1// shared_ptr and weak_ptr implementation details -*- C++ -*-
2
3// Copyright (C) 2007-2017 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25// GCC Note: Based on files from version 1.32.0 of the Boost library.
26
27// shared_count.hpp
28// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
29
30// shared_ptr.hpp
31// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32// Copyright (C) 2001, 2002, 2003 Peter Dimov
33
34// weak_ptr.hpp
35// Copyright (C) 2001, 2002, 2003 Peter Dimov
36
37// enable_shared_from_this.hpp
38// Copyright (C) 2002 Peter Dimov
39
40// Distributed under the Boost Software License, Version 1.0. (See
41// accompanying file LICENSE_1_0.txt or copy at
42// http://www.boost.org/LICENSE_1_0.txt)
43
44/** @file 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#if __cpp_rtti
53# include <typeinfo>
54#endif
55#include <bits/allocated_ptr.h>
56#include <bits/refwrap.h>
57#include <bits/stl_function.h>
58#include <ext/aligned_buffer.h>
59
60namespace std _GLIBCXX_VISIBILITY(default)
61{
62#if !__cpp_rtti
63 class type_info;
64#endif
65
66_GLIBCXX_BEGIN_NAMESPACE_VERSION
67
68#if _GLIBCXX_USE_DEPRECATED
69#pragma GCC diagnostic push
70#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
71 template<typename> class auto_ptr;
72#pragma GCC diagnostic pop
73#endif
74
75 /**
76 * @brief Exception possibly thrown by @c shared_ptr.
77 * @ingroup exceptions
78 */
79 class bad_weak_ptr : public std::exception
80 {
81 public:
82 virtual char const* what() const noexcept;
83
84 virtual ~bad_weak_ptr() noexcept;
85 };
86
87 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
88 inline void
89 __throw_bad_weak_ptr()
90 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
91
92 using __gnu_cxx::_Lock_policy;
93 using __gnu_cxx::__default_lock_policy;
94 using __gnu_cxx::_S_single;
95 using __gnu_cxx::_S_mutex;
96 using __gnu_cxx::_S_atomic;
97
98 // Empty helper class except when the template argument is _S_mutex.
99 template<_Lock_policy _Lp>
100 class _Mutex_base
101 {
102 protected:
103 // The atomic policy uses fully-fenced builtins, single doesn't care.
104 enum { _S_need_barriers = 0 };
105 };
106
107 template<>
108 class _Mutex_base<_S_mutex>
109 : public __gnu_cxx::__mutex
110 {
111 protected:
112 // This policy is used when atomic builtins are not available.
113 // The replacement atomic operations might not have the necessary
114 // memory barriers.
115 enum { _S_need_barriers = 1 };
116 };
117
118 template<_Lock_policy _Lp = __default_lock_policy>
119 class _Sp_counted_base
120 : public _Mutex_base<_Lp>
121 {
122 public:
123 _Sp_counted_base() noexcept
124 : _M_use_count(1), _M_weak_count(1) { }
125
126 virtual
127 ~_Sp_counted_base() noexcept
128 { }
129
130 // Called when _M_use_count drops to zero, to release the resources
131 // managed by *this.
132 virtual void
133 _M_dispose() noexcept = 0;
134
135 // Called when _M_weak_count drops to zero.
136 virtual void
137 _M_destroy() noexcept
138 { delete this; }
139
140 virtual void*
141 _M_get_deleter(const std::type_info&) noexcept = 0;
142
143 void
144 _M_add_ref_copy()
145 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
146
147 void
148 _M_add_ref_lock();
149
150 bool
151 _M_add_ref_lock_nothrow();
152
153 void
154 _M_release() noexcept
155 {
156 // Be race-detector-friendly. For more info see bits/c++config.
157 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
158 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
159 {
160 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
161 _M_dispose();
162 // There must be a memory barrier between dispose() and destroy()
163 // to ensure that the effects of dispose() are observed in the
164 // thread that runs destroy().
165 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
166 if (_Mutex_base<_Lp>::_S_need_barriers)
167 {
168 __atomic_thread_fence (__ATOMIC_ACQ_REL);
169 }
170
171 // Be race-detector-friendly. For more info see bits/c++config.
172 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
173 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
174 -1) == 1)
175 {
176 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
177 _M_destroy();
178 }
179 }
180 }
181
182 void
183 _M_weak_add_ref() noexcept
184 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
185
186 void
187 _M_weak_release() noexcept
188 {
189 // Be race-detector-friendly. For more info see bits/c++config.
190 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
191 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
192 {
193 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
194 if (_Mutex_base<_Lp>::_S_need_barriers)
195 {
196 // See _M_release(),
197 // destroy() must observe results of dispose()
198 __atomic_thread_fence (__ATOMIC_ACQ_REL);
199 }
200 _M_destroy();
201 }
202 }
203
204 long
205 _M_get_use_count() const noexcept
206 {
207 // No memory barrier is used here so there is no synchronization
208 // with other threads.
209 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED);
210 }
211
212 private:
213 _Sp_counted_base(_Sp_counted_base const&) = delete;
214 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete;
215
216 _Atomic_word _M_use_count; // #shared
217 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
218 };
219
220 template<>
221 inline void
222 _Sp_counted_base<_S_single>::
223 _M_add_ref_lock()
224 {
225 if (_M_use_count == 0)
226 __throw_bad_weak_ptr();
227 ++_M_use_count;
228 }
229
230 template<>
231 inline void
232 _Sp_counted_base<_S_mutex>::
233 _M_add_ref_lock()
234 {
235 __gnu_cxx::__scoped_lock sentry(*this);
236 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
237 {
238 _M_use_count = 0;
239 __throw_bad_weak_ptr();
240 }
241 }
242
243 template<>
244 inline void
245 _Sp_counted_base<_S_atomic>::
246 _M_add_ref_lock()
247 {
248 // Perform lock-free add-if-not-zero operation.
249 _Atomic_word __count = _M_get_use_count();
250 do
251 {
252 if (__count == 0)
253 __throw_bad_weak_ptr();
254 // Replace the current counter value with the old value + 1, as
255 // long as it's not changed meanwhile.
