1// Allocators -*- C++ -*-
2
3// Copyright (C) 2001-2019 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/*
26 * Copyright (c) 1996-1997
27 * Silicon Graphics Computer Systems, Inc.
28 *
29 * Permission to use, copy, modify, distribute and sell this software
30 * and its documentation for any purpose is hereby granted without fee,
31 * provided that the above copyright notice appear in all copies and
32 * that both that copyright notice and this permission notice appear
33 * in supporting documentation. Silicon Graphics makes no
34 * representations about the suitability of this software for any
35 * purpose. It is provided "as is" without express or implied warranty.
36 */
37
38/** @file bits/allocator.h
39 * This is an internal header file, included by other library headers.
40 * Do not attempt to use it directly. @headername{memory}
41 */
42
43#ifndef _ALLOCATOR_H
44#define _ALLOCATOR_H 1
45
46#include <bits/c++allocator.h> // Define the base class to std::allocator.
47#include <bits/memoryfwd.h>
48#if __cplusplus >= 201103L
49#include <type_traits>
50#endif
51
52#define __cpp_lib_incomplete_container_elements 201505
53#if __cplusplus >= 201103L
54# define __cpp_lib_allocator_is_always_equal 201411
55#endif
56
57namespace std _GLIBCXX_VISIBILITY(default)
58{
59_GLIBCXX_BEGIN_NAMESPACE_VERSION
60
61 /**
62 * @addtogroup allocators
63 * @{
64 */
65
66 /// allocator<void> specialization.
67 template<>
68 class allocator<void>
69 {
70 public:
71 typedef size_t size_type;
72 typedef ptrdiff_t difference_type;
73 typedef void* pointer;
74 typedef const void* const_pointer;
75 typedef void value_type;
76
77 template<typename _Tp1>
78 struct rebind
79 { typedef allocator<_Tp1> other; };
80
81#if __cplusplus >= 201103L
82 // _GLIBCXX_RESOLVE_LIB_DEFECTS
83 // 2103. std::allocator propagate_on_container_move_assignment
84 typedef true_type propagate_on_container_move_assignment;
85
86 typedef true_type is_always_equal;
87
88 template<typename _Up, typename... _Args>
89 void
90 construct(_Up* __p, _Args&&... __args)
91 noexcept(noexcept(::new((void *)__p)
92 _Up(std::forward<_Args>(__args)...)))
93 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
94
95 template<typename _Up>
96 void
97 destroy(_Up* __p)
98 noexcept(noexcept(__p->~_Up()))
99 { __p->~_Up(); }
100#endif
101 };
102
103 /**
104 * @brief The @a standard allocator, as per [20.4].
105 *
106 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
107 * for further details.
108 *
109 * @tparam _Tp Type of allocated object.
110 */
111 template<typename _Tp>
112 class allocator : public __allocator_base<_Tp>
113 {
114 public:
115 typedef size_t size_type;
116 typedef ptrdiff_t difference_type;
117 typedef _Tp* pointer;
118 typedef const _Tp* const_pointer;
119 typedef _Tp& reference;
120 typedef const _Tp& const_reference;
121 typedef _Tp value_type;
122
123 template<typename _Tp1>
124 struct rebind
125 { typedef allocator<_Tp1> other; };
126
127#if __cplusplus >= 201103L
128 // _GLIBCXX_RESOLVE_LIB_DEFECTS
129 // 2103. std::allocator propagate_on_container_move_assignment
130 typedef true_type propagate_on_container_move_assignment;
131
132 typedef true_type is_always_equal;
133#endif
134
135 // _GLIBCXX_RESOLVE_LIB_DEFECTS
136 // 3035. std::allocator's constructors should be constexpr
137 _GLIBCXX20_CONSTEXPR
138 allocator() _GLIBCXX_NOTHROW { }
139
140 _GLIBCXX20_CONSTEXPR
141 allocator(const allocator& __a) _GLIBCXX_NOTHROW
142 : __allocator_base<_Tp>(__a) { }
143
144#if __cplusplus >= 201103L
145 // Avoid implicit deprecation.
