1 | // shared_ptr and weak_ptr implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2007-2021 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 | // 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 | /** |
104 | * @brief A smart pointer with reference-counted copy semantics. |
105 | * |
106 | * A `shared_ptr` object is either empty or _owns_ a pointer passed |
107 | * to the constructor. Copies of a `shared_ptr` share ownership of |
108 | * the same pointer. When the last `shared_ptr` that owns the pointer |
109 | * is destroyed or reset, the owned pointer is freed (either by `delete` |
110 | * or by invoking a custom deleter that was passed to the constructor). |
111 | * |
112 | * A `shared_ptr` also stores another pointer, which is usually |
113 | * (but not always) the same pointer as it owns. The stored pointer |
114 | * can be retrieved by calling the `get()` member function. |
115 | * |
116 | * The equality and relational operators for `shared_ptr` only compare |
117 | * the stored pointer returned by `get()`, not the owned pointer. |
118 | * To test whether two `shared_ptr` objects share ownership of the same |
119 | * pointer see `std::shared_ptr::owner_before` and `std::owner_less`. |
120 | */ |
121 | template<typename _Tp> |
122 | class shared_ptr : public __shared_ptr<_Tp> |
123 | { |
124 | template<typename... _Args> |
125 | using _Constructible = typename enable_if< |
126 | is_constructible<__shared_ptr<_Tp>, _Args...>::value |
127 | >::type; |
128 | |
129 | template<typename _Arg> |
130 | using _Assignable = typename enable_if< |
131 | is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& |
132 | >::type; |
133 | |
134 | public: |
135 | |
136 | /// The type pointed to by the stored pointer, remove_extent_t<_Tp> |
137 | using element_type = typename __shared_ptr<_Tp>::element_type; |
138 | |
139 | #if __cplusplus >= 201703L |
140 | # define __cpp_lib_shared_ptr_weak_type 201606 |
141 | /// The corresponding weak_ptr type for this shared_ptr |
142 | using weak_type = weak_ptr<_Tp>; |
143 | #endif |
144 | /** |
145 | * @brief Construct an empty %shared_ptr. |
146 | * @post use_count()==0 && get()==0 |
147 | */ |
148 | constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } |
149 | |
150 | shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor |
151 | |
152 | /** |
153 | * @brief Construct a %shared_ptr that owns the pointer @a __p. |
154 | * @param __p A pointer that is convertible to element_type*. |
155 | * @post use_count() == 1 && get() == __p |
156 | * @throw std::bad_alloc, in which case @c delete @a __p is called. |
157 | */ |
158 | template<typename _Yp, typename = _Constructible<_Yp*>> |
159 | explicit |
160 | shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } |
161 | |
162 | /** |
163 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
164 | * and the deleter @a __d. |
165 | * @param __p A pointer. |
166 | * @param __d A deleter. |
167 | * @post use_count() == 1 && get() == __p |
168 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
169 | * |
170 | * Requirements: _Deleter's copy constructor and destructor must |
171 | * not throw |
172 | * |
173 | * __shared_ptr will release __p by calling __d(__p) |
174 | */ |
175 | template<typename _Yp, typename _Deleter, |
176 | typename = _Constructible<_Yp*, _Deleter>> |
177 | shared_ptr(_Yp* __p, _Deleter __d) |
178 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
179 | |
180 | /** |
181 | * @brief Construct a %shared_ptr that owns a null pointer |
182 | * and the deleter @a __d. |
183 | * @param __p A null pointer constant. |
184 | * @param __d A deleter. |
185 | * @post use_count() == 1 && get() == __p |
186 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
187 | * |
188 | * Requirements: _Deleter's copy constructor and destructor must |
189 | * not throw |
190 | * |
191 | * The last owner will call __d(__p) |
