1// shared_ptr and weak_ptr implementation details -*- C++ -*-
2
3// Copyright (C) 2007-2019 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25// GCC Note: Based on files from version 1.32.0 of the Boost library.
26
27// shared_count.hpp
28// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
29
30// shared_ptr.hpp
31// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32// Copyright (C) 2001, 2002, 2003 Peter Dimov
33
34// weak_ptr.hpp
35// Copyright (C) 2001, 2002, 2003 Peter Dimov
36
37// enable_shared_from_this.hpp
38// Copyright (C) 2002 Peter Dimov
39
40// Distributed under the Boost Software License, Version 1.0. (See
41// accompanying file LICENSE_1_0.txt or copy at
42// http://www.boost.org/LICENSE_1_0.txt)
43
44/** @file 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/refwrap.h>
55#include <bits/stl_function.h>
56#include <ext/aligned_buffer.h>
57
58namespace std _GLIBCXX_VISIBILITY(default)
59{
60_GLIBCXX_BEGIN_NAMESPACE_VERSION
61
62#if _GLIBCXX_USE_DEPRECATED
63#pragma GCC diagnostic push
64#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
65 template<typename> class auto_ptr;
66#pragma GCC diagnostic pop
67#endif
68
69 /**
70 * @brief Exception possibly thrown by @c shared_ptr.
71 * @ingroup exceptions
72 */
73 class bad_weak_ptr : public std::exception
74 {
75 public:
76 virtual char const* what() const noexcept;
77
78 virtual ~bad_weak_ptr() noexcept;
79 };
80
81 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
82 inline void
83 __throw_bad_weak_ptr()
84 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
85
86 using __gnu_cxx::_Lock_policy;
87 using __gnu_cxx::__default_lock_policy;
88 using __gnu_cxx::_S_single;
89 using __gnu_cxx::_S_mutex;
90 using __gnu_cxx::_S_atomic;
91
92 // Empty helper class except when the template argument is _S_mutex.
93 template<_Lock_policy _Lp>
94 class _Mutex_base
95 {
96 protected:
97 // The atomic policy uses fully-fenced builtins, single doesn't care.
98 enum { _S_need_barriers = 0 };
99 };
100
101 template<>
102 class _Mutex_base<_S_mutex>
103 : public __gnu_cxx::__mutex
104 {
105 protected:
106 // This policy is used when atomic builtins are not available.
107 // The replacement atomic operations might not have the necessary
108 // memory barriers.
109 enum { _S_need_barriers = 1 };
110 };
111
112 template<_Lock_policy _Lp = __default_lock_policy>
113 class _Sp_counted_base
114 : public _Mutex_base<_Lp>
115 {
116 public:
117 _Sp_counted_base() noexcept
118 : _M_use_count(1), _M_weak_count(1) { }
119
120 virtual
121 ~_Sp_counted_base() noexcept
122 { }
123
124 // Called when _M_use_count drops to zero, to release the resources
125 // managed by *this.
126 virtual void
127 _M_dispose() noexcept = 0;
128
129 // Called when _M_weak_count drops to zero.
130 virtual void
131 _M_destroy() noexcept
132 { delete this; }
133
134 virtual void*
135 _M_get_deleter(const std::type_info&) noexcept = 0;
136
137 void
138 _M_add_ref_copy()
139 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
140
141 void
142 _M_add_ref_lock();
143
144 bool
145 _M_add_ref_lock_nothrow();
146
147 void
148 _M_release() noexcept
149 {
150 // Be race-detector-friendly. For more info see bits/c++config.
151 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
152 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
153 {
154 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
155 _M_dispose();
156 // There must be a memory barrier between dispose() and destroy()
157 // to ensure that the effects of dispose() are observed in the
158 // thread that runs destroy().
159 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
160 if (_Mutex_base<_Lp>::_S_need_barriers)
161 {
162 __atomic_thread_fence (__ATOMIC_ACQ_REL);
163 }
164
165 // Be race-detector-friendly. For more info see bits/c++config.
166 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
167 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
168 -1) == 1)
169 {
170 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
171 _M_destroy();
172 }
173 }
174 }
175
176 void
177 _M_weak_add_ref() noexcept
178 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
179
180 void
181 _M_weak_release() noexcept
182 {
183 // Be race-detector-friendly. For more info see bits/c++config.
184 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
185 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
186 {
187 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
188 if (_Mutex_base<_Lp>::_S_need_barriers)
189 {
190 // See _M_release(),
191 // destroy() must observe results of dispose()
192 __atomic_thread_fence (__ATOMIC_ACQ_REL);
193 }
194 _M_destroy();
195 }
196 }
197
198 long
199 _M_get_use_count() const noexcept
200 {
201 // No memory barrier is used here so there is no synchronization
202 // with other threads.
203 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED);
204 }
205
206 private:
207 _Sp_counted_base(_Sp_counted_base const&) = delete;
208 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete;
209
210 _Atomic_word _M_use_count; // #shared
211 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
212 };
213
214 template<>
215 inline void
216 _Sp_counted_base<_S_single>::
217 _M_add_ref_lock()
218 {
219 if (_M_use_count == 0)
220 __throw_bad_weak_ptr();
221 ++_M_use_count;
222 }
223
224 template<>
225 inline void
226 _Sp_counted_base<_S_mutex>::
227 _M_add_ref_lock()
228 {
229 __gnu_cxx::__scoped_lock sentry(*this);
230 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
231 {
232 _M_use_count = 0;
233 __throw_bad_weak_ptr();
234 }
235 }
236
237 template<>
238 inline void
239 _Sp_counted_base<_S_atomic>::
240 _M_add_ref_lock()
241 {
242 // Perform lock-free add-if-not-zero operation.
243 _Atomic_word __count = _M_get_use_count();
244 do
245 {
246 if (__count == 0)
247 __throw_bad_weak_ptr();
248 // Replace the current counter value with the old value + 1, as
249 // long as it's not changed meanwhile.
250 }
251 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
252 true, __ATOMIC_ACQ_REL,
253 __ATOMIC_RELAXED));
254 }
255
256 template<>
257 inline bool
258 _Sp_counted_base<_S_single>::
259 _M_add_ref_lock_nothrow()
260 {
261 if (_M_use_count == 0)
262 return false;
263 ++_M_use_count;
264 return true;
265 }
266
267 template<>
268 inline bool
269 _Sp_counted_base<_S_mutex>::
270 _M_add_ref_lock_nothrow()
271 {
272 __gnu_cxx::__scoped_lock sentry(*this);
273 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
274 {
275 _M_use_count = 0;
276 return false;
277 }
278 return true;
279 }
280
281 template<>
282 inline bool
283 _Sp_counted_base<_S_atomic>::
284 _M_add_ref_lock_nothrow()
285 {
286 // Perform lock-free add-if-not-zero operation.
