1 | // shared_ptr and weak_ptr implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2007-2017 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 <bits/shared_ptr_base.h> |
53 | |
54 | namespace std _GLIBCXX_VISIBILITY(default) |
55 | { |
56 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
57 | |
58 | /** |
59 | * @addtogroup pointer_abstractions |
60 | * @{ |
61 | */ |
62 | |
63 | /// 20.7.2.2.11 shared_ptr I/O |
64 | template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp> |
65 | inline std::basic_ostream<_Ch, _Tr>& |
66 | operator<<(std::basic_ostream<_Ch, _Tr>& __os, |
67 | const __shared_ptr<_Tp, _Lp>& __p) |
68 | { |
69 | __os << __p.get(); |
70 | return __os; |
71 | } |
72 | |
73 | /// 20.7.2.2.10 shared_ptr get_deleter |
74 | template<typename _Del, typename _Tp, _Lock_policy _Lp> |
75 | inline _Del* |
76 | get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept |
77 | { |
78 | #if __cpp_rtti |
79 | return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); |
80 | #else |
81 | return 0; |
82 | #endif |
83 | } |
84 | |
85 | |
86 | /** |
87 | * @brief A smart pointer with reference-counted copy semantics. |
88 | * |
89 | * The object pointed to is deleted when the last shared_ptr pointing to |
90 | * it is destroyed or reset. |
91 | */ |
92 | template<typename _Tp> |
93 | class shared_ptr : public __shared_ptr<_Tp> |
94 | { |
95 | template<typename... _Args> |
96 | using _Constructible = typename enable_if< |
97 | is_constructible<__shared_ptr<_Tp>, _Args...>::value |
98 | >::type; |
99 | |
100 | template<typename _Arg> |
101 | using _Assignable = typename enable_if< |
102 | is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& |
103 | >::type; |
104 | |
105 | public: |
106 | |
107 | using element_type = typename __shared_ptr<_Tp>::element_type; |
108 | |
109 | #if __cplusplus > 201402L |
110 | # define __cpp_lib_shared_ptr_weak_type 201606 |
111 | using weak_type = weak_ptr<_Tp>; |
112 | #endif |
113 | /** |
114 | * @brief Construct an empty %shared_ptr. |
115 | * @post use_count()==0 && get()==0 |
116 | */ |
117 | constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } |
118 | |
119 | shared_ptr(const shared_ptr&) noexcept = default; |
120 | |
121 | /** |
122 | * @brief Construct a %shared_ptr that owns the pointer @a __p. |
123 | * @param __p A pointer that is convertible to element_type*. |
124 | * @post use_count() == 1 && get() == __p |
125 | * @throw std::bad_alloc, in which case @c delete @a __p is called. |
126 | */ |
127 | template<typename _Yp, typename = _Constructible<_Yp*>> |
128 | explicit |
129 | shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } |
130 | |
131 | /** |
132 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
133 | * and the deleter @a __d. |
134 | * @param __p A pointer. |
135 | * @param __d A deleter. |
136 | * @post use_count() == 1 && get() == __p |
137 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
138 | * |
139 | * Requirements: _Deleter's copy constructor and destructor must |
140 | * not throw |
141 | * |
142 | * __shared_ptr will release __p by calling __d(__p) |
143 | */ |
144 | template<typename _Yp, typename _Deleter, |
145 | typename = _Constructible<_Yp*, _Deleter>> |
146 | shared_ptr(_Yp* __p, _Deleter __d) |
147 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
148 | |
149 | /** |
150 | * @brief Construct a %shared_ptr that owns a null pointer |
151 | * and the deleter @a __d. |
152 | * @param __p A null pointer constant. |
153 | * @param __d A deleter. |
154 | * @post use_count() == 1 && get() == __p |
155 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
156 | * |
157 | * Requirements: _Deleter's copy constructor and destructor must |
158 | * not throw |
159 | * |
160 | * The last owner will call __d(__p) |
161 | */ |
162 | template<typename _Deleter> |
163 | shared_ptr(nullptr_t __p, _Deleter __d) |