192 | */ |
193 | template<typename _Deleter> |
194 | shared_ptr(nullptr_t __p, _Deleter __d) |
195 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
196 | |
197 | /** |
198 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
199 | * and the deleter @a __d. |
200 | * @param __p A pointer. |
201 | * @param __d A deleter. |
202 | * @param __a An allocator. |
203 | * @post use_count() == 1 && get() == __p |
204 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
205 | * |
206 | * Requirements: _Deleter's copy constructor and destructor must |
207 | * not throw _Alloc's copy constructor and destructor must not |
208 | * throw. |
209 | * |
210 | * __shared_ptr will release __p by calling __d(__p) |
211 | */ |
212 | template<typename _Yp, typename _Deleter, typename _Alloc, |
213 | typename = _Constructible<_Yp*, _Deleter, _Alloc>> |
214 | shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) |
215 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
216 | |
217 | /** |
218 | * @brief Construct a %shared_ptr that owns a null pointer |
219 | * and the deleter @a __d. |
220 | * @param __p A null pointer constant. |
221 | * @param __d A deleter. |
222 | * @param __a An allocator. |
223 | * @post use_count() == 1 && get() == __p |
224 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
225 | * |
226 | * Requirements: _Deleter's copy constructor and destructor must |
227 | * not throw _Alloc's copy constructor and destructor must not |
228 | * throw. |
229 | * |
230 | * The last owner will call __d(__p) |
231 | */ |
232 | template<typename _Deleter, typename _Alloc> |
233 | shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) |
234 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
235 | |
236 | // Aliasing constructor |
237 | |
238 | /** |
239 | * @brief Constructs a `shared_ptr` instance that stores `__p` |
240 | * and shares ownership with `__r`. |
241 | * @param __r A `shared_ptr`. |
242 | * @param __p A pointer that will remain valid while `*__r` is valid. |
243 | * @post `get() == __p && use_count() == __r.use_count()` |
244 | * |
245 | * This can be used to construct a `shared_ptr` to a sub-object |
246 | * of an object managed by an existing `shared_ptr`. The complete |
247 | * object will remain valid while any `shared_ptr` owns it, even |
248 | * if they don't store a pointer to the complete object. |
249 | * |
250 | * @code |
251 | * shared_ptr<pair<int,int>> pii(new pair<int,int>()); |
252 | * shared_ptr<int> pi(pii, &pii->first); |
253 | * assert(pii.use_count() == 2); |
254 | * @endcode |
255 | */ |
256 | template<typename _Yp> |
257 | shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept |
258 | : __shared_ptr<_Tp>(__r, __p) { } |
259 | |
260 | #if __cplusplus > 201703L |
261 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
262 | // 2996. Missing rvalue overloads for shared_ptr operations |
263 | /** |
264 | * @brief Constructs a `shared_ptr` instance that stores `__p` |
265 | * and shares ownership with `__r`. |
266 | * @param __r A `shared_ptr`. |
267 | * @param __p A pointer that will remain valid while `*__r` is valid. |
268 | * @post `get() == __p && !__r.use_count() && !__r.get()` |
269 | * |
270 | * This can be used to construct a `shared_ptr` to a sub-object |
271 | * of an object managed by an existing `shared_ptr`. The complete |
272 | * object will remain valid while any `shared_ptr` owns it, even |
273 | * if they don't store a pointer to the complete object. |
274 | * |
275 | * @code |
276 | * shared_ptr<pair<int,int>> pii(new pair<int,int>()); |
277 | * shared_ptr<int> pi1(pii, &pii->first); |
278 | * assert(pii.use_count() == 2); |
279 | * shared_ptr<int> pi2(std::move(pii), &pii->second); |
280 | * assert(pii.use_count() == 0); |
281 | * @endcode |
282 | */ |
283 | template<typename _Yp> |
284 | shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept |
