1 | // shared_ptr and weak_ptr implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2007-2024 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 | // GCC Note: Based on files from version 1.32.0 of the Boost library. |
26 | |
27 | // shared_count.hpp |
28 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. |
29 | |
30 | // shared_ptr.hpp |
31 | // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes. |
32 | // Copyright (C) 2001, 2002, 2003 Peter Dimov |
33 | |
34 | // weak_ptr.hpp |
35 | // Copyright (C) 2001, 2002, 2003 Peter Dimov |
36 | |
37 | // enable_shared_from_this.hpp |
38 | // Copyright (C) 2002 Peter Dimov |
39 | |
40 | // Distributed under the Boost Software License, Version 1.0. (See |
41 | // accompanying file LICENSE_1_0.txt or copy at |
42 | // http://www.boost.org/LICENSE_1_0.txt) |
43 | |
44 | /** @file |
45 | * This is an internal header file, included by other library headers. |
46 | * Do not attempt to use it directly. @headername{memory} |
47 | */ |
48 | |
49 | #ifndef _SHARED_PTR_H |
50 | #define _SHARED_PTR_H 1 |
51 | |
52 | #include <iosfwd> // std::basic_ostream |
53 | #include <bits/shared_ptr_base.h> |
54 | |
55 | namespace std _GLIBCXX_VISIBILITY(default) |
56 | { |
57 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
58 | |
59 | /** |
60 | * @addtogroup pointer_abstractions |
61 | * @{ |
62 | */ |
63 | |
64 | // 20.7.2.2.11 shared_ptr I/O |
65 | |
66 | /// Write the stored pointer to an ostream. |
67 | /// @relates shared_ptr |
68 | template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp> |
69 | inline std::basic_ostream<_Ch, _Tr>& |
70 | operator<<(std::basic_ostream<_Ch, _Tr>& __os, |
71 | const __shared_ptr<_Tp, _Lp>& __p) |
72 | { |
73 | __os << __p.get(); |
74 | return __os; |
75 | } |
76 | |
77 | template<typename _Del, typename _Tp, _Lock_policy _Lp> |
78 | inline _Del* |
79 | get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept |
80 | { |
81 | #if __cpp_rtti |
82 | return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); |
83 | #else |
84 | return 0; |
85 | #endif |
86 | } |
87 | |
88 | /// 20.7.2.2.10 shared_ptr get_deleter |
89 | |
90 | /// If `__p` has a deleter of type `_Del`, return a pointer to it. |
91 | /// @relates shared_ptr |
92 | template<typename _Del, typename _Tp> |
93 | inline _Del* |
94 | get_deleter(const shared_ptr<_Tp>& __p) noexcept |
95 | { |
96 | #if __cpp_rtti |
97 | return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); |
98 | #else |
99 | return 0; |
100 | #endif |
101 | } |
102 | |
103 | /// @cond undocumented |
104 | |
105 | // Constraint for overloads taking non-array types. |
106 | #if __cpp_concepts && __glibcxx_type_trait_variable_templates |
107 | template<typename _Tp> |
108 | requires (!is_array_v<_Tp>) |
109 | using _NonArray = _Tp; |
110 | #else |
111 | template<typename _Tp> |
112 | using _NonArray = __enable_if_t<!is_array<_Tp>::value, _Tp>; |
113 | #endif |
114 | |
115 | #if __glibcxx_shared_ptr_arrays >= 201707L |
116 | // Constraint for overloads taking array types with unknown bound, U[]. |
117 | #if __cpp_concepts |
118 | template<typename _Tp> |
119 | requires is_array_v<_Tp> && (extent_v<_Tp> == 0) |
120 | using _UnboundedArray = _Tp; |
121 | #else |
122 | template<typename _Tp> |
123 | using _UnboundedArray |
124 | = __enable_if_t<__is_array_unknown_bounds<_Tp>::value, _Tp>; |
125 | #endif |
126 | |
127 | // Constraint for overloads taking array types with known bound, U[N]. |
128 | #if __cpp_concepts |
129 | template<typename _Tp> |
130 | requires (extent_v<_Tp> != 0) |
131 | using _BoundedArray = _Tp; |
132 | #else |
133 | template<typename _Tp> |
134 | using _BoundedArray |
135 | = __enable_if_t<__is_array_known_bounds<_Tp>::value, _Tp>; |
136 | #endif |
137 | |
138 | #if __glibcxx_smart_ptr_for_overwrite |
139 | // Constraint for overloads taking either non-array or bounded array, U[N]. |
140 | #if __cpp_concepts |
141 | template<typename _Tp> |
142 | requires (!is_array_v<_Tp>) || (extent_v<_Tp> != 0) |
143 | using _NotUnboundedArray = _Tp; |
144 | #else |
145 | template<typename _Tp> |
146 | using _NotUnboundedArray |
147 | = __enable_if_t<!__is_array_unknown_bounds<_Tp>::value, _Tp>; |
148 | #endif |
149 | #endif // smart_ptr_for_overwrite |
150 | #endif // shared_ptr_arrays |
151 | |
152 | /// @endcond |
153 | |
154 | /** |
155 | * @brief A smart pointer with reference-counted copy semantics. |
156 | * @headerfile memory |
157 | * @since C++11 |
158 | * |
159 | * A `shared_ptr` object is either empty or _owns_ a pointer passed |
160 | * to the constructor. Copies of a `shared_ptr` share ownership of |
161 | * the same pointer. When the last `shared_ptr` that owns the pointer |
162 | * is destroyed or reset, the owned pointer is freed (either by `delete` |
163 | * or by invoking a custom deleter that was passed to the constructor). |
164 | * |
165 | * A `shared_ptr` also stores another pointer, which is usually |
166 | * (but not always) the same pointer as it owns. The stored pointer |
167 | * can be retrieved by calling the `get()` member function. |
168 | * |
169 | * The equality and relational operators for `shared_ptr` only compare |
170 | * the stored pointer returned by `get()`, not the owned pointer. |
171 | * To test whether two `shared_ptr` objects share ownership of the same |
172 | * pointer see `std::shared_ptr::owner_before` and `std::owner_less`. |
