1 | // shared_ptr and weak_ptr implementation details -*- C++ -*- |
2 | |
3 | // Copyright (C) 2007-2024 Free Software Foundation, Inc. |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free |
6 | // software; you can redistribute it and/or modify it under the |
7 | // terms of the GNU General Public License as published by the |
8 | // Free Software Foundation; either version 3, or (at your option) |
9 | // any later version. |
10 | |
11 | // This library is distributed in the hope that it will be useful, |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | // GNU General Public License for more details. |
15 | |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version |
18 | // 3.1, as published by the Free Software Foundation. |
19 | |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | // <http://www.gnu.org/licenses/>. |
24 | |
25 | // GCC Note: Based on files from version 1.32.0 of the Boost library. |
26 | |
27 | // shared_count.hpp |
28 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. |
29 | |
30 | // shared_ptr.hpp |
31 | // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes. |
32 | // Copyright (C) 2001, 2002, 2003 Peter Dimov |
33 | |
34 | // weak_ptr.hpp |
35 | // Copyright (C) 2001, 2002, 2003 Peter Dimov |
36 | |
37 | // enable_shared_from_this.hpp |
38 | // Copyright (C) 2002 Peter Dimov |
39 | |
40 | // Distributed under the Boost Software License, Version 1.0. (See |
41 | // accompanying file LICENSE_1_0.txt or copy at |
42 | // http://www.boost.org/LICENSE_1_0.txt) |
43 | |
44 | /** @file bits/shared_ptr_base.h |
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_BASE_H |
50 | #define _SHARED_PTR_BASE_H 1 |
51 | |
52 | #include <typeinfo> |
53 | #include <bits/allocated_ptr.h> |
54 | #include <bits/allocator.h> |
55 | #include <bits/exception_defines.h> |
56 | #include <bits/functional_hash.h> |
57 | #include <bits/refwrap.h> |
58 | #include <bits/stl_function.h> // std::less |
59 | #include <bits/unique_ptr.h> |
60 | #include <ext/aligned_buffer.h> |
61 | #include <ext/atomicity.h> |
62 | #include <ext/concurrence.h> |
63 | #if __cplusplus >= 202002L |
64 | # include <bit> // __bit_floor |
65 | # include <compare> |
66 | # include <bits/align.h> // std::align |
67 | # include <bits/stl_uninitialized.h> |
68 | #endif |
69 | |
70 | namespace std _GLIBCXX_VISIBILITY(default) |
71 | { |
72 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
73 | |
74 | #if _GLIBCXX_USE_DEPRECATED |
75 | #pragma GCC diagnostic push |
76 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
77 | template<typename> class auto_ptr; |
78 | #pragma GCC diagnostic pop |
79 | #endif |
80 | |
81 | /** |
82 | * @brief Exception possibly thrown by @c shared_ptr. |
83 | * @ingroup exceptions |
84 | */ |
85 | class bad_weak_ptr : public std::exception |
86 | { |
87 | public: |
88 | virtual char const* what() const noexcept; |
89 | |
90 | virtual ~bad_weak_ptr() noexcept; |
91 | }; |
92 | |
93 | // Substitute for bad_weak_ptr object in the case of -fno-exceptions. |
94 | inline void |
95 | __throw_bad_weak_ptr() |
96 | { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } |
97 | |
98 | using __gnu_cxx::_Lock_policy; |
99 | using __gnu_cxx::__default_lock_policy; |
100 | using __gnu_cxx::_S_single; |
101 | using __gnu_cxx::_S_mutex; |
102 | using __gnu_cxx::_S_atomic; |
103 | |
104 | // Empty helper class except when the template argument is _S_mutex. |
105 | template<_Lock_policy _Lp> |
106 | class _Mutex_base |
107 | { |
108 | protected: |
109 | // The atomic policy uses fully-fenced builtins, single doesn't care. |
110 | enum { _S_need_barriers = 0 }; |
111 | }; |
112 | |
113 | template<> |
114 | class _Mutex_base<_S_mutex> |
115 | : public __gnu_cxx::__mutex |
116 | { |
117 | protected: |
118 | // This policy is used when atomic builtins are not available. |
119 | // The replacement atomic operations might not have the necessary |
120 | // memory barriers. |
121 | enum { _S_need_barriers = 1 }; |
122 | }; |
123 | |
124 | template<_Lock_policy _Lp = __default_lock_policy> |
125 | class _Sp_counted_base |
126 | : public _Mutex_base<_Lp> |
127 | { |
128 | public: |
129 | _Sp_counted_base() noexcept |
130 | : _M_use_count(1), _M_weak_count(1) { } |
131 | |
132 | virtual |
133 | ~_Sp_counted_base() noexcept |
134 | { } |
135 | |
136 | // Called when _M_use_count drops to zero, to release the resources |
137 | // managed by *this. |
138 | virtual void |
139 | _M_dispose() noexcept = 0; |
140 | |
141 | // Called when _M_weak_count drops to zero. |
142 | virtual void |
143 | _M_destroy() noexcept |
144 | { delete this; } |
145 | |
146 | virtual void* |
147 | _M_get_deleter(const std::type_info&) noexcept = 0; |
148 | |
149 | // Increment the use count (used when the count is greater than zero). |
150 | void |
151 | _M_add_ref_copy() |
152 | { __gnu_cxx::__atomic_add_dispatch(mem: &_M_use_count, val: 1); } |
153 | |
154 | // Increment the use count if it is non-zero, throw otherwise. |
155 | void |
156 | _M_add_ref_lock() |
157 | { |
158 | if (!_M_add_ref_lock_nothrow()) |
159 | __throw_bad_weak_ptr(); |
160 | } |
161 | |
162 | // Increment the use count if it is non-zero. |
163 | bool |
164 | _M_add_ref_lock_nothrow() noexcept; |
165 | |
166 | // Decrement the use count. |
167 | void |
168 | _M_release() noexcept; |
169 | |
170 | // Called by _M_release() when the use count reaches zero. |
171 | void |
172 | _M_release_last_use() noexcept |
173 | { |
174 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); |
175 | _M_dispose(); |
176 | // There must be a memory barrier between dispose() and destroy() |
177 | // to ensure that the effects of dispose() are observed in the |
178 | // thread that runs destroy(). |
179 | // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html |
180 | if (_Mutex_base<_Lp>::_S_need_barriers) |
181 | { |
182 | __atomic_thread_fence (__ATOMIC_ACQ_REL); |
183 | } |
184 | |
185 | // Be race-detector-friendly. For more info see bits/c++config. |
186 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); |
187 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_weak_count, |
188 | val: -1) == 1) |
189 | { |
190 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); |
191 | _M_destroy(); |
192 | } |
193 | } |
194 | |
195 | // As above, but 'noinline' to reduce code size on the cold path. |
196 | __attribute__((__noinline__)) |
197 | void |
198 | _M_release_last_use_cold() noexcept |
199 | { _M_release_last_use(); } |
200 | |
201 | // Increment the weak count. |
202 | void |
203 | _M_weak_add_ref() noexcept |
204 | { __gnu_cxx::__atomic_add_dispatch(mem: &_M_weak_count, val: 1); } |
205 | |
206 | // Decrement the weak count. |
207 | void |
208 | _M_weak_release() noexcept |
209 | { |
210 | // Be race-detector-friendly. For more info see bits/c++config. |
211 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); |
212 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_weak_count, val: -1) == 1) |
213 | { |
214 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); |
215 | if (_Mutex_base<_Lp>::_S_need_barriers) |
216 | { |
217 | // See _M_release(), |
218 | // destroy() must observe results of dispose() |
219 | __atomic_thread_fence (__ATOMIC_ACQ_REL); |
220 | } |
221 | _M_destroy(); |
222 | } |
223 | } |
224 | |
225 | long |
226 | _M_get_use_count() const noexcept |
227 | { |
228 | // No memory barrier is used here so there is no synchronization |
229 | // with other threads. |
230 | return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); |
231 | } |
232 | |
233 | private: |
234 | _Sp_counted_base(_Sp_counted_base const&) = delete; |
235 | _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; |
236 | |
237 | _Atomic_word _M_use_count; // #shared |
238 | _Atomic_word _M_weak_count; // #weak + (#shared != 0) |
239 | }; |
240 | |
241 | template<> |
242 | inline bool |
243 | _Sp_counted_base<_S_single>:: |
244 | _M_add_ref_lock_nothrow() noexcept |
245 | { |
246 | if (_M_use_count == 0) |
247 | return false; |
248 | ++_M_use_count; |
249 | return true; |
250 | } |
251 | |
252 | template<> |
253 | inline bool |
254 | _Sp_counted_base<_S_mutex>:: |
255 | _M_add_ref_lock_nothrow() noexcept |
256 | { |
257 | __gnu_cxx::__scoped_lock sentry(*this); |
258 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: 1) == 0) |
259 | { |
260 | _M_use_count = 0; |
261 | return false; |
262 | } |
263 | return true; |
264 | } |
265 | |
266 | template<> |
267 | inline bool |
268 | _Sp_counted_base<_S_atomic>:: |
269 | _M_add_ref_lock_nothrow() noexcept |
270 | { |
271 | // Perform lock-free add-if-not-zero operation. |
272 | _Atomic_word __count = _M_get_use_count(); |
273 | do |
274 | { |
275 | if (__count == 0) |
276 | return false; |
277 | // Replace the current counter value with the old value + 1, as |
278 | // long as it's not changed meanwhile. |
279 | } |
280 | while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, |
281 | true, __ATOMIC_ACQ_REL, |
282 | __ATOMIC_RELAXED)); |
283 | return true; |
284 | } |
285 | |
286 | template<> |
287 | inline void |
288 | _Sp_counted_base<_S_single>::_M_add_ref_copy() |
289 | { ++_M_use_count; } |
290 | |
291 | template<> |
292 | inline void |
293 | _Sp_counted_base<_S_single>::_M_release() noexcept |
294 | { |
295 | if (--_M_use_count == 0) |
296 | { |
297 | _M_dispose(); |
298 | if (--_M_weak_count == 0) |
299 | _M_destroy(); |
300 | } |
301 | } |
302 | |
303 | template<> |
304 | inline void |
305 | _Sp_counted_base<_S_mutex>::_M_release() noexcept |
306 | { |
307 | // Be race-detector-friendly. For more info see bits/c++config. |
308 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); |
309 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: -1) == 1) |
