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_GLIBCXX_BEGIN_NAMESPACE_VERSION
63
64#if _GLIBCXX_USE_DEPRECATED
65 template<typename> class auto_ptr;
66#endif
67
68 /**
69 * @brief Exception possibly thrown by @c shared_ptr.
70 * @ingroup exceptions
71 */
72 class bad_weak_ptr : public std::exception
73 {
74 public:
75 virtual char const* what() const noexcept;
76
77 virtual ~bad_weak_ptr() noexcept;
78 };
79
80 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
81 inline void
82 __throw_bad_weak_ptr()
83 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
84
85 using __gnu_cxx::_Lock_policy;
86 using __gnu_cxx::__default_lock_policy;
87 using __gnu_cxx::_S_single;
88 using __gnu_cxx::_S_mutex;
89 using __gnu_cxx::_S_atomic;
90
91 // Empty helper class except when the template argument is _S_mutex.
92 template<_Lock_policy _Lp>
93 class _Mutex_base
94 {
95 protected:
96 // The atomic policy uses fully-fenced builtins, single doesn't care.
97 enum { _S_need_barriers = 0 };
98 };
99
100 template<>
101 class _Mutex_base<_S_mutex>
102 : public __gnu_cxx::__mutex
103 {
104 protected:
105 // This policy is used when atomic builtins are not available.
106 // The replacement atomic operations might not have the necessary
107 // memory barriers.
108 enum { _S_need_barriers = 1 };
109 };
110
111 template<_Lock_policy _Lp = __default_lock_policy>
112 class _Sp_counted_base
113 : public _Mutex_base<_Lp>
114 {
115 public:
116 _Sp_counted_base() noexcept
117 : _M_use_count(1), _M_weak_count(1) { }
118
119 virtual
120 ~_Sp_counted_base() noexcept
121 { }
122
123 // Called when _M_use_count drops to zero, to release the resources
124 // managed by *this.
125 virtual void
126 _M_dispose() noexcept = 0;
127
128 // Called when _M_weak_count drops to zero.
129 virtual void
130 _M_destroy() noexcept
131 { delete this; }
132
133 virtual void*
134 _M_get_deleter(const std::type_info&) noexcept = 0;
135
136 void
137 _M_add_ref_copy()
138 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
139
140 void
141 _M_add_ref_lock();
142
143 bool
144 _M_add_ref_lock_nothrow();
145
146 void
147 _M_release() noexcept
148 {
149 // Be race-detector-friendly. For more info see bits/c++config.
150 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
151 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
152 {
153 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
154 _M_dispose();
155 // There must be a memory barrier between dispose() and destroy()
156 // to ensure that the effects of dispose() are observed in the
157 // thread that runs destroy().
158 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
159 if (_Mutex_base<_Lp>::_S_need_barriers)
160 {
161 __atomic_thread_fence (__ATOMIC_ACQ_REL);
162 }
163
164 // Be race-detector-friendly. For more info see bits/c++config.
165 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
166 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
167 -1) == 1)
168 {
169 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
170 _M_destroy();
171 }
172 }
173 }
174
175 void
176 _M_weak_add_ref() noexcept
177 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
178
179 void
180 _M_weak_release() noexcept
181 {
182 // Be race-detector-friendly. For more info see bits/c++config.
183 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
184 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
185 {
186 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
187 if (_Mutex_base<_Lp>::_S_need_barriers)
188 {
189 // See _M_release(),
190 // destroy() must observe results of dispose()
191 __atomic_thread_fence (__ATOMIC_ACQ_REL);
192 }
193 _M_destroy();
194 }
195 }
196
197 long
198 _M_get_use_count() const noexcept
199 {
200 // No memory barrier is used here so there is no synchronization
201 // with other threads.
202 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED);
203 }
204
205 private:
206 _Sp_counted_base(_Sp_counted_base const&) = delete;
207 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete;
208
209 _Atomic_word _M_use_count; // #shared
210 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
211 };
212
213 template<>
214 inline void
215 _Sp_counted_base<_S_single>::
216 _M_add_ref_lock()
217 {
218 if (_M_use_count == 0)
219 __throw_bad_weak_ptr();
220 ++_M_use_count;
221 }
222
223 template<>
224 inline void
225 _Sp_counted_base<_S_mutex>::
226 _M_add_ref_lock()
227 {
228 __gnu_cxx::__scoped_lock sentry(*this);
229 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
230 {
231 _M_use_count = 0;
232 __throw_bad_weak_ptr();
233 }
234 }
235
236 template<>
237 inline void
238 _Sp_counted_base<_S_atomic>::
239 _M_add_ref_lock()
240 {
241 // Perform lock-free add-if-not-zero operation.
242 _Atomic_word __count = _M_get_use_count();
243 do
244 {
245 if (__count == 0)
246 __throw_bad_weak_ptr();
247 // Replace the current counter value with the old value + 1, as
248 // long as it's not changed meanwhile.