285 | : __shared_ptr<_Tp>(std::move(__r), __p) { } |
286 | #endif |
287 | /** |
288 | * @brief If @a __r is empty, constructs an empty %shared_ptr; |
289 | * otherwise construct a %shared_ptr that shares ownership |
290 | * with @a __r. |
291 | * @param __r A %shared_ptr. |
292 | * @post get() == __r.get() && use_count() == __r.use_count() |
293 | */ |
294 | template<typename _Yp, |
295 | typename = _Constructible<const shared_ptr<_Yp>&>> |
296 | shared_ptr(const shared_ptr<_Yp>& __r) noexcept |
297 | : __shared_ptr<_Tp>(__r) { } |
298 | |
299 | /** |
300 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
301 | * @param __r A %shared_ptr rvalue. |
302 | * @post *this contains the old value of @a __r, @a __r is empty. |
303 | */ |
304 | shared_ptr(shared_ptr&& __r) noexcept |
305 | : __shared_ptr<_Tp>(std::move(__r)) { } |
306 | |
307 | /** |
308 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
309 | * @param __r A %shared_ptr rvalue. |
310 | * @post *this contains the old value of @a __r, @a __r is empty. |
311 | */ |
312 | template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> |
313 | shared_ptr(shared_ptr<_Yp>&& __r) noexcept |
314 | : __shared_ptr<_Tp>(std::move(__r)) { } |
315 | |
316 | /** |
317 | * @brief Constructs a %shared_ptr that shares ownership with @a __r |
318 | * and stores a copy of the pointer stored in @a __r. |
319 | * @param __r A weak_ptr. |
320 | * @post use_count() == __r.use_count() |
321 | * @throw bad_weak_ptr when __r.expired(), |
322 | * in which case the constructor has no effect. |
323 | */ |
324 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
325 | explicit shared_ptr(const weak_ptr<_Yp>& __r) |
326 | : __shared_ptr<_Tp>(__r) { } |
327 | |
328 | #if _GLIBCXX_USE_DEPRECATED |
329 | #pragma GCC diagnostic push |
330 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
331 | template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> |
332 | shared_ptr(auto_ptr<_Yp>&& __r); |
333 | #pragma GCC diagnostic pop |
334 | #endif |
335 | |
336 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
337 | // 2399. shared_ptr's constructor from unique_ptr should be constrained |
338 | template<typename _Yp, typename _Del, |
339 | typename = _Constructible<unique_ptr<_Yp, _Del>>> |
340 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
341 | : __shared_ptr<_Tp>(std::move(__r)) { } |
342 | |
343 | #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED |
344 | // This non-standard constructor exists to support conversions that |
345 | // were possible in C++11 and C++14 but are ill-formed in C++17. |
346 | // If an exception is thrown this constructor has no effect. |
347 | template<typename _Yp, typename _Del, |
348 | _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> |
349 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
350 | : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } |
351 | #endif |
352 | |
353 | /** |
354 | * @brief Construct an empty %shared_ptr. |
355 | * @post use_count() == 0 && get() == nullptr |
356 | */ |
357 | constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } |
358 | |
359 | shared_ptr& operator=(const shared_ptr&) noexcept = default; |
360 | |
361 | template<typename _Yp> |
362 | _Assignable<const shared_ptr<_Yp>&> |
363 | operator=(const shared_ptr<_Yp>& __r) noexcept |
364 | { |
365 | this->__shared_ptr<_Tp>::operator=(__r); |
366 | return *this; |
367 | } |
368 | |
369 | #if _GLIBCXX_USE_DEPRECATED |
370 | #pragma GCC diagnostic push |
371 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
372 | template<typename _Yp> |
373 | _Assignable<auto_ptr<_Yp>> |
374 | operator=(auto_ptr<_Yp>&& __r) |
375 | { |
376 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
377 | return *this; |
378 | } |
379 | #pragma GCC diagnostic pop |
380 | #endif |
381 | |
382 | shared_ptr& |