310 | { |
311 | _M_release_last_use(); |
312 | } |
313 | } |
314 | |
315 | template<> |
316 | inline void |
317 | _Sp_counted_base<_S_atomic>::_M_release() noexcept |
318 | { |
319 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); |
320 | #if ! _GLIBCXX_TSAN |
321 | constexpr bool __lock_free |
322 | = __atomic_always_lock_free(sizeof(long long), 0) |
323 | && __atomic_always_lock_free(sizeof(_Atomic_word), 0); |
324 | constexpr bool __double_word |
325 | = sizeof(long long) == 2 * sizeof(_Atomic_word); |
326 | // The ref-count members follow the vptr, so are aligned to |
327 | // alignof(void*). |
328 | constexpr bool __aligned = __alignof(long long) <= alignof(void*); |
329 | if _GLIBCXX17_CONSTEXPR (__lock_free && __double_word && __aligned) |
330 | { |
331 | constexpr int __wordbits = __CHAR_BIT__ * sizeof(_Atomic_word); |
332 | constexpr int __shiftbits = __double_word ? __wordbits : 0; |
333 | constexpr long long __unique_ref = 1LL + (1LL << __shiftbits); |
334 | auto __both_counts = reinterpret_cast<long long*>(&_M_use_count); |
335 | |
336 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); |
337 | if (__atomic_load_n(__both_counts, __ATOMIC_ACQUIRE) == __unique_ref) |
338 | { |
339 | // Both counts are 1, so there are no weak references and |
340 | // we are releasing the last strong reference. No other |
341 | // threads can observe the effects of this _M_release() |
342 | // call (e.g. calling use_count()) without a data race. |
343 | _M_weak_count = _M_use_count = 0; |
344 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); |
345 | _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); |
346 | _M_dispose(); |
347 | _M_destroy(); |
348 | return; |
349 | } |
350 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: -1) == 1) |
351 | [[__unlikely__]] |
352 | { |
353 | _M_release_last_use_cold(); |
354 | return; |
355 | } |
356 | } |
357 | else |
358 | #endif |
359 | if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: -1) == 1) |
360 | { |
361 | _M_release_last_use(); |
362 | } |
363 | } |
364 | |
365 | template<> |
366 | inline void |
367 | _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept |
368 | { ++_M_weak_count; } |
369 | |
370 | template<> |
371 | inline void |
372 | _Sp_counted_base<_S_single>::_M_weak_release() noexcept |
373 | { |
374 | if (--_M_weak_count == 0) |
375 | _M_destroy(); |
376 | } |
377 | |
378 | template<> |
379 | inline long |
380 | _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept |
381 | { return _M_use_count; } |
382 | |
383 | |
384 | // Forward declarations. |
385 | template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> |
386 | class __shared_ptr; |
387 | |
388 | template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> |
389 | class __weak_ptr; |
390 | |
391 | template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> |
392 | class __enable_shared_from_this; |
393 | |
394 | template<typename _Tp> |
395 | class shared_ptr; |
396 | |
397 | template<typename _Tp> |
398 | class weak_ptr; |
399 | |
400 | template<typename _Tp> |
401 | struct owner_less; |
402 | |
403 | template<typename _Tp> |
404 | class enable_shared_from_this; |
405 | |
406 | template<_Lock_policy _Lp = __default_lock_policy> |
407 | class __weak_count; |
408 | |
409 | template<_Lock_policy _Lp = __default_lock_policy> |
410 | class __shared_count; |
411 | |
412 | #ifdef __glibcxx_atomic_shared_ptr |
413 | template<typename> |
414 | class _Sp_atomic; |
415 | #endif |
416 | |
417 | // Counted ptr with no deleter or allocator support |
418 | template<typename _Ptr, _Lock_policy _Lp> |
419 | class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> |
420 | { |
421 | public: |
422 | explicit |
423 | _Sp_counted_ptr(_Ptr __p) noexcept |
424 | : _M_ptr(__p) { } |
425 | |
426 | virtual void |
427 | _M_dispose() noexcept |
428 | { delete _M_ptr; } |
429 | |
430 | virtual void |
431 | _M_destroy() noexcept |
432 | { delete this; } |
433 | |
434 | virtual void* |
435 | _M_get_deleter(const std::type_info&) noexcept |
436 | { return nullptr; } |
437 | |
438 | _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; |
439 | _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; |
440 | |
441 | private: |
442 | _Ptr _M_ptr; |
443 | }; |
444 | |
445 | template<> |
446 | inline void |
447 | _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } |
448 | |
449 | template<> |
450 | inline void |
451 | _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } |
452 | |
453 | template<> |
454 | inline void |
455 | _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } |
456 | |
457 | // FIXME: once __has_cpp_attribute(__no_unique_address__)) is true for |
458 | // all supported compilers we can greatly simplify _Sp_ebo_helper. |
459 | // N.B. unconditionally applying the attribute could change layout for |
460 | // final types, which currently cannot use EBO so have a unique address. |
461 | |
462 | template<int _Nm, typename _Tp, |
463 | bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)> |
464 | struct _Sp_ebo_helper; |
465 | |
466 | /// Specialization using EBO. |
467 | template<int _Nm, typename _Tp> |
468 | struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp |
469 | { |
470 | explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { } |
471 | explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { } |
472 | |
473 | static _Tp& |
474 | _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); } |
475 | }; |
476 | |
477 | /// Specialization not using EBO. |
478 | template<int _Nm, typename _Tp> |
479 | struct _Sp_ebo_helper<_Nm, _Tp, false> |
480 | { |
481 | explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { } |
482 | explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { } |
483 | |
484 | static _Tp& |
485 | _S_get(_Sp_ebo_helper& __eboh) |
486 | { return __eboh._M_tp; } |
487 | |
488 | private: |
489 | _Tp _M_tp; |
490 | }; |
491 | |
492 | // Support for custom deleter and/or allocator |
493 | template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> |
494 | class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> |
495 | { |
496 | class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc> |
497 | { |
498 | typedef _Sp_ebo_helper<0, _Deleter> _Del_base; |
499 | typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base; |
500 | |
501 | public: |
502 | _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept |
503 | : _Del_base(std::move(__d)), _Alloc_base(__a), _M_ptr(__p) |
504 | { } |
505 | |
506 | _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); } |
507 | _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); } |
508 | |
509 | _Ptr _M_ptr; |
510 | }; |
511 | |
512 | public: |
513 | using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>; |
514 | |
515 | // __d(__p) must not throw. |
516 | _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept |
517 | : _M_impl(__p, std::move(__d), _Alloc()) { } |
518 | |
519 | // __d(__p) must not throw. |
520 | _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept |
521 | : _M_impl(__p, std::move(__d), __a) { } |
522 | |
523 | ~_Sp_counted_deleter() noexcept { } |
524 | |
525 | virtual void |
526 | _M_dispose() noexcept |
527 | { _M_impl._M_del()(_M_impl._M_ptr); } |
528 | |
529 | virtual void |
530 | _M_destroy() noexcept |
531 | { |
532 | __allocator_type __a(_M_impl._M_alloc()); |
533 | __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; |
534 | this->~_Sp_counted_deleter(); |
535 | } |
536 | |
537 | virtual void* |
538 | _M_get_deleter(const type_info& __ti [[__gnu__::__unused__]]) noexcept |
539 | { |
540 | #if __cpp_rtti |
541 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
542 | // 2400. shared_ptr's get_deleter() should use addressof() |
543 | return __ti == typeid(_Deleter) |
544 | ? std::__addressof(_M_impl._M_del()) |
545 | : nullptr; |
546 | #else |
547 | return nullptr; |
548 | #endif |
549 | } |
550 | |
551 | private: |
552 | #ifdef __glibcxx_out_ptr |
553 | template<typename, typename, typename...> friend class out_ptr_t; |
554 | #endif |
555 | _Impl _M_impl; |
556 | }; |
557 | |
558 | // helpers for make_shared / allocate_shared |
559 | |
560 | struct _Sp_make_shared_tag |
561 | { |
562 | private: |
563 | template<typename _Tp, typename _Alloc, _Lock_policy _Lp> |
564 | friend class _Sp_counted_ptr_inplace; |
565 | |
566 | static const type_info& |
567 | _S_ti() noexcept _GLIBCXX_VISIBILITY(default) |
568 | { |
569 | alignas(type_info) static constexpr char __tag[sizeof(type_info)] = { }; |
570 | return reinterpret_cast<const type_info&>(__tag); |
571 | } |
572 | |
573 | static bool _S_eq(const type_info&) noexcept; |
574 | }; |
575 | |
576 | template<typename _Alloc> |
577 | struct _Sp_alloc_shared_tag |
578 | { |
579 | const _Alloc& _M_a; |
580 | }; |
581 | |
582 | template<typename _Tp, typename _Alloc, _Lock_policy _Lp> |
583 | class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> |
584 | { |
585 | class _Impl : _Sp_ebo_helper<0, _Alloc> |
586 | { |
587 | typedef _Sp_ebo_helper<0, _Alloc> _A_base; |
588 | |
589 | public: |
590 | explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { } |
591 | |
592 | _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); } |
593 | |
594 | __gnu_cxx::__aligned_buffer<_Tp> _M_storage; |
595 | }; |
596 | |
597 | public: |
598 | using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>; |
599 | |
600 | // Alloc parameter is not a reference so doesn't alias anything in __args |
601 | template<typename... _Args> |
602 | _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) |
603 | : _M_impl(__a) |
604 | { |
605 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
