libstdc++
uses_allocator_args.h
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1 // Utility functions for uses-allocator construction -*- C++ -*-
2 
3 // Copyright (C) 2019-2024 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 
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22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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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_ARGS
31 #define _USES_ALLOCATOR_ARGS 1
32 
33 #pragma GCC system_header
34 
35 #include <bits/version.h>
36 
37 #ifdef __glibcxx_make_obj_using_allocator // C++ >= 20 && concepts
38 #include <new> // for placement operator new
39 #include <tuple> // for tuple, make_tuple, make_from_tuple
40 #include <bits/stl_construct.h> // construct_at
41 #include <bits/stl_pair.h> // pair
42 
43 namespace std _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 
47  template<typename _Tp>
48  concept _Std_pair = __is_pair<remove_cv_t<_Tp>>;
49 
50 /** @addtogroup allocators
51  * @{
52  */
53  template<typename _Tp, typename _Alloc, typename... _Args>
54  constexpr auto
55  uses_allocator_construction_args(const _Alloc& __a,
56  _Args&&... __args) noexcept
57  requires (! _Std_pair<_Tp>)
58  {
59  if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
60  {
61  if constexpr (is_constructible_v<_Tp, allocator_arg_t,
62  const _Alloc&, _Args...>)
63  {
64  return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
65  allocator_arg, __a, std::forward<_Args>(__args)...);
66  }
67  else
68  {
69  static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
70  "construction with an allocator must be possible"
71  " if uses_allocator is true");
72 
73  return tuple<_Args&&..., const _Alloc&>(
74  std::forward<_Args>(__args)..., __a);
75  }
76  }
77  else
78  {
79  static_assert(is_constructible_v<_Tp, _Args...>);
80 
81  return tuple<_Args&&...>(std::forward<_Args>(__args)...);
82  }
83  }
84 
85  template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
86  constexpr auto
87  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
88  _Tuple1&& __x, _Tuple2&& __y) noexcept;
89 
90  template<_Std_pair _Tp, typename _Alloc>
91  constexpr auto
92  uses_allocator_construction_args(const _Alloc&) noexcept;
93 
94  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
95  constexpr auto
96  uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
97 
98  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
99  constexpr auto
100  uses_allocator_construction_args(const _Alloc&,
101  const pair<_Up, _Vp>&) noexcept;
102 
103  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
104  constexpr auto
105  uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
106 
107 #if __cplusplus > 202002L
108  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
109  constexpr auto
110  uses_allocator_construction_args(const _Alloc&,
111  pair<_Up, _Vp>&) noexcept;
112 
113  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
114  constexpr auto
115  uses_allocator_construction_args(const _Alloc&, const pair<_Up, _Vp>&&) noexcept;
116 #endif // C++23
117 
118  template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
119  constexpr auto
120  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
121  _Tuple1&& __x, _Tuple2&& __y) noexcept
122  {
123  using _Tp1 = typename _Tp::first_type;
124  using _Tp2 = typename _Tp::second_type;
125 
127  std::apply([&__a](auto&&... __args1) {
128  return std::uses_allocator_construction_args<_Tp1>(
129  __a, std::forward<decltype(__args1)>(__args1)...);
130  }, std::forward<_Tuple1>(__x)),
131  std::apply([&__a](auto&&... __args2) {
132  return std::uses_allocator_construction_args<_Tp2>(
133  __a, std::forward<decltype(__args2)>(__args2)...);
134  }, std::forward<_Tuple2>(__y)));
135  }
136 
137  template<_Std_pair _Tp, typename _Alloc>
138  constexpr auto
139  uses_allocator_construction_args(const _Alloc& __a) noexcept
140  {
141  using _Tp1 = typename _Tp::first_type;
142  using _Tp2 = typename _Tp::second_type;
143 
145  std::uses_allocator_construction_args<_Tp1>(__a),
146  std::uses_allocator_construction_args<_Tp2>(__a));
147  }
148 
149  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
150  constexpr auto
151  uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
152  noexcept
153  {
154  using _Tp1 = typename _Tp::first_type;
155  using _Tp2 = typename _Tp::second_type;
156 
158  std::uses_allocator_construction_args<_Tp1>(__a,
159  std::forward<_Up>(__u)),
160  std::uses_allocator_construction_args<_Tp2>(__a,
161  std::forward<_Vp>(__v)));
162  }
163 
164  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
165  constexpr auto
166  uses_allocator_construction_args(const _Alloc& __a,
167  const pair<_Up, _Vp>& __pr) noexcept
168  {
169  using _Tp1 = typename _Tp::first_type;
170  using _Tp2 = typename _Tp::second_type;
171 
173  std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
174  std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
175  }
176 
177  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
178  constexpr auto
179  uses_allocator_construction_args(const _Alloc& __a,
180  pair<_Up, _Vp>&& __pr) noexcept
181  {
182  using _Tp1 = typename _Tp::first_type;
183  using _Tp2 = typename _Tp::second_type;
184 
185  // _GLIBCXX_RESOLVE_LIB_DEFECTS
186  // 3527. uses_allocator_construction_args handles rvalue pairs
187  // of rvalue references incorrectly
189  std::uses_allocator_construction_args<_Tp1>(__a,
190  std::get<0>(std::move(__pr))),
191  std::uses_allocator_construction_args<_Tp2>(__a,
192  std::get<1>(std::move(__pr))));
193  }
194 
195 #if __cplusplus > 202002L
196  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
197  constexpr auto
198  uses_allocator_construction_args(const _Alloc& __a,
199  pair<_Up, _Vp>& __pr) noexcept
200  {
201  using _Tp1 = typename _Tp::first_type;
202  using _Tp2 = typename _Tp::second_type;
203 
205  std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
206  std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
207  }
208 
209  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
210  constexpr auto
211  uses_allocator_construction_args(const _Alloc& __a,
212  const pair<_Up, _Vp>&& __pr) noexcept
213  {
214  using _Tp1 = typename _Tp::first_type;
215  using _Tp2 = typename _Tp::second_type;
216 
218  std::uses_allocator_construction_args<_Tp1>(__a,
219  std::get<0>(std::move(__pr))),
220  std::uses_allocator_construction_args<_Tp2>(__a,
221  std::get<1>(std::move(__pr))));
222  }
223 #endif // C++23
224 
225  template<typename _Tp, typename _Alloc, typename... _Args>
226  constexpr _Tp
227  make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
228  {
229  return std::make_from_tuple<_Tp>(
230  std::uses_allocator_construction_args<_Tp>(__a,
231  std::forward<_Args>(__args)...));
232  }
233 
234  template<typename _Tp, typename _Alloc, typename... _Args>
235  constexpr _Tp*
236  uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
237  _Args&&... __args)
238  {
239  return std::apply([&](auto&&... __xs) {
240  return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
241  }, std::uses_allocator_construction_args<_Tp>(__a,
242  std::forward<_Args>(__args)...));
243  }
244 /// @}
245 _GLIBCXX_END_NAMESPACE_VERSION
246 } // namespace std
247 #endif // __glibcxx_make_obj_using_allocator
248 #endif // _USES_ALLOCATOR_ARGS
ISO C++ entities toplevel namespace is std.
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:70
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:82
constexpr tuple< typename __decay_and_strip< _Elements >::__type... > make_tuple(_Elements &&... __args)
Create a tuple containing copies of the arguments.
Definition: tuple:2638
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:126