383 | operator=(shared_ptr&& __r) noexcept |
384 | { |
385 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
386 | return *this; |
387 | } |
388 | |
389 | template<class _Yp> |
390 | _Assignable<shared_ptr<_Yp>> |
391 | operator=(shared_ptr<_Yp>&& __r) noexcept |
392 | { |
393 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
394 | return *this; |
395 | } |
396 | |
397 | template<typename _Yp, typename _Del> |
398 | _Assignable<unique_ptr<_Yp, _Del>> |
399 | operator=(unique_ptr<_Yp, _Del>&& __r) |
400 | { |
401 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
402 | return *this; |
403 | } |
404 | |
405 | private: |
406 | // This constructor is non-standard, it is used by allocate_shared. |
407 | template<typename _Alloc, typename... _Args> |
408 | shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args) |
409 | : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...) |
410 | { } |
411 | |
412 | template<typename _Yp, typename _Alloc, typename... _Args> |
413 | friend shared_ptr<_Yp> |
414 | allocate_shared(const _Alloc& __a, _Args&&... __args); |
415 | |
416 | // This constructor is non-standard, it is used by weak_ptr::lock(). |
417 | shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept |
418 | : __shared_ptr<_Tp>(__r, std::nothrow) { } |
419 | |
420 | friend class weak_ptr<_Tp>; |
421 | }; |
422 | |
423 | #if __cpp_deduction_guides >= 201606 |
424 | template<typename _Tp> |
425 | shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; |
426 | template<typename _Tp, typename _Del> |
427 | shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; |
428 | #endif |
429 | |
430 | // 20.7.2.2.7 shared_ptr comparisons |
431 | |
432 | /// @relates shared_ptr @{ |
433 | |
434 | /// Equality operator for shared_ptr objects, compares the stored pointers |
435 | template<typename _Tp, typename _Up> |
436 | _GLIBCXX_NODISCARD inline bool |
437 | operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
438 | { return __a.get() == __b.get(); } |
439 | |
440 | /// shared_ptr comparison with nullptr |
441 | template<typename _Tp> |
442 | _GLIBCXX_NODISCARD inline bool |
443 | operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
444 | { return !__a; } |
445 | |
446 | #ifdef __cpp_lib_three_way_comparison |
447 | template<typename _Tp, typename _Up> |
448 | inline strong_ordering |
449 | operator<=>(const shared_ptr<_Tp>& __a, |
450 | const shared_ptr<_Up>& __b) noexcept |
451 | { return compare_three_way()(__a.get(), __b.get()); } |
452 | |
453 | template<typename _Tp> |
454 | inline strong_ordering |
455 | operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
456 | { |
457 | using pointer = typename shared_ptr<_Tp>::element_type*; |
458 | return compare_three_way()(__a.get(), static_cast<pointer>(nullptr)); |
459 | } |
460 | #else |
461 | /// shared_ptr comparison with nullptr |
462 | template<typename _Tp> |
463 | _GLIBCXX_NODISCARD inline bool |
464 | operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
465 | { return !__a; } |
466 | |
467 | /// Inequality operator for shared_ptr objects, compares the stored pointers |
468 | template<typename _Tp, typename _Up> |
469 | _GLIBCXX_NODISCARD inline bool |
470 | operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
471 | { return __a.get() != __b.get(); } |
472 | |
473 | /// shared_ptr comparison with nullptr |
474 | template<typename _Tp> |
475 | _GLIBCXX_NODISCARD inline bool |
476 | operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
477 | { return (bool)__a; } |
478 | |
479 | /// shared_ptr comparison with nullptr |
480 | template<typename _Tp> |
481 | _GLIBCXX_NODISCARD inline bool |
482 | operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
483 | { return (bool)__a; } |
484 | |
485 | /// Relational operator for shared_ptr objects, compares the stored pointers |
486 | template<typename _Tp, typename _Up> |