606 | // 2070. allocate_shared should use allocator_traits<A>::construct |
607 | allocator_traits<_Alloc>::construct(__a, _M_ptr(), |
608 | std::forward<_Args>(__args)...); // might throw |
609 | } |
610 | |
611 | ~_Sp_counted_ptr_inplace() noexcept { } |
612 | |
613 | virtual void |
614 | _M_dispose() noexcept |
615 | { |
616 | allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr()); |
617 | } |
618 | |
619 | // Override because the allocator needs to know the dynamic type |
620 | virtual void |
621 | _M_destroy() noexcept |
622 | { |
623 | __allocator_type __a(_M_impl._M_alloc()); |
624 | __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; |
625 | this->~_Sp_counted_ptr_inplace(); |
626 | } |
627 | |
628 | private: |
629 | friend class __shared_count<_Lp>; // To be able to call _M_ptr(). |
630 | |
631 | // No longer used, but code compiled against old libstdc++ headers |
632 | // might still call it from __shared_ptr ctor to get the pointer out. |
633 | virtual void* |
634 | _M_get_deleter(const std::type_info& __ti) noexcept override |
635 | { |
636 | auto __ptr = const_cast<typename remove_cv<_Tp>::type*>(_M_ptr()); |
637 | // Check for the fake type_info first, so we don't try to access it |
638 | // as a real type_info object. Otherwise, check if it's the real |
639 | // type_info for this class. With RTTI enabled we can check directly, |
640 | // or call a library function to do it. |
641 | if (&__ti == &_Sp_make_shared_tag::_S_ti() |
642 | || |
643 | #if __cpp_rtti |
644 | __ti == typeid(_Sp_make_shared_tag) |
645 | #else |
646 | _Sp_make_shared_tag::_S_eq(__ti) |
647 | #endif |
648 | ) |
649 | return __ptr; |
650 | return nullptr; |
651 | } |
652 | |
653 | _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); } |
654 | |
655 | _Impl _M_impl; |
656 | }; |
657 | |
658 | #ifdef __glibcxx_smart_ptr_for_overwrite // C++ >= 20 && HOSTED |
659 | struct _Sp_overwrite_tag { }; |
660 | |
661 | // Partial specialization used for make_shared_for_overwrite<non-array>(). |
662 | // This partial specialization is used when the allocator's value type |
663 | // is the special _Sp_overwrite_tag type. |
664 | #if __cpp_concepts |
665 | template<typename _Tp, typename _Alloc, _Lock_policy _Lp> |
666 | requires is_same_v<typename _Alloc::value_type, _Sp_overwrite_tag> |
667 | class _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> final |
668 | #else |
669 | template<typename _Tp, template<typename> class _Alloc, _Lock_policy _Lp> |
670 | class _Sp_counted_ptr_inplace<_Tp, _Alloc<_Sp_overwrite_tag>, _Lp> final |
671 | #endif |
672 | : public _Sp_counted_base<_Lp> |
673 | { |
674 | [[no_unique_address]] _Alloc _M_alloc; |
675 | |
676 | union { |
677 | _Tp _M_obj; |
678 | char _M_unused; |
679 | }; |
680 | |
681 | friend class __shared_count<_Lp>; // To be able to call _M_ptr(). |
682 | |
683 | _Tp* _M_ptr() noexcept { return std::__addressof(_M_obj); } |
684 | |
685 | public: |
686 | using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>; |
687 | |
688 | _Sp_counted_ptr_inplace(const _Alloc& __a) |
689 | : _M_alloc(__a) |
690 | { |
691 | ::new((void*)_M_ptr()) _Tp; // default-initialized, for overwrite. |
692 | } |
693 | |
694 | ~_Sp_counted_ptr_inplace() noexcept { } |
695 | |
696 | virtual void |
697 | _M_dispose() noexcept |
698 | { |
699 | _M_obj.~_Tp(); |
700 | } |
701 | |
702 | // Override because the allocator needs to know the dynamic type |
703 | virtual void |
704 | _M_destroy() noexcept |
705 | { |
706 | using pointer = typename allocator_traits<__allocator_type>::pointer; |
707 | __allocator_type __a(_M_alloc); |
708 | auto __p = pointer_traits<pointer>::pointer_to(*this); |
709 | __allocated_ptr<__allocator_type> __guard_ptr{ __a, __p }; |
710 | this->~_Sp_counted_ptr_inplace(); |
711 | } |
712 | |
713 | void* |
714 | _M_get_deleter(const std::type_info&) noexcept override |
715 | { return nullptr; } |
716 | }; |
717 | #endif // __glibcxx_smart_ptr_for_overwrite |
718 | |
719 | #if __glibcxx_shared_ptr_arrays >= 201707L // C++ >= 20 && HOSTED |
720 | struct _Sp_overwrite_tag; |
721 | |
722 | // For make_shared<T[]>, make_shared<T[N]>, allocate_shared<T[]> etc. |
723 | template<typename _Alloc> |
724 | struct _Sp_counted_array_base |
725 | { |
726 | [[no_unique_address]] _Alloc _M_alloc{}; |
727 | size_t _M_n = 0; |
728 | bool _M_overwrite = false; |
729 | |
730 | typename allocator_traits<_Alloc>::pointer |
731 | _M_alloc_array(size_t __tail) |
732 | { |
733 | return allocator_traits<_Alloc>::allocate(_M_alloc, _M_n + __tail); |
734 | } |
735 | |
736 | void |
737 | _M_dealloc_array(typename allocator_traits<_Alloc>::pointer __p, |
738 | size_t __tail) |
739 | { |
740 | allocator_traits<_Alloc>::deallocate(_M_alloc, __p, _M_n + __tail); |
741 | } |
742 | |
743 | // Init the array elements |
744 | template<typename _Init> |
745 | void |
746 | _M_init(typename allocator_traits<_Alloc>::value_type* __p, |
747 | _Init __init) |
748 | { |
749 | using _Tp = remove_pointer_t<_Init>; |
750 | using _Up = typename allocator_traits<_Alloc>::value_type; |
751 | |
752 | if constexpr (is_same_v<_Init, _Sp_overwrite_tag>) |
753 | { |
754 | std::uninitialized_default_construct_n(__p, _M_n); |
755 | _M_overwrite = true; |
756 | } |
757 | else if (__init == nullptr) |
758 | std::__uninitialized_default_n_a(__p, _M_n, _M_alloc); |
759 | else if constexpr (!is_array_v<_Tp>) |
760 | std::__uninitialized_fill_n_a(__p, _M_n, *__init, _M_alloc); |
761 | else |
762 | { |
763 | #pragma GCC diagnostic push |
764 | #pragma GCC diagnostic ignored "-Wunused-local-typedefs" |
765 | struct _Iter |
766 | { |
767 | using value_type = _Up; |
768 | using difference_type = ptrdiff_t; |
769 | using pointer = const _Up*; |
770 | using reference = const _Up&; |
771 | using iterator_category = forward_iterator_tag; |
772 | |
773 | const _Up* _M_p; |
774 | size_t _M_len; |
775 | size_t _M_pos; |
776 | |
777 | _Iter& operator++() { ++_M_pos; return *this; } |
778 | _Iter operator++(int) { auto __i(*this); ++_M_pos; return __i; } |
779 | |
780 | reference operator*() const { return _M_p[_M_pos % _M_len]; } |
781 | pointer operator->() const { return _M_p + (_M_pos % _M_len); } |
782 | |
783 | bool operator==(const _Iter& __i) const |
784 | { return _M_pos == __i._M_pos; } |
785 | }; |
786 | #pragma GCC diagnostic pop |
787 | |
788 | _Iter __first{_S_first_elem(__init), sizeof(_Tp) / sizeof(_Up)}; |
789 | _Iter __last = __first; |
790 | __last._M_pos = _M_n; |
791 | std::__uninitialized_copy_a(__first, __last, __p, _M_alloc); |
792 | } |
793 | } |
794 | |
795 | protected: |
796 | // Destroy the array elements |
797 | void |
798 | _M_dispose_array(typename allocator_traits<_Alloc>::value_type* __p) |
799 | { |
800 | if (_M_overwrite) |
801 | std::destroy_n(__p, _M_n); |
802 | else |
803 | { |
804 | size_t __n = _M_n; |
805 | while (__n--) |
806 | allocator_traits<_Alloc>::destroy(_M_alloc, __p + __n); |
807 | } |
808 | } |
809 | |
810 | private: |
811 | template<typename _Tp> |
812 | static _Tp* |
813 | _S_first_elem(_Tp* __p) { return __p; } |
814 | |
815 | template<typename _Tp, size_t _Nm> |
816 | static auto |
817 | _S_first_elem(_Tp (*__p)[_Nm]) { return _S_first_elem(*__p); } |
818 | }; |
819 | |
820 | // Control block for make_shared<T[]>, make_shared<T[N]> etc. that will be |
821 | // placed into unused memory at the end of the array. |
822 | template<typename _Alloc, _Lock_policy _Lp> |
823 | class _Sp_counted_array final |
824 | : public _Sp_counted_base<_Lp>, _Sp_counted_array_base<_Alloc> |
825 | { |
826 | using pointer = typename allocator_traits<_Alloc>::pointer; |
827 | |
828 | pointer _M_alloc_ptr; |
829 | |
830 | auto _M_ptr() const noexcept { return std::to_address(_M_alloc_ptr); } |
831 | |
832 | friend class __shared_count<_Lp>; // To be able to call _M_ptr(). |
833 | |
834 | public: |
835 | _Sp_counted_array(const _Sp_counted_array_base<_Alloc>& __a, |
836 | pointer __p) noexcept |
837 | : _Sp_counted_array_base<_Alloc>(__a), _M_alloc_ptr(__p) |
838 | { } |
839 | |
840 | ~_Sp_counted_array() = default; |
841 | |
842 | virtual void |
843 | _M_dispose() noexcept |
844 | { |
845 | if (this->_M_n) |
846 | this->_M_dispose_array(_M_ptr()); |
847 | } |
848 | |
849 | // Override because the allocator needs to know the dynamic type |
850 | virtual void |
851 | _M_destroy() noexcept |
852 | { |
853 | _Sp_counted_array_base<_Alloc> __a = *this; |
854 | pointer __p = _M_alloc_ptr; |
855 | this->~_Sp_counted_array(); |
856 | __a._M_dealloc_array(__p, _S_tail()); |
857 | } |
858 | |
859 | // Returns the number of additional array elements that must be |
860 | // allocated in order to store a _Sp_counted_array at the end. |
861 | static constexpr size_t |
862 | _S_tail() |
863 | { |
864 | // The array elemenent type. |
865 | using _Tp = typename allocator_traits<_Alloc>::value_type; |
866 | |
867 | // The space needed to store a _Sp_counted_array object. |
868 | size_t __bytes = sizeof(_Sp_counted_array); |
869 | |
870 | // Add any padding needed for manual alignment within the buffer. |
871 | if constexpr (alignof(_Tp) < alignof(_Sp_counted_array)) |
872 | __bytes += alignof(_Sp_counted_array) - alignof(_Tp); |
873 | |
874 | return (__bytes + sizeof(_Tp) - 1) / sizeof(_Tp); |
875 | } |
876 | |
877 | void* |
878 | _M_get_deleter(const std::type_info&) noexcept override |
879 | { return nullptr; } |
880 | }; |
881 | #endif // __glibcxx_shared_ptr_arrays >= 201707L |
882 | |
883 | // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>. |
884 | struct __sp_array_delete |
885 | { |
886 | template<typename _Yp> |
887 | void operator()(_Yp* __p) const { delete[] __p; } |
888 | }; |
889 | |
890 | template<_Lock_policy _Lp> |
