Line data Source code
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 247304 : constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }
149 :
150 877902 : 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 19760 : 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 0 : shared_ptr(_Yp* __p, _Deleter __d)
178 0 : : __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 143232 : shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
258 143232 : : __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 3080 : shared_ptr(const shared_ptr<_Yp>& __r) noexcept
297 3080 : : __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 163541 : shared_ptr(shared_ptr&& __r) noexcept
305 163541 : : __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 19688 : shared_ptr(shared_ptr<_Yp>&& __r) noexcept
314 19688 : : __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 81111 : explicit shared_ptr(const weak_ptr<_Yp>& __r)
326 81111 : : __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 1211 : shared_ptr(unique_ptr<_Yp, _Del>&& __r)
341 1211 : : __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 18914 : constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }
358 :
359 44529 : shared_ptr& operator=(const shared_ptr&) noexcept = default;
360 :
361 : template<typename _Yp>
362 : _Assignable<const shared_ptr<_Yp>&>
363 28 : operator=(const shared_ptr<_Yp>& __r) noexcept
364 : {
365 28 : this->__shared_ptr<_Tp>::operator=(__r);
366 28 : 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 116347 : operator=(shared_ptr&& __r) noexcept
384 : {
385 116347 : this->__shared_ptr<_Tp>::operator=(std::move(__r));
386 116347 : return *this;
387 : }
388 :
389 : template<class _Yp>
390 : _Assignable<shared_ptr<_Yp>>
391 1359 : operator=(shared_ptr<_Yp>&& __r) noexcept
392 : {
393 1359 : this->__shared_ptr<_Tp>::operator=(std::move(__r));
394 1359 : return *this;
395 : }
396 :
397 : template<typename _Yp, typename _Del>
398 : _Assignable<unique_ptr<_Yp, _Del>>
399 0 : operator=(unique_ptr<_Yp, _Del>&& __r)
400 : {
401 0 : this->__shared_ptr<_Tp>::operator=(std::move(__r));
402 0 : 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 122198 : shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
409 122198 : : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...)
410 122197 : { }
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 133928 : shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept
418 133928 : : __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 18033 : operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
438 18033 : { return __a.get() == __b.get(); }
439 :
440 : /// shared_ptr comparison with nullptr
441 : template<typename _Tp>
442 : _GLIBCXX_NODISCARD inline bool
443 23138 : operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
444 23138 : { 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 1108 : operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
471 1108 : { return __a.get() != __b.get(); }
472 :
473 : /// shared_ptr comparison with nullptr
474 : template<typename _Tp>
475 : _GLIBCXX_NODISCARD inline bool
476 4451 : operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
477 4451 : { 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 1656 : 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 1656 : 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 20 : swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
575 20 : { __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 131898 : static_pointer_cast(const shared_ptr<_Up>& __r) noexcept
583 : {
584 : using _Sp = shared_ptr<_Tp>;
585 131898 : 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 11701 : dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept
601 : {
602 : using _Sp = shared_ptr<_Tp>;
603 11701 : if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
604 11340 : return _Sp(__r, __p);
605 361 : 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 11265 : constexpr weak_ptr() noexcept = default;
700 :
701 : template<typename _Yp,
702 : typename = _Constructible<const shared_ptr<_Yp>&>>
703 80674 : weak_ptr(const shared_ptr<_Yp>& __r) noexcept
704 80674 : : __weak_ptr<_Tp>(__r) { }
705 :
706 108216 : 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 145194 : 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 2828 : operator=(const shared_ptr<_Yp>& __r) noexcept
732 : {
733 2828 : this->__weak_ptr<_Tp>::operator=(__r);
734 2828 : return *this;
735 : }
736 :
737 : weak_ptr&
738 0 : 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 133928 : lock() const noexcept
750 133928 : { 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 2 : swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
764 2 : { __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 6566 : 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 6556 : ~enable_shared_from_this() { }
804 :
805 : public:
806 : shared_ptr<_Tp>
807 81111 : shared_from_this()
808 81111 : { return shared_ptr<_Tp>(this->_M_weak_this); }
809 :
810 : shared_ptr<const _Tp>
811 0 : shared_from_this() const
812 0 : { 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 37358 : weak_from_this() noexcept
818 37358 : { 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 7897 : _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
829 7897 : { _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 7897 : __enable_shared_from_this_base(const __shared_count<>&,
834 : const enable_shared_from_this* __p)
835 7897 : { 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 122198 : 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 122198 : 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 122198 : make_shared(_Args&&... __args)
876 : {
877 : typedef typename std::remove_cv<_Tp>::type _Tp_nc;
878 244396 : return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
879 307228 : 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
|
