1 | // shared_ptr and weak_ptr implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2007-2019 Free Software Foundation, Inc. |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free |
6 | // software; you can redistribute it and/or modify it under the |
7 | // terms of the GNU General Public License as published by the |
8 | // Free Software Foundation; either version 3, or (at your option) |
9 | // any later version. |
10 | |
11 | // This library is distributed in the hope that it will be useful, |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | // GNU General Public License for more details. |
15 | |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version |
18 | // 3.1, as published by the Free Software Foundation. |
19 | |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | // <http://www.gnu.org/licenses/>. |
24 | |
25 | // 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 | template<typename _Del, typename _Tp, _Lock_policy _Lp> |
74 | inline _Del* |
75 | get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept |
76 | { |
77 | #if __cpp_rtti |
78 | return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); |
79 | #else |
80 | return 0; |
81 | #endif |
82 | } |
83 | |
84 | /// 20.7.2.2.10 shared_ptr get_deleter |
85 | template<typename _Del, typename _Tp> |
86 | inline _Del* |
87 | get_deleter(const shared_ptr<_Tp>& __p) noexcept |
88 | { |
89 | #if __cpp_rtti |
90 | return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); |
91 | #else |
92 | return 0; |
93 | #endif |
94 | } |
95 | |
96 | /** |
97 | * @brief A smart pointer with reference-counted copy semantics. |
98 | * |
99 | * The object pointed to is deleted when the last shared_ptr pointing to |
100 | * it is destroyed or reset. |
101 | */ |
102 | template<typename _Tp> |
103 | class shared_ptr : public __shared_ptr<_Tp> |
104 | { |
105 | template<typename... _Args> |
106 | using _Constructible = typename enable_if< |
107 | is_constructible<__shared_ptr<_Tp>, _Args...>::value |
108 | >::type; |
109 | |
110 | template<typename _Arg> |
111 | using _Assignable = typename enable_if< |
112 | is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& |
113 | >::type; |
114 | |
115 | public: |
116 | |
117 | using element_type = typename __shared_ptr<_Tp>::element_type; |
118 | |
119 | #if __cplusplus > 201402L |
120 | # define __cpp_lib_shared_ptr_weak_type 201606 |
121 | using weak_type = weak_ptr<_Tp>; |
122 | #endif |
123 | /** |
124 | * @brief Construct an empty %shared_ptr. |
125 | * @post use_count()==0 && get()==0 |
126 | */ |
127 | constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } |
128 | |
129 | shared_ptr(const shared_ptr&) noexcept = default; |
130 | |
131 | /** |
132 | * @brief Construct a %shared_ptr that owns the pointer @a __p. |
133 | * @param __p A pointer that is convertible to element_type*. |
134 | * @post use_count() == 1 && get() == __p |
135 | * @throw std::bad_alloc, in which case @c delete @a __p is called. |
136 | */ |
137 | template<typename _Yp, typename = _Constructible<_Yp*>> |
138 | explicit |
139 | shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } |
140 | |
141 | /** |
142 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
143 | * and the deleter @a __d. |
144 | * @param __p A pointer. |
145 | * @param __d A deleter. |
146 | * @post use_count() == 1 && get() == __p |
147 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
148 | * |
149 | * Requirements: _Deleter's copy constructor and destructor must |
150 | * not throw |
151 | * |
152 | * __shared_ptr will release __p by calling __d(__p) |
153 | */ |
154 | template<typename _Yp, typename _Deleter, |
155 | typename = _Constructible<_Yp*, _Deleter>> |
156 | shared_ptr(_Yp* __p, _Deleter __d) |
157 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
158 | |
159 | /** |
160 | * @brief Construct a %shared_ptr that owns a null pointer |
161 | * and the deleter @a __d. |
162 | * @param __p A null pointer constant. |
163 | * @param __d A deleter. |
164 | * @post use_count() == 1 && get() == __p |
165 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
166 | * |
167 | * Requirements: _Deleter's copy constructor and destructor must |