256 }
257 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
258 true, __ATOMIC_ACQ_REL,
259 __ATOMIC_RELAXED));
260 }
261
262 template<>
263 inline bool
264 _Sp_counted_base<_S_single>::
265 _M_add_ref_lock_nothrow()
266 {
267 if (_M_use_count == 0)
268 return false;
269 ++_M_use_count;
270 return true;
271 }
272
273 template<>
274 inline bool
275 _Sp_counted_base<_S_mutex>::
276 _M_add_ref_lock_nothrow()
277 {
278 __gnu_cxx::__scoped_lock sentry(*this);
279 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
280 {
281 _M_use_count = 0;
282 return false;
283 }
284 return true;
285 }
286
287 template<>
288 inline bool
289 _Sp_counted_base<_S_atomic>::
290 _M_add_ref_lock_nothrow()
291 {
292 // Perform lock-free add-if-not-zero operation.
293 _Atomic_word __count = _M_get_use_count();
294 do
295 {
296 if (__count == 0)
297 return false;
298 // Replace the current counter value with the old value + 1, as
299 // long as it's not changed meanwhile.
300 }
301 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
302 true, __ATOMIC_ACQ_REL,
303 __ATOMIC_RELAXED));
304 return true;
305 }
306
307 template<>
308 inline void
309 _Sp_counted_base<_S_single>::_M_add_ref_copy()
310 { ++_M_use_count; }
311
312 template<>
313 inline void
314 _Sp_counted_base<_S_single>::_M_release() noexcept
315 {
316 if (--_M_use_count == 0)
317 {
318 _M_dispose();
319 if (--_M_weak_count == 0)
320 _M_destroy();
321 }
322 }
323
324 template<>
325 inline void
326 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
327 { ++_M_weak_count; }
328
329 template<>
330 inline void
331 _Sp_counted_base<_S_single>::_M_weak_release() noexcept
332 {
333 if (--_M_weak_count == 0)
334 _M_destroy();
335 }
336
337 template<>
338 inline long
339 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
340 { return _M_use_count; }
341
342
343 // Forward declarations.
344 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
345 class __shared_ptr;
346
347 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
348 class __weak_ptr;
349
350 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
351 class __enable_shared_from_this;
352
353 template<typename _Tp>
354 class shared_ptr;
355
356 template<typename _Tp>
357 class weak_ptr;
358
359 template<typename _Tp>
360 struct owner_less;
361
362 template<typename _Tp>
363 class enable_shared_from_this;
364
365 template<_Lock_policy _Lp = __default_lock_policy>
366 class __weak_count;
367
368 template<_Lock_policy _Lp = __default_lock_policy>
369 class __shared_count;
370
371
372 // Counted ptr with no deleter or allocator support
373 template<typename _Ptr, _Lock_policy _Lp>
374 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
375 {
376 public:
377 explicit
378 _Sp_counted_ptr(_Ptr __p) noexcept
379 : _M_ptr(__p) { }
380
381 virtual void
382 _M_dispose() noexcept
383 { delete _M_ptr; }
384
385 virtual void
386 _M_destroy() noexcept
387 { delete this; }
388
389 virtual void*
390 _M_get_deleter(const std::type_info&) noexcept
391 { return nullptr; }
392
393 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
394 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
395
396 private:
397 _Ptr _M_ptr;
398 };
399
400 template<>
401 inline void
402 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }
403
404 template<>
405 inline void
406 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }
407
408 template<>
409 inline void
410 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }
411
412 template<int _Nm, typename _Tp,
413 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
414 struct _Sp_ebo_helper;
415
416 /// Specialization using EBO.
417 template<int _Nm, typename _Tp>
418 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
419 {
420 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
421 explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { }
422
423 static _Tp&
424 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
425 };
426
427 /// Specialization not using EBO.
428 template<int _Nm, typename _Tp>
429 struct _Sp_ebo_helper<_Nm, _Tp, false>
430 {
431 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
432 explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { }
433
434 static _Tp&
435 _S_get(_Sp_ebo_helper& __eboh)
436 { return __eboh._M_tp; }
437
438 private:
439 _Tp _M_tp;
440 };
441
442 // Support for custom deleter and/or allocator
443 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
444 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
445 {
446 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
447 {
448 typedef _Sp_ebo_helper<0, _Deleter> _Del_base;
449 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base;
450
451 public:
452 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
453 : _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a)
454 { }
455
456 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
457 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }
458
459 _Ptr _M_ptr;
460 };
461
462 public:
463 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>;
464
465 // __d(__p) must not throw.
466 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
467 : _M_impl(__p, std::move(__d), _Alloc()) { }
468
469 // __d(__p) must not throw.
470 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
471 : _M_impl(__p, std::move(__d), __a) { }
472
473 ~_Sp_counted_deleter() noexcept { }
474
475 virtual void
476 _M_dispose() noexcept
477 { _M_impl._M_del()(_M_impl._M_ptr); }
478
479 virtual void
480 _M_destroy() noexcept
481 {
482 __allocator_type __a(_M_impl._M_alloc());
483 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
484 this->~_Sp_counted_deleter();
485 }
486
487 virtual void*
488 _M_get_deleter(const std::type_info& __ti) noexcept
489 {
490#if __cpp_rtti
491 // _GLIBCXX_RESOLVE_LIB_DEFECTS
492 // 2400. shared_ptr's get_deleter() should use addressof()
493 return __ti == typeid(_Deleter)
494 ? std::__addressof(_M_impl._M_del())
495 : nullptr;
496#else
497 return nullptr;
498#endif
499 }
500
501 private:
502 _Impl _M_impl;
503 };
504
505 // helpers for make_shared / allocate_shared
506
507 struct _Sp_make_shared_tag
508 {
509#if !__cpp_rtti
510 private:
511 template<typename _Tp, _Lock_policy _Lp>
512 friend class __shared_ptr;
513 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
514 friend class _Sp_counted_ptr_inplace;
515
516 static const type_info&
517 _S_ti() noexcept
518 {
519 static constexpr _Sp_make_shared_tag __tag;
520 return reinterpret_cast<const type_info&>(__tag);
521 }
522#endif
523 };
524
525 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
526 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
527 {
528 class _Impl : _Sp_ebo_helper<0, _Alloc>
529 {
530 typedef _Sp_ebo_helper<0, _Alloc> _A_base;
531
532 public:
533 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }
534
535 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }
536
537 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
538 };
539
540 public:
541 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>;
542
543 template<typename... _Args>
544 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
545 : _M_impl(__a)
546 {
547 // _GLIBCXX_RESOLVE_LIB_DEFECTS
548 // 2070. allocate_shared should use allocator_traits<A>::construct
549 allocator_traits<_Alloc>::construct(__a, _M_ptr(),
550 std::forward<_Args>(__args)...); // might throw
551 }
552
553 ~_Sp_counted_ptr_inplace() noexcept { }
554
555 virtual void
556 _M_dispose() noexcept
557 {
558 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
559 }
560
561 // Override because the allocator needs to know the dynamic type
562 virtual void
563 _M_destroy() noexcept
564 {
565 __allocator_type __a(_M_impl._M_alloc());
566 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
567 this->~_Sp_counted_ptr_inplace();
568 }
569
570 // Sneaky trick so __shared_ptr can get the managed pointer
571 virtual void*
572 _M_get_deleter(const std::type_info& __ti) noexcept
573 {
574#if __cpp_rtti
575 if (__ti == typeid(_Sp_make_shared_tag))
576#else
577 if (&__ti == &_Sp_make_shared_tag::_S_ti())
578#endif
579 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
580 return nullptr;
581 }
582
583 private:
584 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }
585
586 _Impl _M_impl;
587 };
588
589 // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>.
