libstdc++
ext/alloc_traits.h
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1 // Allocator traits -*- C++ -*-
2 
3 // Copyright (C) 2011-2025 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 ext/alloc_traits.h
26  * This file is a GNU extension to the Standard C++ Library.
27  */
28 
29 #ifndef _EXT_ALLOC_TRAITS_H
30 #define _EXT_ALLOC_TRAITS_H 1
31 
32 #ifdef _GLIBCXX_SYSHDR
33 #pragma GCC system_header
34 #endif
35 
36 # include <bits/alloc_traits.h>
37 
38 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
39 {
40 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 
42 /**
43  * @brief Uniform interface to C++98 and C++11 allocators.
44  * @ingroup allocators
45 */
46 template<typename _Alloc, typename = typename _Alloc::value_type>
48 #if __cplusplus >= 201103L
50 #endif
51  {
52  typedef _Alloc allocator_type;
53 #if __cplusplus >= 201103L
55  typedef typename _Base_type::value_type value_type;
56  typedef typename _Base_type::pointer pointer;
58  typedef typename _Base_type::size_type size_type;
60  // C++11 allocators do not define reference or const_reference
61  typedef value_type& reference;
62  typedef const value_type& const_reference;
63  using _Base_type::allocate;
64  using _Base_type::deallocate;
65  using _Base_type::construct;
66  using _Base_type::destroy;
67  using _Base_type::max_size;
68 
69  private:
70  template<typename _Ptr>
71  using __is_custom_pointer
72  = std::__and_<std::is_same<pointer, _Ptr>,
73  std::__not_<std::is_pointer<_Ptr>>>;
74 
75  public:
76  // overload construct for non-standard pointer types
77  template<typename _Ptr, typename... _Args>
78  [[__gnu__::__always_inline__]]
79  static _GLIBCXX14_CONSTEXPR
80  std::__enable_if_t<__is_custom_pointer<_Ptr>::value>
81  construct(_Alloc& __a, _Ptr __p, _Args&&... __args)
82  noexcept(noexcept(_Base_type::construct(__a, std::__to_address(__p),
83  std::forward<_Args>(__args)...)))
84  {
85  _Base_type::construct(__a, std::__to_address(__p),
86  std::forward<_Args>(__args)...);
87  }
88 
89  // overload destroy for non-standard pointer types
90  template<typename _Ptr>
91  [[__gnu__::__always_inline__]]
92  static _GLIBCXX14_CONSTEXPR
93  std::__enable_if_t<__is_custom_pointer<_Ptr>::value>
94  destroy(_Alloc& __a, _Ptr __p)
95  noexcept(noexcept(_Base_type::destroy(__a, std::__to_address(__p))))
96  { _Base_type::destroy(__a, std::__to_address(__p)); }
97 
98  [[__gnu__::__always_inline__]]
99  static constexpr _Alloc _S_select_on_copy(const _Alloc& __a)
100  { return _Base_type::select_on_container_copy_construction(__a); }
101 
102  [[__gnu__::__always_inline__]]
103  static _GLIBCXX14_CONSTEXPR void _S_on_swap(_Alloc& __a, _Alloc& __b)
104  { std::__alloc_on_swap(__a, __b); }
105 
106  [[__gnu__::__always_inline__]]
107  static constexpr bool _S_propagate_on_copy_assign()
108  { return _Base_type::propagate_on_container_copy_assignment::value; }
109 
110  [[__gnu__::__always_inline__]]
111  static constexpr bool _S_propagate_on_move_assign()
112  { return _Base_type::propagate_on_container_move_assignment::value; }
113 
114  [[__gnu__::__always_inline__]]
115  static constexpr bool _S_propagate_on_swap()
116  { return _Base_type::propagate_on_container_swap::value; }
117 
118  [[__gnu__::__always_inline__]]
119  static constexpr bool _S_always_equal()
120  { return _Base_type::is_always_equal::value; }
121 
122  __attribute__((__always_inline__))
123  static constexpr bool _S_nothrow_move()
124  { return _S_propagate_on_move_assign() || _S_always_equal(); }
125 
126  template<typename _Tp>
127  struct rebind
128  { typedef typename _Base_type::template rebind_alloc<_Tp> other; };
129 #else // ! C++11
130 
131  typedef typename _Alloc::pointer pointer;
132  typedef typename _Alloc::const_pointer const_pointer;
133  typedef typename _Alloc::value_type value_type;
134  typedef typename _Alloc::reference reference;
135  typedef typename _Alloc::const_reference const_reference;
136  typedef typename _Alloc::size_type size_type;
137  typedef typename _Alloc::difference_type difference_type;
138 
139  __attribute__((__always_inline__)) _GLIBCXX_NODISCARD
140  static pointer
141  allocate(_Alloc& __a, size_type __n)
142  { return __a.allocate(__n); }
143 
144  template<typename _Hint>
145  __attribute__((__always_inline__)) _GLIBCXX_NODISCARD
146  static pointer
147  allocate(_Alloc& __a, size_type __n, _Hint __hint)
148  { return __a.allocate(__n, __hint); }
149 
150  __attribute__((__always_inline__))
151  static void deallocate(_Alloc& __a, pointer __p, size_type __n)
152  { __a.deallocate(__p, __n); }
153 
154  template<typename _Tp>
155  __attribute__((__always_inline__))
156  static void construct(_Alloc& __a, pointer __p, const _Tp& __arg)
157  { __a.construct(__p, __arg); }
158 
159  __attribute__((__always_inline__))
160  static void destroy(_Alloc& __a, pointer __p)
161  { __a.destroy(__p); }
162 
163  __attribute__((__always_inline__))
164  static size_type max_size(const _Alloc& __a)
165  { return __a.max_size(); }
166 
167  __attribute__((__always_inline__))
168  static const _Alloc& _S_select_on_copy(const _Alloc& __a) { return __a; }
169 
170  __attribute__((__always_inline__))
171  static void _S_on_swap(_Alloc& __a, _Alloc& __b)
172  {
173  // _GLIBCXX_RESOLVE_LIB_DEFECTS
174  // 431. Swapping containers with unequal allocators.
175  std::__alloc_swap<_Alloc>::_S_do_it(__a, __b);
176  }
177 
178  template<typename _Tp>
179  struct rebind
180  { typedef typename _Alloc::template rebind<_Tp>::other other; };
181 #endif // C++11
182  };
183 
184 _GLIBCXX_END_NAMESPACE_VERSION
185 } // namespace __gnu_cxx
186 
187 #endif
GNU extensions for public use.
Uniform interface to all allocator types.
__detected_or_t< value_type *, __pointer, _Alloc > pointer
The allocator's pointer type.
typename _Size< _Alloc, difference_type >::type size_type
The allocator's size type.
typename _Diff< _Alloc, pointer >::type difference_type
The allocator's difference type.
typename _Ptr< __c_pointer, const value_type >::type const_pointer
The allocator's const pointer type.
_Alloc::value_type value_type
The allocated type.
_Alloc allocator_type
The allocator type.
Uniform interface to C++98 and C++11 allocators.