1// Uses-allocator Construction -*- C++ -*- 
2 
3// Copyright (C) 2010-2019 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 
35namespace 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 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 inline __uses_alloc_t<_Tp, _Alloc, _Args...> 
113 __use_alloc(const _Alloc& __a) 
114 { 
115 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret; 
116 __ret._M_a = std::__addressof(__a); 
117 return __ret; 
118 } 
119 
120 template<typename _Tp, typename _Alloc, typename... _Args> 
121 void 
122 __use_alloc(const _Alloc&&) = delete; 
123 
124#if __cplusplus > 201402L 
125 template <typename _Tp, typename _Alloc> 
126 inline constexpr bool uses_allocator_v = 
127 uses_allocator<_Tp, _Alloc>::value; 
128#endif // C++17 
129 
130 template<template<typename...> class _Predicate, 
131 typename _Tp, typename _Alloc, typename... _Args> 
132 struct __is_uses_allocator_predicate 
133 : conditional<uses_allocator<_Tp, _Alloc>::value, 
134 __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>, 
135 _Predicate<_Tp, _Args..., _Alloc>>, 
136 _Predicate<_Tp, _Args...>>::type { }; 
137 
138 template<typename _Tp, typename _Alloc, typename... _Args> 
139 struct __is_uses_allocator_constructible 
140 : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...> 
141 { }; 
142 
143#if __cplusplus >= 201402L 
144 template<typename _Tp, typename _Alloc, typename... _Args> 
145 _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v = 
146 __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 
147#endif // C++14 
148 
149 template<typename _Tp, typename _Alloc, typename... _Args> 
150 struct __is_nothrow_uses_allocator_constructible 
151 : __is_uses_allocator_predicate<is_nothrow_constructible, 
152 _Tp, _Alloc, _Args...> 
153 { }; 
154 
155 
156#if __cplusplus >= 201402L 
157 template<typename _Tp, typename _Alloc, typename... _Args> 
158 _GLIBCXX17_INLINE constexpr bool 
159 __is_nothrow_uses_allocator_constructible_v = 
160 __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value; 
161#endif // C++14 
162 
163 template<typename _Tp, typename... _Args> 
164 void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr, 
165 _Args&&... __args) 
166 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); } 
167 
168 template<typename _Tp, typename _Alloc, typename... _Args> 
169 void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr, 
170 _Args&&... __args) 
171 { 
172 ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a, 
173 std::forward<_Args>(__args)...); 
174 } 
175 
176 template<typename _Tp, typename _Alloc, typename... _Args> 
177 void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr, 
178 _Args&&... __args) 
179 { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); } 
180 
181 template<typename _Tp, typename _Alloc, typename... _Args> 
182 void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr, 
183 _Args&&... __args) 
184 { 
185 std::__uses_allocator_construct_impl( 
186 std::__use_alloc<_Tp, _Alloc, _Args...>(__a), __ptr, 
187 std::forward<_Args>(__args)...); 
188 } 
189 
190_GLIBCXX_END_NAMESPACE_VERSION 
191} // namespace std 
192 
193#endif 
194#endif 
195