator_helper<_Tp, _Alloc, 67 __void_t<typename _Tp::allocator_type>> 68 : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type 69 { }; 70 71 /// [allocator.uses.trait] 72 template<typename _Tp, typename _Alloc> 73 struct uses_allocator 74 : __uses_allocator_helper<_Tp, _Alloc>::type 75 { }; 76 77 struct __uses_alloc_base { }; 78 79 struct __uses_alloc0 : __uses_alloc_base 80 { 81 struct _Sink { void _GLIBCXX20_CONSTEXPR operator=(const void*) { } } _M_a; 82 }; 83 84 template<typename _Alloc> 85 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; }; 86 87 template<typename _Alloc> 88 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; }; 89 90 template<bool, typename _Tp, typename _Alloc, typename... _Args> 91 struct __uses_alloc; 92 93 template<typename _Tp, typename _Alloc, typename... _Args> 94 struct __uses_alloc<true, _Tp, _Alloc, _Args...> 95 : __conditional_t< 96 is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>::value, 97 __uses_alloc1<_Alloc>, 98 __uses_alloc2<_Alloc>> 99 { 100 // _GLIBCXX_RESOLVE_LIB_DEFECTS 101 // 2586. Wrong value category used in scoped_allocator_adaptor::construct 102 static_assert(__or_< 103 is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>, 104 is_constructible<_Tp, _Args..., const _Alloc&>>::value, 105 "construction with an allocator must be possible" 106 " if uses_allocator is true"); 107 }; 108 109 template<typename _Tp, typename _Alloc, typename... _Args> 110 struct __uses_alloc<false, _Tp, _Alloc, _Args...> 111 : __uses_alloc0 { }; 112 113 template<typename _Tp, typename _Alloc, typename... _Args> 114 using __uses_alloc_t = 115 __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>; 116 117 template<typename _Tp, typename _Alloc, typename... _Args> 118 _GLIBCXX20_CONSTEXPR 119 inline __uses_alloc_t<_Tp, _Alloc, _Args...> 120 __use_alloc(const _Alloc& __a) 121 { 122 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret; 123 __ret._M_a = std::__addressof(__a); 124 return __ret; 125 } 126 127 template<typename _Tp, typename _Alloc, typename... _Args> 128 void 129 __use_alloc(const _Alloc&&) = delete; 130 131 #if __cplusplus > 201402L 132 template <typename _Tp, typename _Alloc> 133 inline constexpr bool uses_allocator_v = 134 uses_allocator<_Tp, _Alloc>::value; 135 #endif // C++17 136 137 template<template<typename...> class _Predicate, 138 typename _Tp, typename _Alloc, typename... _Args> 139 struct __is_uses_allocator_predicate 140 : __conditional_t<uses_allocator<_Tp, _Alloc>::value, 141 __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>, 142 _Predicate<_Tp, _Args..., _Alloc>>, 143 _Predicate<_Tp, _Args...>> { }; 144 145 template<typename _Tp, typename _Alloc, typename... _Args> 146 struct __is_uses_allocator_constructible 147 : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...> 148 { }; 149 150 #if __cplusplus >= 201402L 151 template<typename _Tp, typename _Alloc, typename... _Args> 152 _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v = 153 __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 154 #endif // C++14 155 156 template<typename _Tp, typename _Alloc, typename... _Args> 157 struct __is_nothrow_uses_allocator_constructible 158 : __is_uses_allocator_predicate<is_nothrow_constructible, 159 _Tp, _Alloc, _Args...> 160 { }; 161 162 163 #if __cplusplus >= 201402L 164 template<typename _Tp, typename _Alloc, typename... _Args> 165 _GLIBCXX17_INLINE constexpr bool 166 __is_nothrow_uses_allocator_constructible_v = 167 __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 168 #endif // C++14 169 170 template<typename _Tp, typename... _Args> 171 void __uses_allocator_construct_impl(__uses_alloc0, _Tp* __ptr, 172 _Args&&... __args) 173 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); } 174 175 template<typename _Tp, typename _Alloc, typename... _Args> 176 void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr, 177 _Args&&... __args) 178 { 179 ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a, 180 std::forward<_Args>(__args)...); 181 } 182 183 template<typename _Tp, typename _Alloc, typename... _Args> 184 void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr, 185 _Args&&... __args) 186 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); } 187 188 template<typename _Tp, typename _Alloc, typename... _Args> 189 void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr, 190 _Args&&... __args) 191 { 192 std::__uses_allocator_construct_impl( 193 std::__use_alloc<_Tp, _Alloc, _Args...>(__a), __ptr, 194 std::forward<_Args>(__args)...); 195 } 196 197 /// @endcond 198 _GLIBCXX_END_NAMESPACE_VERSION 199 } // namespace std 200 201 #endif 202 #endif 203
Indexes created Tue Mar 03 05:31:39 UTC 2026