146 allocator& operator=(const allocator&) = default;
147#endif
148
149 template<typename _Tp1>
150 _GLIBCXX20_CONSTEXPR
151 allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { }
152
153 ~allocator() _GLIBCXX_NOTHROW { }
154
155 friend bool
156 operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
157 { return true; }
158
159 friend bool
160 operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW
161 { return false; }
162
163 // Inherit everything else.
164 };
165
166 template<typename _T1, typename _T2>
167 inline bool
168 operator==(const allocator<_T1>&, const allocator<_T2>&)
169 _GLIBCXX_NOTHROW
170 { return true; }
171
172 template<typename _T1, typename _T2>
173 inline bool
174 operator!=(const allocator<_T1>&, const allocator<_T2>&)
175 _GLIBCXX_NOTHROW
176 { return false; }
177
178 // Invalid allocator<cv T> partial specializations.
179 // allocator_traits::rebind_alloc can be used to form a valid allocator type.
180 template<typename _Tp>
181 class allocator<const _Tp>
182 {
183 public:
184 typedef _Tp value_type;
185 template<typename _Up> allocator(const allocator<_Up>&) { }
186 };
187
188 template<typename _Tp>
189 class allocator<volatile _Tp>
190 {
191 public:
192 typedef _Tp value_type;
193 template<typename _Up> allocator(const allocator<_Up>&) { }
194 };
195
196 template<typename _Tp>
197 class allocator<const volatile _Tp>
198 {
199 public:
200 typedef _Tp value_type;
201 template<typename _Up> allocator(const allocator<_Up>&) { }
202 };
203
204 /// @} group allocator
205
206 // Inhibit implicit instantiations for required instantiations,
207 // which are defined via explicit instantiations elsewhere.
208#if _GLIBCXX_EXTERN_TEMPLATE
209 extern template class allocator<char>;
210 extern template class allocator<wchar_t>;
211#endif
212
213 // Undefine.
214#undef __allocator_base
215
216 // To implement Option 3 of DR 431.
217 template<typename _Alloc, bool = __is_empty(_Alloc)>
218 struct __alloc_swap
219 { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
220
221 template<typename _Alloc>
222 struct __alloc_swap<_Alloc, false>
223 {
224 static void
225 _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
226 {
227 // Precondition: swappable allocators.
228 if (__one != __two)
229 swap(__one, __two);
230 }
231 };
232
233 // Optimize for stateless allocators.
234 template<typename _Alloc, bool = __is_empty(_Alloc)>
235 struct __alloc_neq
236 {
237 static bool
238 _S_do_it(const _Alloc&, const _Alloc&)
239 { return false; }
240 };
241
242 template<typename _Alloc>
243 struct __alloc_neq<_Alloc, false>
244 {
245 static bool
246 _S_do_it(const _Alloc& __one, const _Alloc& __two)
247 { return __one != __two; }
248 };
249
250#if __cplusplus >= 201103L
251 template<typename _Tp, bool
252 = __or_<is_copy_constructible<typename _Tp::value_type>,
253 is_nothrow_move_constructible<typename _Tp::value_type>>::value>
254 struct __shrink_to_fit_aux
255 { static bool _S_do_it(_Tp&) noexcept { return false; } };
256
257 template<typename _Tp>
258 struct __shrink_to_fit_aux<_Tp, true>
259 {
260 static bool
261 _S_do_it(_Tp& __c) noexcept
262 {
263#if __cpp_exceptions
264 try
265 {
266 _Tp(__make_move_if_noexcept_iterator(__c.begin()),
267 __make_move_if_noexcept_iterator(__c.end()),
268 __c.get_allocator()).swap(__c);
269 return true;
270 }
271 catch(...)
272 { return false; }
273#else
274 return false;
275#endif
276 }
277 };
278#endif
279
280_GLIBCXX_END_NAMESPACE_VERSION
281} // namespace std
282
283#endif
284