libstdc++

uses_allocator.h
1 // Uses-allocator Construction -*- C++ -*-
2
3 // Copyright (C) 2010-2013 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
34 namespace std _GLIBCXX_VISIBILITY(default)
35 {
36 _GLIBCXX_BEGIN_NAMESPACE_VERSION
37
38 /// [allocator.tag]
39 struct allocator_arg_t { };
40
41 constexpr allocator_arg_t allocator_arg = allocator_arg_t();
42
43 _GLIBCXX_HAS_NESTED_TYPE(allocator_type)
44
45 template<typename _Tp, typename _Alloc,
46 bool = __has_allocator_type<_Tp>::value>
47 struct __uses_allocator_helper
48 : public false_type { };
49
50 template<typename _Tp, typename _Alloc>
51 struct __uses_allocator_helper<_Tp, _Alloc, true>
52 : public integral_constant<bool, is_convertible<_Alloc,
53 typename _Tp::allocator_type>::value>
54 { };
55
56 /// [allocator.uses.trait]
57 template<typename _Tp, typename _Alloc>
58 struct uses_allocator
59 : public integral_constant<bool,
60 __uses_allocator_helper<_Tp, _Alloc>::value>
61 { };
62
63 template<typename _Tp, typename _Alloc, typename... _Args>
64 struct __uses_allocator_arg
65 : is_constructible<_Tp, _Alloc, _Args...>
66 { static_assert( uses_allocator<_Tp, _Alloc>::value, "uses allocator" ); };
67
68 struct __uses_alloc_base { };
69 struct __uses_alloc0 : __uses_alloc_base
70 { struct _Anything { _Anything(...) { } } _M_a; };
71 template<typename _Alloc>
72 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
73 template<typename _Alloc>
74 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
75
76 template<bool, typename _Alloc, typename... _Args>
77 struct __uses_alloc;
78
79 template<typename _Tp, typename _Alloc, typename... _Args>
80 struct __uses_alloc<true, _Tp, _Alloc, _Args...>
81 : conditional<
82 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value,
83 __uses_alloc1<_Alloc>,
84 __uses_alloc2<_Alloc>>::type
85 { };
86
87 template<typename _Tp, typename _Alloc, typename... _Args>
88 struct __uses_alloc<false, _Tp, _Alloc, _Args...>
89 : __uses_alloc0 { };
90
91 template<typename _Tp, typename _Alloc, typename... _Args>
92 struct __uses_alloc_impl
93 : __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>
94 { };
95
96 template<typename _Tp, typename _Alloc, typename... _Args>
97 __uses_alloc_impl<_Tp, _Alloc, _Args...>
98 __use_alloc(const _Alloc& __a)
99 {
100 __uses_alloc_impl<_Tp, _Alloc, _Args...> __ret;
101 __ret._M_a = &__a;
102 return __ret;
103 }
104
105 _GLIBCXX_END_NAMESPACE_VERSION
106 } // namespace std
107
108 #endif
109 #endif