487 | _GLIBCXX_NODISCARD inline bool |
488 | operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
489 | { |
490 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
491 | using _Up_elt = typename shared_ptr<_Up>::element_type; |
492 | using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; |
493 | return less<_Vp>()(__a.get(), __b.get()); |
494 | } |
495 | |
496 | /// shared_ptr comparison with nullptr |
497 | template<typename _Tp> |
498 | _GLIBCXX_NODISCARD inline bool |
499 | operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
500 | { |
501 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
502 | return less<_Tp_elt*>()(__a.get(), nullptr); |
503 | } |
504 | |
505 | /// shared_ptr comparison with nullptr |
506 | template<typename _Tp> |
507 | _GLIBCXX_NODISCARD inline bool |
508 | operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
509 | { |
510 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
511 | return less<_Tp_elt*>()(nullptr, __a.get()); |
512 | } |
513 | |
514 | /// Relational operator for shared_ptr objects, compares the stored pointers |
515 | template<typename _Tp, typename _Up> |
516 | _GLIBCXX_NODISCARD inline bool |
517 | operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
518 | { return !(__b < __a); } |
519 | |
520 | /// shared_ptr comparison with nullptr |
521 | template<typename _Tp> |
522 | _GLIBCXX_NODISCARD inline bool |
523 | operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
524 | { return !(nullptr < __a); } |
525 | |
526 | /// shared_ptr comparison with nullptr |
527 | template<typename _Tp> |
528 | _GLIBCXX_NODISCARD inline bool |
529 | operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
530 | { return !(__a < nullptr); } |
531 | |
532 | /// Relational operator for shared_ptr objects, compares the stored pointers |
533 | template<typename _Tp, typename _Up> |
534 | _GLIBCXX_NODISCARD inline bool |
535 | operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
536 | { return (__b < __a); } |
537 | |
538 | /// shared_ptr comparison with nullptr |
539 | template<typename _Tp> |
540 | _GLIBCXX_NODISCARD inline bool |
541 | operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
542 | { return nullptr < __a; } |
543 | |
544 | /// shared_ptr comparison with nullptr |
545 | template<typename _Tp> |
546 | _GLIBCXX_NODISCARD inline bool |
547 | operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
548 | { return __a < nullptr; } |
549 | |
550 | /// Relational operator for shared_ptr objects, compares the stored pointers |
551 | template<typename _Tp, typename _Up> |
552 | _GLIBCXX_NODISCARD inline bool |
553 | operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
554 | { return !(__a < __b); } |
555 | |
556 | /// shared_ptr comparison with nullptr |
557 | template<typename _Tp> |
558 | _GLIBCXX_NODISCARD inline bool |
559 | operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
560 | { return !(__a < nullptr); } |
561 | |
562 | /// shared_ptr comparison with nullptr |
563 | template<typename _Tp> |
564 | _GLIBCXX_NODISCARD inline bool |
565 | operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
566 | { return !(nullptr < __a); } |
567 | #endif |
568 | |
569 | // 20.7.2.2.8 shared_ptr specialized algorithms. |
570 | |
571 | /// Swap overload for shared_ptr |
572 | template<typename _Tp> |
573 | inline void |
574 | swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept |
575 | { __a.swap(__b); } |
576 | |
577 | // 20.7.2.2.9 shared_ptr casts. |
578 | |
579 | /// Convert type of `shared_ptr`, via `static_cast` |
580 | template<typename _Tp, typename _Up> |
581 | inline shared_ptr<_Tp> |
582 | static_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
583 | { |
584 | using _Sp = shared_ptr<_Tp>; |
585 | return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); |
586 | } |
587 | |
588 | /// Convert type of `shared_ptr`, via `const_cast` |