173 | */ |
174 | template<typename _Tp> |
175 | class shared_ptr : public __shared_ptr<_Tp> |
176 | { |
177 | template<typename... _Args> |
178 | using _Constructible = typename enable_if< |
179 | is_constructible<__shared_ptr<_Tp>, _Args...>::value |
180 | >::type; |
181 | |
182 | template<typename _Arg> |
183 | using _Assignable = typename enable_if< |
184 | is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& |
185 | >::type; |
186 | |
187 | public: |
188 | |
189 | /// The type pointed to by the stored pointer, remove_extent_t<_Tp> |
190 | using element_type = typename __shared_ptr<_Tp>::element_type; |
191 | |
192 | #ifdef __glibcxx_shared_ptr_weak_type // C++ >= 17 && HOSTED |
193 | /// The corresponding weak_ptr type for this shared_ptr |
194 | /// @since C++17 |
195 | using weak_type = weak_ptr<_Tp>; |
196 | #endif |
197 | /** |
198 | * @brief Construct an empty %shared_ptr. |
199 | * @post use_count()==0 && get()==0 |
200 | */ |
201 | constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } |
202 | |
203 | shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor |
204 | |
205 | /** |
206 | * @brief Construct a %shared_ptr that owns the pointer @a __p. |
207 | * @param __p A pointer that is convertible to element_type*. |
208 | * @post use_count() == 1 && get() == __p |
209 | * @throw std::bad_alloc, in which case @c delete @a __p is called. |
210 | */ |
211 | template<typename _Yp, typename = _Constructible<_Yp*>> |
212 | explicit |
213 | shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } |
214 | |
215 | /** |
216 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
217 | * and the deleter @a __d. |
218 | * @param __p A pointer. |
219 | * @param __d A deleter. |
220 | * @post use_count() == 1 && get() == __p |
221 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
222 | * |
223 | * Requirements: _Deleter's copy constructor and destructor must |
224 | * not throw |
225 | * |
226 | * __shared_ptr will release __p by calling __d(__p) |
227 | */ |
228 | template<typename _Yp, typename _Deleter, |
229 | typename = _Constructible<_Yp*, _Deleter>> |
230 | shared_ptr(_Yp* __p, _Deleter __d) |
231 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
232 | |
233 | /** |
234 | * @brief Construct a %shared_ptr that owns a null pointer |
235 | * and the deleter @a __d. |
236 | * @param __p A null pointer constant. |
237 | * @param __d A deleter. |
238 | * @post use_count() == 1 && get() == __p |
239 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
240 | * |
241 | * Requirements: _Deleter's copy constructor and destructor must |
242 | * not throw |
243 | * |
244 | * The last owner will call __d(__p) |
245 | */ |
246 | template<typename _Deleter> |
247 | shared_ptr(nullptr_t __p, _Deleter __d) |
248 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
249 | |
250 | /** |
251 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
252 | * and the deleter @a __d. |
253 | * @param __p A pointer. |
254 | * @param __d A deleter. |
255 | * @param __a An allocator. |
256 | * @post use_count() == 1 && get() == __p |
257 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
258 | * |
259 | * Requirements: _Deleter's copy constructor and destructor must |
260 | * not throw _Alloc's copy constructor and destructor must not |
261 | * throw. |
262 | * |
263 | * __shared_ptr will release __p by calling __d(__p) |
264 | */ |
265 | template<typename _Yp, typename _Deleter, typename _Alloc, |
266 | typename = _Constructible<_Yp*, _Deleter, _Alloc>> |
267 | shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) |
268 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
269 | |
270 | /** |
271 | * @brief Construct a %shared_ptr that owns a null pointer |
272 | * and the deleter @a __d. |
273 | * @param __p A null pointer constant. |
274 | * @param __d A deleter. |
275 | * @param __a An allocator. |
276 | * @post use_count() == 1 && get() == __p |
277 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
278 | * |
279 | * Requirements: _Deleter's copy constructor and destructor must |
280 | * not throw _Alloc's copy constructor and destructor must not |
281 | * throw. |
282 | * |
283 | * The last owner will call __d(__p) |
284 | */ |
285 | template<typename _Deleter, typename _Alloc> |
286 | shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) |
287 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
288 | |
289 | // Aliasing constructor |
290 | |
291 | /** |
292 | * @brief Constructs a `shared_ptr` instance that stores `__p` |
293 | * and shares ownership with `__r`. |
294 | * @param __r A `shared_ptr`. |
295 | * @param __p A pointer that will remain valid while `*__r` is valid. |
296 | * @post `get() == __p && use_count() == __r.use_count()` |
297 | * |
298 | * This can be used to construct a `shared_ptr` to a sub-object |
299 | * of an object managed by an existing `shared_ptr`. The complete |
300 | * object will remain valid while any `shared_ptr` owns it, even |
301 | * if they don't store a pointer to the complete object. |
302 | * |
303 | * @code |
304 | * shared_ptr<pair<int,int>> pii(new pair<int,int>()); |
305 | * shared_ptr<int> pi(pii, &pii->first); |
306 | * assert(pii.use_count() == 2); |
307 | * @endcode |
308 | */ |
309 | template<typename _Yp> |
310 | shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept |
