libstdc++
uses_allocator_args.h
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1 // Utility functions for uses-allocator construction -*- C++ -*-
2 
3 // Copyright (C) 2019-2021 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_ARGS
31 #define _USES_ALLOCATOR_ARGS 1
32 
33 #pragma GCC system_header
34 
35 #if __cplusplus > 201703L && __cpp_concepts
36 
37 #include <new> // for placement operator new
38 #include <tuple> // for tuple, make_tuple, make_from_tuple
39 #include <bits/stl_construct.h> // construct_at
40 #include <bits/stl_pair.h> // pair
41 
42 namespace std _GLIBCXX_VISIBILITY(default)
43 {
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45  template<typename _Tp>
46  inline constexpr bool __is_pair = false;
47  template<typename _Tp, typename _Up>
48  inline constexpr bool __is_pair<pair<_Tp, _Up>> = true;
49  template<typename _Tp, typename _Up>
50  inline constexpr bool __is_pair<const pair<_Tp, _Up>> = true;
51 
52  template<typename _Tp>
53  concept _Std_pair = __is_pair<_Tp>;
54 
55 /** @addtogroup allocators
56  * @{
57  */
58 
59 // Not specified by C++20, used internally
60 #define __cpp_lib_make_obj_using_allocator 201811L
61 
62  template<typename _Tp, typename _Alloc, typename... _Args>
63  constexpr auto
64  uses_allocator_construction_args(const _Alloc& __a,
65  _Args&&... __args) noexcept
66  requires (! _Std_pair<_Tp>)
67  {
68  if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
69  {
70  if constexpr (is_constructible_v<_Tp, allocator_arg_t,
71  const _Alloc&, _Args...>)
72  {
73  return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
74  allocator_arg, __a, std::forward<_Args>(__args)...);
75  }
76  else
77  {
78  static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
79  "construction with an allocator must be possible"
80  " if uses_allocator is true");
81 
82  return tuple<_Args&&..., const _Alloc&>(
83  std::forward<_Args>(__args)..., __a);
84  }
85  }
86  else
87  {
88  static_assert(is_constructible_v<_Tp, _Args...>);
89 
90  return tuple<_Args&&...>(std::forward<_Args>(__args)...);
91  }
92  }
93 
94  template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
95  constexpr auto
96  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
97  _Tuple1&& __x, _Tuple2&& __y) noexcept;
98 
99  template<_Std_pair _Tp, typename _Alloc>
100  constexpr auto
101  uses_allocator_construction_args(const _Alloc&) noexcept;
102 
103  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
104  constexpr auto
105  uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
106 
107  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
108  constexpr auto
109  uses_allocator_construction_args(const _Alloc&,
110  const pair<_Up, _Vp>&) noexcept;
111 
112  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
113  constexpr auto
114  uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
115 
116  template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
117  constexpr auto
118  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
119  _Tuple1&& __x, _Tuple2&& __y) noexcept
120  {
121  using _Tp1 = typename _Tp::first_type;
122  using _Tp2 = typename _Tp::second_type;
123 
124  return std::make_tuple(piecewise_construct,
125  std::apply([&__a](auto&&... __args1) {
126  return std::uses_allocator_construction_args<_Tp1>(
127  __a, std::forward<decltype(__args1)>(__args1)...);
128  }, std::forward<_Tuple1>(__x)),
129  std::apply([&__a](auto&&... __args2) {
130  return std::uses_allocator_construction_args<_Tp2>(
131  __a, std::forward<decltype(__args2)>(__args2)...);
132  }, std::forward<_Tuple2>(__y)));
133  }
134 
135  template<_Std_pair _Tp, typename _Alloc>
136  constexpr auto
137  uses_allocator_construction_args(const _Alloc& __a) noexcept
138  {
139  using _Tp1 = typename _Tp::first_type;
140  using _Tp2 = typename _Tp::second_type;
141 
142  return std::make_tuple(piecewise_construct,
143  std::uses_allocator_construction_args<_Tp1>(__a),
144  std::uses_allocator_construction_args<_Tp2>(__a));
145  }
146 
147  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
148  constexpr auto
149  uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
150  noexcept
151  {
152  using _Tp1 = typename _Tp::first_type;
153  using _Tp2 = typename _Tp::second_type;
154 
155  return std::make_tuple(piecewise_construct,
156  std::uses_allocator_construction_args<_Tp1>(__a,
157  std::forward<_Up>(__u)),
158  std::uses_allocator_construction_args<_Tp2>(__a,
159  std::forward<_Vp>(__v)));
160  }
161 
162  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
163  constexpr auto
164  uses_allocator_construction_args(const _Alloc& __a,
165  const pair<_Up, _Vp>& __pr) noexcept
166  {
167  using _Tp1 = typename _Tp::first_type;
168  using _Tp2 = typename _Tp::second_type;
169 
170  return std::make_tuple(piecewise_construct,
171  std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
172  std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
173  }
174 
175  template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
176  constexpr auto
177  uses_allocator_construction_args(const _Alloc& __a,
178  pair<_Up, _Vp>&& __pr) noexcept
179  {
180  using _Tp1 = typename _Tp::first_type;
181  using _Tp2 = typename _Tp::second_type;
182 
183  // _GLIBCXX_RESOLVE_LIB_DEFECTS
184  // 3527. uses_allocator_construction_args handles rvalue pairs
185  // of rvalue references incorrectly
186  return std::make_tuple(piecewise_construct,
187  std::uses_allocator_construction_args<_Tp1>(__a,
188  std::get<0>(std::move(__pr))),
189  std::uses_allocator_construction_args<_Tp2>(__a,
190  std::get<1>(std::move(__pr))));
191  }
192 
193  template<typename _Tp, typename _Alloc, typename... _Args>
194  constexpr _Tp
195  make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
196  {
197  return std::make_from_tuple<_Tp>(
198  std::uses_allocator_construction_args<_Tp>(__a,
199  std::forward<_Args>(__args)...));
200  }
201 
202  template<typename _Tp, typename _Alloc, typename... _Args>
203  constexpr _Tp*
204  uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
205  _Args&&... __args)
206  {
207  return std::apply([&](auto&&... __xs) {
208  return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
209  }, std::uses_allocator_construction_args<_Tp>(__a,
210  std::forward<_Args>(__args)...));
211  }
212 /// @}
213 _GLIBCXX_END_NAMESPACE_VERSION
214 } // namespace std
215 #endif // C++20
216 #endif // _USES_ALLOCATOR_ARGS
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:83
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
ISO C++ entities toplevel namespace is std.