164 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
165 | |
166 | /** |
167 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
168 | * and the deleter @a __d. |
169 | * @param __p A pointer. |
170 | * @param __d A deleter. |
171 | * @param __a An allocator. |
172 | * @post use_count() == 1 && get() == __p |
173 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
174 | * |
175 | * Requirements: _Deleter's copy constructor and destructor must |
176 | * not throw _Alloc's copy constructor and destructor must not |
177 | * throw. |
178 | * |
179 | * __shared_ptr will release __p by calling __d(__p) |
180 | */ |
181 | template<typename _Yp, typename _Deleter, typename _Alloc, |
182 | typename = _Constructible<_Yp*, _Deleter, _Alloc>> |
183 | shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) |
184 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
185 | |
186 | /** |
187 | * @brief Construct a %shared_ptr that owns a null pointer |
188 | * and the deleter @a __d. |
189 | * @param __p A null pointer constant. |
190 | * @param __d A deleter. |
191 | * @param __a An allocator. |
192 | * @post use_count() == 1 && get() == __p |
193 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
194 | * |
195 | * Requirements: _Deleter's copy constructor and destructor must |
196 | * not throw _Alloc's copy constructor and destructor must not |
197 | * throw. |
198 | * |
199 | * The last owner will call __d(__p) |
200 | */ |
201 | template<typename _Deleter, typename _Alloc> |
202 | shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) |
203 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
204 | |
205 | // Aliasing constructor |
206 | |
207 | /** |
208 | * @brief Constructs a %shared_ptr instance that stores @a __p |
209 | * and shares ownership with @a __r. |
210 | * @param __r A %shared_ptr. |
211 | * @param __p A pointer that will remain valid while @a *__r is valid. |
212 | * @post get() == __p && use_count() == __r.use_count() |
213 | * |
214 | * This can be used to construct a @c shared_ptr to a sub-object |
215 | * of an object managed by an existing @c shared_ptr. |
216 | * |
217 | * @code |
218 | * shared_ptr< pair<int,int> > pii(new pair<int,int>()); |
219 | * shared_ptr<int> pi(pii, &pii->first); |
220 | * assert(pii.use_count() == 2); |
221 | * @endcode |
222 | */ |
223 | template<typename _Yp> |
224 | shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept |
225 | : __shared_ptr<_Tp>(__r, __p) { } |
226 | |
227 | /** |
228 | * @brief If @a __r is empty, constructs an empty %shared_ptr; |
229 | * otherwise construct a %shared_ptr that shares ownership |
230 | * with @a __r. |
231 | * @param __r A %shared_ptr. |
232 | * @post get() == __r.get() && use_count() == __r.use_count() |
233 | */ |
234 | template<typename _Yp, |
235 | typename = _Constructible<const shared_ptr<_Yp>&>> |
236 | shared_ptr(const shared_ptr<_Yp>& __r) noexcept |
237 | : __shared_ptr<_Tp>(__r) { } |
238 | |
239 | /** |
240 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
241 | * @param __r A %shared_ptr rvalue. |
242 | * @post *this contains the old value of @a __r, @a __r is empty. |
243 | */ |
244 | shared_ptr(shared_ptr&& __r) noexcept |
245 | : __shared_ptr<_Tp>(std::move(__r)) { } |
246 | |
247 | /** |
248 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
249 | * @param __r A %shared_ptr rvalue. |
250 | * @post *this contains the old value of @a __r, @a __r is empty. |
251 | */ |
252 | template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> |
253 | shared_ptr(shared_ptr<_Yp>&& __r) noexcept |
254 | : __shared_ptr<_Tp>(std::move(__r)) { } |
255 | |
256 | /** |
257 | * @brief Constructs a %shared_ptr that shares ownership with @a __r |
258 | * and stores a copy of the pointer stored in @a __r. |
259 | * @param __r A weak_ptr. |
260 | * @post use_count() == __r.use_count() |
261 | * @throw bad_weak_ptr when __r.expired(), |
262 | * in which case the constructor has no effect. |