891 | class __shared_count |
892 | { |
893 | // Prevent _Sp_alloc_shared_tag from matching the shared_ptr(P, D) ctor. |
894 | template<typename _Tp> |
895 | struct __not_alloc_shared_tag { using type = void; }; |
896 | |
897 | template<typename _Tp> |
898 | struct __not_alloc_shared_tag<_Sp_alloc_shared_tag<_Tp>> { }; |
899 | |
900 | #if __glibcxx_shared_ptr_arrays >= 201707L // C++ >= 20 && HOSTED |
901 | template<typename _Alloc> |
902 | struct __not_alloc_shared_tag<_Sp_counted_array_base<_Alloc>> { }; |
903 | #endif |
904 | |
905 | public: |
906 | constexpr __shared_count() noexcept : _M_pi(0) |
907 | { } |
908 | |
909 | template<typename _Ptr> |
910 | explicit |
911 | __shared_count(_Ptr __p) : _M_pi(0) |
912 | { |
913 | __try |
914 | { |
915 | _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); |
916 | } |
917 | __catch(...) |
918 | { |
919 | delete __p; |
920 | __throw_exception_again; |
921 | } |
922 | } |
923 | |
924 | template<typename _Ptr> |
925 | __shared_count(_Ptr __p, /* is_array = */ false_type) |
926 | : __shared_count(__p) |
927 | { } |
928 | |
929 | template<typename _Ptr> |
930 | __shared_count(_Ptr __p, /* is_array = */ true_type) |
931 | : __shared_count(__p, __sp_array_delete{}, allocator<void>()) |
932 | { } |
933 | |
934 | template<typename _Ptr, typename _Deleter, |
935 | typename = typename __not_alloc_shared_tag<_Deleter>::type> |
936 | __shared_count(_Ptr __p, _Deleter __d) |
937 | : __shared_count(__p, std::move(__d), allocator<void>()) |
938 | { } |
939 | |
940 | template<typename _Ptr, typename _Deleter, typename _Alloc, |
941 | typename = typename __not_alloc_shared_tag<_Deleter>::type> |
942 | __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) |
943 | { |
944 | typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; |
945 | __try |
946 | { |
947 | typename _Sp_cd_type::__allocator_type __a2(__a); |
948 | auto __guard = std::__allocate_guarded(__a2); |
949 | _Sp_cd_type* __mem = __guard.get(); |
950 | ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a)); |
951 | _M_pi = __mem; |
952 | __guard = nullptr; |
953 | } |
954 | __catch(...) |
955 | { |
956 | __d(__p); // Call _Deleter on __p. |
957 | __throw_exception_again; |
958 | } |
959 | } |
960 | |
961 | template<typename _Tp, typename _Alloc, typename... _Args> |
962 | __shared_count(_Tp*& __p, _Sp_alloc_shared_tag<_Alloc> __a, |
963 | _Args&&... __args) |
964 | { |
965 | typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; |
966 | typename _Sp_cp_type::__allocator_type __a2(__a._M_a); |
967 | auto __guard = std::__allocate_guarded(__a2); |
968 | _Sp_cp_type* __mem = __guard.get(); |
969 | auto __pi = ::new (__mem) |
970 | _Sp_cp_type(__a._M_a, std::forward<_Args>(__args)...); |
971 | __guard = nullptr; |
972 | _M_pi = __pi; |
973 | __p = __pi->_M_ptr(); |
974 | } |
975 | |
976 | #if __glibcxx_shared_ptr_arrays >= 201707L // C++ >= 20 && HOSTED |
977 | template<typename _Tp, typename _Alloc, typename _Init> |
978 | __shared_count(_Tp*& __p, const _Sp_counted_array_base<_Alloc>& __a, |
979 | _Init __init) |
980 | { |
981 | using _Up = remove_all_extents_t<_Tp>; |
982 | static_assert(is_same_v<_Up, typename _Alloc::value_type>); |
983 | |
984 | using _Sp_ca_type = _Sp_counted_array<_Alloc, _Lp>; |
985 | const size_t __tail = _Sp_ca_type::_S_tail(); |
986 | |
987 | struct _Guarded_ptr : _Sp_counted_array_base<_Alloc> |
988 | { |
989 | typename allocator_traits<_Alloc>::pointer _M_ptr; |
990 | |
991 | _Guarded_ptr(_Sp_counted_array_base<_Alloc> __a) |
992 | : _Sp_counted_array_base<_Alloc>(__a), |
993 | _M_ptr(this->_M_alloc_array(_Sp_ca_type::_S_tail())) |
994 | { } |
995 | |
996 | ~_Guarded_ptr() |
997 | { |
998 | if (_M_ptr) |
999 | this->_M_dealloc_array(_M_ptr, _Sp_ca_type::_S_tail()); |
1000 | } |
1001 | }; |
1002 | |
1003 | _Guarded_ptr __guard{__a}; |
1004 | _Up* const __raw = std::to_address(__guard._M_ptr); |
1005 | __guard._M_init(__raw, __init); // might throw |
1006 | |
1007 | void* __c = __raw + __a._M_n; |
1008 | if constexpr (alignof(_Up) < alignof(_Sp_ca_type)) |
1009 | { |
1010 | size_t __space = sizeof(_Up) * __tail; |
1011 | __c = std::align(alignof(_Sp_ca_type), sizeof(_Sp_ca_type), |
1012 | __c, __space); |
1013 | } |
1014 | auto __pi = ::new(__c) _Sp_ca_type(__guard, __guard._M_ptr); |
1015 | __guard._M_ptr = nullptr; |
1016 | _M_pi = __pi; |
1017 | __p = reinterpret_cast<_Tp*>(__raw); |
1018 | } |
1019 | #endif |
1020 | |
1021 | #if _GLIBCXX_USE_DEPRECATED |
1022 | #pragma GCC diagnostic push |
1023 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
1024 | // Special case for auto_ptr<_Tp> to provide the strong guarantee. |
1025 | template<typename _Tp> |
1026 | explicit |
1027 | __shared_count(std::auto_ptr<_Tp>&& __r); |
1028 | #pragma GCC diagnostic pop |
1029 | #endif |
1030 | |
1031 | // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. |
1032 | template<typename _Tp, typename _Del> |
1033 | explicit |
1034 | __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0) |
1035 | { |
1036 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
1037 | // 2415. Inconsistency between unique_ptr and shared_ptr |
1038 | if (__r.get() == nullptr) |
1039 | return; |
1040 | |
1041 | using _Ptr = typename unique_ptr<_Tp, _Del>::pointer; |
1042 | using _Del2 = __conditional_t<is_reference<_Del>::value, |
1043 | reference_wrapper<typename remove_reference<_Del>::type>, |
1044 | _Del>; |
1045 | using _Sp_cd_type |
1046 | = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>; |
1047 | using _Alloc = allocator<_Sp_cd_type>; |
1048 | using _Alloc_traits = allocator_traits<_Alloc>; |
1049 | _Alloc __a; |
1050 | _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1); |
1051 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
1052 | // 3548. shared_ptr construction from unique_ptr should move |
1053 | // (not copy) the deleter |
1054 | _Alloc_traits::construct(__a, __mem, __r.release(), |
1055 | std::forward<_Del>(__r.get_deleter())); |
1056 | _M_pi = __mem; |
1057 | } |
1058 | |
1059 | // Throw bad_weak_ptr when __r._M_get_use_count() == 0. |
1060 | explicit __shared_count(const __weak_count<_Lp>& __r); |
1061 | |
1062 | // Does not throw if __r._M_get_use_count() == 0, caller must check. |
1063 | explicit |
1064 | __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t) noexcept; |
1065 | |
1066 | ~__shared_count() noexcept |
1067 | { |
1068 | if (_M_pi != nullptr) |
1069 | _M_pi->_M_release(); |
1070 | } |
1071 | |
1072 | __shared_count(const __shared_count& __r) noexcept |
1073 | : _M_pi(__r._M_pi) |
1074 | { |
1075 | if (_M_pi != nullptr) |
1076 | _M_pi->_M_add_ref_copy(); |
1077 | } |
1078 | |
1079 | __shared_count& |
1080 | operator=(const __shared_count& __r) noexcept |
1081 | { |
1082 | _Sp_counted_base<_Lp>* __tmp = __r._M_pi; |
1083 | if (__tmp != _M_pi) |
1084 | { |
1085 | if (__tmp != nullptr) |
1086 | __tmp->_M_add_ref_copy(); |
1087 | if (_M_pi != nullptr) |
1088 | _M_pi->_M_release(); |
1089 | _M_pi = __tmp; |
1090 | } |
1091 | return *this; |
1092 | } |
1093 | |
1094 | void |
1095 | _M_swap(__shared_count& __r) noexcept |
1096 | { |
1097 | _Sp_counted_base<_Lp>* __tmp = __r._M_pi; |
1098 | __r._M_pi = _M_pi; |
1099 | _M_pi = __tmp; |
1100 | } |
1101 | |
1102 | long |
1103 | _M_get_use_count() const noexcept |
1104 | { return _M_pi ? _M_pi->_M_get_use_count() : 0; } |
1105 | |
1106 | bool |
1107 | _M_unique() const noexcept |
1108 | { return this->_M_get_use_count() == 1; } |
1109 | |
1110 | void* |
1111 | _M_get_deleter(const std::type_info& __ti) const noexcept |
1112 | { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; } |
1113 | |
1114 | bool |
1115 | _M_less(const __shared_count& __rhs) const noexcept |
1116 | { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } |
1117 | |
1118 | bool |
1119 | _M_less(const __weak_count<_Lp>& __rhs) const noexcept |
1120 | { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } |
1121 | |
1122 | // Friend function injected into enclosing namespace and found by ADL |
1123 | friend inline bool |
1124 | operator==(const __shared_count& __a, const __shared_count& __b) noexcept |
1125 | { return __a._M_pi == __b._M_pi; } |
1126 | |
1127 | private: |
1128 | friend class __weak_count<_Lp>; |
1129 | #ifdef __glibcxx_atomic_shared_ptr |
1130 | template<typename> friend class _Sp_atomic; |
1131 | #endif |
1132 | #ifdef __glibcxx_out_ptr |
1133 | template<typename, typename, typename...> friend class out_ptr_t; |
1134 | #endif |
1135 | |
1136 | _Sp_counted_base<_Lp>* _M_pi; |
1137 | }; |
1138 | |
1139 | |
1140 | template<_Lock_policy _Lp> |
1141 | class __weak_count |
1142 | { |
1143 | public: |
1144 | constexpr __weak_count() noexcept : _M_pi(nullptr) |
1145 | { } |
1146 | |
1147 | __weak_count(const __shared_count<_Lp>& __r) noexcept |
1148 | : _M_pi(__r._M_pi) |
1149 | { |
1150 | if (_M_pi != nullptr) |
1151 | _M_pi->_M_weak_add_ref(); |
1152 | } |
1153 | |
1154 | __weak_count(const __weak_count& __r) noexcept |
1155 | : _M_pi(__r._M_pi) |
1156 | { |
1157 | if (_M_pi != nullptr) |
1158 | _M_pi->_M_weak_add_ref(); |
1159 | } |
1160 | |
1161 | __weak_count(__weak_count&& __r) noexcept |
1162 | : _M_pi(__r._M_pi) |
1163 | { __r._M_pi = nullptr; } |
1164 | |
1165 | ~__weak_count() noexcept |
1166 | { |
1167 | if (_M_pi != nullptr) |
1168 | _M_pi->_M_weak_release(); |
1169 | } |
1170 | |
1171 | __weak_count& |
1172 | operator=(const __shared_count<_Lp>& __r) noexcept |
1173 | { |
1174 | _Sp_counted_base<_Lp>* __tmp = __r._M_pi; |
1175 | if (__tmp != nullptr) |
1176 | __tmp->_M_weak_add_ref(); |
1177 | if (_M_pi != nullptr) |
1178 | _M_pi->_M_weak_release(); |
1179 | _M_pi = __tmp; |
1180 | return *this; |
1181 | } |
1182 | |
1183 | __weak_count& |