590 struct __sp_array_delete
591 {
592 template<typename _Yp>
593 void operator()(_Yp* __p) const { delete[] __p; }
594 };
595
596 template<_Lock_policy _Lp>
597 class __shared_count
598 {
599 public:
600 constexpr __shared_count() noexcept : _M_pi(0)
601 { }
602
603 template<typename _Ptr>
604 explicit
605 __shared_count(_Ptr __p) : _M_pi(0)
606 {
607 __try
608 {
609 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
610 }
611 __catch(...)
612 {
613 delete __p;
614 __throw_exception_again;
615 }
616 }
617
618 template<typename _Ptr>
619 __shared_count(_Ptr __p, /* is_array = */ false_type)
620 : __shared_count(__p)
621 { }
622
623 template<typename _Ptr>
624 __shared_count(_Ptr __p, /* is_array = */ true_type)
625 : __shared_count(__p, __sp_array_delete{}, allocator<void>())
626 { }
627
628 template<typename _Ptr, typename _Deleter>
629 __shared_count(_Ptr __p, _Deleter __d)
630 : __shared_count(__p, std::move(__d), allocator<void>())
631 { }
632
633 template<typename _Ptr, typename _Deleter, typename _Alloc>
634 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
635 {
636 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
637 __try
638 {
639 typename _Sp_cd_type::__allocator_type __a2(__a);
640 auto __guard = std::__allocate_guarded(__a2);
641 _Sp_cd_type* __mem = __guard.get();
642 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a));
643 _M_pi = __mem;
644 __guard = nullptr;
645 }
646 __catch(...)
647 {
648 __d(__p); // Call _Deleter on __p.
649 __throw_exception_again;
650 }
651 }
652
653 template<typename _Tp, typename _Alloc, typename... _Args>
654 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a,
655 _Args&&... __args)
656 : _M_pi(0)
657 {
658 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
659 typename _Sp_cp_type::__allocator_type __a2(__a);
660 auto __guard = std::__allocate_guarded(__a2);
661 _Sp_cp_type* __mem = __guard.get();
662 ::new (__mem) _Sp_cp_type(std::move(__a),
663 std::forward<_Args>(__args)...);
664 _M_pi = __mem;
665 __guard = nullptr;
666 }
667
668#if _GLIBCXX_USE_DEPRECATED
669#pragma GCC diagnostic push
670#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
671 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
672 template<typename _Tp>
673 explicit
674 __shared_count(std::auto_ptr<_Tp>&& __r);
675#pragma GCC diagnostic pop
676#endif
677
678 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
679 template<typename _Tp, typename _Del>
680 explicit
681 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
682 {
683 // _GLIBCXX_RESOLVE_LIB_DEFECTS
684 // 2415. Inconsistency between unique_ptr and shared_ptr
685 if (__r.get() == nullptr)
686 return;
687
688 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
689 using _Del2 = typename conditional<is_reference<_Del>::value,
690 reference_wrapper<typename remove_reference<_Del>::type>,
691 _Del>::type;
692 using _Sp_cd_type
693 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
694 using _Alloc = allocator<_Sp_cd_type>;
695 using _Alloc_traits = allocator_traits<_Alloc>;
696 _Alloc __a;
697 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
698 _Alloc_traits::construct(__a, __mem, __r.release(),
699 __r.get_deleter()); // non-throwing
700 _M_pi = __mem;
701 }
702
703 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
704 explicit __shared_count(const __weak_count<_Lp>& __r);
705
706 // Does not throw if __r._M_get_use_count() == 0, caller must check.