311 | : __shared_ptr<_Tp>(__r, __p) { } |
312 | |
313 | #if __cplusplus > 201703L |
314 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
315 | // 2996. Missing rvalue overloads for shared_ptr operations |
316 | /** |
317 | * @brief Constructs a `shared_ptr` instance that stores `__p` |
318 | * and shares ownership with `__r`. |
319 | * @param __r A `shared_ptr`. |
320 | * @param __p A pointer that will remain valid while `*__r` is valid. |
321 | * @post `get() == __p && !__r.use_count() && !__r.get()` |
322 | * @since C++17 |
323 | * |
324 | * This can be used to construct a `shared_ptr` to a sub-object |
325 | * of an object managed by an existing `shared_ptr`. The complete |
326 | * object will remain valid while any `shared_ptr` owns it, even |
327 | * if they don't store a pointer to the complete object. |
328 | * |
329 | * @code |
330 | * shared_ptr<pair<int,int>> pii(new pair<int,int>()); |
331 | * shared_ptr<int> pi1(pii, &pii->first); |
332 | * assert(pii.use_count() == 2); |
333 | * shared_ptr<int> pi2(std::move(pii), &pii->second); |
334 | * assert(pii.use_count() == 0); |
335 | * @endcode |
336 | */ |
337 | template<typename _Yp> |
338 | shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept |
339 | : __shared_ptr<_Tp>(std::move(__r), __p) { } |
340 | #endif |
341 | /** |
342 | * @brief If @a __r is empty, constructs an empty %shared_ptr; |
343 | * otherwise construct a %shared_ptr that shares ownership |
344 | * with @a __r. |
345 | * @param __r A %shared_ptr. |
346 | * @post get() == __r.get() && use_count() == __r.use_count() |
347 | */ |
348 | template<typename _Yp, |
349 | typename = _Constructible<const shared_ptr<_Yp>&>> |
350 | shared_ptr(const shared_ptr<_Yp>& __r) noexcept |
351 | : __shared_ptr<_Tp>(__r) { } |
352 | |
353 | /** |
354 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
355 | * @param __r A %shared_ptr rvalue. |
356 | * @post *this contains the old value of @a __r, @a __r is empty. |
357 | */ |
358 | shared_ptr(shared_ptr&& __r) noexcept |
359 | : __shared_ptr<_Tp>(std::move(__r)) { } |
360 | |
361 | /** |
362 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
363 | * @param __r A %shared_ptr rvalue. |
364 | * @post *this contains the old value of @a __r, @a __r is empty. |
365 | */ |
366 | template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> |
367 | shared_ptr(shared_ptr<_Yp>&& __r) noexcept |
368 | : __shared_ptr<_Tp>(std::move(__r)) { } |
369 | |
370 | /** |
371 | * @brief Constructs a %shared_ptr that shares ownership with @a __r |
372 | * and stores a copy of the pointer stored in @a __r. |
373 | * @param __r A weak_ptr. |
374 | * @post use_count() == __r.use_count() |
375 | * @throw bad_weak_ptr when __r.expired(), |
376 | * in which case the constructor has no effect. |
377 | */ |
378 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
379 | explicit shared_ptr(const weak_ptr<_Yp>& __r) |
380 | : __shared_ptr<_Tp>(__r) { } |
381 | |
382 | #if _GLIBCXX_USE_DEPRECATED |
383 | #pragma GCC diagnostic push |
384 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
385 | template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> |
386 | shared_ptr(auto_ptr<_Yp>&& __r); |
387 | #pragma GCC diagnostic pop |
388 | #endif |
389 | |
390 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
391 | // 2399. shared_ptr's constructor from unique_ptr should be constrained |
392 | template<typename _Yp, typename _Del, |
393 | typename = _Constructible<unique_ptr<_Yp, _Del>>> |
394 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
395 | : __shared_ptr<_Tp>(std::move(__r)) { } |
396 | |
397 | #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED |
398 | // This non-standard constructor exists to support conversions that |
399 | // were possible in C++11 and C++14 but are ill-formed in C++17. |
400 | // If an exception is thrown this constructor has no effect. |
401 | template<typename _Yp, typename _Del, |
402 | _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> |
403 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
404 | : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } |
405 | #endif |
406 | |
407 | /** |
408 | * @brief Construct an empty %shared_ptr. |
409 | * @post use_count() == 0 && get() == nullptr |
410 | */ |
411 | constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } |
412 | |
413 | shared_ptr& operator=(const shared_ptr&) noexcept = default; |
414 | |
415 | template<typename _Yp> |
416 | _Assignable<const shared_ptr<_Yp>&> |
417 | operator=(const shared_ptr<_Yp>& __r) noexcept |
418 | { |
419 | this->__shared_ptr<_Tp>::operator=(__r); |
420 | return *this; |
421 | } |
422 | |
423 | #if _GLIBCXX_USE_DEPRECATED |
424 | #pragma GCC diagnostic push |
425 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
426 | template<typename _Yp> |
427 | _Assignable<auto_ptr<_Yp>> |
428 | operator=(auto_ptr<_Yp>&& __r) |
429 | { |
430 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
431 | return *this; |
432 | } |
433 | #pragma GCC diagnostic pop |
434 | #endif |
435 | |
436 | shared_ptr& |
437 | operator=(shared_ptr&& __r) noexcept |
438 | { |
439 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
440 | return *this; |
441 | } |
442 | |
443 | template<class _Yp> |
444 | _Assignable<shared_ptr<_Yp>> |
445 | operator=(shared_ptr<_Yp>&& __r) noexcept |
446 | { |
447 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
