libstdc++
uses_allocator.h
1 // Uses-allocator Construction -*- C++ -*-
2 
3 // Copyright (C) 2010, 2011 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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
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>
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