707 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
708
709 ~__shared_count() noexcept
710 {
711 if (_M_pi != nullptr)
712 _M_pi->_M_release();
713 }
714
715 __shared_count(const __shared_count& __r) noexcept
716 : _M_pi(__r._M_pi)
717 {
718 if (_M_pi != 0)
719 _M_pi->_M_add_ref_copy();
720 }
721
722 __shared_count&
723 operator=(const __shared_count& __r) noexcept
724 {
725 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
726 if (__tmp != _M_pi)
727 {
728 if (__tmp != 0)
729 __tmp->_M_add_ref_copy();
730 if (_M_pi != 0)
731 _M_pi->_M_release();
732 _M_pi = __tmp;
733 }
734 return *this;
735 }
736
737 void
738 _M_swap(__shared_count& __r) noexcept
739 {
740 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
741 __r._M_pi = _M_pi;
742 _M_pi = __tmp;
743 }
744
745 long
746 _M_get_use_count() const noexcept
747 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
748
749 bool
750 _M_unique() const noexcept
751 { return this->_M_get_use_count() == 1; }
752
753 void*
754 _M_get_deleter(const std::type_info& __ti) const noexcept
755 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }
756
757 bool
758 _M_less(const __shared_count& __rhs) const noexcept
759 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
760
761 bool
762 _M_less(const __weak_count<_Lp>& __rhs) const noexcept
763 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
764
765 // Friend function injected into enclosing namespace and found by ADL
766 friend inline bool
767 operator==(const __shared_count& __a, const __shared_count& __b) noexcept
768 { return __a._M_pi == __b._M_pi; }
769
770 private:
771 friend class __weak_count<_Lp>;
772
773 _Sp_counted_base<_Lp>* _M_pi;
774 };
775
776
777 template<_Lock_policy _Lp>
778 class __weak_count
779 {
780 public:
781 constexpr __weak_count() noexcept : _M_pi(nullptr)
782 { }
783
784 __weak_count(const __shared_count<_Lp>& __r) noexcept
785 : _M_pi(__r._M_pi)
786 {
787 if (_M_pi != nullptr)
788 _M_pi->_M_weak_add_ref();
789 }
790
791 __weak_count(const __weak_count& __r) noexcept
792 : _M_pi(__r._M_pi)
793 {
794 if (_M_pi != nullptr)
795 _M_pi->_M_weak_add_ref();
796 }
797
798 __weak_count(__weak_count&& __r) noexcept
799 : _M_pi(__r._M_pi)
800 { __r._M_pi = nullptr; }
801
802 ~__weak_count() noexcept
803 {
804 if (_M_pi != nullptr)
805 _M_pi->_M_weak_release();
806 }
807
808 __weak_count&
809 operator=(const __shared_count<_Lp>& __r) noexcept
810 {
811 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
812 if (__tmp != nullptr)
813 __tmp->_M_weak_add_ref();
814 if (_M_pi != nullptr)
815 _M_pi->_M_weak_release();
816 _M_pi = __tmp;
817 return *this;
818 }
819
820 __weak_count&
821 operator=(const __weak_count& __r) noexcept
822 {
823 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
824 if (__tmp != nullptr)
825 __tmp->_M_weak_add_ref();
826 if (_M_pi != nullptr)
827 _M_pi->_M_weak_release();
828 _M_pi = __tmp;
829 return *this;
830 }
831
832 __weak_count&
833 operator=(__weak_count&& __r) noexcept
834 {
835 if (_M_pi != nullptr)
836 _M_pi->_M_weak_release();
837 _M_pi = __r._M_pi;
838 __r._M_pi = nullptr;
839 return *this;
840 }
841
842 void
843 _M_swap(__weak_count& __r) noexcept
844 {
845 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
846 __r._M_pi = _M_pi;
847 _M_pi = __tmp;
848 }
849
850 long
851 _M_get_use_count() const noexcept
852 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; }
853
854 bool
855 _M_less(const __weak_count& __rhs) const noexcept
856 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
857
858 bool
859 _M_less(const __shared_count<_Lp>& __rhs) const noexcept
860 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
861
862 // Friend function injected into enclosing namespace and found by ADL
863 friend inline bool
864 operator==(const __weak_count& __a, const __weak_count& __b) noexcept
865 { return __a._M_pi == __b._M_pi; }
866
867 private:
868 friend class __shared_count<_Lp>;
869
870 _Sp_counted_base<_Lp>* _M_pi;
871 };
872
873 // Now that __weak_count is defined we can define this constructor:
874 template<_Lock_policy _Lp>
875 inline
876 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
877 : _M_pi(__r._M_pi)
878 {
879 if (_M_pi != nullptr)
880 _M_pi->_M_add_ref_lock();
881 else
882 __throw_bad_weak_ptr();
883 }
884
885 // Now that __weak_count is defined we can define this constructor:
886 template<_Lock_policy _Lp>
887 inline
888 __shared_count<_Lp>::
889 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
890 : _M_pi(__r._M_pi)
891 {
892 if (_M_pi != nullptr)
893 if (!_M_pi->_M_add_ref_lock_nothrow())
894 _M_pi = nullptr;
895 }
896
897#define __cpp_lib_shared_ptr_arrays 201603
898
899 // Helper traits for shared_ptr of array:
900
901 // A pointer type Y* is said to be compatible with a pointer type T* when
902 // either Y* is convertible to T* or Y is U[N] and T is U cv [].
903 template<typename _Yp_ptr, typename _Tp_ptr>
904 struct __sp_compatible_with
905 : false_type
906 { };
907
908 template<typename _Yp, typename _Tp>
909 struct __sp_compatible_with<_Yp*, _Tp*>
910 : is_convertible<_Yp*, _Tp*>::type
911 { };
912
913 template<typename _Up, size_t _Nm>
914 struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]>
915 : true_type
916 { };
917
918 template<typename _Up, size_t _Nm>
919 struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]>
920 : true_type
921 { };
922
923 template<typename _Up, size_t _Nm>
924 struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]>
925 : true_type
926 { };
927
928 template<typename _Up, size_t _Nm>
929 struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]>
930 : true_type
931 { };
932
933 // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N].
934 template<typename _Up, size_t _Nm, typename _Yp, typename = void>
935 struct __sp_is_constructible_arrN
936 : false_type
937 { };
938
939 template<typename _Up, size_t _Nm, typename _Yp>
940 struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>>
941 : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type
942 { };
943
944 // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[].
945 template<typename _Up, typename _Yp, typename = void>
946 struct __sp_is_constructible_arr
947 : false_type
948 { };
949
950 template<typename _Up, typename _Yp>
951 struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>>
952 : is_convertible<_Yp(*)[], _Up(*)[]>::type
953 { };
954
955 // Trait to check if shared_ptr<T> can be constructed from Y*.
956 template<typename _Tp, typename _Yp>
957 struct __sp_is_constructible;
958
959 // When T is U[N], Y(*)[N] shall be convertible to T*;
960 template<typename _Up, size_t _Nm, typename _Yp>
961 struct __sp_is_constructible<_Up[_Nm], _Yp>
962 : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type
963 { };
964
965 // when T is U[], Y(*)[] shall be convertible to T*;
966 template<typename _Up, typename _Yp>
967 struct __sp_is_constructible<_Up[], _Yp>
968 : __sp_is_constructible_arr<_Up, _Yp>::type
969 { };
970
971 // otherwise, Y* shall be convertible to T*.
972 template<typename _Tp, typename _Yp>
973 struct __sp_is_constructible
974 : is_convertible<_Yp*, _Tp*>::type
975 { };
976
977
978 // Define operator* and operator-> for shared_ptr<T>.
979 template<typename _Tp, _Lock_policy _Lp,
980 bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>
981 class __shared_ptr_access
982 {
983 public:
984 using element_type = _Tp;
985
986 element_type&
987 operator*() const noexcept
988 {
989 __glibcxx_assert(_M_get() != nullptr);
990 return *_M_get();
991 }
992
993 element_type*
994 operator->() const noexcept
995 {
996 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
997 return _M_get();
998 }
999
1000 private:
1001 element_type*
1002 _M_get() const noexcept
1003 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
1004 };
1005
1006 // Define operator-> for shared_ptr<cv void>.
