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
_GLIBCXX_VISIBILITY(default)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