libstdc++
uses_allocator.h
1 // Uses-allocator Construction -*- C++ -*-
2 
3 // Copyright (C) 2010-2023 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 /** @file include/bits/uses_allocator_args.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{memory}
28  */
29 
30 #ifndef _USES_ALLOCATOR_H
31 #define _USES_ALLOCATOR_H 1
32 
33 #if __cplusplus < 201103L
34 # include <bits/c++0x_warning.h>
35 #else
36 
37 #include <type_traits>
38 #include <bits/move.h>
39 
40 namespace std _GLIBCXX_VISIBILITY(default)
41 {
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 /// @cond undocumented
44 
45  // This is used for std::experimental::erased_type from Library Fundamentals.
46  struct __erased_type { };
47 
48  // This also supports the "type-erased allocator" protocol from the
49  // Library Fundamentals TS, where allocator_type is erased_type.
50  // The second condition will always be false for types not using the TS.
51  template<typename _Alloc, typename _Tp>
52  using __is_erased_or_convertible
53  = __or_<is_convertible<_Alloc, _Tp>, is_same<_Tp, __erased_type>>;
54 
55  /// [allocator.tag]
56  struct allocator_arg_t { explicit allocator_arg_t() = default; };
57 
58  _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg =
59  allocator_arg_t();
60 
61  template<typename _Tp, typename _Alloc, typename = __void_t<>>
62  struct __uses_allocator_helper
63  : false_type { };
64 
65  template<typename _Tp, typename _Alloc>
66  struct __uses_allocator_helper<_Tp, _Alloc,
67  __void_t<typename _Tp::allocator_type>>
68  : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type
69  { };
70 
71  /// [allocator.uses.trait]
72  template<typename _Tp, typename _Alloc>
73  struct uses_allocator
74  : __uses_allocator_helper<_Tp, _Alloc>::type
75  { };
76 
77  struct __uses_alloc_base { };
78 
79  struct __uses_alloc0 : __uses_alloc_base
80  {
81  struct _Sink { void _GLIBCXX20_CONSTEXPR operator=(const void*) { } } _M_a;
82  };
83 
84  template<typename _Alloc>
85  struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
86 
87  template<typename _Alloc>
88  struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
89 
90  template<bool, typename _Tp, typename _Alloc, typename... _Args>
91  struct __uses_alloc;
92 
93  template<typename _Tp, typename _Alloc, typename... _Args>
94  struct __uses_alloc<true, _Tp, _Alloc, _Args...>
95  : __conditional_t<
96  is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>::value,
97  __uses_alloc1<_Alloc>,
98  __uses_alloc2<_Alloc>>
99  {
100  // _GLIBCXX_RESOLVE_LIB_DEFECTS
101  // 2586. Wrong value category used in scoped_allocator_adaptor::construct
102  static_assert(__or_<
103  is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>,
104  is_constructible<_Tp, _Args..., const _Alloc&>>::value,
105  "construction with an allocator must be possible"
106  " if uses_allocator is true");
107  };
108 
109  template<typename _Tp, typename _Alloc, typename... _Args>
110  struct __uses_alloc<false, _Tp, _Alloc, _Args...>
111  : __uses_alloc0 { };
112 
113  template<typename _Tp, typename _Alloc, typename... _Args>
114  using __uses_alloc_t =
115  __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
116 
117  template<typename _Tp, typename _Alloc, typename... _Args>
118  _GLIBCXX20_CONSTEXPR
119  inline __uses_alloc_t<_Tp, _Alloc, _Args...>
120  __use_alloc(const _Alloc& __a)
121  {
122  __uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
123  __ret._M_a = std::__addressof(__a);
124  return __ret;
125  }
126 
127  template<typename _Tp, typename _Alloc, typename... _Args>
128  void
129  __use_alloc(const _Alloc&&) = delete;
130 
131 #if __cplusplus > 201402L
132  template <typename _Tp, typename _Alloc>
133  inline constexpr bool uses_allocator_v =
134  uses_allocator<_Tp, _Alloc>::value;
135 #endif // C++17
136 
137  template<template<typename...> class _Predicate,
138  typename _Tp, typename _Alloc, typename... _Args>
139  struct __is_uses_allocator_predicate
140  : __conditional_t<uses_allocator<_Tp, _Alloc>::value,
141  __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>,
142  _Predicate<_Tp, _Args..., _Alloc>>,
143  _Predicate<_Tp, _Args...>> { };
144 
145  template<typename _Tp, typename _Alloc, typename... _Args>
146  struct __is_uses_allocator_constructible
147  : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...>
148  { };
149 
150 #if __cplusplus >= 201402L
151  template<typename _Tp, typename _Alloc, typename... _Args>
152  _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v =
153  __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
154 #endif // C++14
155 
156  template<typename _Tp, typename _Alloc, typename... _Args>
157  struct __is_nothrow_uses_allocator_constructible
158  : __is_uses_allocator_predicate<is_nothrow_constructible,
159  _Tp, _Alloc, _Args...>
160  { };
161 
162 
163 #if __cplusplus >= 201402L
164  template<typename _Tp, typename _Alloc, typename... _Args>
165  _GLIBCXX17_INLINE constexpr bool
166  __is_nothrow_uses_allocator_constructible_v =
167  __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
168 #endif // C++14
169 
170  template<typename _Tp, typename... _Args>
171  void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
172  _Args&&... __args)
173  { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); }
174 
175  template<typename _Tp, typename _Alloc, typename... _Args>
176  void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr,
177  _Args&&... __args)
178  {
179  ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a,
180  std::forward<_Args>(__args)...);
181  }
182 
183  template<typename _Tp, typename _Alloc, typename... _Args>
184  void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr,
185  _Args&&... __args)
186  { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); }
187 
188  template<typename _Tp, typename _Alloc, typename... _Args>
189  void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr,
190  _Args&&... __args)
191  {
192  std::__uses_allocator_construct_impl(
193  std::__use_alloc<_Tp, _Alloc, _Args...>(__a), __ptr,
194  std::forward<_Args>(__args)...);
195  }
196 
197 /// @endcond
198 _GLIBCXX_END_NAMESPACE_VERSION
199 } // namespace std
200 
201 #endif
202 #endif
type_traits
std::__addressof
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:51
move.h
c++0x_warning.h
std::false_type
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:85
std
ISO C++ entities toplevel namespace is std.