287 _Atomic_word __count = _M_get_use_count();
288 do
289 {
290 if (__count == 0)
291 return false;
292 // Replace the current counter value with the old value + 1, as
293 // long as it's not changed meanwhile.
294 }
295 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
296 true, __ATOMIC_ACQ_REL,
297 __ATOMIC_RELAXED));
298 return true;
299 }
300
301 template<>
302 inline void
303 _Sp_counted_base<_S_single>::_M_add_ref_copy()
304 { ++_M_use_count; }
305
306 template<>
307 inline void
308 _Sp_counted_base<_S_single>::_M_release() noexcept
309 {
310 if (--_M_use_count == 0)
311 {
312 _M_dispose();
313 if (--_M_weak_count == 0)
314 _M_destroy();
315 }
316 }
317
318 template<>
319 inline void
320 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
321 { ++_M_weak_count; }
322
323 template<>
324 inline void
325 _Sp_counted_base<_S_single>::_M_weak_release() noexcept
326 {
327 if (--_M_weak_count == 0)
328 _M_destroy();
329 }
330
331 template<>
332 inline long
333 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
334 { return _M_use_count; }
335
336
337 // Forward declarations.
338 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
339 class __shared_ptr;
340
341 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
342 class __weak_ptr;
343
344 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
345 class __enable_shared_from_this;
346
347 template<typename _Tp>
348 class shared_ptr;
349
350 template<typename _Tp>
351 class weak_ptr;
352
353 template<typename _Tp>
354 struct owner_less;
355
356 template<typename _Tp>
357 class enable_shared_from_this;
358
359 template<_Lock_policy _Lp = __default_lock_policy>
360 class __weak_count;
361
362 template<_Lock_policy _Lp = __default_lock_policy>
363 class __shared_count;
364
365
366 // Counted ptr with no deleter or allocator support
367 template<typename _Ptr, _Lock_policy _Lp>
368 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
369 {
370 public:
371 explicit
372 _Sp_counted_ptr(_Ptr __p) noexcept
373 : _M_ptr(__p) { }
374
375 virtual void
376 _M_dispose() noexcept
377 { delete _M_ptr; }
378
379 virtual void
380 _M_destroy() noexcept
381 { delete this; }
382
383 virtual void*
384 _M_get_deleter(const std::type_info&) noexcept
385 { return nullptr; }
386
387 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
388 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
389
390 private:
391 _Ptr _M_ptr;
392 };
393
394 template<>
395 inline void
396 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }
397
398 template<>
399 inline void
400 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }
401
402 template<>
403 inline void
404 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }
405
406 template<int _Nm, typename _Tp,
407 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
408 struct _Sp_ebo_helper;
409
410 /// Specialization using EBO.
411 template<int _Nm, typename _Tp>
412 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
413 {
414 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
415 explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { }
416
417 static _Tp&
418 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
419 };
420
421 /// Specialization not using EBO.
422 template<int _Nm, typename _Tp>
423 struct _Sp_ebo_helper<_Nm, _Tp, false>
424 {
425 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
426 explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { }
427
428 static _Tp&
429 _S_get(_Sp_ebo_helper& __eboh)
430 { return __eboh._M_tp; }
431
432 private:
433 _Tp _M_tp;
434 };
435
436 // Support for custom deleter and/or allocator
437 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
438 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
439 {
440 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
441 {
442 typedef _Sp_ebo_helper<0, _Deleter> _Del_base;
443 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base;
444
445 public:
446 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
447 : _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a)
448 { }
449
450 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
451 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }
452
453 _Ptr _M_ptr;
454 };
455
456 public:
457 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>;
458
459 // __d(__p) must not throw.
460 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
461 : _M_impl(__p, std::move(__d), _Alloc()) { }
462
463 // __d(__p) must not throw.
464 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
465 : _M_impl(__p, std::move(__d), __a) { }
466
467 ~_Sp_counted_deleter() noexcept { }
468
469 virtual void
470 _M_dispose() noexcept
471 { _M_impl._M_del()(_M_impl._M_ptr); }
472
473 virtual void
474 _M_destroy() noexcept
475 {
476 __allocator_type __a(_M_impl._M_alloc());
477 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
478 this->~_Sp_counted_deleter();
479 }
480
481 virtual void*
482 _M_get_deleter(const std::type_info& __ti) noexcept
483 {
484#if __cpp_rtti
485 // _GLIBCXX_RESOLVE_LIB_DEFECTS
486 // 2400. shared_ptr's get_deleter() should use addressof()
487 return __ti == typeid(_Deleter)
488 ? std::__addressof(_M_impl._M_del())
489 : nullptr;
490#else
491 return nullptr;
492#endif
493 }
494
495 private:
496 _Impl _M_impl;
497 };
498
499 // helpers for make_shared / allocate_shared
500
501 struct _Sp_make_shared_tag
502 {
503 private:
504 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
505 friend class _Sp_counted_ptr_inplace;
506
507 static const type_info&
508 _S_ti() noexcept _GLIBCXX_VISIBILITY(default)
509 {
510 alignas(type_info) static constexpr char __tag[sizeof(type_info)] = { };
511 return reinterpret_cast<const type_info&>(__tag);
512 }
513
514 static bool _S_eq(const type_info&) noexcept;
515 };
516
517 template<typename _Alloc>
518 struct _Sp_alloc_shared_tag
519 {
520 const _Alloc& _M_a;
521 };
522
523 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
524 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
525 {
526 class _Impl : _Sp_ebo_helper<0, _Alloc>
527 {
528 typedef _Sp_ebo_helper<0, _Alloc> _A_base;
529
530 public:
531 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }
532
533 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }
534
535 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
536 };
537
538 public:
539 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>;
540
541 // Alloc parameter is not a reference so doesn't alias anything in __args
542 template<typename... _Args>
543 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
544 : _M_impl(__a)
545 {
546 // _GLIBCXX_RESOLVE_LIB_DEFECTS
547 // 2070. allocate_shared should use allocator_traits<A>::construct
548 allocator_traits<_Alloc>::construct(__a, _M_ptr(),
549 std::forward<_Args>(__args)...); // might throw
550 }
551
552 ~_Sp_counted_ptr_inplace() noexcept { }
553
554 virtual void
555 _M_dispose() noexcept
556 {
557 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
558 }
559
560 // Override because the allocator needs to know the dynamic type
561 virtual void
562 _M_destroy() noexcept
563 {
564 __allocator_type __a(_M_impl._M_alloc());
565 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
566 this->~_Sp_counted_ptr_inplace();
567 }
568
569 private:
570 friend class __shared_count<_Lp>; // To be able to call _M_ptr().