263 | */ |
264 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
265 | explicit shared_ptr(const weak_ptr<_Yp>& __r) |
266 | : __shared_ptr<_Tp>(__r) { } |
267 | |
268 | #if _GLIBCXX_USE_DEPRECATED |
269 | template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> |
270 | shared_ptr(auto_ptr<_Yp>&& __r); |
271 | #endif |
272 | |
273 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
274 | // 2399. shared_ptr's constructor from unique_ptr should be constrained |
275 | template<typename _Yp, typename _Del, |
276 | typename = _Constructible<unique_ptr<_Yp, _Del>>> |
277 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
278 | : __shared_ptr<_Tp>(std::move(__r)) { } |
279 | |
280 | #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED |
281 | // This non-standard constructor exists to support conversions that |
282 | // were possible in C++11 and C++14 but are ill-formed in C++17. |
283 | // If an exception is thrown this constructor has no effect. |
284 | template<typename _Yp, typename _Del, |
285 | _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> |
286 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
287 | : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } |
288 | #endif |
289 | |
290 | /** |
291 | * @brief Construct an empty %shared_ptr. |
292 | * @post use_count() == 0 && get() == nullptr |
293 | */ |
294 | constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } |
295 | |
296 | shared_ptr& operator=(const shared_ptr&) noexcept = default; |
297 | |
298 | template<typename _Yp> |
299 | _Assignable<const shared_ptr<_Yp>&> |
300 | operator=(const shared_ptr<_Yp>& __r) noexcept |
301 | { |
302 | this->__shared_ptr<_Tp>::operator=(__r); |
303 | return *this; |
304 | } |
305 | |
306 | #if _GLIBCXX_USE_DEPRECATED |
307 | template<typename _Yp> |
308 | _Assignable<auto_ptr<_Yp>> |
309 | operator=(auto_ptr<_Yp>&& __r) |
310 | { |
311 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
312 | return *this; |
313 | } |
314 | #endif |
315 | |
316 | shared_ptr& |
317 | operator=(shared_ptr&& __r) noexcept |
318 | { |
319 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
320 | return *this; |
321 | } |
322 | |
323 | template<class _Yp> |
324 | _Assignable<shared_ptr<_Yp>> |
325 | operator=(shared_ptr<_Yp>&& __r) noexcept |
326 | { |
327 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
328 | return *this; |
329 | } |
330 | |
331 | template<typename _Yp, typename _Del> |
332 | _Assignable<unique_ptr<_Yp, _Del>> |
333 | operator=(unique_ptr<_Yp, _Del>&& __r) |
334 | { |
335 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
336 | return *this; |
337 | } |
338 | |
339 | private: |
340 | // This constructor is non-standard, it is used by allocate_shared. |
341 | template<typename _Alloc, typename... _Args> |
342 | shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, |
343 | _Args&&... __args) |
344 | : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...) |
345 | { } |
346 | |
347 | template<typename _Yp, typename _Alloc, typename... _Args> |
348 | friend shared_ptr<_Yp> |
349 | allocate_shared(const _Alloc& __a, _Args&&... __args); |
350 | |
351 | // This constructor is non-standard, it is used by weak_ptr::lock(). |
352 | shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) |
353 | : __shared_ptr<_Tp>(__r, std::nothrow) { } |
354 | |
355 | friend class weak_ptr<_Tp>; |
356 | }; |
357 | |
358 | #if __cpp_deduction_guides >= 201606 |
359 | template<typename _Tp> |
360 | shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; |
361 | template<typename _Tp, typename _Del> |
362 | shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; |
363 | #endif |
364 | |
365 | // 20.7.2.2.7 shared_ptr comparisons |
366 | template<typename _Tp, typename _Up> |
367 | inline bool |
368 | operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
369 | { return __a.get() == __b.get(); } |
