1 // Uses-allocator Construction -*- C++ -*-
2
3 // Copyright (C) 2010-2016 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 struct __erased_type { };
40
41 template<typename _Alloc, typename _Tp>
42 using __is_erased_or_convertible
43 = __or_<is_same<_Tp, __erased_type>, is_convertible<_Alloc, _Tp>>;
44
45 /// [allocator.tag]
46 struct allocator_arg_t { explicit allocator_arg_t() = default; };
47
48 constexpr allocator_arg_t allocator_arg = allocator_arg_t();
49
50 template<typename _Tp, typename _Alloc, typename = __void_t<>>
51 struct __uses_allocator_helper
52 : false_type { };
53
54 template<typename _Tp, typename _Alloc>
55 struct __uses_allocator_helper<_Tp, _Alloc,
56 __void_t<typename _Tp::allocator_type>>
57 : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type
58 { };
59
60 /// [allocator.uses.trait]
61 template<typename _Tp, typename _Alloc>
62 struct uses_allocator
63 : __uses_allocator_helper<_Tp, _Alloc>::type
64 { };
65
66 struct __uses_alloc_base { };
67
68 struct __uses_alloc0 : __uses_alloc_base
69 {
70 struct _Sink { void operator=(const void*) { } } _M_a;
71 };
72
73 template<typename _Alloc>
74 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
75
76 template<typename _Alloc>
77 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
78
79 template<bool, typename _Tp, typename _Alloc, typename... _Args>
80 struct __uses_alloc;
81
82 template<typename _Tp, typename _Alloc, typename... _Args>
83 struct __uses_alloc<true, _Tp, _Alloc, _Args...>
84 : conditional<
85 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value,
86 __uses_alloc1<_Alloc>,
87 __uses_alloc2<_Alloc>>::type
88 {
89 static_assert(__or_<
90 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>,
91 is_constructible<_Tp, _Args..., _Alloc>>::value, "construction with"
92 " an allocator must be possible if uses_allocator is true");
93 };
94
95 template<typename _Tp, typename _Alloc, typename... _Args>
96 struct __uses_alloc<false, _Tp, _Alloc, _Args...>
97 : __uses_alloc0 { };
98
99 template<typename _Tp, typename _Alloc, typename... _Args>
100 using __uses_alloc_t =
101 __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
102
103 template<typename _Tp, typename _Alloc, typename... _Args>
104 inline __uses_alloc_t<_Tp, _Alloc, _Args...>
105 __use_alloc(const _Alloc& __a)
106 {
107 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
108 __ret._M_a = std::__addressof(__a);
109 return __ret;
110 }
111
112 _GLIBCXX_END_NAMESPACE_VERSION
113 } // namespace std
114
115 #endif
116 #endif
117