1007 template<typename _Tp, _Lock_policy _Lp>
1008 class __shared_ptr_access<_Tp, _Lp, false, true>
1009 {
1010 public:
1011 using element_type = _Tp;
1012
1013 element_type*
1014 operator->() const noexcept
1015 {
1016 auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get();
1017 _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr);
1018 return __ptr;
1019 }
1020 };
1021
1022 // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>.
1023 template<typename _Tp, _Lock_policy _Lp>
1024 class __shared_ptr_access<_Tp, _Lp, true, false>
1025 {
1026 public:
1027 using element_type = typename remove_extent<_Tp>::type;
1028
1029#if __cplusplus <= 201402L
1030 [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]]
1031 element_type&
1032 operator*() const noexcept
1033 {
1034 __glibcxx_assert(_M_get() != nullptr);
1035 return *_M_get();
1036 }
1037
1038 [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]]
1039 element_type*
1040 operator->() const noexcept
1041 {
1042 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
1043 return _M_get();
1044 }
1045#endif
1046
1047 element_type&
1048 operator[](ptrdiff_t __i) const
1049 {
1050 __glibcxx_assert(_M_get() != nullptr);
1051 __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value);
1052 return _M_get()[__i];
1053 }
1054
1055 private:
1056 element_type*
1057 _M_get() const noexcept
1058 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
1059 };
1060
1061 template<typename _Tp, _Lock_policy _Lp>
1062 class __shared_ptr
1063 : public __shared_ptr_access<_Tp, _Lp>
1064 {
1065 public:
1066 using element_type = typename remove_extent<_Tp>::type;
1067
1068 private:
1069 // Constraint for taking ownership of a pointer of type _Yp*:
1070 template<typename _Yp>
1071 using _SafeConv
1072 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;
1073
1074 // Constraint for construction from shared_ptr and weak_ptr:
1075 template<typename _Yp, typename _Res = void>
1076 using _Compatible = typename
1077 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1078
1079 // Constraint for assignment from shared_ptr and weak_ptr:
1080 template<typename _Yp>
1081 using _Assignable = _Compatible<_Yp, __shared_ptr&>;
1082
1083 // Constraint for construction from unique_ptr:
1084 template<typename _Yp, typename _Del, typename _Res = void,
1085 typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>
1086 using _UniqCompatible = typename enable_if<__and_<
1087 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>
1088 >::value, _Res>::type;
1089
1090 // Constraint for assignment from unique_ptr:
1091 template<typename _Yp, typename _Del>
1092 using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;
1093
1094 public:
1095
1096#if __cplusplus > 201402L
1097 using weak_type = __weak_ptr<_Tp, _Lp>;
1098#endif
1099
1100 constexpr __shared_ptr() noexcept
1101 : _M_ptr(0), _M_refcount()
1102 { }
1103
1104 template<typename _Yp, typename = _SafeConv<_Yp>>
1105 explicit
1106 __shared_ptr(_Yp* __p)
1107 : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type())
1108 {
1109 static_assert( !is_void<_Yp>::value, "incomplete type" );
1110 static_assert( sizeof(_Yp) > 0, "incomplete type" );
1111 _M_enable_shared_from_this_with(__p);
1112 }
1113
1114 template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>
1115 __shared_ptr(_Yp* __p, _Deleter __d)
1116 : _M_ptr(__p), _M_refcount(__p, std::move(__d))
1117 {
1118 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1119 "deleter expression d(p) is well-formed");
1120 _M_enable_shared_from_this_with(__p);
1121 }
1122
1123 template<typename _Yp, typename _Deleter, typename _Alloc,
1124 typename = _SafeConv<_Yp>>
1125 __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
1126 : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a))
1127 {
1128 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1129 "deleter expression d(p) is well-formed");
1130 _M_enable_shared_from_this_with(__p);
1131 }
1132
1133 template<typename _Deleter>
1134 __shared_ptr(nullptr_t __p, _Deleter __d)
1135 : _M_ptr(0), _M_refcount(__p, std::move(__d))
1136 { }
1137
1138 template<typename _Deleter, typename _Alloc>
1139 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
1140 : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a))
1141 { }
1142
1143 template<typename _Yp>
1144 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,
1145 element_type* __p) noexcept
1146 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
1147 { }
1148
1149 __shared_ptr(const __shared_ptr&) noexcept = default;
1150 __shared_ptr& operator=(const __shared_ptr&) noexcept = default;
1151 ~__shared_ptr() = default;
1152
1153 template<typename _Yp, typename = _Compatible<_Yp>>
1154 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1155 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1156 { }
1157
1158 __shared_ptr(__shared_ptr&& __r) noexcept
1159 : _M_ptr(__r._M_ptr), _M_refcount()
1160 {
1161 _M_refcount._M_swap(__r._M_refcount);
1162 __r._M_ptr = 0;
1163 }
1164
1165 template<typename _Yp, typename = _Compatible<_Yp>>
1166 __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1167 : _M_ptr(__r._M_ptr), _M_refcount()
1168 {
1169 _M_refcount._M_swap(__r._M_refcount);
1170 __r._M_ptr = 0;
1171 }
1172
1173 template<typename _Yp, typename = _Compatible<_Yp>>
1174 explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r)
1175 : _M_refcount(__r._M_refcount) // may throw
1176 {
1177 // It is now safe to copy __r._M_ptr, as
1178 // _M_refcount(__r._M_refcount) did not throw.
1179 _M_ptr = __r._M_ptr;
1180 }
1181
1182 // If an exception is thrown this constructor has no effect.
1183 template<typename _Yp, typename _Del,
1184 typename = _UniqCompatible<_Yp, _Del>>
1185 __shared_ptr(unique_ptr<_Yp, _Del>&& __r)
1186 : _M_ptr(__r.get()), _M_refcount()
1187 {
1188 auto __raw = __to_address(__r.get());
1189 _M_refcount = __shared_count<_Lp>(std::move(__r));
1190 _M_enable_shared_from_this_with(__raw);
1191 }
1192
1193#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
1194 protected:
1195 // If an exception is thrown this constructor has no effect.