370 | |
371 | template<typename _Tp> |
372 | inline bool |
373 | operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
374 | { return !__a; } |
375 | |
376 | template<typename _Tp> |
377 | inline bool |
378 | operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
379 | { return !__a; } |
380 | |
381 | template<typename _Tp, typename _Up> |
382 | inline bool |
383 | operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
384 | { return __a.get() != __b.get(); } |
385 | |
386 | template<typename _Tp> |
387 | inline bool |
388 | operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
389 | { return (bool)__a; } |
390 | |
391 | template<typename _Tp> |
392 | inline bool |
393 | operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
394 | { return (bool)__a; } |
395 | |
396 | template<typename _Tp, typename _Up> |
397 | inline bool |
398 | operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
399 | { |
400 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
401 | using _Up_elt = typename shared_ptr<_Up>::element_type; |
402 | using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; |
403 | return less<_Vp>()(__a.get(), __b.get()); |
404 | } |
405 | |
406 | template<typename _Tp> |
407 | inline bool |
408 | operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
409 | { |
410 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
411 | return less<_Tp_elt*>()(__a.get(), nullptr); |
412 | } |
413 | |
414 | template<typename _Tp> |
415 | inline bool |
416 | operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
417 | { |
418 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
419 | return less<_Tp_elt*>()(nullptr, __a.get()); |
420 | } |
421 | |
422 | template<typename _Tp, typename _Up> |
423 | inline bool |
424 | operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
425 | { return !(__b < __a); } |
426 | |
427 | template<typename _Tp> |
428 | inline bool |
429 | operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
430 | { return !(nullptr < __a); } |
431 | |
432 | template<typename _Tp> |
433 | inline bool |
434 | operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
435 | { return !(__a < nullptr); } |
436 | |
437 | template<typename _Tp, typename _Up> |
438 | inline bool |
439 | operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
440 | { return (__b < __a); } |
441 | |
442 | template<typename _Tp> |
443 | inline bool |
444 | operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
445 | { return nullptr < __a; } |
446 | |
447 | template<typename _Tp> |
448 | inline bool |
449 | operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
450 | { return __a < nullptr; } |
451 | |
452 | template<typename _Tp, typename _Up> |
453 | inline bool |
454 | operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
455 | { return !(__a < __b); } |
456 | |
457 | template<typename _Tp> |
458 | inline bool |
459 | operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
460 | { return !(__a < nullptr); } |
461 | |
462 | template<typename _Tp> |
463 | inline bool |
464 | operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
465 | { return !(nullptr < __a); } |
466 | |
467 | template<typename _Tp> |
468 | struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>> |
469 | { }; |
470 | |
471 | // 20.7.2.2.8 shared_ptr specialized algorithms. |
472 | template<typename _Tp> |
473 | inline void |
474 | swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept |
475 | { __a.swap(__b); } |
476 | |
477 | // 20.7.2.2.9 shared_ptr casts. |
478 | template<typename _Tp, typename _Up> |
479 | inline shared_ptr<_Tp> |
480 | static_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
481 | { |
482 | using _Sp = shared_ptr<_Tp>; |
483 | return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); |
484 | } |
485 | |
486 | template<typename _Tp, typename _Up> |
487 | inline shared_ptr<_Tp> |