1184 | operator=(const __weak_count& __r) noexcept |
1185 | { |
1186 | _Sp_counted_base<_Lp>* __tmp = __r._M_pi; |
1187 | if (__tmp != nullptr) |
1188 | __tmp->_M_weak_add_ref(); |
1189 | if (_M_pi != nullptr) |
1190 | _M_pi->_M_weak_release(); |
1191 | _M_pi = __tmp; |
1192 | return *this; |
1193 | } |
1194 | |
1195 | __weak_count& |
1196 | operator=(__weak_count&& __r) noexcept |
1197 | { |
1198 | if (_M_pi != nullptr) |
1199 | _M_pi->_M_weak_release(); |
1200 | _M_pi = __r._M_pi; |
1201 | __r._M_pi = nullptr; |
1202 | return *this; |
1203 | } |
1204 | |
1205 | void |
1206 | _M_swap(__weak_count& __r) noexcept |
1207 | { |
1208 | _Sp_counted_base<_Lp>* __tmp = __r._M_pi; |
1209 | __r._M_pi = _M_pi; |
1210 | _M_pi = __tmp; |
1211 | } |
1212 | |
1213 | long |
1214 | _M_get_use_count() const noexcept |
1215 | { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; } |
1216 | |
1217 | bool |
1218 | _M_less(const __weak_count& __rhs) const noexcept |
1219 | { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } |
1220 | |
1221 | bool |
1222 | _M_less(const __shared_count<_Lp>& __rhs) const noexcept |
1223 | { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } |
1224 | |
1225 | // Friend function injected into enclosing namespace and found by ADL |
1226 | friend inline bool |
1227 | operator==(const __weak_count& __a, const __weak_count& __b) noexcept |
1228 | { return __a._M_pi == __b._M_pi; } |
1229 | |
1230 | private: |
1231 | friend class __shared_count<_Lp>; |
1232 | #ifdef __glibcxx_atomic_shared_ptr |
1233 | template<typename> friend class _Sp_atomic; |
1234 | #endif |
1235 | |
1236 | _Sp_counted_base<_Lp>* _M_pi; |
1237 | }; |
1238 | |
1239 | // Now that __weak_count is defined we can define this constructor: |
1240 | template<_Lock_policy _Lp> |
1241 | inline |
1242 | __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r) |
1243 | : _M_pi(__r._M_pi) |
1244 | { |
1245 | if (_M_pi == nullptr || !_M_pi->_M_add_ref_lock_nothrow()) |
1246 | __throw_bad_weak_ptr(); |
1247 | } |
1248 | |
1249 | // Now that __weak_count is defined we can define this constructor: |
1250 | template<_Lock_policy _Lp> |
1251 | inline |
1252 | __shared_count<_Lp>:: |
1253 | __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t) noexcept |
1254 | : _M_pi(__r._M_pi) |
1255 | { |
1256 | if (_M_pi && !_M_pi->_M_add_ref_lock_nothrow()) |
1257 | _M_pi = nullptr; |
1258 | } |
1259 | |
1260 | // Helper traits for shared_ptr of array: |
1261 | |
1262 | // A pointer type Y* is said to be compatible with a pointer type T* when |
1263 | // either Y* is convertible to T* or Y is U[N] and T is U cv []. |
1264 | template<typename _Yp_ptr, typename _Tp_ptr> |
1265 | struct __sp_compatible_with |
1266 | : false_type |
1267 | { }; |
1268 | |
1269 | template<typename _Yp, typename _Tp> |
1270 | struct __sp_compatible_with<_Yp*, _Tp*> |
1271 | : is_convertible<_Yp*, _Tp*>::type |
1272 | { }; |
1273 | |
1274 | template<typename _Up, size_t _Nm> |
1275 | struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]> |
1276 | : true_type |
1277 | { }; |
1278 | |
1279 | template<typename _Up, size_t _Nm> |
1280 | struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]> |
1281 | : true_type |
1282 | { }; |
1283 | |
1284 | template<typename _Up, size_t _Nm> |
1285 | struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]> |
1286 | : true_type |
1287 | { }; |
1288 | |
1289 | template<typename _Up, size_t _Nm> |
1290 | struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]> |
1291 | : true_type |
1292 | { }; |
1293 | |
1294 | // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N]. |
1295 | template<typename _Up, size_t _Nm, typename _Yp, typename = void> |
1296 | struct __sp_is_constructible_arrN |
1297 | : false_type |
1298 | { }; |
1299 | |
1300 | template<typename _Up, size_t _Nm, typename _Yp> |
1301 | struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>> |
1302 | : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type |
1303 | { }; |
1304 | |
1305 | // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[]. |
1306 | template<typename _Up, typename _Yp, typename = void> |
1307 | struct __sp_is_constructible_arr |
1308 | : false_type |
1309 | { }; |
1310 | |
1311 | template<typename _Up, typename _Yp> |
1312 | struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>> |
1313 | : is_convertible<_Yp(*)[], _Up(*)[]>::type |
1314 | { }; |
1315 | |
1316 | // Trait to check if shared_ptr<T> can be constructed from Y*. |
1317 | template<typename _Tp, typename _Yp> |
1318 | struct __sp_is_constructible; |
1319 | |
1320 | // When T is U[N], Y(*)[N] shall be convertible to T*; |
1321 | template<typename _Up, size_t _Nm, typename _Yp> |
1322 | struct __sp_is_constructible<_Up[_Nm], _Yp> |
1323 | : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type |
1324 | { }; |
1325 | |
1326 | // when T is U[], Y(*)[] shall be convertible to T*; |
1327 | template<typename _Up, typename _Yp> |
1328 | struct __sp_is_constructible<_Up[], _Yp> |
1329 | : __sp_is_constructible_arr<_Up, _Yp>::type |
1330 | { }; |
1331 | |
1332 | // otherwise, Y* shall be convertible to T*. |
1333 | template<typename _Tp, typename _Yp> |
1334 | struct __sp_is_constructible |
1335 | : is_convertible<_Yp*, _Tp*>::type |
1336 | { }; |
1337 | |
1338 | |
1339 | // Define operator* and operator-> for shared_ptr<T>. |
1340 | template<typename _Tp, _Lock_policy _Lp, |
1341 | bool = is_array<_Tp>::value, bool = is_void<_Tp>::value> |
1342 | class __shared_ptr_access |
1343 | { |
1344 | public: |
1345 | using element_type = _Tp; |
1346 | |
1347 | element_type& |
1348 | operator*() const noexcept |
1349 | { |
1350 | __glibcxx_assert(_M_get() != nullptr); |
1351 | return *_M_get(); |
1352 | } |
1353 | |
1354 | element_type* |
1355 | operator->() const noexcept |
1356 | { |
1357 | _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); |
1358 | return _M_get(); |
1359 | } |
1360 | |
1361 | private: |
1362 | element_type* |
1363 | _M_get() const noexcept |
1364 | { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } |
1365 | }; |
1366 | |
1367 | // Define operator-> for shared_ptr<cv void>. |
1368 | template<typename _Tp, _Lock_policy _Lp> |
1369 | class __shared_ptr_access<_Tp, _Lp, false, true> |
1370 | { |
1371 | public: |
1372 | using element_type = _Tp; |
1373 | |
1374 | element_type* |
1375 | operator->() const noexcept |
1376 | { |
1377 | auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); |
1378 | _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr); |
1379 | return __ptr; |
1380 | } |
1381 | }; |
1382 | |
1383 | // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>. |
1384 | template<typename _Tp, _Lock_policy _Lp> |
1385 | class __shared_ptr_access<_Tp, _Lp, true, false> |
1386 | { |
1387 | public: |
1388 | using element_type = typename remove_extent<_Tp>::type; |
1389 | |
1390 | #if __cplusplus <= 201402L |
1391 | [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17" )]] |
1392 | element_type& |
1393 | operator*() const noexcept |
1394 | { |
1395 | __glibcxx_assert(_M_get() != nullptr); |
1396 | return *_M_get(); |
1397 | } |
1398 | |
1399 | [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17" )]] |
1400 | element_type* |
1401 | operator->() const noexcept |
1402 | { |
1403 | _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); |
1404 | return _M_get(); |
1405 | } |
1406 | #endif |
1407 | |
1408 | element_type& |
1409 | operator[](ptrdiff_t __i) const noexcept |
1410 | { |
1411 | __glibcxx_assert(_M_get() != nullptr); |
1412 | __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value); |
1413 | return _M_get()[__i]; |
1414 | } |
1415 | |
1416 | private: |
1417 | element_type* |
1418 | _M_get() const noexcept |
1419 | { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } |
1420 | }; |
1421 | |
1422 | template<typename _Tp, _Lock_policy _Lp> |
1423 | class __shared_ptr |
1424 | : public __shared_ptr_access<_Tp, _Lp> |
1425 | { |
1426 | public: |
1427 | using element_type = typename remove_extent<_Tp>::type; |
1428 | |
1429 | private: |
1430 | // Constraint for taking ownership of a pointer of type _Yp*: |
1431 | template<typename _Yp> |
1432 | using _SafeConv |
1433 | = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type; |
1434 | |
1435 | // Constraint for construction from shared_ptr and weak_ptr: |
1436 | template<typename _Yp, typename _Res = void> |
1437 | using _Compatible = typename |
1438 | enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; |
1439 | |
1440 | // Constraint for assignment from shared_ptr and weak_ptr: |
1441 | template<typename _Yp> |
1442 | using _Assignable = _Compatible<_Yp, __shared_ptr&>; |
1443 | |
1444 | // Constraint for construction from unique_ptr: |
1445 | template<typename _Yp, typename _Del, typename _Res = void, |
1446 | typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer> |
1447 | using _UniqCompatible = __enable_if_t<__and_< |
1448 | __sp_compatible_with<_Yp*, _Tp*>, |
1449 | is_convertible<_Ptr, element_type*>, |
1450 | is_move_constructible<_Del> |
1451 | >::value, _Res>; |
1452 | |
1453 | // Constraint for assignment from unique_ptr: |
1454 | template<typename _Yp, typename _Del> |
1455 | using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>; |
1456 | |
1457 | public: |
1458 | |
1459 | #if __cplusplus > 201402L |
1460 | using weak_type = __weak_ptr<_Tp, _Lp>; |
1461 | #endif |
1462 | |
1463 | constexpr __shared_ptr() noexcept |
1464 | : _M_ptr(0), _M_refcount() |
1465 | { } |
1466 | |
1467 | template<typename _Yp, typename = _SafeConv<_Yp>> |
1468 | explicit |
1469 | __shared_ptr(_Yp* __p) |
1470 | : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type()) |
1471 | { |