571
572 // No longer used, but code compiled against old libstdc++ headers
573 // might still call it from __shared_ptr ctor to get the pointer out.
574 virtual void*
575 _M_get_deleter(const std::type_info& __ti) noexcept override
576 {
577 auto __ptr = const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
578 // Check for the fake type_info first, so we don't try to access it
579 // as a real type_info object. Otherwise, check if it's the real
580 // type_info for this class. With RTTI enabled we can check directly,
581 // or call a library function to do it.
582 if (&__ti == &_Sp_make_shared_tag::_S_ti()
583 ||
584#if __cpp_rtti
585 __ti == typeid(_Sp_make_shared_tag)
586#else
587 _Sp_make_shared_tag::_S_eq(__ti)
588#endif
589 )
590 return __ptr;
591 return nullptr;
592 }
593
594 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }
595
596 _Impl _M_impl;
597 };
598
599 // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>.
600 struct __sp_array_delete
601 {
602 template<typename _Yp>
603 void operator()(_Yp* __p) const { delete[] __p; }
604 };
605
606 template<_Lock_policy _Lp>
607 class __shared_count
608 {
609 template<typename _Tp>
610 struct __not_alloc_shared_tag { using type = void; };
611
612 template<typename _Tp>
613 struct __not_alloc_shared_tag<_Sp_alloc_shared_tag<_Tp>> { };
614
615 public:
616 constexpr __shared_count() noexcept : _M_pi(0)
617 { }
618
619 template<typename _Ptr>
620 explicit
621 __shared_count(_Ptr __p) : _M_pi(0)
622 {
623 __try
624 {
625 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
626 }
627 __catch(...)
628 {
629 delete __p;
630 __throw_exception_again;
631 }
632 }
633
634 template<typename _Ptr>
635 __shared_count(_Ptr __p, /* is_array = */ false_type)
636 : __shared_count(__p)
637 { }
638
639 template<typename _Ptr>
640 __shared_count(_Ptr __p, /* is_array = */ true_type)
641 : __shared_count(__p, __sp_array_delete{}, allocator<void>())
642 { }
643
644 template<typename _Ptr, typename _Deleter,
645 typename = typename __not_alloc_shared_tag<_Deleter>::type>
646 __shared_count(_Ptr __p, _Deleter __d)
647 : __shared_count(__p, std::move(__d), allocator<void>())
648 { }
649
650 template<typename _Ptr, typename _Deleter, typename _Alloc,
651 typename = typename __not_alloc_shared_tag<_Deleter>::type>
652 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
653 {
654 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
655 __try
656 {
657 typename _Sp_cd_type::__allocator_type __a2(__a);
658 auto __guard = std::__allocate_guarded(__a2);
659 _Sp_cd_type* __mem = __guard.get();
660 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a));
661 _M_pi = __mem;
662 __guard = nullptr;
663 }
664 __catch(...)
665 {
666 __d(__p); // Call _Deleter on __p.
667 __throw_exception_again;
668 }
669 }
670
671 template<typename _Tp, typename _Alloc, typename... _Args>
672 __shared_count(_Tp*& __p, _Sp_alloc_shared_tag<_Alloc> __a,
673 _Args&&... __args)
674 {
675 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
676 typename _Sp_cp_type::__allocator_type __a2(__a._M_a);
677 auto __guard = std::__allocate_guarded(__a2);
678 _Sp_cp_type* __mem = __guard.get();
679 auto __pi = ::new (__mem)
680 _Sp_cp_type(__a._M_a, std::forward<_Args>(__args)...);
681 __guard = nullptr;
682 _M_pi = __pi;
683 __p = __pi->_M_ptr();
684 }
685
686#if _GLIBCXX_USE_DEPRECATED
687#pragma GCC diagnostic push
688#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
689 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
690 template<typename _Tp>
691 explicit
692 __shared_count(std::auto_ptr<_Tp>&& __r);
693#pragma GCC diagnostic pop
694#endif
695
696 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
697 template<typename _Tp, typename _Del>
698 explicit
699 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
700 {
701 // _GLIBCXX_RESOLVE_LIB_DEFECTS
702 // 2415. Inconsistency between unique_ptr and shared_ptr
703 if (__r.get() == nullptr)
704 return;
705
706 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
707 using _Del2 = typename conditional<is_reference<_Del>::value,
708 reference_wrapper<typename remove_reference<_Del>::type>,
709 _Del>::type;
710 using _Sp_cd_type
711 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
712 using _Alloc = allocator<_Sp_cd_type>;
713 using _Alloc_traits = allocator_traits<_Alloc>;
714 _Alloc __a;
715 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
716 _Alloc_traits::construct(__a, __mem, __r.release(),
717 __r.get_deleter()); // non-throwing
718 _M_pi = __mem;
719 }
720
721 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
722 explicit __shared_count(const __weak_count<_Lp>& __r);
723
724 // Does not throw if __r._M_get_use_count() == 0, caller must check.