448 | return *this; |
449 | } |
450 | |
451 | template<typename _Yp, typename _Del> |
452 | _Assignable<unique_ptr<_Yp, _Del>> |
453 | operator=(unique_ptr<_Yp, _Del>&& __r) |
454 | { |
455 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
456 | return *this; |
457 | } |
458 | |
459 | private: |
460 | // This constructor is non-standard, it is used by allocate_shared. |
461 | template<typename _Alloc, typename... _Args> |
462 | shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args) |
463 | : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...) |
464 | { } |
465 | |
466 | template<typename _Yp, typename _Alloc, typename... _Args> |
467 | friend shared_ptr<_NonArray<_Yp>> |
468 | allocate_shared(const _Alloc&, _Args&&...); |
469 | |
470 | template<typename _Yp, typename... _Args> |
471 | friend shared_ptr<_NonArray<_Yp>> |
472 | make_shared(_Args&&...); |
473 | |
474 | #if __glibcxx_shared_ptr_arrays >= 201707L |
475 | // This constructor is non-standard, it is used by allocate_shared<T[]>. |
476 | template<typename _Alloc, typename _Init = const remove_extent_t<_Tp>*> |
477 | shared_ptr(const _Sp_counted_array_base<_Alloc>& __a, |
478 | _Init __init = nullptr) |
479 | : __shared_ptr<_Tp>(__a, __init) |
480 | { } |
481 | |
482 | template<typename _Yp, typename _Alloc> |
483 | friend shared_ptr<_UnboundedArray<_Yp>> |
484 | allocate_shared(const _Alloc&, size_t); |
485 | |
486 | template<typename _Yp> |
487 | friend shared_ptr<_UnboundedArray<_Yp>> |
488 | make_shared(size_t); |
489 | |
490 | template<typename _Yp, typename _Alloc> |
491 | friend shared_ptr<_UnboundedArray<_Yp>> |
492 | allocate_shared(const _Alloc&, size_t, const remove_extent_t<_Yp>&); |
493 | |
494 | template<typename _Yp> |
495 | friend shared_ptr<_UnboundedArray<_Yp>> |
496 | make_shared(size_t, const remove_extent_t<_Yp>&); |
497 | |
498 | template<typename _Yp, typename _Alloc> |
499 | friend shared_ptr<_BoundedArray<_Yp>> |
500 | allocate_shared(const _Alloc&); |
501 | |
502 | template<typename _Yp> |
503 | friend shared_ptr<_BoundedArray<_Yp>> |
504 | make_shared(); |
505 | |
506 | template<typename _Yp, typename _Alloc> |
507 | friend shared_ptr<_BoundedArray<_Yp>> |
508 | allocate_shared(const _Alloc&, const remove_extent_t<_Yp>&); |
509 | |
510 | template<typename _Yp> |
511 | friend shared_ptr<_BoundedArray<_Yp>> |
512 | make_shared(const remove_extent_t<_Yp>&); |
513 | |
514 | #if __glibcxx_smart_ptr_for_overwrite |
515 | template<typename _Yp, typename _Alloc> |
516 | friend shared_ptr<_NotUnboundedArray<_Yp>> |
517 | allocate_shared_for_overwrite(const _Alloc&); |
518 | |
519 | template<typename _Yp> |
520 | friend shared_ptr<_NotUnboundedArray<_Yp>> |
521 | make_shared_for_overwrite(); |
522 | |
523 | template<typename _Yp, typename _Alloc> |
524 | friend shared_ptr<_UnboundedArray<_Yp>> |
525 | allocate_shared_for_overwrite(const _Alloc&, size_t); |
526 | |
527 | template<typename _Yp> |
528 | friend shared_ptr<_UnboundedArray<_Yp>> |
529 | make_shared_for_overwrite(size_t); |
530 | #endif |
531 | #endif |
532 | |
533 | // This constructor is non-standard, it is used by weak_ptr::lock(). |
534 | shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept |
535 | : __shared_ptr<_Tp>(__r, std::nothrow) { } |
536 | |
537 | friend class weak_ptr<_Tp>; |
538 | }; |
539 | |
540 | #if __cpp_deduction_guides >= 201606 |
541 | template<typename _Tp> |
542 | shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; |
543 | template<typename _Tp, typename _Del> |
544 | shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; |
545 | #endif |
546 | |
547 | // 20.7.2.2.7 shared_ptr comparisons |
548 | |
549 | /// @relates shared_ptr @{ |
550 | |
551 | /// Equality operator for shared_ptr objects, compares the stored pointers |
552 | template<typename _Tp, typename _Up> |
553 | _GLIBCXX_NODISCARD inline bool |
554 | operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
555 | { return __a.get() == __b.get(); } |
556 | |
557 | /// shared_ptr comparison with nullptr |
558 | template<typename _Tp> |
559 | _GLIBCXX_NODISCARD inline bool |
560 | operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
561 | { return !__a; } |
562 | |
563 | #ifdef __cpp_lib_three_way_comparison |
564 | template<typename _Tp, typename _Up> |
565 | inline strong_ordering |
566 | operator<=>(const shared_ptr<_Tp>& __a, |
567 | const shared_ptr<_Up>& __b) noexcept |
568 | { return compare_three_way()(__a.get(), __b.get()); } |
569 | |
570 | template<typename _Tp> |
571 | inline strong_ordering |
572 | operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
573 | { |
574 | using pointer = typename shared_ptr<_Tp>::element_type*; |
575 | return compare_three_way()(__a.get(), static_cast<pointer>(nullptr)); |
576 | } |
577 | #else |
578 | /// shared_ptr comparison with nullptr |
579 | template<typename _Tp> |
580 | _GLIBCXX_NODISCARD inline bool |
581 | operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
582 | { return !__a; } |
583 | |
584 | /// Inequality operator for shared_ptr objects, compares the stored pointers |
585 | template<typename _Tp, typename _Up> |
586 | _GLIBCXX_NODISCARD inline bool |
587 | operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
588 | { return __a.get() != __b.get(); } |
589 | |
590 | /// shared_ptr comparison with nullptr |
591 | template<typename _Tp> |