168 | * not throw |
169 | * |
170 | * The last owner will call __d(__p) |
171 | */ |
172 | template<typename _Deleter> |
173 | shared_ptr(nullptr_t __p, _Deleter __d) |
174 | : __shared_ptr<_Tp>(__p, std::move(__d)) { } |
175 | |
176 | /** |
177 | * @brief Construct a %shared_ptr that owns the pointer @a __p |
178 | * and the deleter @a __d. |
179 | * @param __p A pointer. |
180 | * @param __d A deleter. |
181 | * @param __a An allocator. |
182 | * @post use_count() == 1 && get() == __p |
183 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
184 | * |
185 | * Requirements: _Deleter's copy constructor and destructor must |
186 | * not throw _Alloc's copy constructor and destructor must not |
187 | * throw. |
188 | * |
189 | * __shared_ptr will release __p by calling __d(__p) |
190 | */ |
191 | template<typename _Yp, typename _Deleter, typename _Alloc, |
192 | typename = _Constructible<_Yp*, _Deleter, _Alloc>> |
193 | shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) |
194 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
195 | |
196 | /** |
197 | * @brief Construct a %shared_ptr that owns a null pointer |
198 | * and the deleter @a __d. |
199 | * @param __p A null pointer constant. |
200 | * @param __d A deleter. |
201 | * @param __a An allocator. |
202 | * @post use_count() == 1 && get() == __p |
203 | * @throw std::bad_alloc, in which case @a __d(__p) is called. |
204 | * |
205 | * Requirements: _Deleter's copy constructor and destructor must |
206 | * not throw _Alloc's copy constructor and destructor must not |
207 | * throw. |
208 | * |
209 | * The last owner will call __d(__p) |
210 | */ |
211 | template<typename _Deleter, typename _Alloc> |
212 | shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) |
213 | : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } |
214 | |
215 | // Aliasing constructor |
216 | |
217 | /** |
218 | * @brief Constructs a %shared_ptr instance that stores @a __p |
219 | * and shares ownership with @a __r. |
220 | * @param __r A %shared_ptr. |
221 | * @param __p A pointer that will remain valid while @a *__r is valid. |
222 | * @post get() == __p && use_count() == __r.use_count() |
223 | * |
224 | * This can be used to construct a @c shared_ptr to a sub-object |
225 | * of an object managed by an existing @c shared_ptr. |
226 | * |
227 | * @code |
228 | * shared_ptr< pair<int,int> > pii(new pair<int,int>()); |
229 | * shared_ptr<int> pi(pii, &pii->first); |
230 | * assert(pii.use_count() == 2); |
231 | * @endcode |
232 | */ |
233 | template<typename _Yp> |
234 | shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept |
235 | : __shared_ptr<_Tp>(__r, __p) { } |
236 | |
237 | /** |
238 | * @brief If @a __r is empty, constructs an empty %shared_ptr; |
239 | * otherwise construct a %shared_ptr that shares ownership |
240 | * with @a __r. |
241 | * @param __r A %shared_ptr. |
242 | * @post get() == __r.get() && use_count() == __r.use_count() |
243 | */ |
244 | template<typename _Yp, |
245 | typename = _Constructible<const shared_ptr<_Yp>&>> |
246 | shared_ptr(const shared_ptr<_Yp>& __r) noexcept |
247 | : __shared_ptr<_Tp>(__r) { } |
248 | |
249 | /** |
250 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
251 | * @param __r A %shared_ptr rvalue. |
252 | * @post *this contains the old value of @a __r, @a __r is empty. |
253 | */ |
254 | shared_ptr(shared_ptr&& __r) noexcept |
255 | : __shared_ptr<_Tp>(std::move(__r)) { } |
256 | |
257 | /** |
258 | * @brief Move-constructs a %shared_ptr instance from @a __r. |
259 | * @param __r A %shared_ptr rvalue. |
260 | * @post *this contains the old value of @a __r, @a __r is empty. |
261 | */ |
262 | template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> |
263 | shared_ptr(shared_ptr<_Yp>&& __r) noexcept |
264 | : __shared_ptr<_Tp>(std::move(__r)) { } |
265 | |
266 | /** |
267 | * @brief Constructs a %shared_ptr that shares ownership with @a __r |
268 | * and stores a copy of the pointer stored in @a __r. |
269 | * @param __r A weak_ptr. |
270 | * @post use_count() == __r.use_count() |
271 | * @throw bad_weak_ptr when __r.expired(), |