488 | const_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
489 | { |
490 | using _Sp = shared_ptr<_Tp>; |
491 | return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); |
492 | } |
493 | |
494 | template<typename _Tp, typename _Up> |
495 | inline shared_ptr<_Tp> |
496 | dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
497 | { |
498 | using _Sp = shared_ptr<_Tp>; |
499 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
500 | return _Sp(__r, __p); |
501 | return _Sp(); |
502 | } |
503 | |
504 | #if __cplusplus > 201402L |
505 | template<typename _Tp, typename _Up> |
506 | inline shared_ptr<_Tp> |
507 | reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
508 | { |
509 | using _Sp = shared_ptr<_Tp>; |
510 | return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
511 | } |
512 | #endif |
513 | |
514 | /** |
515 | * @brief A smart pointer with weak semantics. |
516 | * |
517 | * With forwarding constructors and assignment operators. |
518 | */ |
519 | template<typename _Tp> |
520 | class weak_ptr : public __weak_ptr<_Tp> |
521 | { |
522 | template<typename _Arg> |
523 | using _Constructible = typename enable_if< |
524 | is_constructible<__weak_ptr<_Tp>, _Arg>::value |
525 | >::type; |
526 | |
527 | template<typename _Arg> |
528 | using _Assignable = typename enable_if< |
529 | is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& |
530 | >::type; |
531 | |
532 | public: |
533 | constexpr weak_ptr() noexcept = default; |
534 | |
535 | template<typename _Yp, |
536 | typename = _Constructible<const shared_ptr<_Yp>&>> |
537 | weak_ptr(const shared_ptr<_Yp>& __r) noexcept |
538 | : __weak_ptr<_Tp>(__r) { } |
539 | |
540 | weak_ptr(const weak_ptr&) noexcept = default; |
541 | |
542 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
543 | weak_ptr(const weak_ptr<_Yp>& __r) noexcept |
544 | : __weak_ptr<_Tp>(__r) { } |
545 | |
546 | weak_ptr(weak_ptr&&) noexcept = default; |
547 | |
548 | template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> |
549 | weak_ptr(weak_ptr<_Yp>&& __r) noexcept |
550 | : __weak_ptr<_Tp>(std::move(__r)) { } |
551 | |
552 | weak_ptr& |
553 | operator=(const weak_ptr& __r) noexcept = default; |
554 | |
555 | template<typename _Yp> |
556 | _Assignable<const weak_ptr<_Yp>&> |
557 | operator=(const weak_ptr<_Yp>& __r) noexcept |
558 | { |
559 | this->__weak_ptr<_Tp>::operator=(__r); |
560 | return *this; |
561 | } |
562 | |
563 | template<typename _Yp> |
564 | _Assignable<const shared_ptr<_Yp>&> |
565 | operator=(const shared_ptr<_Yp>& __r) noexcept |
566 | { |
567 | this->__weak_ptr<_Tp>::operator=(__r); |
568 | return *this; |
569 | } |
570 | |
571 | weak_ptr& |
572 | operator=(weak_ptr&& __r) noexcept = default; |
573 | |
574 | template<typename _Yp> |
575 | _Assignable<weak_ptr<_Yp>> |
576 | operator=(weak_ptr<_Yp>&& __r) noexcept |
577 | { |
578 | this->__weak_ptr<_Tp>::operator=(std::move(__r)); |
579 | return *this; |
580 | } |
581 | |
582 | shared_ptr<_Tp> |
583 | lock() const noexcept |
584 | { return shared_ptr<_Tp>(*this, std::nothrow); } |
585 | }; |
586 | |
587 | #if __cpp_deduction_guides >= 201606 |
588 | template<typename _Tp> |
589 | weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; |
590 | #endif |
591 | |
592 | // 20.7.2.3.6 weak_ptr specialized algorithms. |
593 | template<typename _Tp> |
594 | inline void |
595 | swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept |
596 | { __a.swap(__b); } |
597 | |
598 | |
599 | /// Primary template owner_less |
600 | template<typename _Tp = void> |
601 | struct owner_less; |
602 | |
603 | /// Void specialization of owner_less |
604 | template<> |
605 | struct owner_less<void> : _Sp_owner_less<void, void> |
606 | { }; |
607 | |
608 | /// Partial specialization of owner_less for shared_ptr. |
609 | template<typename _Tp> |
610 | struct owner_less<shared_ptr<_Tp>> |
611 | : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> |
