1 | // Allocators -*- C++ -*- |
2 | |
3 | // Copyright (C) 2001-2024 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 | |
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 | namespace std _GLIBCXX_VISIBILITY(default) |
53 | { |
54 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
55 | |
56 | /** |
57 | * @addtogroup allocators |
58 | * @{ |
59 | */ |
60 | |
61 | // Since C++20 the primary template should be used for allocator<void>, |
62 | // but then it would have a non-trivial default ctor and dtor for C++20, |
63 | // but trivial for C++98-17, which would be an ABI incompatibility between |
64 | // different standard dialects. So C++20 still uses the allocator<void> |
65 | // explicit specialization, with the historical ABI properties, but with |
66 | // the same members that are present in the primary template. |
67 | |
68 | /** std::allocator<void> specialization. |
69 | * |
70 | * @headerfile memory |
71 | */ |
72 | template<> |
73 | class allocator<void> |
74 | { |
75 | public: |
76 | typedef void value_type; |
77 | typedef size_t size_type; |
78 | typedef ptrdiff_t difference_type; |
79 | |
80 | #if __cplusplus <= 201703L |
81 | // These were removed for C++20, allocator_traits does the right thing. |
82 | typedef void* pointer; |
83 | typedef const void* const_pointer; |
84 | |
85 | template<typename _Tp1> |
86 | struct rebind |
87 | { typedef allocator<_Tp1> other; }; |
88 | #endif |
89 | |
90 | #if __cplusplus >= 201103L |
91 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
92 | // 2103. std::allocator propagate_on_container_move_assignment |
93 | using propagate_on_container_move_assignment = true_type; |
94 | |
95 | using is_always_equal |
96 | _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal" ) |
97 | = true_type; |
98 | |
99 | #if __cplusplus >= 202002L |
100 | // As noted above, these members are present for C++20 to provide the |
101 | // same API as the primary template, but still trivial as in pre-C++20. |
102 | allocator() = default; |
103 | ~allocator() = default; |
104 | |
105 | template<typename _Up> |
106 | __attribute__((__always_inline__)) |
107 | constexpr |
108 | allocator(const allocator<_Up>&) noexcept { } |
109 | |
110 | // No allocate member because it's ill-formed by LWG 3307. |
111 | // No deallocate member because it would be undefined to call it |
112 | // with any pointer which wasn't obtained from allocate. |
113 | #endif // C++20 |
114 | #endif // C++11 |
115 | }; |
116 | |
117 | /** |
118 | * @brief The @a standard allocator, as per C++03 [20.4.1]. |
119 | * |
120 | * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator |
121 | * for further details. |
122 | * |
123 | * @tparam _Tp Type of allocated object. |
124 | * |
125 | * @headerfile memory |
126 | */ |
127 | template<typename _Tp> |
128 | class allocator : public __allocator_base<_Tp> |
129 | { |
130 | public: |
131 | typedef _Tp value_type; |
132 | typedef size_t size_type; |
133 | typedef ptrdiff_t difference_type; |
134 | |
135 | #if __cplusplus <= 201703L |
136 | // These were removed for C++20. |
137 | typedef _Tp* pointer; |
138 | typedef const _Tp* const_pointer; |
139 | typedef _Tp& reference; |
140 | typedef const _Tp& const_reference; |
141 | |
142 | template<typename _Tp1> |
143 | struct rebind |
144 | { typedef allocator<_Tp1> other; }; |
145 | #endif |
146 | |
147 | #if __cplusplus >= 201103L |
148 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
149 | // 2103. std::allocator propagate_on_container_move_assignment |
150 | using propagate_on_container_move_assignment = true_type; |
151 | |
152 | using is_always_equal |
153 | _GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal" ) |
154 | = true_type; |
155 | #endif |
156 | |
157 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
158 | // 3035. std::allocator's constructors should be constexpr |
159 | __attribute__((__always_inline__)) |
160 | _GLIBCXX20_CONSTEXPR |
161 | allocator() _GLIBCXX_NOTHROW { } |
162 | |
163 | __attribute__((__always_inline__)) |