589 | template<typename _Tp, typename _Up> |
590 | inline shared_ptr<_Tp> |
591 | const_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
592 | { |
593 | using _Sp = shared_ptr<_Tp>; |
594 | return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); |
595 | } |
596 | |
597 | /// Convert type of `shared_ptr`, via `dynamic_cast` |
598 | template<typename _Tp, typename _Up> |
599 | inline shared_ptr<_Tp> |
600 | dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
601 | { |
602 | using _Sp = shared_ptr<_Tp>; |
603 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
604 | return _Sp(__r, __p); |
605 | return _Sp(); |
606 | } |
607 | |
608 | #if __cplusplus >= 201703L |
609 | /// Convert type of `shared_ptr`, via `reinterpret_cast` |
610 | template<typename _Tp, typename _Up> |
611 | inline shared_ptr<_Tp> |
612 | reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
613 | { |
614 | using _Sp = shared_ptr<_Tp>; |
615 | return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
616 | } |
617 | |
618 | #if __cplusplus > 201703L |
619 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
620 | // 2996. Missing rvalue overloads for shared_ptr operations |
621 | |
622 | /// Convert type of `shared_ptr` rvalue, via `static_cast` |
623 | template<typename _Tp, typename _Up> |
624 | inline shared_ptr<_Tp> |
625 | static_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
626 | { |
627 | using _Sp = shared_ptr<_Tp>; |
628 | return _Sp(std::move(__r), |
629 | static_cast<typename _Sp::element_type*>(__r.get())); |
630 | } |
631 | |
632 | /// Convert type of `shared_ptr` rvalue, via `const_cast` |
633 | template<typename _Tp, typename _Up> |
634 | inline shared_ptr<_Tp> |
635 | const_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
636 | { |
637 | using _Sp = shared_ptr<_Tp>; |
638 | return _Sp(std::move(__r), |
639 | const_cast<typename _Sp::element_type*>(__r.get())); |
640 | } |
641 | |
642 | /// Convert type of `shared_ptr` rvalue, via `dynamic_cast` |
643 | template<typename _Tp, typename _Up> |
644 | inline shared_ptr<_Tp> |
645 | dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
646 | { |
647 | using _Sp = shared_ptr<_Tp>; |
648 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
649 | return _Sp(std::move(__r), __p); |
650 | return _Sp(); |
651 | } |
652 | |
653 | /// Convert type of `shared_ptr` rvalue, via `reinterpret_cast` |
654 | template<typename _Tp, typename _Up> |
655 | inline shared_ptr<_Tp> |
656 | reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept |
657 | { |
658 | using _Sp = shared_ptr<_Tp>; |
659 | return _Sp(std::move(__r), |
660 | reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
661 | } |
662 | #endif // C++20 |
663 | #endif // C++17 |
664 | |
665 | /// @} |
666 | |
667 | /** |
668 | * @brief A non-owning observer for a pointer owned by a shared_ptr |
669 | * |
670 | * A weak_ptr provides a safe alternative to a raw pointer when you want |
671 | * a non-owning reference to an object that is managed by a shared_ptr. |
672 | * |
673 | * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr |
674 | * that shares ownership with every other shared_ptr that already owns |
675 | * the pointer. In other words you can upgrade from a non-owning "weak" |
676 | * reference to an owning shared_ptr, without having access to any of |
677 | * the existing shared_ptr objects. |
678 | * |
679 | * Also unlike a raw pointer, a weak_ptr does not become "dangling" after |
680 | * the object it points to has been destroyed. Instead, a weak_ptr |
681 | * becomes _expired_ and can no longer be converted to a shared_ptr that |
682 | * owns the freed pointer, so you cannot accidentally access the pointed-to |
683 | * object after it has been destroyed. |
684 | */ |
685 | template<typename _Tp> |
686 | class weak_ptr : public __weak_ptr<_Tp> |
687 | { |
