1 // Uses-allocator Construction -*- C++ -*- 2 3 // Copyright (C) 2010-2020 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 #ifndef _USES_ALLOCATOR_H 26 #define _USES_ALLOCATOR_H 1 27 28 #if __cplusplus < 201103L 29 # include <bits/c++0x_warning.h> 30 #else 31 32 #include <type_traits> 33 #include <bits/move.h> 34 35 namespace std _GLIBCXX_VISIBILITY(default) 36 { 37 _GLIBCXX_BEGIN_NAMESPACE_VERSION 38 39 // This is used for std::experimental::erased_type from Library Fundamentals. 40 struct __erased_type { }; 41 42 // This also supports the "type-erased allocator" protocol from the 43 // Library Fundamentals TS, where allocator_type is erased_type. 44 // The second condition will always be false for types not using the TS. 45 template<typename _Alloc, typename _Tp> 46 using __is_erased_or_convertible 47 = __or_<is_convertible<_Alloc, _Tp>, is_same<_Tp, __erased_type>>; 48 49 /// [allocator.tag] 50 struct allocator_arg_t { explicit allocator_arg_t() = default; }; 51 52 _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg = 53 allocator_arg_t(); 54 55 template<typename _Tp, typename _Alloc, typename = __void_t<>> 56 struct __uses_allocator_helper 57 : false_type { }; 58 59 template<typename _Tp, typename _Alloc> 60 struct __uses_allocator_helper<_Tp, _Alloc, 61 __void_t<typename _Tp::allocator_type>> 62 : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type 63 { }; 64 65 /// [allocator.uses.trait] 66 template<typename _Tp, typename _Alloc> 67 struct uses_allocator 68 : __uses_allocator_helper<_Tp, _Alloc>::type 69 { }; 70 71 struct __uses_alloc_base { }; 72 73 struct __uses_alloc0 : __uses_alloc_base 74 { 75 struct _Sink { void _GLIBCXX20_CONSTEXPR operator=(const void*) { } } _M_a; 76 }; 77 78 template<typename _Alloc> 79 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; }; 80 81 template<typename _Alloc> 82 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; }; 83 84 template<bool, typename _Tp, typename _Alloc, typename... _Args> 85 struct __uses_alloc; 86 87 template<typename _Tp, typename _Alloc, typename... _Args> 88 struct __uses_alloc<true, _Tp, _Alloc, _Args...> 89 : conditional< 90 is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>::value, 91 __uses_alloc1<_Alloc>, 92 __uses_alloc2<_Alloc>>::type 93 { 94 // _GLIBCXX_RESOLVE_LIB_DEFECTS 95 // 2586. Wrong value category used in scoped_allocator_adaptor::construct 96 static_assert(__or_< 97 is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>, 98 is_constructible<_Tp, _Args..., const _Alloc&>>::value, 99 "construction with an allocator must be possible" 100 " if uses_allocator is true"); 101 }; 102 103 template<typename _Tp, typename _Alloc, typename... _Args> 104 struct __uses_alloc<false, _Tp, _Alloc, _Args...> 105 : __uses_alloc0 { }; 106 107 template<typename _Tp, typename _Alloc, typename... _Args> 108 using __uses_alloc_t = 109 __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>; 110 111 template<typename _Tp, typename _Alloc, typename... _Args> 112 _GLIBCXX20_CONSTEXPR 113 inline __uses_alloc_t<_Tp, _Alloc, _Args...> 114 __use_alloc(const _Alloc& __a) 115 { 116 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret; 117 __ret._M_a = std::__addressof(__a); 118 return __ret; 119 } 120 121 template<typename _Tp, typename _Alloc, typename... _Args> 122 void 123 __use_alloc(const _Alloc&&) = delete; 124 125 #if __cplusplus > 201402L 126 template <typename _Tp, typename _Alloc> 127 inline constexpr bool uses_allocator_v = 128 uses_allocator<_Tp, _Alloc>::value; 129 #endif // C++17 130 131 template<template<typename...> class _Predicate, 132 typename _Tp, typename _Alloc, typename... _Args> 133 struct __is_uses_allocator_predicate 134 : conditional<uses_allocator<_Tp, _Alloc>::value, 135 __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>, 136 _Predicate<_Tp, _Args..., _Alloc>>, 137 _Predicate<_Tp, _Args...>>::type { }; 138 139 template<typename _Tp, typename _Alloc, typename... _Args> 140 struct __is_uses_allocator_constructible 141 : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...> 142 { }; 143 144 #if __cplusplus >= 201402L 145 template<typename _Tp, typename _Alloc, typename... _Args> 146 _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v = 147 __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 148 #endif // C++14 149 150 template<typename _Tp, typename _Alloc, typename... _Args> 151 struct __is_nothrow_uses_allocator_constructible 152 : __is_uses_allocator_predicate<is_nothrow_constructible, 153 _Tp, _Alloc, _Args...> 154 { }; 155 156 157 #if __cplusplus >= 201402L 158 template<typename _Tp, typename _Alloc, typename... _Args> 159 _GLIBCXX17_INLINE constexpr bool 160 __is_nothrow_uses_allocator_constructible_v = 161 __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 162 #endif // C++14 163 164 template<typename _Tp, typename... _Args> 165 void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr, 166 _Args&&... __args) 167 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); } 168 169 template<typename _Tp, typename _Alloc, typename... _Args> 170 void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr, 171 _Args&&... __args) 172 { 173 ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a, 174 std::forward<_Args>(__args)...); 175 } 176 177 template<typename _Tp, typename _Alloc, typename... _Args> 178 void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr, 179 _Args&&... __args) 180 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); } 181 182 template<typename _Tp, typename _Alloc, typename... _Args> 183 void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr, 184 _Args&&... __args) 185 { 186 std::__uses_allocator_construct_impl( 187 std::__use_alloc<_Tp, _Alloc, _Args...>(__a), __ptr, 188 std::forward<_Args>(__args)...); 189 } 190 191 _GLIBCXX_END_NAMESPACE_VERSION 192 } // namespace std 193 194 #endif 195 #endif 196