164 | _GLIBCXX20_CONSTEXPR |
165 | allocator(const allocator& __a) _GLIBCXX_NOTHROW |
166 | : __allocator_base<_Tp>(__a) { } |
167 | |
168 | #if __cplusplus >= 201103L |
169 | // Avoid implicit deprecation. |
170 | allocator& operator=(const allocator&) = default; |
171 | #endif |
172 | |
173 | template<typename _Tp1> |
174 | __attribute__((__always_inline__)) |
175 | _GLIBCXX20_CONSTEXPR |
176 | allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { } |
177 | |
178 | __attribute__((__always_inline__)) |
179 | #if __cpp_constexpr_dynamic_alloc |
180 | constexpr |
181 | #endif |
182 | ~allocator() _GLIBCXX_NOTHROW { } |
183 | |
184 | #if __cplusplus > 201703L |
185 | [[nodiscard,__gnu__::__always_inline__]] |
186 | constexpr _Tp* |
187 | allocate(size_t __n) |
188 | { |
189 | if (std::__is_constant_evaluated()) |
190 | { |
191 | if (__builtin_mul_overflow(__n, sizeof(_Tp), &__n)) |
192 | std::__throw_bad_array_new_length(); |
193 | return static_cast<_Tp*>(::operator new(__n)); |
194 | } |
195 | |
196 | return __allocator_base<_Tp>::allocate(__n, 0); |
197 | } |
198 | |
199 | [[__gnu__::__always_inline__]] |
200 | constexpr void |
201 | deallocate(_Tp* __p, size_t __n) |
202 | { |
203 | if (std::__is_constant_evaluated()) |
204 | { |
205 | ::operator delete(__p); |
206 | return; |
207 | } |
208 | __allocator_base<_Tp>::deallocate(__p, __n); |
209 | } |
210 | #endif // C++20 |
211 | |
212 | friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR |
213 | bool |
214 | operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW |
215 | { return true; } |
216 | |
217 | #if __cpp_impl_three_way_comparison < 201907L |
218 | friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR |
219 | bool |
220 | operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW |
221 | { return false; } |
222 | #endif |
223 | |
224 | // Inherit everything else. |
225 | }; |
226 | |
227 | /** Equality comparison for std::allocator objects |
228 | * |
229 | * @return true, for all std::allocator objects. |
230 | * @relates std::allocator |
231 | */ |
232 | template<typename _T1, typename _T2> |
233 | __attribute__((__always_inline__)) |
234 | inline _GLIBCXX20_CONSTEXPR bool |
235 | operator==(const allocator<_T1>&, const allocator<_T2>&) |
236 | _GLIBCXX_NOTHROW |
237 | { return true; } |
238 | |
239 | #if __cpp_impl_three_way_comparison < 201907L |
240 | template<typename _T1, typename _T2> |
241 | __attribute__((__always_inline__)) |
242 | inline _GLIBCXX20_CONSTEXPR bool |
243 | operator!=(const allocator<_T1>&, const allocator<_T2>&) |
244 | _GLIBCXX_NOTHROW |
245 | { return false; } |
246 | #endif |
247 | |
248 | /// @cond undocumented |
249 | |
250 | // Invalid allocator<cv T> partial specializations. |
251 | // allocator_traits::rebind_alloc can be used to form a valid allocator type. |
252 | template<typename _Tp> |
253 | class allocator<const _Tp> |
254 | { |
255 | public: |
256 | typedef _Tp value_type; |
257 | allocator() { } |
258 | template<typename _Up> allocator(const allocator<_Up>&) { } |
259 | }; |
260 | |
261 | template<typename _Tp> |
262 | class allocator<volatile _Tp> |
263 | { |
264 | public: |
265 | typedef _Tp value_type; |
266 | allocator() { } |
267 | template<typename _Up> allocator(const allocator<_Up>&) { } |
268 | }; |
269 | |
270 | template<typename _Tp> |
271 | class allocator<const volatile _Tp> |
272 | { |
273 | public: |
274 | typedef _Tp value_type; |
275 | allocator() { } |
276 | template<typename _Up> allocator(const allocator<_Up>&) { } |
277 | }; |
278 | /// @endcond |
279 | |
280 | /// @} group allocator |
281 | |
282 | // Inhibit implicit instantiations for required instantiations, |
283 | // which are defined via explicit instantiations elsewhere. |
284 | #if _GLIBCXX_EXTERN_TEMPLATE |
285 | extern template class allocator<char>; |
286 | extern template class allocator<wchar_t>; |
287 | #endif |
288 | |
289 | // Undefine. |
290 | #undef __allocator_base |
291 | |
292 | _GLIBCXX_END_NAMESPACE_VERSION |
293 | } // namespace std |
294 | |
295 | #endif |
296 | |