272 | * in which case the constructor has no effect. |
273 | */ |
274 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
275 | explicit shared_ptr(const weak_ptr<_Yp>& __r) |
276 | : __shared_ptr<_Tp>(__r) { } |
277 | |
278 | #if _GLIBCXX_USE_DEPRECATED |
279 | #pragma GCC diagnostic push |
280 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
281 | template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> |
282 | shared_ptr(auto_ptr<_Yp>&& __r); |
283 | #pragma GCC diagnostic pop |
284 | #endif |
285 | |
286 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
287 | // 2399. shared_ptr's constructor from unique_ptr should be constrained |
288 | template<typename _Yp, typename _Del, |
289 | typename = _Constructible<unique_ptr<_Yp, _Del>>> |
290 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
291 | : __shared_ptr<_Tp>(std::move(__r)) { } |
292 | |
293 | #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED |
294 | // This non-standard constructor exists to support conversions that |
295 | // were possible in C++11 and C++14 but are ill-formed in C++17. |
296 | // If an exception is thrown this constructor has no effect. |
297 | template<typename _Yp, typename _Del, |
298 | _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> |
299 | shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
300 | : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } |
301 | #endif |
302 | |
303 | /** |
304 | * @brief Construct an empty %shared_ptr. |
305 | * @post use_count() == 0 && get() == nullptr |
306 | */ |
307 | constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } |
308 | |
309 | shared_ptr& operator=(const shared_ptr&) noexcept = default; |
310 | |
311 | template<typename _Yp> |
312 | _Assignable<const shared_ptr<_Yp>&> |
313 | operator=(const shared_ptr<_Yp>& __r) noexcept |
314 | { |
315 | this->__shared_ptr<_Tp>::operator=(__r); |
316 | return *this; |
317 | } |
318 | |
319 | #if _GLIBCXX_USE_DEPRECATED |
320 | #pragma GCC diagnostic push |
321 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
322 | template<typename _Yp> |
323 | _Assignable<auto_ptr<_Yp>> |
324 | operator=(auto_ptr<_Yp>&& __r) |
325 | { |
326 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
327 | return *this; |
328 | } |
329 | #pragma GCC diagnostic pop |
330 | #endif |
331 | |
332 | shared_ptr& |
333 | operator=(shared_ptr&& __r) noexcept |
334 | { |
335 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
336 | return *this; |
337 | } |
338 | |
339 | template<class _Yp> |
340 | _Assignable<shared_ptr<_Yp>> |
341 | operator=(shared_ptr<_Yp>&& __r) noexcept |
342 | { |
343 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
344 | return *this; |
345 | } |
346 | |
347 | template<typename _Yp, typename _Del> |
348 | _Assignable<unique_ptr<_Yp, _Del>> |
349 | operator=(unique_ptr<_Yp, _Del>&& __r) |
350 | { |
351 | this->__shared_ptr<_Tp>::operator=(std::move(__r)); |
352 | return *this; |
353 | } |
354 | |
355 | private: |
356 | // This constructor is non-standard, it is used by allocate_shared. |
357 | template<typename _Alloc, typename... _Args> |
358 | shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args) |
359 | : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...) |
360 | { } |
361 | |
362 | template<typename _Yp, typename _Alloc, typename... _Args> |
363 | friend shared_ptr<_Yp> |
364 | allocate_shared(const _Alloc& __a, _Args&&... __args); |
365 | |
366 | // This constructor is non-standard, it is used by weak_ptr::lock(). |
367 | shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) |
368 | : __shared_ptr<_Tp>(__r, std::nothrow) { } |
369 | |
370 | friend class weak_ptr<_Tp>; |
371 | }; |
372 | |
373 | #if __cpp_deduction_guides >= 201606 |
374 | template<typename _Tp> |
375 | shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; |
376 | template<typename _Tp, typename _Del> |
377 | shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; |
378 | #endif |
379 | |
380 | // 20.7.2.2.7 shared_ptr comparisons |
381 | template<typename _Tp, typename _Up> |
382 | _GLIBCXX_NODISCARD 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 | _GLIBCXX_NODISCARD inline bool |