1196 template<typename _Tp1, typename _Del,
1197 typename enable_if<__and_<
1198 __not_<is_array<_Tp>>, is_array<_Tp1>,
1199 is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>
1200 >::value, bool>::type = true>
1201 __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
1202 : _M_ptr(__r.get()), _M_refcount()
1203 {
1204 auto __raw = __to_address(__r.get());
1205 _M_refcount = __shared_count<_Lp>(std::move(__r));
1206 _M_enable_shared_from_this_with(__raw);
1207 }
1208 public:
1209#endif
1210
1211#if _GLIBCXX_USE_DEPRECATED
1212#pragma GCC diagnostic push
1213#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1214 // Postcondition: use_count() == 1 and __r.get() == 0
1215 template<typename _Yp, typename = _Compatible<_Yp>>
1216 __shared_ptr(auto_ptr<_Yp>&& __r);
1217#pragma GCC diagnostic pop
1218#endif
1219
1220 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }
1221
1222 template<typename _Yp>
1223 _Assignable<_Yp>
1224 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1225 {
1226 _M_ptr = __r._M_ptr;
1227 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
1228 return *this;
1229 }
1230
1231#if _GLIBCXX_USE_DEPRECATED
1232#pragma GCC diagnostic push
1233#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1234 template<typename _Yp>
1235 _Assignable<_Yp>
1236 operator=(auto_ptr<_Yp>&& __r)
1237 {
1238 __shared_ptr(std::move(__r)).swap(*this);
1239 return *this;
1240 }
1241#pragma GCC diagnostic pop
1242#endif
1243
1244 __shared_ptr&
1245 operator=(__shared_ptr&& __r) noexcept
1246 {
1247 __shared_ptr(std::move(__r)).swap(*this);
1248 return *this;
1249 }
1250
1251 template<class _Yp>
1252 _Assignable<_Yp>
1253 operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1254 {
1255 __shared_ptr(std::move(__r)).swap(*this);
1256 return *this;
1257 }
1258
1259 template<typename _Yp, typename _Del>
1260 _UniqAssignable<_Yp, _Del>
1261 operator=(unique_ptr<_Yp, _Del>&& __r)
1262 {
1263 __shared_ptr(std::move(__r)).swap(*this);
1264 return *this;
1265 }
1266
1267 void
1268 reset() noexcept
1269 { __shared_ptr().swap(*this); }
1270
1271 template<typename _Yp>
1272 _SafeConv<_Yp>
1273 reset(_Yp* __p) // _Yp must be complete.
1274 {
1275 // Catch self-reset errors.
1276 __glibcxx_assert(__p == 0 || __p != _M_ptr);
1277 __shared_ptr(__p).swap(*this);
1278 }
1279
1280 template<typename _Yp, typename _Deleter>
1281 _SafeConv<_Yp>
1282 reset(_Yp* __p, _Deleter __d)
1283 { __shared_ptr(__p, std::move(__d)).swap(*this); }
1284
1285 template<typename _Yp, typename _Deleter, typename _Alloc>
1286 _SafeConv<_Yp>
1287 reset(_Yp* __p, _Deleter __d, _Alloc __a)
1288 { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }
1289
1290 element_type*
1291 get() const noexcept
1292 { return _M_ptr; }
1293
1294 explicit operator bool() const // never throws
1295 { return _M_ptr == 0 ? false : true; }
1296
1297 bool
1298 unique() const noexcept
1299 { return _M_refcount._M_unique(); }
1300
1301 long
1302 use_count() const noexcept
1303 { return _M_refcount._M_get_use_count(); }
1304
1305 void
1306 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
1307 {
1308 std::swap(_M_ptr, __other._M_ptr);
1309 _M_refcount._M_swap(__other._M_refcount);
1310 }
1311
1312 template<typename _Tp1>
1313 bool
1314 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1315 { return _M_refcount._M_less(__rhs._M_refcount); }
1316
1317 template<typename _Tp1>
1318 bool
1319 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1320 { return _M_refcount._M_less(__rhs._M_refcount); }
1321
1322 protected:
1323 // This constructor is non-standard, it is used by allocate_shared.
1324 template<typename _Alloc, typename... _Args>
1325 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1326 _Args&&... __args)
1327 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
1328 std::forward<_Args>(__args)...)
1329 {
1330 // _M_ptr needs to point to the newly constructed object.
1331 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
1332#if __cpp_rtti
1333 void* __p = _M_refcount._M_get_deleter(typeid(__tag));
1334#else
1335 void* __p = _M_refcount._M_get_deleter(_Sp_make_shared_tag::_S_ti());
1336#endif
1337 _M_ptr = static_cast<_Tp*>(__p);
1338 _M_enable_shared_from_this_with(_M_ptr);
1339 }
1340
1341 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
1342 typename... _Args>
1343 friend __shared_ptr<_Tp1, _Lp1>
1344 __allocate_shared(const _Alloc& __a, _Args&&... __args);
1345
1346 // This constructor is used by __weak_ptr::lock() and
1347 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
1348 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
1349 : _M_refcount(__r._M_refcount, std::nothrow)
1350 {
1351 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
1352 }
1353
1354 friend class __weak_ptr<_Tp, _Lp>;
1355
1356 private:
1357
1358 template<typename _Yp>
1359 using __esft_base_t = decltype(__enable_shared_from_this_base(
1360 std::declval<const __shared_count<_Lp>&>(),
1361 std::declval<_Yp*>()));
1362
1363 // Detect an accessible and unambiguous enable_shared_from_this base.
1364 template<typename _Yp, typename = void>
1365 struct __has_esft_base
1366 : false_type { };
1367
1368 template<typename _Yp>
1369 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
1370 : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays
1371
1372 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1373 typename enable_if<__has_esft_base<_Yp2>::value>::type
1374 _M_enable_shared_from_this_with(_Yp* __p) noexcept
1375 {
1376 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))
1377 __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);
1378 }
1379
1380 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1381 typename enable_if<!__has_esft_base<_Yp2>::value>::type
1382 _M_enable_shared_from_this_with(_Yp*) noexcept
1383 { }
1384
1385 void*
1386 _M_get_deleter(const std::type_info& __ti) const noexcept
1387 { return _M_refcount._M_get_deleter(__ti); }
1388
1389 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1390 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1391
1392 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
1393 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;
1394
1395 template<typename _Del, typename _Tp1>
1396 friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept;
1397
1398 element_type* _M_ptr; // Contained pointer.
1399 __shared_count<_Lp> _M_refcount; // Reference counter.