592 | _GLIBCXX_NODISCARD inline bool |
593 | operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
594 | { return (bool)__a; } |
595 | |
596 | /// shared_ptr comparison with nullptr |
597 | template<typename _Tp> |
598 | _GLIBCXX_NODISCARD inline bool |
599 | operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
600 | { return (bool)__a; } |
601 | |
602 | /// Relational operator for shared_ptr objects, compares the stored pointers |
603 | template<typename _Tp, typename _Up> |
604 | _GLIBCXX_NODISCARD inline bool |
605 | operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
606 | { |
607 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
608 | using _Up_elt = typename shared_ptr<_Up>::element_type; |
609 | using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; |
610 | return less<_Vp>()(__a.get(), __b.get()); |
611 | } |
612 | |
613 | /// shared_ptr comparison with nullptr |
614 | template<typename _Tp> |
615 | _GLIBCXX_NODISCARD inline bool |
616 | operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
617 | { |
618 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
619 | return less<_Tp_elt*>()(__a.get(), nullptr); |
620 | } |
621 | |
622 | /// shared_ptr comparison with nullptr |
623 | template<typename _Tp> |
624 | _GLIBCXX_NODISCARD inline bool |
625 | operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
626 | { |
627 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
628 | return less<_Tp_elt*>()(nullptr, __a.get()); |
629 | } |
630 | |
631 | /// Relational operator for shared_ptr objects, compares the stored pointers |
632 | template<typename _Tp, typename _Up> |
633 | _GLIBCXX_NODISCARD inline bool |
634 | operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
635 | { return !(__b < __a); } |
636 | |
637 | /// shared_ptr comparison with nullptr |
638 | template<typename _Tp> |
639 | _GLIBCXX_NODISCARD inline bool |
640 | operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
641 | { return !(nullptr < __a); } |
642 | |
643 | /// shared_ptr comparison with nullptr |
644 | template<typename _Tp> |
645 | _GLIBCXX_NODISCARD inline bool |
646 | operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
647 | { return !(__a < nullptr); } |
648 | |
649 | /// Relational operator for shared_ptr objects, compares the stored pointers |
650 | template<typename _Tp, typename _Up> |
651 | _GLIBCXX_NODISCARD inline bool |
652 | operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
653 | { return (__b < __a); } |
654 | |
655 | /// shared_ptr comparison with nullptr |
656 | template<typename _Tp> |
657 | _GLIBCXX_NODISCARD inline bool |
658 | operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
659 | { return nullptr < __a; } |
660 | |
661 | /// shared_ptr comparison with nullptr |
662 | template<typename _Tp> |
663 | _GLIBCXX_NODISCARD inline bool |
664 | operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
665 | { return __a < nullptr; } |
666 | |
667 | /// Relational operator for shared_ptr objects, compares the stored pointers |
668 | template<typename _Tp, typename _Up> |
669 | _GLIBCXX_NODISCARD inline bool |
670 | operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
671 | { return !(__a < __b); } |
672 | |
673 | /// shared_ptr comparison with nullptr |
674 | template<typename _Tp> |
675 | _GLIBCXX_NODISCARD inline bool |
676 | operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
677 | { return !(__a < nullptr); } |
678 | |
679 | /// shared_ptr comparison with nullptr |
680 | template<typename _Tp> |
681 | _GLIBCXX_NODISCARD inline bool |
682 | operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
683 | { return !(nullptr < __a); } |
684 | #endif |
685 | |
686 | // 20.7.2.2.8 shared_ptr specialized algorithms. |
687 | |
688 | /// Swap overload for shared_ptr |
689 | template<typename _Tp> |
690 | inline void |
691 | swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept |
692 | { __a.swap(__b); } |
693 | |
694 | // 20.7.2.2.9 shared_ptr casts. |
695 | |
696 | /// Convert type of `shared_ptr`, via `static_cast` |
697 | template<typename _Tp, typename _Up> |
698 | inline shared_ptr<_Tp> |
699 | static_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
700 | { |
701 | using _Sp = shared_ptr<_Tp>; |
702 | return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); |
703 | } |
704 | |
705 | /// Convert type of `shared_ptr`, via `const_cast` |
706 | template<typename _Tp, typename _Up> |
707 | inline shared_ptr<_Tp> |
708 | const_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
709 | { |
710 | using _Sp = shared_ptr<_Tp>; |
711 | return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); |
712 | } |
713 | |
714 | /// Convert type of `shared_ptr`, via `dynamic_cast` |
715 | template<typename _Tp, typename _Up> |
716 | inline shared_ptr<_Tp> |
717 | dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
718 | { |
719 | using _Sp = shared_ptr<_Tp>; |
720 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
721 | return _Sp(__r, __p); |
722 | return _Sp(); |
723 | } |
724 | |
725 | #if __cplusplus >= 201703L |
726 | /// Convert type of `shared_ptr`, via `reinterpret_cast` |
727 | /// @since C++17 |
728 | template<typename _Tp, typename _Up> |
729 | inline shared_ptr<_Tp> |
730 | reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
731 | { |
732 | using _Sp = shared_ptr<_Tp>; |
733 | return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