725 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
726
727 ~__shared_count() noexcept
728 {
729 if (_M_pi != nullptr)
730 _M_pi->_M_release();
731 }
732
733 __shared_count(const __shared_count& __r) noexcept
734 : _M_pi(__r._M_pi)
735 {
736 if (_M_pi != 0)
737 _M_pi->_M_add_ref_copy();
738 }
739
740 __shared_count&
741 operator=(const __shared_count& __r) noexcept
742 {
743 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
744 if (__tmp != _M_pi)
745 {
746 if (__tmp != 0)
747 __tmp->_M_add_ref_copy();
748 if (_M_pi != 0)
749 _M_pi->_M_release();
750 _M_pi = __tmp;
751 }
752 return *this;
753 }
754
755 void
756 _M_swap(__shared_count& __r) noexcept
757 {
758 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
759 __r._M_pi = _M_pi;
760 _M_pi = __tmp;
761 }
762
763 long
764 _M_get_use_count() const noexcept
765 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
766
767 bool
768 _M_unique() const noexcept
769 { return this->_M_get_use_count() == 1; }
770
771 void*
772 _M_get_deleter(const std::type_info& __ti) const noexcept
773 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }
774
775 bool
776 _M_less(const __shared_count& __rhs) const noexcept
777 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
778
779 bool
780 _M_less(const __weak_count<_Lp>& __rhs) const noexcept
781 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
782
783 // Friend function injected into enclosing namespace and found by ADL
784 friend inline bool
785 operator==(const __shared_count& __a, const __shared_count& __b) noexcept
786 { return __a._M_pi == __b._M_pi; }
787
788 private:
789 friend class __weak_count<_Lp>;
790
791 _Sp_counted_base<_Lp>* _M_pi;
792 };
793
794
795 template<_Lock_policy _Lp>
796 class __weak_count
797 {
798 public:
799 constexpr __weak_count() noexcept : _M_pi(nullptr)
800 { }
801
802 __weak_count(const __shared_count<_Lp>& __r) noexcept
803 : _M_pi(__r._M_pi)
804 {
805 if (_M_pi != nullptr)
806 _M_pi->_M_weak_add_ref();
807 }
808
809 __weak_count(const __weak_count& __r) noexcept
810 : _M_pi(__r._M_pi)
811 {
812 if (_M_pi != nullptr)
813 _M_pi->_M_weak_add_ref();
814 }
815
816 __weak_count(__weak_count&& __r) noexcept
817 : _M_pi(__r._M_pi)
818 { __r._M_pi = nullptr; }
819
820 ~__weak_count() noexcept
821 {
822 if (_M_pi != nullptr)
823 _M_pi->_M_weak_release();
824 }
825
826 __weak_count&
827 operator=(const __shared_count<_Lp>& __r) noexcept
828 {
829 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
830 if (__tmp != nullptr)
831 __tmp->_M_weak_add_ref();
832 if (_M_pi != nullptr)
833 _M_pi->_M_weak_release();
834 _M_pi = __tmp;
835 return *this;
836 }
837
838 __weak_count&
839 operator=(const __weak_count& __r) noexcept
840 {
841 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
842 if (__tmp != nullptr)
843 __tmp->_M_weak_add_ref();
844 if (_M_pi != nullptr)
845 _M_pi->_M_weak_release();
846 _M_pi = __tmp;
847 return *this;
848 }
849
850 __weak_count&
851 operator=(__weak_count&& __r) noexcept
852 {
853 if (_M_pi != nullptr)
854 _M_pi->_M_weak_release();
855 _M_pi = __r._M_pi;
856 __r._M_pi = nullptr;
857 return *this;
858 }
859
860 void
861 _M_swap(__weak_count& __r) noexcept
862 {
863 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
864 __r._M_pi = _M_pi;
865 _M_pi = __tmp;
866 }
867
868 long
869 _M_get_use_count() const noexcept
870 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; }
871
872 bool
873 _M_less(const __weak_count& __rhs) const noexcept
874 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
875
876 bool
877 _M_less(const __shared_count<_Lp>& __rhs) const noexcept
878 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
879
880 // Friend function injected into enclosing namespace and found by ADL
881 friend inline bool
882 operator==(const __weak_count& __a, const __weak_count& __b) noexcept
883 { return __a._M_pi == __b._M_pi; }
884
885 private:
886 friend class __shared_count<_Lp>;
887
888 _Sp_counted_base<_Lp>* _M_pi;
889 };
890
891 // Now that __weak_count is defined we can define this constructor:
892 template<_Lock_policy _Lp>
893 inline
894 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
895 : _M_pi(__r._M_pi)
896 {
897 if (_M_pi != nullptr)
898 _M_pi->_M_add_ref_lock();
899 else
900 __throw_bad_weak_ptr();
901 }
902
903 // Now that __weak_count is defined we can define this constructor:
904 template<_Lock_policy _Lp>
905 inline
906 __shared_count<_Lp>::
907 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
908 : _M_pi(__r._M_pi)
909 {
910 if (_M_pi != nullptr)
911 if (!_M_pi->_M_add_ref_lock_nothrow())
912 _M_pi = nullptr;
913 }
914
915#define __cpp_lib_shared_ptr_arrays 201611L
916
917 // Helper traits for shared_ptr of array:
918
919 // A pointer type Y* is said to be compatible with a pointer type T* when
920 // either Y* is convertible to T* or Y is U[N] and T is U cv [].
921 template<typename _Yp_ptr, typename _Tp_ptr>
922 struct __sp_compatible_with
923 : false_type
924 { };
925
926 template<typename _Yp, typename _Tp>
927 struct __sp_compatible_with<_Yp*, _Tp*>
928 : is_convertible<_Yp*, _Tp*>::type
929 { };
930
931 template<typename _Up, size_t _Nm>
932 struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]>
933 : true_type
934 { };
935
936 template<typename _Up, size_t _Nm>
937 struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]>
938 : true_type
939 { };
940
941 template<typename _Up, size_t _Nm>
942 struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]>
943 : true_type
944 { };
945
946 template<typename _Up, size_t _Nm>
947 struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]>
948 : true_type
949 { };
950
951 // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N].
952 template<typename _Up, size_t _Nm, typename _Yp, typename = void>
953 struct __sp_is_constructible_arrN
954 : false_type
955 { };
956
957 template<typename _Up, size_t _Nm, typename _Yp>
958 struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>>
959 : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type
960 { };
961
962 // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[].
963 template<typename _Up, typename _Yp, typename = void>
964 struct __sp_is_constructible_arr
965 : false_type
966 { };
967
968 template<typename _Up, typename _Yp>
969 struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>>
970 : is_convertible<_Yp(*)[], _Up(*)[]>::type
971 { };
972
973 // Trait to check if shared_ptr<T> can be constructed from Y*.
974 template<typename _Tp, typename _Yp>
975 struct __sp_is_constructible;
976
977 // When T is U[N], Y(*)[N] shall be convertible to T*;
978 template<typename _Up, size_t _Nm, typename _Yp>
979 struct __sp_is_constructible<_Up[_Nm], _Yp>
980 : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type
981 { };
982
983 // when T is U[], Y(*)[] shall be convertible to T*;
984 template<typename _Up, typename _Yp>
985 struct __sp_is_constructible<_Up[], _Yp>
986 : __sp_is_constructible_arr<_Up, _Yp>::type
987 { };
988
989 // otherwise, Y* shall be convertible to T*.