688 | template<typename _Arg> |
689 | using _Constructible = typename enable_if< |
690 | is_constructible<__weak_ptr<_Tp>, _Arg>::value |
691 | >::type; |
692 | |
693 | template<typename _Arg> |
694 | using _Assignable = typename enable_if< |
695 | is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& |
696 | >::type; |
697 | |
698 | public: |
699 | constexpr weak_ptr() noexcept = default; |
700 | |
701 | template<typename _Yp, |
702 | typename = _Constructible<const shared_ptr<_Yp>&>> |
703 | weak_ptr(const shared_ptr<_Yp>& __r) noexcept |
704 | : __weak_ptr<_Tp>(__r) { } |
705 | |
706 | weak_ptr(const weak_ptr&) noexcept = default; |
707 | |
708 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
709 | weak_ptr(const weak_ptr<_Yp>& __r) noexcept |
710 | : __weak_ptr<_Tp>(__r) { } |
711 | |
712 | weak_ptr(weak_ptr&&) noexcept = default; |
713 | |
714 | template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> |
715 | weak_ptr(weak_ptr<_Yp>&& __r) noexcept |
716 | : __weak_ptr<_Tp>(std::move(__r)) { } |
717 | |
718 | weak_ptr& |
719 | operator=(const weak_ptr& __r) noexcept = default; |
720 | |
721 | template<typename _Yp> |
722 | _Assignable<const weak_ptr<_Yp>&> |
723 | operator=(const weak_ptr<_Yp>& __r) noexcept |
724 | { |
725 | this->__weak_ptr<_Tp>::operator=(__r); |
726 | return *this; |
727 | } |
728 | |
729 | template<typename _Yp> |
730 | _Assignable<const shared_ptr<_Yp>&> |
731 | operator=(const shared_ptr<_Yp>& __r) noexcept |
732 | { |
733 | this->__weak_ptr<_Tp>::operator=(__r); |
734 | return *this; |
735 | } |
736 | |
737 | weak_ptr& |
738 | operator=(weak_ptr&& __r) noexcept = default; |
739 | |
740 | template<typename _Yp> |
741 | _Assignable<weak_ptr<_Yp>> |
742 | operator=(weak_ptr<_Yp>&& __r) noexcept |
743 | { |
744 | this->__weak_ptr<_Tp>::operator=(std::move(__r)); |
745 | return *this; |
746 | } |
747 | |
748 | shared_ptr<_Tp> |
749 | lock() const noexcept |
750 | { return shared_ptr<_Tp>(*this, std::nothrow); } |
751 | }; |
752 | |
753 | #if __cpp_deduction_guides >= 201606 |
754 | template<typename _Tp> |
755 | weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; |
756 | #endif |
757 | |
758 | // 20.7.2.3.6 weak_ptr specialized algorithms. |
759 | /// Swap overload for weak_ptr |
760 | /// @relates weak_ptr |
761 | template<typename _Tp> |
762 | inline void |
763 | swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept |
764 | { __a.swap(__b); } |
765 | |
766 | |
767 | /// Primary template owner_less |
768 | template<typename _Tp = void> |
769 | struct owner_less; |
770 | |
771 | /// Void specialization of owner_less compares either shared_ptr or weak_ptr |
772 | template<> |
773 | struct owner_less<void> : _Sp_owner_less<void, void> |
774 | { }; |
775 | |
776 | /// Partial specialization of owner_less for shared_ptr. |
777 | template<typename _Tp> |
778 | struct owner_less<shared_ptr<_Tp>> |
779 | : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> |
780 | { }; |
781 | |
782 | /// Partial specialization of owner_less for weak_ptr. |
783 | template<typename _Tp> |
784 | struct owner_less<weak_ptr<_Tp>> |
785 | : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> |
786 | { }; |
787 | |
788 | /** |
789 | * @brief Base class allowing use of member function shared_from_this. |
790 | */ |
791 | template<typename _Tp> |
792 | class enable_shared_from_this |
793 | { |
794 | protected: |
795 | constexpr enable_shared_from_this() noexcept { } |
796 | |
797 | enable_shared_from_this(const enable_shared_from_this&) noexcept { } |
798 | |
799 | enable_shared_from_this& |
800 | operator=(const enable_shared_from_this&) noexcept |
801 | { return *this; } |
802 | |
803 | ~enable_shared_from_this() { } |
804 | |
805 | public: |
806 | shared_ptr<_Tp> |
807 | shared_from_this() |
808 | { return shared_ptr<_Tp>(this->_M_weak_this); } |
809 | |
810 | shared_ptr<const _Tp> |