734 | } |
735 | |
736 | #if __cplusplus > 201703L |
737 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
738 | // 2996. Missing rvalue overloads for shared_ptr operations |
739 | |
740 | /// Convert type of `shared_ptr` rvalue, via `static_cast` |
741 | /// @since C++20 |
742 | template<typename _Tp, typename _Up> |
743 | inline shared_ptr<_Tp> |
744 | static_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
745 | { |
746 | using _Sp = shared_ptr<_Tp>; |
747 | return _Sp(std::move(__r), |
748 | static_cast<typename _Sp::element_type*>(__r.get())); |
749 | } |
750 | |
751 | /// Convert type of `shared_ptr` rvalue, via `const_cast` |
752 | /// @since C++20 |
753 | template<typename _Tp, typename _Up> |
754 | inline shared_ptr<_Tp> |
755 | const_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
756 | { |
757 | using _Sp = shared_ptr<_Tp>; |
758 | return _Sp(std::move(__r), |
759 | const_cast<typename _Sp::element_type*>(__r.get())); |
760 | } |
761 | |
762 | /// Convert type of `shared_ptr` rvalue, via `dynamic_cast` |
763 | /// @since C++20 |
764 | template<typename _Tp, typename _Up> |
765 | inline shared_ptr<_Tp> |
766 | dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
767 | { |
768 | using _Sp = shared_ptr<_Tp>; |
769 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
770 | return _Sp(std::move(__r), __p); |
771 | return _Sp(); |
772 | } |
773 | |
774 | /// Convert type of `shared_ptr` rvalue, via `reinterpret_cast` |
775 | /// @since C++20 |
776 | template<typename _Tp, typename _Up> |
777 | inline shared_ptr<_Tp> |
778 | reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
779 | { |
780 | using _Sp = shared_ptr<_Tp>; |
781 | return _Sp(std::move(__r), |
782 | reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
783 | } |
784 | #endif // C++20 |
785 | #endif // C++17 |
786 | |
787 | /// @} |
788 | |
789 | /** |
790 | * @brief A non-owning observer for a pointer owned by a shared_ptr |
791 | * @headerfile memory |
792 | * @since C++11 |
793 | * |
794 | * A weak_ptr provides a safe alternative to a raw pointer when you want |
795 | * a non-owning reference to an object that is managed by a shared_ptr. |
796 | * |
797 | * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr |
798 | * that shares ownership with every other shared_ptr that already owns |
799 | * the pointer. In other words you can upgrade from a non-owning "weak" |
800 | * reference to an owning shared_ptr, without having access to any of |
801 | * the existing shared_ptr objects. |
802 | * |
803 | * Also unlike a raw pointer, a weak_ptr does not become "dangling" after |
804 | * the object it points to has been destroyed. Instead, a weak_ptr |
805 | * becomes _expired_ and can no longer be converted to a shared_ptr that |
806 | * owns the freed pointer, so you cannot accidentally access the pointed-to |
807 | * object after it has been destroyed. |
808 | */ |
809 | template<typename _Tp> |
810 | class weak_ptr : public __weak_ptr<_Tp> |
811 | { |
812 | template<typename _Arg> |
813 | using _Constructible = typename enable_if< |
814 | is_constructible<__weak_ptr<_Tp>, _Arg>::value |
815 | >::type; |
816 | |
817 | template<typename _Arg> |
818 | using _Assignable = typename enable_if< |
819 | is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& |
820 | >::type; |
821 | |
822 | public: |
823 | constexpr weak_ptr() noexcept = default; |
824 | |
825 | template<typename _Yp, |
826 | typename = _Constructible<const shared_ptr<_Yp>&>> |
827 | weak_ptr(const shared_ptr<_Yp>& __r) noexcept |
828 | : __weak_ptr<_Tp>(__r) { } |
829 | |
830 | weak_ptr(const weak_ptr&) noexcept = default; |
831 | |
832 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
833 | weak_ptr(const weak_ptr<_Yp>& __r) noexcept |
834 | : __weak_ptr<_Tp>(__r) { } |
835 | |
836 | weak_ptr(weak_ptr&&) noexcept = default; |
837 | |
838 | template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> |
839 | weak_ptr(weak_ptr<_Yp>&& __r) noexcept |
840 | : __weak_ptr<_Tp>(std::move(__r)) { } |
841 | |
842 | weak_ptr& |
843 | operator=(const weak_ptr& __r) noexcept = default; |
844 | |
845 | template<typename _Yp> |
846 | _Assignable<const weak_ptr<_Yp>&> |
847 | operator=(const weak_ptr<_Yp>& __r) noexcept |
848 | { |
849 | this->__weak_ptr<_Tp>::operator=(__r); |
850 | return *this; |
851 | } |
852 | |
853 | template<typename _Yp> |
854 | _Assignable<const shared_ptr<_Yp>&> |
855 | operator=(const shared_ptr<_Yp>& __r) noexcept |
856 | { |
857 | this->__weak_ptr<_Tp>::operator=(__r); |
858 | return *this; |
859 | } |
860 | |
861 | weak_ptr& |
862 | operator=(weak_ptr&& __r) noexcept = default; |
863 | |
864 | template<typename _Yp> |
865 | _Assignable<weak_ptr<_Yp>> |
866 | operator=(weak_ptr<_Yp>&& __r) noexcept |
867 | { |
868 | this->__weak_ptr<_Tp>::operator=(std::move(__r)); |
869 | return *this; |
870 | } |
871 | |
872 | shared_ptr<_Tp> |
873 | lock() const noexcept |
874 | { return shared_ptr<_Tp>(*this, std::nothrow); } |
875 | }; |
876 | |
877 | #if __cpp_deduction_guides >= 201606 |
878 | template<typename _Tp> |
879 | weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; |
880 | #endif |
881 | |
882 | // 20.7.2.3.6 weak_ptr specialized algorithms. |
883 | /// Swap overload for weak_ptr |
884 | /// @relates weak_ptr |
885 | template<typename _Tp> |
886 | inline void |