1472 | static_assert( !is_void<_Yp>::value, "incomplete type" ); |
1473 | static_assert( sizeof(_Yp) > 0, "incomplete type" ); |
1474 | _M_enable_shared_from_this_with(__p); |
1475 | } |
1476 | |
1477 | template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>> |
1478 | __shared_ptr(_Yp* __p, _Deleter __d) |
1479 | : _M_ptr(__p), _M_refcount(__p, std::move(__d)) |
1480 | { |
1481 | static_assert(__is_invocable<_Deleter&, _Yp*&>::value, |
1482 | "deleter expression d(p) is well-formed" ); |
1483 | _M_enable_shared_from_this_with(__p); |
1484 | } |
1485 | |
1486 | template<typename _Yp, typename _Deleter, typename _Alloc, |
1487 | typename = _SafeConv<_Yp>> |
1488 | __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) |
1489 | : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a)) |
1490 | { |
1491 | static_assert(__is_invocable<_Deleter&, _Yp*&>::value, |
1492 | "deleter expression d(p) is well-formed" ); |
1493 | _M_enable_shared_from_this_with(__p); |
1494 | } |
1495 | |
1496 | template<typename _Deleter> |
1497 | __shared_ptr(nullptr_t __p, _Deleter __d) |
1498 | : _M_ptr(0), _M_refcount(__p, std::move(__d)) |
1499 | { } |
1500 | |
1501 | template<typename _Deleter, typename _Alloc> |
1502 | __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) |
1503 | : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a)) |
1504 | { } |
1505 | |
1506 | // Aliasing constructor |
1507 | template<typename _Yp> |
1508 | __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r, |
1509 | element_type* __p) noexcept |
1510 | : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws |
1511 | { } |
1512 | |
1513 | // Aliasing constructor |
1514 | template<typename _Yp> |
1515 | __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r, |
1516 | element_type* __p) noexcept |
1517 | : _M_ptr(__p), _M_refcount() |
1518 | { |
1519 | _M_refcount._M_swap(__r._M_refcount); |
1520 | __r._M_ptr = nullptr; |
1521 | } |
1522 | |
1523 | __shared_ptr(const __shared_ptr&) noexcept = default; |
1524 | __shared_ptr& operator=(const __shared_ptr&) noexcept = default; |
1525 | ~__shared_ptr() = default; |
1526 | |
1527 | template<typename _Yp, typename = _Compatible<_Yp>> |
1528 | __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept |
1529 | : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) |
1530 | { } |
1531 | |
1532 | __shared_ptr(__shared_ptr&& __r) noexcept |
1533 | : _M_ptr(__r._M_ptr), _M_refcount() |
1534 | { |
1535 | _M_refcount._M_swap(__r._M_refcount); |
1536 | __r._M_ptr = nullptr; |
1537 | } |
1538 | |
1539 | template<typename _Yp, typename = _Compatible<_Yp>> |
1540 | __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept |
1541 | : _M_ptr(__r._M_ptr), _M_refcount() |
1542 | { |
1543 | _M_refcount._M_swap(__r._M_refcount); |
1544 | __r._M_ptr = nullptr; |
1545 | } |
1546 | |
1547 | template<typename _Yp, typename = _Compatible<_Yp>> |
1548 | explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r) |
1549 | : _M_refcount(__r._M_refcount) // may throw |
1550 | { |
1551 | // It is now safe to copy __r._M_ptr, as |
1552 | // _M_refcount(__r._M_refcount) did not throw. |
1553 | _M_ptr = __r._M_ptr; |
1554 | } |
1555 | |
1556 | // If an exception is thrown this constructor has no effect. |
1557 | template<typename _Yp, typename _Del, |
1558 | typename = _UniqCompatible<_Yp, _Del>> |
1559 | __shared_ptr(unique_ptr<_Yp, _Del>&& __r) |
1560 | : _M_ptr(__r.get()), _M_refcount() |
1561 | { |
1562 | auto __raw = __to_address(__r.get()); |
1563 | _M_refcount = __shared_count<_Lp>(std::move(__r)); |
1564 | _M_enable_shared_from_this_with(__raw); |
1565 | } |
1566 | |
1567 | #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED |
1568 | protected: |
1569 | // If an exception is thrown this constructor has no effect. |
1570 | template<typename _Tp1, typename _Del, |
1571 | typename enable_if<__and_< |
1572 | __not_<is_array<_Tp>>, is_array<_Tp1>, |
1573 | is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*> |
1574 | >::value, bool>::type = true> |
1575 | __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete) |
1576 | : _M_ptr(__r.get()), _M_refcount() |
1577 | { |
1578 | auto __raw = __to_address(__r.get()); |
1579 | _M_refcount = __shared_count<_Lp>(std::move(__r)); |
1580 | _M_enable_shared_from_this_with(__raw); |
1581 | } |
1582 | public: |
1583 | #endif |
1584 | |
1585 | #if _GLIBCXX_USE_DEPRECATED |
1586 | #pragma GCC diagnostic push |
1587 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
1588 | // Postcondition: use_count() == 1 and __r.get() == 0 |
1589 | template<typename _Yp, typename = _Compatible<_Yp>> |
1590 | __shared_ptr(auto_ptr<_Yp>&& __r); |
1591 | #pragma GCC diagnostic pop |
1592 | #endif |
1593 | |
1594 | constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { } |
1595 | |
1596 | template<typename _Yp> |
1597 | _Assignable<_Yp> |
1598 | operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept |
1599 | { |
1600 | _M_ptr = __r._M_ptr; |
1601 | _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw |
1602 | return *this; |
1603 | } |
1604 | |
1605 | #if _GLIBCXX_USE_DEPRECATED |
1606 | #pragma GCC diagnostic push |
1607 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
1608 | template<typename _Yp> |
1609 | _Assignable<_Yp> |
1610 | operator=(auto_ptr<_Yp>&& __r) |
1611 | { |
1612 | __shared_ptr(std::move(__r)).swap(*this); |
1613 | return *this; |
1614 | } |
1615 | #pragma GCC diagnostic pop |
1616 | #endif |
1617 | |
1618 | __shared_ptr& |
1619 | operator=(__shared_ptr&& __r) noexcept |
1620 | { |
1621 | __shared_ptr(std::move(__r)).swap(*this); |
1622 | return *this; |
1623 | } |
1624 | |
1625 | template<class _Yp> |
1626 | _Assignable<_Yp> |
1627 | operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept |
1628 | { |
1629 | __shared_ptr(std::move(__r)).swap(*this); |
1630 | return *this; |
1631 | } |
1632 | |
1633 | template<typename _Yp, typename _Del> |
1634 | _UniqAssignable<_Yp, _Del> |
1635 | operator=(unique_ptr<_Yp, _Del>&& __r) |
1636 | { |
1637 | __shared_ptr(std::move(__r)).swap(*this); |
1638 | return *this; |
1639 | } |
1640 | |
1641 | void |
1642 | reset() noexcept |
1643 | { __shared_ptr().swap(*this); } |
1644 | |
1645 | template<typename _Yp> |
1646 | _SafeConv<_Yp> |
1647 | reset(_Yp* __p) // _Yp must be complete. |
1648 | { |
1649 | // Catch self-reset errors. |
1650 | __glibcxx_assert(__p == nullptr || __p != _M_ptr); |
1651 | __shared_ptr(__p).swap(*this); |
1652 | } |
1653 | |
1654 | template<typename _Yp, typename _Deleter> |
1655 | _SafeConv<_Yp> |
1656 | reset(_Yp* __p, _Deleter __d) |
1657 | { __shared_ptr(__p, std::move(__d)).swap(*this); } |
1658 | |
1659 | template<typename _Yp, typename _Deleter, typename _Alloc> |
1660 | _SafeConv<_Yp> |
1661 | reset(_Yp* __p, _Deleter __d, _Alloc __a) |
1662 | { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); } |
1663 | |
1664 | /// Return the stored pointer. |
1665 | element_type* |
1666 | get() const noexcept |
1667 | { return _M_ptr; } |
1668 | |
1669 | /// Return true if the stored pointer is not null. |
1670 | explicit operator bool() const noexcept |
1671 | { return _M_ptr != nullptr; } |
1672 | |
1673 | /// Return true if use_count() == 1. |
1674 | bool |
1675 | unique() const noexcept |
1676 | { return _M_refcount._M_unique(); } |
1677 | |
1678 | /// If *this owns a pointer, return the number of owners, otherwise zero. |
1679 | long |
1680 | use_count() const noexcept |
1681 | { return _M_refcount._M_get_use_count(); } |
1682 | |
1683 | /// Exchange both the owned pointer and the stored pointer. |
1684 | void |
1685 | swap(__shared_ptr<_Tp, _Lp>& __other) noexcept |
1686 | { |
1687 | std::swap(_M_ptr, __other._M_ptr); |
1688 | _M_refcount._M_swap(__other._M_refcount); |
1689 | } |
1690 | |
1691 | /** @brief Define an ordering based on ownership. |
1692 | * |
1693 | * This function defines a strict weak ordering between two shared_ptr |
1694 | * or weak_ptr objects, such that one object is less than the other |
1695 | * unless they share ownership of the same pointer, or are both empty. |
1696 | * @{ |
1697 | */ |
1698 | template<typename _Tp1> |
1699 | bool |
1700 | owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept |
1701 | { return _M_refcount._M_less(__rhs._M_refcount); } |
1702 | |
1703 | template<typename _Tp1> |
1704 | bool |
1705 | owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept |
1706 | { return _M_refcount._M_less(__rhs._M_refcount); } |
1707 | /// @} |
1708 | |
1709 | protected: |
1710 | // This constructor is non-standard, it is used by allocate_shared. |
1711 | template<typename _Alloc, typename... _Args> |
1712 | __shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args) |
1713 | : _M_ptr(), _M_refcount(_M_ptr, __tag, std::forward<_Args>(__args)...) |
1714 | { _M_enable_shared_from_this_with(_M_ptr); } |
1715 | |
1716 | template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, |
1717 | typename... _Args> |
1718 | friend __shared_ptr<_Tp1, _Lp1> |
1719 | __allocate_shared(const _Alloc& __a, _Args&&... __args); |
1720 | |
1721 | #if __glibcxx_shared_ptr_arrays >= 201707L // C++ >= 20 && HOSTED |
1722 | // This constructor is non-standard, it is used by allocate_shared<T[]>. |
1723 | template<typename _Alloc, typename _Init = const remove_extent_t<_Tp>*> |
1724 | __shared_ptr(const _Sp_counted_array_base<_Alloc>& __a, |
1725 | _Init __init = nullptr) |
1726 | : _M_ptr(), _M_refcount(_M_ptr, __a, __init) |
1727 | { } |
1728 | #endif |
1729 | |
1730 | // This constructor is used by __weak_ptr::lock() and |
1731 | // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t). |
1732 | __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t) noexcept |