1400 };
1401
1402
1403 // 20.7.2.2.7 shared_ptr comparisons
1404 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1405 inline bool
1406 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
1407 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1408 { return __a.get() == __b.get(); }
1409
1410 template<typename _Tp, _Lock_policy _Lp>
1411 inline bool
1412 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1413 { return !__a; }
1414
1415 template<typename _Tp, _Lock_policy _Lp>
1416 inline bool
1417 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1418 { return !__a; }
1419
1420 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1421 inline bool
1422 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
1423 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1424 { return __a.get() != __b.get(); }
1425
1426 template<typename _Tp, _Lock_policy _Lp>
1427 inline bool
1428 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1429 { return (bool)__a; }
1430
1431 template<typename _Tp, _Lock_policy _Lp>
1432 inline bool
1433 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1434 { return (bool)__a; }
1435
1436 template<typename _Tp, typename _Up, _Lock_policy _Lp>
1437 inline bool
1438 operator<(const __shared_ptr<_Tp, _Lp>& __a,
1439 const __shared_ptr<_Up, _Lp>& __b) noexcept
1440 {
1441 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1442 using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type;
1443 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
1444 return less<_Vp>()(__a.get(), __b.get());
1445 }
1446
1447 template<typename _Tp, _Lock_policy _Lp>
1448 inline bool
1449 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1450 {
1451 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1452 return less<_Tp_elt*>()(__a.get(), nullptr);
1453 }
1454
1455 template<typename _Tp, _Lock_policy _Lp>
1456 inline bool
1457 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1458 {
1459 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1460 return less<_Tp_elt*>()(nullptr, __a.get());
1461 }
1462
1463 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1464 inline bool
1465 operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
1466 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1467 { return !(__b < __a); }
1468
1469 template<typename _Tp, _Lock_policy _Lp>
1470 inline bool
1471 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1472 { return !(nullptr < __a); }
1473
1474 template<typename _Tp, _Lock_policy _Lp>
1475 inline bool
1476 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1477 { return !(__a < nullptr); }
1478
1479 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1480 inline bool
1481 operator>(const __shared_ptr<_Tp1, _Lp>& __a,
1482 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1483 { return (__b < __a); }
1484
1485 template<typename _Tp, _Lock_policy _Lp>
1486 inline bool
1487 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1488 { return nullptr < __a; }
1489
1490 template<typename _Tp, _Lock_policy _Lp>
1491 inline bool
1492 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1493 { return __a < nullptr; }
1494
1495 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1496 inline bool
1497 operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
1498 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1499 { return !(__a < __b); }
1500
1501 template<typename _Tp, _Lock_policy _Lp>
1502 inline bool
1503 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1504 { return !(__a < nullptr); }
1505
1506 template<typename _Tp, _Lock_policy _Lp>
1507 inline bool
1508 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1509 { return !(nullptr < __a); }
1510
1511 template<typename _Sp>
1512 struct _Sp_less : public binary_function<_Sp, _Sp, bool>
1513 {
1514 bool
1515 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept
1516 {
1517 typedef typename _Sp::element_type element_type;
1518 return std::less<element_type*>()(__lhs.get(), __rhs.get());
1519 }
1520 };
1521
1522 template<typename _Tp, _Lock_policy _Lp>
1523 struct less<__shared_ptr<_Tp, _Lp>>
1524 : public _Sp_less<__shared_ptr<_Tp, _Lp>>
1525 { };
1526
1527 // 20.7.2.2.8 shared_ptr specialized algorithms.
1528 template<typename _Tp, _Lock_policy _Lp>
1529 inline void
1530 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
1531 { __a.swap(__b); }
1532
1533 // 20.7.2.2.9 shared_ptr casts
1534
1535 // The seemingly equivalent code:
1536 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
1537 // will eventually result in undefined behaviour, attempting to
1538 // delete the same object twice.
1539 /// static_pointer_cast
1540 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1541 inline __shared_ptr<_Tp, _Lp>
1542 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1543 {
1544 using _Sp = __shared_ptr<_Tp, _Lp>;
1545 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
1546 }
1547
1548 // The seemingly equivalent code:
1549 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
1550 // will eventually result in undefined behaviour, attempting to
1551 // delete the same object twice.
1552 /// const_pointer_cast
1553 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1554 inline __shared_ptr<_Tp, _Lp>
1555 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1556 {
1557 using _Sp = __shared_ptr<_Tp, _Lp>;
1558 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
1559 }
1560
1561 // The seemingly equivalent code:
1562 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
1563 // will eventually result in undefined behaviour, attempting to
1564 // delete the same object twice.
1565 /// dynamic_pointer_cast
1566 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1567 inline __shared_ptr<_Tp, _Lp>
1568 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1569 {
1570 using _Sp = __shared_ptr<_Tp, _Lp>;
1571 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
1572 return _Sp(__r, __p);
1573 return _Sp();
1574 }
1575
1576#if __cplusplus > 201402L
1577 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1578 inline __shared_ptr<_Tp, _Lp>
1579 reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1580 {
1581 using _Sp = __shared_ptr<_Tp, _Lp>;
1582 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
1583 }
1584#endif
1585
1586 template<typename _Tp, _Lock_policy _Lp>
1587 class __weak_ptr
1588 {
1589 template<typename _Yp, typename _Res = void>
1590 using _Compatible = typename
1591 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1592
1593 // Constraint for assignment from shared_ptr and weak_ptr:
1594 template<typename _Yp>
1595 using _Assignable = _Compatible<_Yp, __weak_ptr&>;
1596
1597 public:
1598 using element_type = typename remove_extent<_Tp>::type;
1599
1600 constexpr __weak_ptr() noexcept
1601 : _M_ptr(nullptr), _M_refcount()
1602 { }
1603
1604 __weak_ptr(const __weak_ptr&) noexcept = default;
1605
1606 ~__weak_ptr() = default;
1607
1608 // The "obvious" converting constructor implementation:
1609 //
1610 // template<typename _Tp1>
1611 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1612 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1613 // { }
1614 //
1615 // has a serious problem.
1616 //
1617 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1618 // conversion may require access to *__r._M_ptr (virtual inheritance).