388 | operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
389 | { return !__a; } |
390 | |
391 | template<typename _Tp> |
392 | _GLIBCXX_NODISCARD inline bool |
393 | operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
394 | { return !__a; } |
395 | |
396 | template<typename _Tp, typename _Up> |
397 | _GLIBCXX_NODISCARD inline bool |
398 | operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
399 | { return __a.get() != __b.get(); } |
400 | |
401 | template<typename _Tp> |
402 | _GLIBCXX_NODISCARD inline bool |
403 | operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
404 | { return (bool)__a; } |
405 | |
406 | template<typename _Tp> |
407 | _GLIBCXX_NODISCARD inline bool |
408 | operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
409 | { return (bool)__a; } |
410 | |
411 | template<typename _Tp, typename _Up> |
412 | _GLIBCXX_NODISCARD inline bool |
413 | operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
414 | { |
415 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
416 | using _Up_elt = typename shared_ptr<_Up>::element_type; |
417 | using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; |
418 | return less<_Vp>()(__a.get(), __b.get()); |
419 | } |
420 | |
421 | template<typename _Tp> |
422 | _GLIBCXX_NODISCARD inline bool |
423 | operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
424 | { |
425 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
426 | return less<_Tp_elt*>()(__a.get(), nullptr); |
427 | } |
428 | |
429 | template<typename _Tp> |
430 | _GLIBCXX_NODISCARD inline bool |
431 | operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
432 | { |
433 | using _Tp_elt = typename shared_ptr<_Tp>::element_type; |
434 | return less<_Tp_elt*>()(nullptr, __a.get()); |
435 | } |
436 | |
437 | template<typename _Tp, typename _Up> |
438 | _GLIBCXX_NODISCARD 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 | _GLIBCXX_NODISCARD inline bool |
444 | operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
445 | { return !(nullptr < __a); } |
446 | |
447 | template<typename _Tp> |
448 | _GLIBCXX_NODISCARD inline bool |
449 | operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
450 | { return !(__a < nullptr); } |
451 | |
452 | template<typename _Tp, typename _Up> |
453 | _GLIBCXX_NODISCARD inline bool |
454 | operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
455 | { return (__b < __a); } |
456 | |
457 | template<typename _Tp> |
458 | _GLIBCXX_NODISCARD inline bool |
459 | operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
460 | { return nullptr < __a; } |
461 | |
462 | template<typename _Tp> |
463 | _GLIBCXX_NODISCARD inline bool |
464 | operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
465 | { return __a < nullptr; } |
466 | |
467 | template<typename _Tp, typename _Up> |
468 | _GLIBCXX_NODISCARD inline bool |
469 | operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept |
470 | { return !(__a < __b); } |
471 | |
472 | template<typename _Tp> |
473 | _GLIBCXX_NODISCARD inline bool |
474 | operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept |
475 | { return !(__a < nullptr); } |
476 | |
477 | template<typename _Tp> |
478 | _GLIBCXX_NODISCARD inline bool |
479 | operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept |
480 | { return !(nullptr < __a); } |
481 | |
482 | // 20.7.2.2.8 shared_ptr specialized algorithms. |
483 | template<typename _Tp> |
484 | inline void |
485 | swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept |
486 | { __a.swap(__b); } |
487 | |
488 | // 20.7.2.2.9 shared_ptr casts. |
489 | template<typename _Tp, typename _Up> |
490 | inline shared_ptr<_Tp> |
491 | static_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
492 | { |
493 | using _Sp = shared_ptr<_Tp>; |
494 | return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); |
495 | } |
496 | |
497 | template<typename _Tp, typename _Up> |
498 | inline shared_ptr<_Tp> |
499 | const_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
500 | { |
501 | using _Sp = shared_ptr<_Tp>; |
502 | return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); |
503 | } |
504 | |
505 | template<typename _Tp, typename _Up> |