990 template<typename _Tp, typename _Yp>
991 struct __sp_is_constructible
992 : is_convertible<_Yp*, _Tp*>::type
993 { };
994
995
996 // Define operator* and operator-> for shared_ptr<T>.
997 template<typename _Tp, _Lock_policy _Lp,
998 bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>
999 class __shared_ptr_access
1000 {
1001 public:
1002 using element_type = _Tp;
1003
1004 element_type&
1005 operator*() const noexcept
1006 {
1007 __glibcxx_assert(_M_get() != nullptr);
1008 return *_M_get();
1009 }
1010
1011 element_type*
1012 operator->() const noexcept
1013 {
1014 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
1015 return _M_get();
1016 }
1017
1018 private:
1019 element_type*
1020 _M_get() const noexcept
1021 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
1022 };
1023
1024 // Define operator-> for shared_ptr<cv void>.
1025 template<typename _Tp, _Lock_policy _Lp>
1026 class __shared_ptr_access<_Tp, _Lp, false, true>
1027 {
1028 public:
1029 using element_type = _Tp;
1030
1031 element_type*
1032 operator->() const noexcept
1033 {
1034 auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get();
1035 _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr);
1036 return __ptr;
1037 }
1038 };
1039
1040 // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>.
1041 template<typename _Tp, _Lock_policy _Lp>
1042 class __shared_ptr_access<_Tp, _Lp, true, false>
1043 {
1044 public:
1045 using element_type = typename remove_extent<_Tp>::type;
1046
1047#if __cplusplus <= 201402L
1048 [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]]
1049 element_type&
1050 operator*() const noexcept
1051 {
1052 __glibcxx_assert(_M_get() != nullptr);
1053 return *_M_get();
1054 }
1055
1056 [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]]
1057 element_type*
1058 operator->() const noexcept
1059 {
1060 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
1061 return _M_get();
1062 }
1063#endif
1064
1065 element_type&
1066 operator[](ptrdiff_t __i) const
1067 {
1068 __glibcxx_assert(_M_get() != nullptr);
1069 __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value);
1070 return _M_get()[__i];
1071 }
1072
1073 private:
1074 element_type*
1075 _M_get() const noexcept
1076 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
1077 };
1078
1079 template<typename _Tp, _Lock_policy _Lp>
1080 class __shared_ptr
1081 : public __shared_ptr_access<_Tp, _Lp>
1082 {
1083 public:
1084 using element_type = typename remove_extent<_Tp>::type;
1085
1086 private:
1087 // Constraint for taking ownership of a pointer of type _Yp*:
1088 template<typename _Yp>
1089 using _SafeConv
1090 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;
1091
1092 // Constraint for construction from shared_ptr and weak_ptr:
1093 template<typename _Yp, typename _Res = void>
1094 using _Compatible = typename
1095 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1096
1097 // Constraint for assignment from shared_ptr and weak_ptr:
1098 template<typename _Yp>
1099 using _Assignable = _Compatible<_Yp, __shared_ptr&>;
1100
1101 // Constraint for construction from unique_ptr:
1102 template<typename _Yp, typename _Del, typename _Res = void,
1103 typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>
1104 using _UniqCompatible = typename enable_if<__and_<
1105 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>
1106 >::value, _Res>::type;
1107
1108 // Constraint for assignment from unique_ptr:
1109 template<typename _Yp, typename _Del>
1110 using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;
1111
1112 public:
1113
1114#if __cplusplus > 201402L
1115 using weak_type = __weak_ptr<_Tp, _Lp>;
1116#endif
1117
1118 constexpr __shared_ptr() noexcept
1119 : _M_ptr(0), _M_refcount()
1120 { }
1121
1122 template<typename _Yp, typename = _SafeConv<_Yp>>
1123 explicit
1124 __shared_ptr(_Yp* __p)
1125 : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type())
1126 {
1127 static_assert( !is_void<_Yp>::value, "incomplete type" );
1128 static_assert( sizeof(_Yp) > 0, "incomplete type" );
1129 _M_enable_shared_from_this_with(__p);
1130 }
1131
1132 template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>
1133 __shared_ptr(_Yp* __p, _Deleter __d)
1134 : _M_ptr(__p), _M_refcount(__p, std::move(__d))
1135 {
1136 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1137 "deleter expression d(p) is well-formed");
1138 _M_enable_shared_from_this_with(__p);
1139 }
1140
1141 template<typename _Yp, typename _Deleter, typename _Alloc,
1142 typename = _SafeConv<_Yp>>
1143 __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
1144 : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a))
1145 {
1146 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1147 "deleter expression d(p) is well-formed");
1148 _M_enable_shared_from_this_with(__p);
1149 }
1150
1151 template<typename _Deleter>
1152 __shared_ptr(nullptr_t __p, _Deleter __d)
1153 : _M_ptr(0), _M_refcount(__p, std::move(__d))
1154 { }
1155
1156 template<typename _Deleter, typename _Alloc>
1157 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
1158 : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a))
1159 { }
1160
1161 template<typename _Yp>
1162 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,
1163 element_type* __p) noexcept
1164 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
1165 { }
1166
1167 __shared_ptr(const __shared_ptr&) noexcept = default;
1168 __shared_ptr& operator=(const __shared_ptr&) noexcept = default;
1169 ~__shared_ptr() = default;
1170
1171 template<typename _Yp, typename = _Compatible<_Yp>>
1172 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1173 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1174 { }
1175
1176 __shared_ptr(__shared_ptr&& __r) noexcept
1177 : _M_ptr(__r._M_ptr), _M_refcount()
1178 {
1179 _M_refcount._M_swap(__r._M_refcount);
1180 __r._M_ptr = 0;
1181 }
1182
1183 template<typename _Yp, typename = _Compatible<_Yp>>
1184 __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1185 : _M_ptr(__r._M_ptr), _M_refcount()
1186 {
1187 _M_refcount._M_swap(__r._M_refcount);
1188 __r._M_ptr = 0;
1189 }
1190
1191 template<typename _Yp, typename = _Compatible<_Yp>>
1192 explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r)
1193 : _M_refcount(__r._M_refcount) // may throw
1194 {
1195 // It is now safe to copy __r._M_ptr, as
1196 // _M_refcount(__r._M_refcount) did not throw.
1197 _M_ptr = __r._M_ptr;
1198 }
1199
1200 // If an exception is thrown this constructor has no effect.