811 | shared_from_this() const |
812 | { return shared_ptr<const _Tp>(this->_M_weak_this); } |
813 | |
814 | #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 |
815 | #define __cpp_lib_enable_shared_from_this 201603 |
816 | weak_ptr<_Tp> |
817 | weak_from_this() noexcept |
818 | { return this->_M_weak_this; } |
819 | |
820 | weak_ptr<const _Tp> |
821 | weak_from_this() const noexcept |
822 | { return this->_M_weak_this; } |
823 | #endif |
824 | |
825 | private: |
826 | template<typename _Tp1> |
827 | void |
828 | _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept |
829 | { _M_weak_this._M_assign(__p, __n); } |
830 | |
831 | // Found by ADL when this is an associated class. |
832 | friend const enable_shared_from_this* |
833 | __enable_shared_from_this_base(const __shared_count<>&, |
834 | const enable_shared_from_this* __p) |
835 | { return __p; } |
836 | |
837 | template<typename, _Lock_policy> |
838 | friend class __shared_ptr; |
839 | |
840 | mutable weak_ptr<_Tp> _M_weak_this; |
841 | }; |
842 | |
843 | /// @relates shared_ptr @{ |
844 | |
845 | /** |
846 | * @brief Create an object that is owned by a shared_ptr. |
847 | * @param __a An allocator. |
848 | * @param __args Arguments for the @a _Tp object's constructor. |
849 | * @return A shared_ptr that owns the newly created object. |
850 | * @throw An exception thrown from @a _Alloc::allocate or from the |
851 | * constructor of @a _Tp. |
852 | * |
853 | * A copy of @a __a will be used to allocate memory for the shared_ptr |
854 | * and the new object. |
855 | */ |
856 | template<typename _Tp, typename _Alloc, typename... _Args> |
857 | inline shared_ptr<_Tp> |
858 | allocate_shared(const _Alloc& __a, _Args&&... __args) |
859 | { |
860 | static_assert(!is_array<_Tp>::value, "make_shared<T[]> not supported" ); |
861 | |
862 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a}, |
863 | std::forward<_Args>(__args)...); |
864 | } |
865 | |
866 | /** |
867 | * @brief Create an object that is owned by a shared_ptr. |
868 | * @param __args Arguments for the @a _Tp object's constructor. |
869 | * @return A shared_ptr that owns the newly created object. |
870 | * @throw std::bad_alloc, or an exception thrown from the |
871 | * constructor of @a _Tp. |
872 | */ |
873 | template<typename _Tp, typename... _Args> |
874 | inline shared_ptr<_Tp> |
875 | make_shared(_Args&&... __args) |
876 | { |
877 | typedef typename std::remove_cv<_Tp>::type _Tp_nc; |
878 | return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(), |
879 | std::forward<_Args>(__args)...); |
880 | } |
881 | |
882 | /// std::hash specialization for shared_ptr. |
883 | template<typename _Tp> |
884 | struct hash<shared_ptr<_Tp>> |
885 | : public __hash_base<size_t, shared_ptr<_Tp>> |
886 | { |
887 | size_t |
888 | operator()(const shared_ptr<_Tp>& __s) const noexcept |
889 | { |
890 | return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); |
891 | } |
892 | }; |
893 | |
894 | /// @} relates shared_ptr |
895 | /// @} group pointer_abstractions |
896 | |
897 | #if __cplusplus >= 201703L |
898 | namespace __detail::__variant |
899 | { |
900 | template<typename> struct _Never_valueless_alt; // see <variant> |
901 | |
902 | // Provide the strong exception-safety guarantee when emplacing a |
903 | // shared_ptr into a variant. |
904 | template<typename _Tp> |
905 | struct _Never_valueless_alt<std::shared_ptr<_Tp>> |
906 | : std::true_type |
907 | { }; |
908 | |
909 | // Provide the strong exception-safety guarantee when emplacing a |
910 | // weak_ptr into a variant. |
911 | template<typename _Tp> |
912 | struct _Never_valueless_alt<std::weak_ptr<_Tp>> |
913 | : std::true_type |
914 | { }; |
915 | } // namespace __detail::__variant |
916 | #endif // C++17 |
917 | |
918 | _GLIBCXX_END_NAMESPACE_VERSION |
919 | } // namespace |
920 | |
921 | #endif // _SHARED_PTR_H |
922 | |