1733 | : _M_refcount(__r._M_refcount, std::nothrow) |
1734 | { |
1735 | _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr; |
1736 | } |
1737 | |
1738 | friend class __weak_ptr<_Tp, _Lp>; |
1739 | |
1740 | private: |
1741 | |
1742 | template<typename _Yp> |
1743 | using __esft_base_t = decltype(__enable_shared_from_this_base( |
1744 | std::declval<const __shared_count<_Lp>&>(), |
1745 | std::declval<_Yp*>())); |
1746 | |
1747 | // Detect an accessible and unambiguous enable_shared_from_this base. |
1748 | template<typename _Yp, typename = void> |
1749 | struct __has_esft_base |
1750 | : false_type { }; |
1751 | |
1752 | template<typename _Yp> |
1753 | struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>> |
1754 | : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays |
1755 | |
1756 | template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> |
1757 | typename enable_if<__has_esft_base<_Yp2>::value>::type |
1758 | _M_enable_shared_from_this_with(_Yp* __p) noexcept |
1759 | { |
1760 | if (auto __base = __enable_shared_from_this_base(_M_refcount, __p)) |
1761 | __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount); |
1762 | } |
1763 | |
1764 | template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> |
1765 | typename enable_if<!__has_esft_base<_Yp2>::value>::type |
1766 | _M_enable_shared_from_this_with(_Yp*) noexcept |
1767 | { } |
1768 | |
1769 | void* |
1770 | _M_get_deleter(const std::type_info& __ti) const noexcept |
1771 | { return _M_refcount._M_get_deleter(__ti); } |
1772 | |
1773 | template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; |
1774 | template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; |
1775 | |
1776 | template<typename _Del, typename _Tp1, _Lock_policy _Lp1> |
1777 | friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; |
1778 | |
1779 | template<typename _Del, typename _Tp1> |
1780 | friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept; |
1781 | |
1782 | #ifdef __glibcxx_atomic_shared_ptr |
1783 | friend _Sp_atomic<shared_ptr<_Tp>>; |
1784 | #endif |
1785 | #ifdef __glibcxx_out_ptr |
1786 | template<typename, typename, typename...> friend class out_ptr_t; |
1787 | #endif |
1788 | |
1789 | element_type* _M_ptr; // Contained pointer. |
1790 | __shared_count<_Lp> _M_refcount; // Reference counter. |
1791 | }; |
1792 | |
1793 | |
1794 | // 20.7.2.2.7 shared_ptr comparisons |
1795 | template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> |
1796 | inline bool |
1797 | operator==(const __shared_ptr<_Tp1, _Lp>& __a, |
1798 | const __shared_ptr<_Tp2, _Lp>& __b) noexcept |
1799 | { return __a.get() == __b.get(); } |
1800 | |
1801 | template<typename _Tp, _Lock_policy _Lp> |
1802 | inline bool |
1803 | operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1804 | { return !__a; } |
1805 | |
1806 | #ifdef __cpp_lib_three_way_comparison |
1807 | template<typename _Tp, typename _Up, _Lock_policy _Lp> |
1808 | inline strong_ordering |
1809 | operator<=>(const __shared_ptr<_Tp, _Lp>& __a, |
1810 | const __shared_ptr<_Up, _Lp>& __b) noexcept |
1811 | { return compare_three_way()(__a.get(), __b.get()); } |
1812 | |
1813 | template<typename _Tp, _Lock_policy _Lp> |
1814 | inline strong_ordering |
1815 | operator<=>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1816 | { |
1817 | using pointer = typename __shared_ptr<_Tp, _Lp>::element_type*; |
1818 | return compare_three_way()(__a.get(), static_cast<pointer>(nullptr)); |
1819 | } |
1820 | #else |
1821 | template<typename _Tp, _Lock_policy _Lp> |
1822 | inline bool |
1823 | operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1824 | { return !__a; } |
1825 | |
1826 | template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> |
1827 | inline bool |
1828 | operator!=(const __shared_ptr<_Tp1, _Lp>& __a, |
1829 | const __shared_ptr<_Tp2, _Lp>& __b) noexcept |
1830 | { return __a.get() != __b.get(); } |
1831 | |
1832 | template<typename _Tp, _Lock_policy _Lp> |
1833 | inline bool |
1834 | operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1835 | { return (bool)__a; } |
1836 | |
1837 | template<typename _Tp, _Lock_policy _Lp> |
1838 | inline bool |
1839 | operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1840 | { return (bool)__a; } |
1841 | |
1842 | template<typename _Tp, typename _Up, _Lock_policy _Lp> |
1843 | inline bool |
1844 | operator<(const __shared_ptr<_Tp, _Lp>& __a, |
1845 | const __shared_ptr<_Up, _Lp>& __b) noexcept |
1846 | { |
1847 | using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; |
1848 | using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type; |
1849 | using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; |
1850 | return less<_Vp>()(__a.get(), __b.get()); |
1851 | } |
1852 | |
1853 | template<typename _Tp, _Lock_policy _Lp> |
1854 | inline bool |
1855 | operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1856 | { |
1857 | using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; |
1858 | return less<_Tp_elt*>()(__a.get(), nullptr); |
1859 | } |
1860 | |
1861 | template<typename _Tp, _Lock_policy _Lp> |
1862 | inline bool |
1863 | operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1864 | { |
1865 | using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; |
1866 | return less<_Tp_elt*>()(nullptr, __a.get()); |
1867 | } |
1868 | |
1869 | template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> |
1870 | inline bool |
1871 | operator<=(const __shared_ptr<_Tp1, _Lp>& __a, |
1872 | const __shared_ptr<_Tp2, _Lp>& __b) noexcept |
1873 | { return !(__b < __a); } |
1874 | |
1875 | template<typename _Tp, _Lock_policy _Lp> |
1876 | inline bool |
1877 | operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1878 | { return !(nullptr < __a); } |
1879 | |
1880 | template<typename _Tp, _Lock_policy _Lp> |
1881 | inline bool |
1882 | operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1883 | { return !(__a < nullptr); } |
1884 | |
1885 | template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> |
1886 | inline bool |
1887 | operator>(const __shared_ptr<_Tp1, _Lp>& __a, |
1888 | const __shared_ptr<_Tp2, _Lp>& __b) noexcept |
1889 | { return (__b < __a); } |
1890 | |
1891 | template<typename _Tp, _Lock_policy _Lp> |
1892 | inline bool |
1893 | operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1894 | { return nullptr < __a; } |
1895 | |
1896 | template<typename _Tp, _Lock_policy _Lp> |
1897 | inline bool |
1898 | operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1899 | { return __a < nullptr; } |
1900 | |
1901 | template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> |
1902 | inline bool |
1903 | operator>=(const __shared_ptr<_Tp1, _Lp>& __a, |
1904 | const __shared_ptr<_Tp2, _Lp>& __b) noexcept |
1905 | { return !(__a < __b); } |
1906 | |
1907 | template<typename _Tp, _Lock_policy _Lp> |
1908 | inline bool |
1909 | operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept |
1910 | { return !(__a < nullptr); } |
1911 | |
1912 | template<typename _Tp, _Lock_policy _Lp> |
1913 | inline bool |
1914 | operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept |
1915 | { return !(nullptr < __a); } |
1916 | #endif // three-way comparison |
1917 | |
1918 | // 20.7.2.2.8 shared_ptr specialized algorithms. |
1919 | template<typename _Tp, _Lock_policy _Lp> |
1920 | inline void |
1921 | swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept |
1922 | { __a.swap(__b); } |
1923 | |
1924 | // 20.7.2.2.9 shared_ptr casts |
1925 | |
1926 | // The seemingly equivalent code: |
1927 | // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) |
1928 | // will eventually result in undefined behaviour, attempting to |
1929 | // delete the same object twice. |
1930 | /// static_pointer_cast |
1931 | template<typename _Tp, typename _Tp1, _Lock_policy _Lp> |
1932 | inline __shared_ptr<_Tp, _Lp> |
1933 | static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept |
1934 | { |
1935 | using _Sp = __shared_ptr<_Tp, _Lp>; |
1936 | return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); |
1937 | } |
1938 | |
1939 | // The seemingly equivalent code: |
1940 | // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) |
1941 | // will eventually result in undefined behaviour, attempting to |
1942 | // delete the same object twice. |
1943 | /// const_pointer_cast |
1944 | template<typename _Tp, typename _Tp1, _Lock_policy _Lp> |
1945 | inline __shared_ptr<_Tp, _Lp> |
1946 | const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept |
1947 | { |
1948 | using _Sp = __shared_ptr<_Tp, _Lp>; |
1949 | return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); |
1950 | } |
1951 | |
1952 | // The seemingly equivalent code: |
1953 | // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) |
1954 | // will eventually result in undefined behaviour, attempting to |
1955 | // delete the same object twice. |
1956 | /// dynamic_pointer_cast |
1957 | template<typename _Tp, typename _Tp1, _Lock_policy _Lp> |
1958 | inline __shared_ptr<_Tp, _Lp> |
1959 | dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept |
1960 | { |
1961 | using _Sp = __shared_ptr<_Tp, _Lp>; |
1962 | if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) |
1963 | return _Sp(__r, __p); |
1964 | return _Sp(); |
1965 | } |
1966 | |
1967 | #if __cplusplus > 201402L |
1968 | template<typename _Tp, typename _Tp1, _Lock_policy _Lp> |
1969 | inline __shared_ptr<_Tp, _Lp> |
1970 | reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept |
1971 | { |
1972 | using _Sp = __shared_ptr<_Tp, _Lp>; |
1973 | return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); |
1974 | } |
1975 | #endif |
1976 | |
1977 | template<typename _Tp, _Lock_policy _Lp> |
1978 | class __weak_ptr |