1201 template<typename _Yp, typename _Del,
1202 typename = _UniqCompatible<_Yp, _Del>>
1203 __shared_ptr(unique_ptr<_Yp, _Del>&& __r)
1204 : _M_ptr(__r.get()), _M_refcount()
1205 {
1206 auto __raw = __to_address(__r.get());
1207 _M_refcount = __shared_count<_Lp>(std::move(__r));
1208 _M_enable_shared_from_this_with(__raw);
1209 }
1210
1211#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
1212 protected:
1213 // If an exception is thrown this constructor has no effect.
1214 template<typename _Tp1, typename _Del,
1215 typename enable_if<__and_<
1216 __not_<is_array<_Tp>>, is_array<_Tp1>,
1217 is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>
1218 >::value, bool>::type = true>
1219 __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
1220 : _M_ptr(__r.get()), _M_refcount()
1221 {
1222 auto __raw = __to_address(__r.get());
1223 _M_refcount = __shared_count<_Lp>(std::move(__r));
1224 _M_enable_shared_from_this_with(__raw);
1225 }
1226 public:
1227#endif
1228
1229#if _GLIBCXX_USE_DEPRECATED
1230#pragma GCC diagnostic push
1231#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1232 // Postcondition: use_count() == 1 and __r.get() == 0
1233 template<typename _Yp, typename = _Compatible<_Yp>>
1234 __shared_ptr(auto_ptr<_Yp>&& __r);
1235#pragma GCC diagnostic pop
1236#endif
1237
1238 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }
1239
1240 template<typename _Yp>
1241 _Assignable<_Yp>
1242 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1243 {
1244 _M_ptr = __r._M_ptr;
1245 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
1246 return *this;
1247 }
1248
1249#if _GLIBCXX_USE_DEPRECATED
1250#pragma GCC diagnostic push
1251#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1252 template<typename _Yp>
1253 _Assignable<_Yp>
1254 operator=(auto_ptr<_Yp>&& __r)
1255 {
1256 __shared_ptr(std::move(__r)).swap(*this);
1257 return *this;
1258 }
1259#pragma GCC diagnostic pop
1260#endif
1261
1262 __shared_ptr&
1263 operator=(__shared_ptr&& __r) noexcept
1264 {
1265 __shared_ptr(std::move(__r)).swap(*this);
1266 return *this;
1267 }
1268
1269 template<class _Yp>
1270 _Assignable<_Yp>
1271 operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1272 {
1273 __shared_ptr(std::move(__r)).swap(*this);
1274 return *this;
1275 }
1276
1277 template<typename _Yp, typename _Del>
1278 _UniqAssignable<_Yp, _Del>
1279 operator=(unique_ptr<_Yp, _Del>&& __r)
1280 {
1281 __shared_ptr(std::move(__r)).swap(*this);
1282 return *this;
1283 }
1284
1285 void
1286 reset() noexcept
1287 { __shared_ptr().swap(*this); }
1288
1289 template<typename _Yp>
1290 _SafeConv<_Yp>
1291 reset(_Yp* __p) // _Yp must be complete.
1292 {
1293 // Catch self-reset errors.
1294 __glibcxx_assert(__p == 0 || __p != _M_ptr);
1295 __shared_ptr(__p).swap(*this);
1296 }
1297
1298 template<typename _Yp, typename _Deleter>
1299 _SafeConv<_Yp>
1300 reset(_Yp* __p, _Deleter __d)
1301 { __shared_ptr(__p, std::move(__d)).swap(*this); }
1302
1303 template<typename _Yp, typename _Deleter, typename _Alloc>
1304 _SafeConv<_Yp>
1305 reset(_Yp* __p, _Deleter __d, _Alloc __a)
1306 { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }
1307
1308 element_type*
1309 get() const noexcept
1310 { return _M_ptr; }
1311
1312 explicit operator bool() const // never throws
1313 { return _M_ptr == 0 ? false : true; }
1314
1315 bool
1316 unique() const noexcept
1317 { return _M_refcount._M_unique(); }
1318
1319 long
1320 use_count() const noexcept
1321 { return _M_refcount._M_get_use_count(); }
1322
1323 void
1324 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
1325 {
1326 std::swap(_M_ptr, __other._M_ptr);
1327 _M_refcount._M_swap(__other._M_refcount);
1328 }
1329
1330 template<typename _Tp1>
1331 bool
1332 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1333 { return _M_refcount._M_less(__rhs._M_refcount); }
1334
1335 template<typename _Tp1>
1336 bool
1337 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1338 { return _M_refcount._M_less(__rhs._M_refcount); }
1339
1340 protected:
1341 // This constructor is non-standard, it is used by allocate_shared.
1342 template<typename _Alloc, typename... _Args>
1343 __shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
1344 : _M_ptr(), _M_refcount(_M_ptr, __tag, std::forward<_Args>(__args)...)
1345 { _M_enable_shared_from_this_with(_M_ptr); }
1346
1347 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
1348 typename... _Args>
1349 friend __shared_ptr<_Tp1, _Lp1>
1350 __allocate_shared(const _Alloc& __a, _Args&&... __args);
1351
1352 // This constructor is used by __weak_ptr::lock() and
1353 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
1354 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
1355 : _M_refcount(__r._M_refcount, std::nothrow)
1356 {
1357 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
1358 }
1359
1360 friend class __weak_ptr<_Tp, _Lp>;
1361
1362 private:
1363
1364 template<typename _Yp>
1365 using __esft_base_t = decltype(__enable_shared_from_this_base(
1366 std::declval<const __shared_count<_Lp>&>(),
1367 std::declval<_Yp*>()));
1368
1369 // Detect an accessible and unambiguous enable_shared_from_this base.
1370 template<typename _Yp, typename = void>
1371 struct __has_esft_base
1372 : false_type { };
1373
1374 template<typename _Yp>
1375 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
1376 : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays
1377
1378 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1379 typename enable_if<__has_esft_base<_Yp2>::value>::type
1380 _M_enable_shared_from_this_with(_Yp* __p) noexcept
1381 {
1382 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))
1383 __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);
1384 }
1385
1386 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1387 typename enable_if<!__has_esft_base<_Yp2>::value>::type
1388 _M_enable_shared_from_this_with(_Yp*) noexcept
1389 { }
1390
1391 void*
1392 _M_get_deleter(const std::type_info& __ti) const noexcept
1393 { return _M_refcount._M_get_deleter(__ti); }
1394
1395 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1396 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1397
1398 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
1399 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;
1400
1401 template<typename _Del, typename _Tp1>
1402 friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept;
1403
1404 element_type* _M_ptr; // Contained pointer.