887 | swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept |
888 | { __a.swap(__b); } |
889 | |
890 | |
891 | /// Primary template owner_less |
892 | template<typename _Tp = void> |
893 | struct owner_less; |
894 | |
895 | /// Void specialization of owner_less compares either shared_ptr or weak_ptr |
896 | template<> |
897 | struct owner_less<void> : _Sp_owner_less<void, void> |
898 | { }; |
899 | |
900 | /// Partial specialization of owner_less for shared_ptr. |
901 | template<typename _Tp> |
902 | struct owner_less<shared_ptr<_Tp>> |
903 | : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> |
904 | { }; |
905 | |
906 | /// Partial specialization of owner_less for weak_ptr. |
907 | template<typename _Tp> |
908 | struct owner_less<weak_ptr<_Tp>> |
909 | : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> |
910 | { }; |
911 | |
912 | /** |
913 | * @brief Base class allowing use of the member function `shared_from_this`. |
914 | * @headerfile memory |
915 | * @since C++11 |
916 | */ |
917 | template<typename _Tp> |
918 | class enable_shared_from_this |
919 | { |
920 | protected: |
921 | constexpr enable_shared_from_this() noexcept { } |
922 | |
923 | enable_shared_from_this(const enable_shared_from_this&) noexcept { } |
924 | |
925 | enable_shared_from_this& |
926 | operator=(const enable_shared_from_this&) noexcept |
927 | { return *this; } |
928 | |
929 | ~enable_shared_from_this() { } |
930 | |
931 | public: |
932 | shared_ptr<_Tp> |
933 | shared_from_this() |
934 | { return shared_ptr<_Tp>(this->_M_weak_this); } |
935 | |
936 | shared_ptr<const _Tp> |
937 | shared_from_this() const |
938 | { return shared_ptr<const _Tp>(this->_M_weak_this); } |
939 | |
940 | #ifdef __glibcxx_enable_shared_from_this // C++ >= 17 && HOSTED |
941 | /** @{ |
942 | * Get a `weak_ptr` referring to the object that has `*this` as its base. |
943 | * @since C++17 |
944 | */ |
945 | weak_ptr<_Tp> |
946 | weak_from_this() noexcept |
947 | { return this->_M_weak_this; } |
948 | |
949 | weak_ptr<const _Tp> |
950 | weak_from_this() const noexcept |
951 | { return this->_M_weak_this; } |
952 | /// @} |
953 | #endif |
954 | |
955 | private: |
956 | template<typename _Tp1> |
957 | void |
958 | _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept |
959 | { _M_weak_this._M_assign(__p, __n); } |
960 | |
961 | // Found by ADL when this is an associated class. |
962 | friend const enable_shared_from_this* |
963 | __enable_shared_from_this_base(const __shared_count<>&, |
964 | const enable_shared_from_this* __p) |
965 | { return __p; } |
966 | |
967 | template<typename, _Lock_policy> |
968 | friend class __shared_ptr; |
969 | |
970 | mutable weak_ptr<_Tp> _M_weak_this; |
971 | }; |
972 | |
973 | /// @relates shared_ptr @{ |
974 | |
975 | /** |
976 | * @brief Create an object that is owned by a shared_ptr. |
977 | * @param __a An allocator. |
978 | * @param __args Arguments for the @a _Tp object's constructor. |
979 | * @return A shared_ptr that owns the newly created object. |
980 | * @throw An exception thrown from @a _Alloc::allocate or from the |
981 | * constructor of @a _Tp. |
982 | * |
983 | * A copy of @a __a will be used to allocate memory for the shared_ptr |
984 | * and the new object. |
985 | */ |
986 | template<typename _Tp, typename _Alloc, typename... _Args> |
987 | inline shared_ptr<_NonArray<_Tp>> |
988 | allocate_shared(const _Alloc& __a, _Args&&... __args) |
989 | { |
990 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a}, |
991 | std::forward<_Args>(__args)...); |
992 | } |
993 | |
994 | /** |
995 | * @brief Create an object that is owned by a shared_ptr. |
996 | * @param __args Arguments for the @a _Tp object's constructor. |
997 | * @return A shared_ptr that owns the newly created object. |
998 | * @throw std::bad_alloc, or an exception thrown from the |
999 | * constructor of @a _Tp. |
1000 | */ |
1001 | template<typename _Tp, typename... _Args> |
1002 | inline shared_ptr<_NonArray<_Tp>> |
1003 | make_shared(_Args&&... __args) |
1004 | { |
1005 | using _Alloc = allocator<void>; |
1006 | _Alloc __a; |
1007 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{._M_a: __a}, |
1008 | std::forward<_Args>(__args)...); |
1009 | } |
1010 | |
1011 | #if __glibcxx_shared_ptr_arrays >= 201707L |
1012 | /// @cond undocumented |
1013 | template<typename _Tp, typename _Alloc = allocator<void>> |
1014 | auto |
1015 | __make_shared_arr_tag(size_t __n, const _Alloc& __a = _Alloc()) noexcept |
1016 | { |
1017 | using _Up = remove_all_extents_t<_Tp>; |
1018 | using _UpAlloc = __alloc_rebind<_Alloc, _Up>; |
1019 | size_t __s = sizeof(remove_extent_t<_Tp>) / sizeof(_Up); |
1020 | if (__builtin_mul_overflow(__s, __n, &__n)) |
1021 | std::__throw_bad_array_new_length(); |
1022 | return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n}; |
1023 | } |
1024 | /// @endcond |
1025 | |
1026 | template<typename _Tp, typename _Alloc> |
1027 | inline shared_ptr<_UnboundedArray<_Tp>> |
1028 | allocate_shared(const _Alloc& __a, size_t __n) |
1029 | { |
1030 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a)); |
1031 | } |
1032 | |
1033 | template<typename _Tp> |
1034 | inline shared_ptr<_UnboundedArray<_Tp>> |
1035 | make_shared(size_t __n) |
1036 | { |
1037 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n)); |
1038 | } |
1039 | |
1040 | template<typename _Tp, typename _Alloc> |