1619 //
1620 // It is not possible to avoid spurious access violations since
1621 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1622 template<typename _Yp, typename = _Compatible<_Yp>>
1623 __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1624 : _M_refcount(__r._M_refcount)
1625 { _M_ptr = __r.lock().get(); }
1626
1627 template<typename _Yp, typename = _Compatible<_Yp>>
1628 __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1629 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1630 { }
1631
1632 __weak_ptr(__weak_ptr&& __r) noexcept
1633 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount))
1634 { __r._M_ptr = nullptr; }
1635
1636 template<typename _Yp, typename = _Compatible<_Yp>>
1637 __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1638 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount))
1639 { __r._M_ptr = nullptr; }
1640
1641 __weak_ptr&
1642 operator=(const __weak_ptr& __r) noexcept = default;
1643
1644 template<typename _Yp>
1645 _Assignable<_Yp>
1646 operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1647 {
1648 _M_ptr = __r.lock().get();
1649 _M_refcount = __r._M_refcount;
1650 return *this;
1651 }
1652
1653 template<typename _Yp>
1654 _Assignable<_Yp>
1655 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1656 {
1657 _M_ptr = __r._M_ptr;
1658 _M_refcount = __r._M_refcount;
1659 return *this;
1660 }
1661
1662 __weak_ptr&
1663 operator=(__weak_ptr&& __r) noexcept
1664 {
1665 _M_ptr = __r._M_ptr;
1666 _M_refcount = std::move(__r._M_refcount);
1667 __r._M_ptr = nullptr;
1668 return *this;
1669 }
1670
1671 template<typename _Yp>
1672 _Assignable<_Yp>
1673 operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1674 {
1675 _M_ptr = __r.lock().get();
1676 _M_refcount = std::move(__r._M_refcount);
1677 __r._M_ptr = nullptr;
1678 return *this;
1679 }
1680
1681 __shared_ptr<_Tp, _Lp>
1682 lock() const noexcept
1683 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
1684
1685 long
1686 use_count() const noexcept
1687 { return _M_refcount._M_get_use_count(); }
1688
1689 bool
1690 expired() const noexcept
1691 { return _M_refcount._M_get_use_count() == 0; }
1692
1693 template<typename _Tp1>
1694 bool
1695 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept
1696 { return _M_refcount._M_less(__rhs._M_refcount); }
1697
1698 template<typename _Tp1>
1699 bool
1700 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept
1701 { return _M_refcount._M_less(__rhs._M_refcount); }
1702
1703 void
1704 reset() noexcept
1705 { __weak_ptr().swap(*this); }
1706
1707 void
1708 swap(__weak_ptr& __s) noexcept
1709 {
1710 std::swap(_M_ptr, __s._M_ptr);
1711 _M_refcount._M_swap(__s._M_refcount);
1712 }
1713
1714 private:
1715 // Used by __enable_shared_from_this.
1716 void
1717 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
1718 {
1719 if (use_count() == 0)
1720 {
1721 _M_ptr = __ptr;
1722 _M_refcount = __refcount;
1723 }
1724 }
1725
1726 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1727 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1728 friend class __enable_shared_from_this<_Tp, _Lp>;
1729 friend class enable_shared_from_this<_Tp>;
1730
1731 element_type* _M_ptr; // Contained pointer.
1732 __weak_count<_Lp> _M_refcount; // Reference counter.
1733 };
1734
1735 // 20.7.2.3.6 weak_ptr specialized algorithms.
1736 template<typename _Tp, _Lock_policy _Lp>
1737 inline void
1738 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
1739 { __a.swap(__b); }
1740
1741 template<typename _Tp, typename _Tp1>
1742 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1743 {
1744 bool
1745 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept
1746 { return __lhs.owner_before(__rhs); }
1747
1748 bool
1749 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept
1750 { return __lhs.owner_before(__rhs); }
1751
1752 bool
1753 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept
1754 { return __lhs.owner_before(__rhs); }
1755 };
1756
1757 template<>
1758 struct _Sp_owner_less<void, void>
1759 {
1760 template<typename _Tp, typename _Up>
1761 auto
1762 operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept
1763 -> decltype(__lhs.owner_before(__rhs))
1764 { return __lhs.owner_before(__rhs); }
1765
1766 using is_transparent = void;
1767 };
1768
1769 template<typename _Tp, _Lock_policy _Lp>
1770 struct owner_less<__shared_ptr<_Tp, _Lp>>
1771 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1772 { };
1773
1774 template<typename _Tp, _Lock_policy _Lp>
1775 struct owner_less<__weak_ptr<_Tp, _Lp>>
1776 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1777 { };
1778
1779
1780 template<typename _Tp, _Lock_policy _Lp>
1781 class __enable_shared_from_this
1782 {
1783 protected:
1784 constexpr __enable_shared_from_this() noexcept { }
1785
1786 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { }
1787
1788 __enable_shared_from_this&
1789 operator=(const __enable_shared_from_this&) noexcept
1790 { return *this; }
1791
1792 ~__enable_shared_from_this() { }
1793
1794 public:
1795 __shared_ptr<_Tp, _Lp>
1796 shared_from_this()
1797 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1798
1799 __shared_ptr<const _Tp, _Lp>
1800 shared_from_this() const
1801 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1802
1803#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1804 __weak_ptr<_Tp, _Lp>
1805 weak_from_this() noexcept
1806 { return this->_M_weak_this; }
1807
1808 __weak_ptr<const _Tp, _Lp>
1809 weak_from_this() const noexcept
1810 { return this->_M_weak_this; }
1811#endif
1812
1813 private:
1814 template<typename _Tp1>
1815 void
1816 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
1817 { _M_weak_this._M_assign(__p, __n); }
1818
1819 friend const __enable_shared_from_this*
1820 __enable_shared_from_this_base(const __shared_count<_Lp>&,
1821 const __enable_shared_from_this* __p)
1822 { return __p; }
1823
1824 template<typename, _Lock_policy>
1825 friend class __shared_ptr;
1826
1827 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1828 };
1829
1830 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
1831 inline __shared_ptr<_Tp, _Lp>
1832 __allocate_shared(const _Alloc& __a, _Args&&... __args)
1833 {
1834 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a,
1835 std::forward<_Args>(__args)...);
1836 }
1837
1838 template<typename _Tp, _Lock_policy _Lp, typename... _Args>
1839 inline __shared_ptr<_Tp, _Lp>
1840 __make_shared(_Args&&... __args)
1841 {
1842 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1843 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1844 std::forward<_Args>(__args)...);
1845 }
1846
1847 /// std::hash specialization for __shared_ptr.
1848 template<typename _Tp, _Lock_policy _Lp>
1849 struct hash<__shared_ptr<_Tp, _Lp>>
1850 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
1851 {
1852 size_t
1853 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
1854 {
1855 return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()(
1856 __s.get());
1857 }
1858 };
1859
1860_GLIBCXX_END_NAMESPACE_VERSION
1861} // namespace
1862
1863#endif // _SHARED_PTR_BASE_H
1864