1405 __shared_count<_Lp> _M_refcount; // Reference counter.
1406 };
1407
1408
1409 // 20.7.2.2.7 shared_ptr comparisons
1410 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1411 inline bool
1412 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
1413 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1414 { return __a.get() == __b.get(); }
1415
1416 template<typename _Tp, _Lock_policy _Lp>
1417 inline bool
1418 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1419 { return !__a; }
1420
1421 template<typename _Tp, _Lock_policy _Lp>
1422 inline bool
1423 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1424 { return !__a; }
1425
1426 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1427 inline bool
1428 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
1429 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1430 { return __a.get() != __b.get(); }
1431
1432 template<typename _Tp, _Lock_policy _Lp>
1433 inline bool
1434 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1435 { return (bool)__a; }
1436
1437 template<typename _Tp, _Lock_policy _Lp>
1438 inline bool
1439 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1440 { return (bool)__a; }
1441
1442 template<typename _Tp, typename _Up, _Lock_policy _Lp>
1443 inline bool
1444 operator<(const __shared_ptr<_Tp, _Lp>& __a,
1445 const __shared_ptr<_Up, _Lp>& __b) noexcept
1446 {
1447 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1448 using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type;
1449 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
1450 return less<_Vp>()(__a.get(), __b.get());
1451 }
1452
1453 template<typename _Tp, _Lock_policy _Lp>
1454 inline bool
1455 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1456 {
1457 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1458 return less<_Tp_elt*>()(__a.get(), nullptr);
1459 }
1460
1461 template<typename _Tp, _Lock_policy _Lp>
1462 inline bool
1463 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1464 {
1465 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1466 return less<_Tp_elt*>()(nullptr, __a.get());
1467 }
1468
1469 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1470 inline bool
1471 operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
1472 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1473 { return !(__b < __a); }
1474
1475 template<typename _Tp, _Lock_policy _Lp>
1476 inline bool
1477 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1478 { return !(nullptr < __a); }
1479
1480 template<typename _Tp, _Lock_policy _Lp>
1481 inline bool
1482 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1483 { return !(__a < nullptr); }
1484
1485 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1486 inline bool
1487 operator>(const __shared_ptr<_Tp1, _Lp>& __a,
1488 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1489 { return (__b < __a); }
1490
1491 template<typename _Tp, _Lock_policy _Lp>
1492 inline bool
1493 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1494 { return nullptr < __a; }
1495
1496 template<typename _Tp, _Lock_policy _Lp>
1497 inline bool
1498 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1499 { return __a < nullptr; }
1500
1501 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1502 inline bool
1503 operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
1504 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1505 { return !(__a < __b); }
1506
1507 template<typename _Tp, _Lock_policy _Lp>
1508 inline bool
1509 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1510 { return !(__a < nullptr); }
1511
1512 template<typename _Tp, _Lock_policy _Lp>
1513 inline bool
1514 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1515 { return !(nullptr < __a); }
1516
1517 // 20.7.2.2.8 shared_ptr specialized algorithms.
1518 template<typename _Tp, _Lock_policy _Lp>
1519 inline void
1520 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
1521 { __a.swap(__b); }
1522
1523 // 20.7.2.2.9 shared_ptr casts
1524
1525 // The seemingly equivalent code:
1526 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
1527 // will eventually result in undefined behaviour, attempting to
1528 // delete the same object twice.
1529 /// static_pointer_cast
1530 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1531 inline __shared_ptr<_Tp, _Lp>
1532 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1533 {
1534 using _Sp = __shared_ptr<_Tp, _Lp>;
1535 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
1536 }
1537
1538 // The seemingly equivalent code:
1539 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
1540 // will eventually result in undefined behaviour, attempting to
1541 // delete the same object twice.
1542 /// const_pointer_cast
1543 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1544 inline __shared_ptr<_Tp, _Lp>
1545 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1546 {
1547 using _Sp = __shared_ptr<_Tp, _Lp>;
1548 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
1549 }
1550
1551 // The seemingly equivalent code:
1552 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
1553 // will eventually result in undefined behaviour, attempting to
1554 // delete the same object twice.
1555 /// dynamic_pointer_cast
1556 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1557 inline __shared_ptr<_Tp, _Lp>
1558 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1559 {
1560 using _Sp = __shared_ptr<_Tp, _Lp>;
1561 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
1562 return _Sp(__r, __p);
1563 return _Sp();
1564 }
1565
1566#if __cplusplus > 201402L
1567 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1568 inline __shared_ptr<_Tp, _Lp>
1569 reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1570 {
1571 using _Sp = __shared_ptr<_Tp, _Lp>;
1572 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
1573 }
1574#endif
1575
1576 template<typename _Tp, _Lock_policy _Lp>
1577 class __weak_ptr
1578 {
1579 template<typename _Yp, typename _Res = void>
1580 using _Compatible = typename
1581 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1582
1583 // Constraint for assignment from shared_ptr and weak_ptr:
1584 template<typename _Yp>
1585 using _Assignable = _Compatible<_Yp, __weak_ptr&>;
1586
1587 public:
1588 using element_type = typename remove_extent<_Tp>::type;
1589
1590 constexpr __weak_ptr() noexcept
1591 : _M_ptr(nullptr), _M_refcount()
1592 { }
1593
1594 __weak_ptr(const __weak_ptr&) noexcept = default;
1595
1596 ~__weak_ptr() = default;
1597
1598 // The "obvious" converting constructor implementation:
1599 //
1600 // template<typename _Tp1>
1601 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1602 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1603 // { }
1604 //
1605 // has a serious problem.
1606 //
1607 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1608 // conversion may require access to *__r._M_ptr (virtual inheritance).