506 | inline shared_ptr<_Tp> |
507 | dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
508 | { |
509 | using _Sp = shared_ptr<_Tp>; |
510 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
511 | return _Sp(__r, __p); |
512 | return _Sp(); |
513 | } |
514 | |
515 | #if __cplusplus > 201402L |
516 | template<typename _Tp, typename _Up> |
517 | inline shared_ptr<_Tp> |
518 | reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept |
519 | { |
520 | using _Sp = shared_ptr<_Tp>; |
521 | return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
522 | } |
523 | #endif |
524 | |
525 | /** |
526 | * @brief A smart pointer with weak semantics. |
527 | * |
528 | * With forwarding constructors and assignment operators. |
529 | */ |
530 | template<typename _Tp> |
531 | class weak_ptr : public __weak_ptr<_Tp> |
532 | { |
533 | template<typename _Arg> |
534 | using _Constructible = typename enable_if< |
535 | is_constructible<__weak_ptr<_Tp>, _Arg>::value |
536 | >::type; |
537 | |
538 | template<typename _Arg> |
539 | using _Assignable = typename enable_if< |
540 | is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& |
541 | >::type; |
542 | |
543 | public: |
544 | constexpr weak_ptr() noexcept = default; |
545 | |
546 | template<typename _Yp, |
547 | typename = _Constructible<const shared_ptr<_Yp>&>> |
548 | weak_ptr(const shared_ptr<_Yp>& __r) noexcept |
549 | : __weak_ptr<_Tp>(__r) { } |
550 | |
551 | weak_ptr(const weak_ptr&) noexcept = default; |
552 | |
553 | template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> |
554 | weak_ptr(const weak_ptr<_Yp>& __r) noexcept |
555 | : __weak_ptr<_Tp>(__r) { } |
556 | |
557 | weak_ptr(weak_ptr&&) noexcept = default; |
558 | |
559 | template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> |
560 | weak_ptr(weak_ptr<_Yp>&& __r) noexcept |
561 | : __weak_ptr<_Tp>(std::move(__r)) { } |
562 | |
563 | weak_ptr& |
564 | operator=(const weak_ptr& __r) noexcept = default; |
565 | |
566 | template<typename _Yp> |
567 | _Assignable<const weak_ptr<_Yp>&> |
568 | operator=(const weak_ptr<_Yp>& __r) noexcept |
569 | { |
570 | this->__weak_ptr<_Tp>::operator=(__r); |
571 | return *this; |
572 | } |
573 | |
574 | template<typename _Yp> |
575 | _Assignable<const shared_ptr<_Yp>&> |
576 | operator=(const shared_ptr<_Yp>& __r) noexcept |
577 | { |
578 | this->__weak_ptr<_Tp>::operator=(__r); |
579 | return *this; |
580 | } |
581 | |
582 | weak_ptr& |
583 | operator=(weak_ptr&& __r) noexcept = default; |
584 | |
585 | template<typename _Yp> |
586 | _Assignable<weak_ptr<_Yp>> |
587 | operator=(weak_ptr<_Yp>&& __r) noexcept |
588 | { |
589 | this->__weak_ptr<_Tp>::operator=(std::move(__r)); |
590 | return *this; |
591 | } |
592 | |
593 | shared_ptr<_Tp> |
594 | lock() const noexcept |
595 | { return shared_ptr<_Tp>(*this, std::nothrow); } |
596 | }; |
597 | |
598 | #if __cpp_deduction_guides >= 201606 |
599 | template<typename _Tp> |
600 | weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; |
601 | #endif |
602 | |
603 | // 20.7.2.3.6 weak_ptr specialized algorithms. |
604 | template<typename _Tp> |
605 | inline void |
606 | swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept |
607 | { __a.swap(__b); } |
608 | |
609 | |
610 | /// Primary template owner_less |
611 | template<typename _Tp = void> |
612 | struct owner_less; |
613 | |
614 | /// Void specialization of owner_less |
615 | template<> |
616 | struct owner_less<void> : _Sp_owner_less<void, void> |
617 | { }; |
618 | |
619 | /// Partial specialization of owner_less for shared_ptr. |
620 | template<typename _Tp> |
621 | struct owner_less<shared_ptr<_Tp>> |
622 | : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> |
623 | { }; |
624 | |
625 | /// Partial specialization of owner_less for weak_ptr. |
626 | template<typename _Tp> |
627 | struct owner_less<weak_ptr<_Tp>> |
628 | : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> |
629 | { }; |
630 | |
631 | /** |
632 | * @brief Base class allowing use of member function shared_from_this. |
633 | */ |
634 | template<typename _Tp> |
635 | class enable_shared_from_this |
636 | { |
637 | protected: |
638 | constexpr enable_shared_from_this() noexcept { } |