1041 | inline shared_ptr<_UnboundedArray<_Tp>> |
1042 | allocate_shared(const _Alloc& __a, size_t __n, |
1043 | const remove_extent_t<_Tp>& __u) |
1044 | { |
1045 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a), |
1046 | std::__addressof(__u)); |
1047 | } |
1048 | |
1049 | template<typename _Tp> |
1050 | inline shared_ptr<_UnboundedArray<_Tp>> |
1051 | make_shared(size_t __n, const remove_extent_t<_Tp>& __u) |
1052 | { |
1053 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n), |
1054 | std::__addressof(__u)); |
1055 | } |
1056 | |
1057 | /// @cond undocumented |
1058 | template<typename _Tp, typename _Alloc = allocator<void>> |
1059 | auto |
1060 | __make_shared_arrN_tag(const _Alloc& __a = _Alloc()) noexcept |
1061 | { |
1062 | using _Up = remove_all_extents_t<_Tp>; |
1063 | using _UpAlloc = __alloc_rebind<_Alloc, _Up>; |
1064 | size_t __n = sizeof(_Tp) / sizeof(_Up); |
1065 | return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n}; |
1066 | } |
1067 | /// @endcond |
1068 | |
1069 | template<typename _Tp, typename _Alloc> |
1070 | inline shared_ptr<_BoundedArray<_Tp>> |
1071 | allocate_shared(const _Alloc& __a) |
1072 | { |
1073 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a)); |
1074 | } |
1075 | |
1076 | template<typename _Tp> |
1077 | inline shared_ptr<_BoundedArray<_Tp>> |
1078 | make_shared() |
1079 | { |
1080 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>()); |
1081 | } |
1082 | |
1083 | template<typename _Tp, typename _Alloc> |
1084 | inline shared_ptr<_BoundedArray<_Tp>> |
1085 | allocate_shared(const _Alloc& __a, const remove_extent_t<_Tp>& __u) |
1086 | { |
1087 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a), |
1088 | std::__addressof(__u)); |
1089 | } |
1090 | |
1091 | template<typename _Tp> |
1092 | inline shared_ptr<_BoundedArray<_Tp>> |
1093 | make_shared(const remove_extent_t<_Tp>& __u) |
1094 | { |
1095 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(), |
1096 | std::__addressof(__u)); |
1097 | } |
1098 | |
1099 | #if __glibcxx_smart_ptr_for_overwrite |
1100 | template<typename _Tp, typename _Alloc> |
1101 | inline shared_ptr<_NotUnboundedArray<_Tp>> |
1102 | allocate_shared_for_overwrite(const _Alloc& __a) |
1103 | { |
1104 | if constexpr (is_array_v<_Tp>) |
1105 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a), |
1106 | _Sp_overwrite_tag{}); |
1107 | else |
1108 | { |
1109 | // Rebind the allocator to _Sp_overwrite_tag, so that the |
1110 | // relevant _Sp_counted_ptr_inplace specialization is used. |
1111 | using _Alloc2 = __alloc_rebind<_Alloc, _Sp_overwrite_tag>; |
1112 | _Alloc2 __a2 = __a; |
1113 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc2>{__a2}); |
1114 | } |
1115 | } |
1116 | |
1117 | template<typename _Tp> |
1118 | inline shared_ptr<_NotUnboundedArray<_Tp>> |
1119 | make_shared_for_overwrite() |
1120 | { |
1121 | if constexpr (is_array_v<_Tp>) |
1122 | return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(), |
1123 | _Sp_overwrite_tag{}); |
1124 | else |
1125 | { |
1126 | using _Alloc = allocator<_Sp_overwrite_tag>; |
1127 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{{}}); |
1128 | } |
1129 | } |
1130 | |
1131 | template<typename _Tp, typename _Alloc> |
1132 | inline shared_ptr<_UnboundedArray<_Tp>> |
1133 | allocate_shared_for_overwrite(const _Alloc& __a, size_t __n) |
1134 | { |
1135 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a), |
1136 | _Sp_overwrite_tag{}); |
1137 | } |
1138 | |
1139 | template<typename _Tp> |
1140 | inline shared_ptr<_UnboundedArray<_Tp>> |
1141 | make_shared_for_overwrite(size_t __n) |
1142 | { |
1143 | return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n), |
1144 | _Sp_overwrite_tag{}); |
1145 | } |
1146 | #endif // smart_ptr_for_overwrite |
1147 | #endif // shared_ptr_arrays |
1148 | |
1149 | /// std::hash specialization for shared_ptr. |
1150 | template<typename _Tp> |
1151 | struct hash<shared_ptr<_Tp>> |
1152 | : public __hash_base<size_t, shared_ptr<_Tp>> |
1153 | { |
1154 | size_t |
1155 | operator()(const shared_ptr<_Tp>& __s) const noexcept |
1156 | { |
1157 | return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); |
1158 | } |
1159 | }; |
1160 | |
1161 | #if __cpp_variable_templates |
1162 | template<typename _Tp> |
1163 | static constexpr bool __is_shared_ptr = false; |
1164 | template<typename _Tp> |
1165 | static constexpr bool __is_shared_ptr<shared_ptr<_Tp>> = true; |
1166 | #endif |
1167 | |
1168 | /// @} relates shared_ptr |
1169 | /// @} group pointer_abstractions |
1170 | |
1171 | #if __cplusplus >= 201703L |
1172 | namespace __detail::__variant |
1173 | { |
1174 | template<typename> struct _Never_valueless_alt; // see <variant> |
1175 | |
1176 | // Provide the strong exception-safety guarantee when emplacing a |
1177 | // shared_ptr into a variant. |
1178 | template<typename _Tp> |
1179 | struct _Never_valueless_alt<std::shared_ptr<_Tp>> |
1180 | : std::true_type |
1181 | { }; |
1182 | |
1183 | // Provide the strong exception-safety guarantee when emplacing a |
1184 | // weak_ptr into a variant. |
1185 | template<typename _Tp> |
1186 | struct _Never_valueless_alt<std::weak_ptr<_Tp>> |
1187 | : std::true_type |
1188 | { }; |
1189 | } // namespace __detail::__variant |
1190 | #endif // C++17 |
1191 | |
1192 | _GLIBCXX_END_NAMESPACE_VERSION |
1193 | } // namespace |
1194 | |
1195 | #endif // _SHARED_PTR_H |
1196 | |