1609 //
1610 // It is not possible to avoid spurious access violations since
1611 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1612 template<typename _Yp, typename = _Compatible<_Yp>>
1613 __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1614 : _M_refcount(__r._M_refcount)
1615 { _M_ptr = __r.lock().get(); }
1616
1617 template<typename _Yp, typename = _Compatible<_Yp>>
1618 __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1619 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1620 { }
1621
1622 __weak_ptr(__weak_ptr&& __r) noexcept
1623 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount))
1624 { __r._M_ptr = nullptr; }
1625
1626 template<typename _Yp, typename = _Compatible<_Yp>>
1627 __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1628 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount))
1629 { __r._M_ptr = nullptr; }
1630
1631 __weak_ptr&
1632 operator=(const __weak_ptr& __r) noexcept = default;
1633
1634 template<typename _Yp>
1635 _Assignable<_Yp>
1636 operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1637 {
1638 _M_ptr = __r.lock().get();
1639 _M_refcount = __r._M_refcount;
1640 return *this;
1641 }
1642
1643 template<typename _Yp>
1644 _Assignable<_Yp>
1645 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1646 {
1647 _M_ptr = __r._M_ptr;
1648 _M_refcount = __r._M_refcount;
1649 return *this;
1650 }
1651
1652 __weak_ptr&
1653 operator=(__weak_ptr&& __r) noexcept
1654 {
1655 _M_ptr = __r._M_ptr;
1656 _M_refcount = std::move(__r._M_refcount);
1657 __r._M_ptr = nullptr;
1658 return *this;
1659 }
1660
1661 template<typename _Yp>
1662 _Assignable<_Yp>
1663 operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1664 {
1665 _M_ptr = __r.lock().get();
1666 _M_refcount = std::move(__r._M_refcount);
1667 __r._M_ptr = nullptr;
1668 return *this;
1669 }
1670
1671 __shared_ptr<_Tp, _Lp>
1672 lock() const noexcept
1673 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
1674
1675 long
1676 use_count() const noexcept
1677 { return _M_refcount._M_get_use_count(); }
1678
1679 bool
1680 expired() const noexcept
1681 { return _M_refcount._M_get_use_count() == 0; }
1682
1683 template<typename _Tp1>
1684 bool
1685 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept
1686 { return _M_refcount._M_less(__rhs._M_refcount); }
1687
1688 template<typename _Tp1>
1689 bool
1690 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept
1691 { return _M_refcount._M_less(__rhs._M_refcount); }
1692
1693 void
1694 reset() noexcept
1695 { __weak_ptr().swap(*this); }
1696
1697 void
1698 swap(__weak_ptr& __s) noexcept
1699 {
1700 std::swap(_M_ptr, __s._M_ptr);
1701 _M_refcount._M_swap(__s._M_refcount);
1702 }
1703
1704 private:
1705 // Used by __enable_shared_from_this.
1706 void
1707 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
1708 {
1709 if (use_count() == 0)
1710 {
1711 _M_ptr = __ptr;
1712 _M_refcount = __refcount;
1713 }
1714 }
1715
1716 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1717 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1718 friend class __enable_shared_from_this<_Tp, _Lp>;
1719 friend class enable_shared_from_this<_Tp>;
1720
1721 element_type* _M_ptr; // Contained pointer.
1722 __weak_count<_Lp> _M_refcount; // Reference counter.
1723 };
1724
1725 // 20.7.2.3.6 weak_ptr specialized algorithms.
1726 template<typename _Tp, _Lock_policy _Lp>
1727 inline void
1728 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
1729 { __a.swap(__b); }
1730
1731 template<typename _Tp, typename _Tp1>
1732 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1733 {
1734 bool
1735 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept
1736 { return __lhs.owner_before(__rhs); }
1737
1738 bool
1739 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept
1740 { return __lhs.owner_before(__rhs); }
1741
1742 bool
1743 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept
1744 { return __lhs.owner_before(__rhs); }
1745 };
1746
1747 template<>
1748 struct _Sp_owner_less<void, void>
1749 {
1750 template<typename _Tp, typename _Up>
1751 auto
1752 operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept
1753 -> decltype(__lhs.owner_before(__rhs))
1754 { return __lhs.owner_before(__rhs); }
1755
1756 using is_transparent = void;
1757 };
1758
1759 template<typename _Tp, _Lock_policy _Lp>
1760 struct owner_less<__shared_ptr<_Tp, _Lp>>
1761 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1762 { };
1763
1764 template<typename _Tp, _Lock_policy _Lp>
1765 struct owner_less<__weak_ptr<_Tp, _Lp>>
1766 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1767 { };
1768
1769
1770 template<typename _Tp, _Lock_policy _Lp>
1771 class __enable_shared_from_this
1772 {
1773 protected:
1774 constexpr __enable_shared_from_this() noexcept { }
1775
1776 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { }
1777
1778 __enable_shared_from_this&
1779 operator=(const __enable_shared_from_this&) noexcept
1780 { return *this; }
1781
1782 ~__enable_shared_from_this() { }
1783
1784 public:
1785 __shared_ptr<_Tp, _Lp>
1786 shared_from_this()
1787 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1788
1789 __shared_ptr<const _Tp, _Lp>
1790 shared_from_this() const
1791 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1792
1793#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1794 __weak_ptr<_Tp, _Lp>
1795 weak_from_this() noexcept
1796 { return this->_M_weak_this; }
1797
1798 __weak_ptr<const _Tp, _Lp>
1799 weak_from_this() const noexcept
1800 { return this->_M_weak_this; }
1801#endif
1802
1803 private:
1804 template<typename _Tp1>
1805 void
1806 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
1807 { _M_weak_this._M_assign(__p, __n); }
1808
1809 friend const __enable_shared_from_this*
1810 __enable_shared_from_this_base(const __shared_count<_Lp>&,
1811 const __enable_shared_from_this* __p)
1812 { return __p; }
1813
1814 template<typename, _Lock_policy>
1815 friend class __shared_ptr;
1816
1817 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1818 };
1819
1820 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy,
1821 typename _Alloc, typename... _Args>
1822 inline __shared_ptr<_Tp, _Lp>
1823 __allocate_shared(const _Alloc& __a, _Args&&... __args)
1824 {
1825 return __shared_ptr<_Tp, _Lp>(_Sp_alloc_shared_tag<_Alloc>{__a},
1826 std::forward<_Args>(__args)...);
1827 }
1828
1829 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy,
1830 typename... _Args>
1831 inline __shared_ptr<_Tp, _Lp>
1832 __make_shared(_Args&&... __args)
1833 {
1834 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1835 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1836 std::forward<_Args>(__args)...);
1837 }
1838
1839 /// std::hash specialization for __shared_ptr.
1840 template<typename _Tp, _Lock_policy _Lp>
1841 struct hash<__shared_ptr<_Tp, _Lp>>
1842 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
1843 {
1844 size_t
1845 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
1846 {
1847 return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()(
1848 __s.get());
1849 }
1850 };
1851
1852_GLIBCXX_END_NAMESPACE_VERSION
1853} // namespace
1854
1855#endif // _SHARED_PTR_BASE_H
1856