639 | |
640 | enable_shared_from_this(const enable_shared_from_this&) noexcept { } |
641 | |
642 | enable_shared_from_this& |
643 | operator=(const enable_shared_from_this&) noexcept |
644 | { return *this; } |
645 | |
646 | ~enable_shared_from_this() { } |
647 | |
648 | public: |
649 | shared_ptr<_Tp> |
650 | shared_from_this() |
651 | { return shared_ptr<_Tp>(this->_M_weak_this); } |
652 | |
653 | shared_ptr<const _Tp> |
654 | shared_from_this() const |
655 | { return shared_ptr<const _Tp>(this->_M_weak_this); } |
656 | |
657 | #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 |
658 | #define __cpp_lib_enable_shared_from_this 201603 |
659 | weak_ptr<_Tp> |
660 | weak_from_this() noexcept |
661 | { return this->_M_weak_this; } |
662 | |
663 | weak_ptr<const _Tp> |
664 | weak_from_this() const noexcept |
665 | { return this->_M_weak_this; } |
666 | #endif |
667 | |
668 | private: |
669 | template<typename _Tp1> |
670 | void |
671 | _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept |
672 | { _M_weak_this._M_assign(__p, __n); } |
673 | |
674 | // Found by ADL when this is an associated class. |
675 | friend const enable_shared_from_this* |
676 | __enable_shared_from_this_base(const __shared_count<>&, |
677 | const enable_shared_from_this* __p) |
678 | { return __p; } |
679 | |
680 | template<typename, _Lock_policy> |
681 | friend class __shared_ptr; |
682 | |
683 | mutable weak_ptr<_Tp> _M_weak_this; |
684 | }; |
685 | |
686 | /** |
687 | * @brief Create an object that is owned by a shared_ptr. |
688 | * @param __a An allocator. |
689 | * @param __args Arguments for the @a _Tp object's constructor. |
690 | * @return A shared_ptr that owns the newly created object. |
691 | * @throw An exception thrown from @a _Alloc::allocate or from the |
692 | * constructor of @a _Tp. |
693 | * |
694 | * A copy of @a __a will be used to allocate memory for the shared_ptr |
695 | * and the new object. |
696 | */ |
697 | template<typename _Tp, typename _Alloc, typename... _Args> |
698 | inline shared_ptr<_Tp> |
699 | allocate_shared(const _Alloc& __a, _Args&&... __args) |
700 | { |
701 | return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a}, |
702 | std::forward<_Args>(__args)...); |
703 | } |
704 | |
705 | /** |
706 | * @brief Create an object that is owned by a shared_ptr. |
707 | * @param __args Arguments for the @a _Tp object's constructor. |
708 | * @return A shared_ptr that owns the newly created object. |
709 | * @throw std::bad_alloc, or an exception thrown from the |
710 | * constructor of @a _Tp. |
711 | */ |
712 | template<typename _Tp, typename... _Args> |
713 | inline shared_ptr<_Tp> |
714 | make_shared(_Args&&... __args) |
715 | { |
716 | typedef typename std::remove_cv<_Tp>::type _Tp_nc; |
717 | return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(), |
718 | std::forward<_Args>(__args)...); |
719 | } |
720 | |
721 | /// std::hash specialization for shared_ptr. |
722 | template<typename _Tp> |
723 | struct hash<shared_ptr<_Tp>> |
724 | : public __hash_base<size_t, shared_ptr<_Tp>> |
725 | { |
726 | size_t |
727 | operator()(const shared_ptr<_Tp>& __s) const noexcept |
728 | { |
729 | return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); |
730 | } |
731 | }; |
732 | |
733 | // @} group pointer_abstractions |
734 | |
735 | #if __cplusplus >= 201703L |
736 | namespace __detail::__variant |
737 | { |
738 | template<typename> struct _Never_valueless_alt; // see <variant> |
739 | |
740 | // Provide the strong exception-safety guarantee when emplacing a |
741 | // shared_ptr into a variant. |
742 | template<typename _Tp> |
743 | struct _Never_valueless_alt<std::shared_ptr<_Tp>> |
744 | : std::true_type |
745 | { }; |
746 | |
747 | // Provide the strong exception-safety guarantee when emplacing a |
748 | // weak_ptr into a variant. |
749 | template<typename _Tp> |
750 | struct _Never_valueless_alt<std::weak_ptr<_Tp>> |
751 | : std::true_type |
752 | { }; |
753 | } // namespace __detail::__variant |
754 | #endif // C++17 |
755 | |
756 | _GLIBCXX_END_NAMESPACE_VERSION |
757 | } // namespace |
758 | |
759 | #endif // _SHARED_PTR_H |
760 | |