612 | { }; |
613 | |
614 | /// Partial specialization of owner_less for weak_ptr. |
615 | template<typename _Tp> |
616 | struct owner_less<weak_ptr<_Tp>> |
617 | : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> |
618 | { }; |
619 | |
620 | /** |
621 | * @brief Base class allowing use of member function shared_from_this. |
622 | */ |
623 | template<typename _Tp> |
624 | class enable_shared_from_this |
625 | { |
626 | protected: |
627 | constexpr enable_shared_from_this() noexcept { } |
628 | |
629 | enable_shared_from_this(const enable_shared_from_this&) noexcept { } |
630 | |
631 | enable_shared_from_this& |
632 | operator=(const enable_shared_from_this&) noexcept |
633 | { return *this; } |
634 | |
635 | ~enable_shared_from_this() { } |
636 | |
637 | public: |
638 | shared_ptr<_Tp> |
639 | shared_from_this() |
640 | { return shared_ptr<_Tp>(this->_M_weak_this); } |
641 | |
642 | shared_ptr<const _Tp> |
643 | shared_from_this() const |
644 | { return shared_ptr<const _Tp>(this->_M_weak_this); } |
645 | |
646 | #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 |
647 | #define __cpp_lib_enable_shared_from_this 201603 |
648 | weak_ptr<_Tp> |
649 | weak_from_this() noexcept |
650 | { return this->_M_weak_this; } |
651 | |
652 | weak_ptr<const _Tp> |
653 | weak_from_this() const noexcept |
654 | { return this->_M_weak_this; } |
655 | #endif |
656 | |
657 | private: |
658 | template<typename _Tp1> |
659 | void |
660 | _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept |
661 | { _M_weak_this._M_assign(__p, __n); } |
662 | |
663 | // Found by ADL when this is an associated class. |
664 | friend const enable_shared_from_this* |
665 | __enable_shared_from_this_base(const __shared_count<>&, |
666 | const enable_shared_from_this* __p) |
667 | { return __p; } |
668 | |
669 | template<typename, _Lock_policy> |
670 | friend class __shared_ptr; |
671 | |
672 | mutable weak_ptr<_Tp> _M_weak_this; |
673 | }; |
674 | |
675 | /** |
676 | * @brief Create an object that is owned by a shared_ptr. |
677 | * @param __a An allocator. |
678 | * @param __args Arguments for the @a _Tp object's constructor. |
679 | * @return A shared_ptr that owns the newly created object. |
680 | * @throw An exception thrown from @a _Alloc::allocate or from the |
681 | * constructor of @a _Tp. |
682 | * |
683 | * A copy of @a __a will be used to allocate memory for the shared_ptr |
684 | * and the new object. |
685 | */ |
686 | template<typename _Tp, typename _Alloc, typename... _Args> |
687 | inline shared_ptr<_Tp> |
688 | allocate_shared(const _Alloc& __a, _Args&&... __args) |
689 | { |
690 | return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a, |
691 | std::forward<_Args>(__args)...); |
692 | } |
693 | |
694 | /** |
695 | * @brief Create an object that is owned by a shared_ptr. |
696 | * @param __args Arguments for the @a _Tp object's constructor. |
697 | * @return A shared_ptr that owns the newly created object. |
698 | * @throw std::bad_alloc, or an exception thrown from the |
699 | * constructor of @a _Tp. |
700 | */ |
701 | template<typename _Tp, typename... _Args> |
702 | inline shared_ptr<_Tp> |
703 | make_shared(_Args&&... __args) |
704 | { |
705 | typedef typename std::remove_const<_Tp>::type _Tp_nc; |
706 | return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(), |
707 | std::forward<_Args>(__args)...); |
708 | } |
709 | |
710 | /// std::hash specialization for shared_ptr. |
711 | template<typename _Tp> |
712 | struct hash<shared_ptr<_Tp>> |
713 | : public __hash_base<size_t, shared_ptr<_Tp>> |
714 | { |
715 | size_t |
716 | operator()(const shared_ptr<_Tp>& __s) const noexcept |
717 | { |
718 | return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); |
719 | } |
720 | }; |
721 | |
722 | // @} group pointer_abstractions |
723 | |
724 | _GLIBCXX_END_NAMESPACE_VERSION |
725 | } // namespace |
726 | |
727 | #endif // _SHARED_PTR_H |
728 | |