1979 | { |
1980 | template<typename _Yp, typename _Res = void> |
1981 | using _Compatible = typename |
1982 | enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; |
1983 | |
1984 | // Constraint for assignment from shared_ptr and weak_ptr: |
1985 | template<typename _Yp> |
1986 | using _Assignable = _Compatible<_Yp, __weak_ptr&>; |
1987 | |
1988 | public: |
1989 | using element_type = typename remove_extent<_Tp>::type; |
1990 | |
1991 | constexpr __weak_ptr() noexcept |
1992 | : _M_ptr(nullptr), _M_refcount() |
1993 | { } |
1994 | |
1995 | __weak_ptr(const __weak_ptr&) noexcept = default; |
1996 | |
1997 | ~__weak_ptr() = default; |
1998 | |
1999 | // The "obvious" converting constructor implementation: |
2000 | // |
2001 | // template<typename _Tp1> |
2002 | // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) |
2003 | // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws |
2004 | // { } |
2005 | // |
2006 | // has a serious problem. |
2007 | // |
2008 | // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) |
2009 | // conversion may require access to *__r._M_ptr (virtual inheritance). |
2010 | // |
2011 | // It is not possible to avoid spurious access violations since |
2012 | // in multithreaded programs __r._M_ptr may be invalidated at any point. |
2013 | template<typename _Yp, typename = _Compatible<_Yp>> |
2014 | __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept |
2015 | : _M_refcount(__r._M_refcount) |
2016 | { _M_ptr = __r.lock().get(); } |
2017 | |
2018 | template<typename _Yp, typename = _Compatible<_Yp>> |
2019 | __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept |
2020 | : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) |
2021 | { } |
2022 | |
2023 | __weak_ptr(__weak_ptr&& __r) noexcept |
2024 | : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount)) |
2025 | { __r._M_ptr = nullptr; } |
2026 | |
2027 | template<typename _Yp, typename = _Compatible<_Yp>> |
2028 | __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept |
2029 | : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount)) |
2030 | { __r._M_ptr = nullptr; } |
2031 | |
2032 | __weak_ptr& |
2033 | operator=(const __weak_ptr& __r) noexcept = default; |
2034 | |
2035 | template<typename _Yp> |
2036 | _Assignable<_Yp> |
2037 | operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept |
2038 | { |
2039 | _M_ptr = __r.lock().get(); |
2040 | _M_refcount = __r._M_refcount; |
2041 | return *this; |
2042 | } |
2043 | |
2044 | template<typename _Yp> |
2045 | _Assignable<_Yp> |
2046 | operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept |
2047 | { |
2048 | _M_ptr = __r._M_ptr; |
2049 | _M_refcount = __r._M_refcount; |
2050 | return *this; |
2051 | } |
2052 | |
2053 | __weak_ptr& |
2054 | operator=(__weak_ptr&& __r) noexcept |
2055 | { |
2056 | __weak_ptr(std::move(__r)).swap(*this); |
2057 | return *this; |
2058 | } |
2059 | |
2060 | template<typename _Yp> |
2061 | _Assignable<_Yp> |
2062 | operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept |
2063 | { |
2064 | _M_ptr = __r.lock().get(); |
2065 | _M_refcount = std::move(__r._M_refcount); |
2066 | __r._M_ptr = nullptr; |
2067 | return *this; |
2068 | } |
2069 | |
2070 | __shared_ptr<_Tp, _Lp> |
2071 | lock() const noexcept |
2072 | { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); } |
2073 | |
2074 | long |
2075 | use_count() const noexcept |
2076 | { return _M_refcount._M_get_use_count(); } |
2077 | |
2078 | bool |
2079 | expired() const noexcept |
2080 | { return _M_refcount._M_get_use_count() == 0; } |
2081 | |
2082 | template<typename _Tp1> |
2083 | bool |
2084 | owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept |
2085 | { return _M_refcount._M_less(__rhs._M_refcount); } |
2086 | |
2087 | template<typename _Tp1> |
2088 | bool |
2089 | owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept |
2090 | { return _M_refcount._M_less(__rhs._M_refcount); } |
2091 | |
2092 | void |
2093 | reset() noexcept |
2094 | { __weak_ptr().swap(*this); } |
2095 | |
2096 | void |
2097 | swap(__weak_ptr& __s) noexcept |
2098 | { |
2099 | std::swap(_M_ptr, __s._M_ptr); |
2100 | _M_refcount._M_swap(__s._M_refcount); |
2101 | } |
2102 | |
2103 | private: |
2104 | // Used by __enable_shared_from_this. |
2105 | void |
2106 | _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept |
2107 | { |
2108 | if (use_count() == 0) |
2109 | { |
2110 | _M_ptr = __ptr; |
2111 | _M_refcount = __refcount; |
2112 | } |
2113 | } |
2114 | |
2115 | template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; |
2116 | template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; |
2117 | friend class __enable_shared_from_this<_Tp, _Lp>; |
2118 | friend class enable_shared_from_this<_Tp>; |
2119 | #ifdef __glibcxx_atomic_shared_ptr |
2120 | friend _Sp_atomic<weak_ptr<_Tp>>; |
2121 | #endif |
2122 | |
2123 | element_type* _M_ptr; // Contained pointer. |
2124 | __weak_count<_Lp> _M_refcount; // Reference counter. |
2125 | }; |
2126 | |
2127 | // 20.7.2.3.6 weak_ptr specialized algorithms. |
2128 | template<typename _Tp, _Lock_policy _Lp> |
2129 | inline void |
2130 | swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept |
2131 | { __a.swap(__b); } |
2132 | |
2133 | #pragma GCC diagnostic push |
2134 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations" |
2135 | template<typename _Tp, typename _Tp1> |
2136 | struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> |
2137 | { |
2138 | bool |
2139 | operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept |
2140 | { return __lhs.owner_before(__rhs); } |
2141 | |
2142 | bool |
2143 | operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept |
2144 | { return __lhs.owner_before(__rhs); } |
2145 | |
2146 | bool |
2147 | operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept |
2148 | { return __lhs.owner_before(__rhs); } |
2149 | }; |
2150 | #pragma GCC diagnostic pop |
2151 | |
2152 | template<> |
2153 | struct _Sp_owner_less<void, void> |
2154 | { |
2155 | template<typename _Tp, typename _Up> |
2156 | auto |
2157 | operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept |
2158 | -> decltype(__lhs.owner_before(__rhs)) |
2159 | { return __lhs.owner_before(__rhs); } |
2160 | |
2161 | using is_transparent = void; |
2162 | }; |
2163 | |
2164 | template<typename _Tp, _Lock_policy _Lp> |
2165 | struct owner_less<__shared_ptr<_Tp, _Lp>> |
2166 | : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> |
2167 | { }; |
2168 | |
2169 | template<typename _Tp, _Lock_policy _Lp> |
2170 | struct owner_less<__weak_ptr<_Tp, _Lp>> |
2171 | : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> |
2172 | { }; |
2173 | |
2174 | |
2175 | template<typename _Tp, _Lock_policy _Lp> |
2176 | class __enable_shared_from_this |
2177 | { |
2178 | protected: |
2179 | constexpr __enable_shared_from_this() noexcept { } |
2180 | |
2181 | __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } |
2182 | |
2183 | __enable_shared_from_this& |
2184 | operator=(const __enable_shared_from_this&) noexcept |
2185 | { return *this; } |
2186 | |
2187 | ~__enable_shared_from_this() { } |
2188 | |
2189 | public: |
2190 | __shared_ptr<_Tp, _Lp> |
2191 | shared_from_this() |
2192 | { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } |
2193 | |
2194 | __shared_ptr<const _Tp, _Lp> |
2195 | shared_from_this() const |
2196 | { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } |
2197 | |
2198 | #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 |
2199 | __weak_ptr<_Tp, _Lp> |
2200 | weak_from_this() noexcept |
2201 | { return this->_M_weak_this; } |
2202 | |
2203 | __weak_ptr<const _Tp, _Lp> |
2204 | weak_from_this() const noexcept |
2205 | { return this->_M_weak_this; } |
2206 | #endif |
2207 | |
2208 | private: |
2209 | template<typename _Tp1> |
2210 | void |
2211 | _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept |
2212 | { _M_weak_this._M_assign(__p, __n); } |
2213 | |
2214 | friend const __enable_shared_from_this* |
2215 | __enable_shared_from_this_base(const __shared_count<_Lp>&, |
2216 | const __enable_shared_from_this* __p) |
2217 | { return __p; } |
2218 | |
2219 | template<typename, _Lock_policy> |
2220 | friend class __shared_ptr; |
2221 | |
2222 | mutable __weak_ptr<_Tp, _Lp> _M_weak_this; |
2223 | }; |
2224 | |
2225 | template<typename _Tp, _Lock_policy _Lp = __default_lock_policy, |
2226 | typename _Alloc, typename... _Args> |
2227 | inline __shared_ptr<_Tp, _Lp> |
2228 | __allocate_shared(const _Alloc& __a, _Args&&... __args) |
2229 | { |
2230 | static_assert(!is_array<_Tp>::value, "make_shared<T[]> not supported" ); |
2231 | |
2232 | return __shared_ptr<_Tp, _Lp>(_Sp_alloc_shared_tag<_Alloc>{__a}, |
2233 | std::forward<_Args>(__args)...); |
2234 | } |
2235 | |
2236 | template<typename _Tp, _Lock_policy _Lp = __default_lock_policy, |
2237 | typename... _Args> |
2238 | inline __shared_ptr<_Tp, _Lp> |
2239 | __make_shared(_Args&&... __args) |
2240 | { |
2241 | typedef typename std::remove_const<_Tp>::type _Tp_nc; |
2242 | return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), |
2243 | std::forward<_Args>(__args)...); |
2244 | } |
2245 | |
2246 | /// std::hash specialization for __shared_ptr. |
2247 | template<typename _Tp, _Lock_policy _Lp> |
2248 | struct hash<__shared_ptr<_Tp, _Lp>> |
2249 | : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> |
2250 | { |
2251 | size_t |
2252 | operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept |
2253 | { |
2254 | return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()( |
2255 | __s.get()); |
2256 | } |
2257 | }; |
2258 | |
2259 | _GLIBCXX_END_NAMESPACE_VERSION |
2260 | } // namespace |
2261 | |
2262 | #endif // _SHARED_PTR_BASE_H |
2263 | |