249 }
250 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
251 true, __ATOMIC_ACQ_REL,
252 __ATOMIC_RELAXED));
253 }
254
255 template<>
256 inline bool
257 _Sp_counted_base<_S_single>::
258 _M_add_ref_lock_nothrow()
259 {
260 if (_M_use_count == 0)
261 return false;
262 ++_M_use_count;
263 return true;
264 }
265
266 template<>
267 inline bool
268 _Sp_counted_base<_S_mutex>::
269 _M_add_ref_lock_nothrow()
270 {
271 __gnu_cxx::__scoped_lock sentry(*this);
272 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
273 {
274 _M_use_count = 0;
275 return false;
276 }
277 return true;
278 }
279
280 template<>
281 inline bool
282 _Sp_counted_base<_S_atomic>::
283 _M_add_ref_lock_nothrow()
284 {
285 // Perform lock-free add-if-not-zero operation.
286 _Atomic_word __count = _M_get_use_count();
287 do
288 {
289 if (__count == 0)
290 return false;
291 // Replace the current counter value with the old value + 1, as
292 // long as it's not changed meanwhile.
293 }
294 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
295 true, __ATOMIC_ACQ_REL,
296 __ATOMIC_RELAXED));
297 return true;
298 }
299
300 template<>
301 inline void
302 _Sp_counted_base<_S_single>::_M_add_ref_copy()
303 { ++_M_use_count; }
304
305 template<>
306 inline void
307 _Sp_counted_base<_S_single>::_M_release() noexcept
308 {
309 if (--_M_use_count == 0)
310 {
311 _M_dispose();
312 if (--_M_weak_count == 0)
313 _M_destroy();
314 }
315 }
316
317 template<>
318 inline void
319 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
320 { ++_M_weak_count; }
321
322 template<>
323 inline void
324 _Sp_counted_base<_S_single>::_M_weak_release() noexcept
325 {
326 if (--_M_weak_count == 0)
327 _M_destroy();
328 }
329
330 template<>
331 inline long
332 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
333 { return _M_use_count; }
334
335
336 // Forward declarations.
337 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
338 class __shared_ptr;
339
340 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
341 class __weak_ptr;
342
343 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
344 class __enable_shared_from_this;
345
346 template<typename _Tp>
347 class shared_ptr;
348
349 template<typename _Tp>
350 class weak_ptr;
351
352 template<typename _Tp>
353 struct owner_less;
354
355 template<typename _Tp>
356 class enable_shared_from_this;
357
358 template<_Lock_policy _Lp = __default_lock_policy>
359 class __weak_count;
360
361 template<_Lock_policy _Lp = __default_lock_policy>
362 class __shared_count;
363
364
365 // Counted ptr with no deleter or allocator support
366 template<typename _Ptr, _Lock_policy _Lp>
367 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
368 {
369 public:
370 explicit
371 _Sp_counted_ptr(_Ptr __p) noexcept
372 : _M_ptr(__p) { }
373
374 virtual void
375 _M_dispose() noexcept
376 { delete _M_ptr; }
377
378 virtual void
379 _M_destroy() noexcept
380 { delete this; }
381
382 virtual void*
383 _M_get_deleter(const std::type_info&) noexcept
384 { return nullptr; }
385
386 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
387 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
388
389 private:
390 _Ptr _M_ptr;
391 };
392
393 template<>
394 inline void
395 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }
396
397 template<>
398 inline void
399 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }
400
401 template<>
402 inline void
403 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }
404
405 template<int _Nm, typename _Tp,
406 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
407 struct _Sp_ebo_helper;
408
409 /// Specialization using EBO.
410 template<int _Nm, typename _Tp>
411 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
412 {
413 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
414 explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { }
415
416 static _Tp&
417 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
418 };
419
420 /// Specialization not using EBO.
421 template<int _Nm, typename _Tp>
422 struct _Sp_ebo_helper<_Nm, _Tp, false>
423 {
424 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
425 explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { }
426
427 static _Tp&
428 _S_get(_Sp_ebo_helper& __eboh)
429 { return __eboh._M_tp; }
430
431 private:
432 _Tp _M_tp;
433 };
434
435 // Support for custom deleter and/or allocator
436 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
437 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
438 {
439 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
440 {
441 typedef _Sp_ebo_helper<0, _Deleter> _Del_base;
442 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base;
443
444 public:
445 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
446 : _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a)
447 { }
448
449 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
450 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }
451
452 _Ptr _M_ptr;
453 };
454
455 public:
456 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>;
457
458 // __d(__p) must not throw.
459 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
460 : _M_impl(__p, std::move(__d), _Alloc()) { }
461
462 // __d(__p) must not throw.
463 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
464 : _M_impl(__p, std::move(__d), __a) { }
465
466 ~_Sp_counted_deleter() noexcept { }
467
468 virtual void
469 _M_dispose() noexcept
470 { _M_impl._M_del()(_M_impl._M_ptr); }
471
472 virtual void
473 _M_destroy() noexcept
474 {
475 __allocator_type __a(_M_impl._M_alloc());
476 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
477 this->~_Sp_counted_deleter();
478 }
479
480 virtual void*
481 _M_get_deleter(const std::type_info& __ti) noexcept
482 {
483#if __cpp_rtti
484 // _GLIBCXX_RESOLVE_LIB_DEFECTS
485 // 2400. shared_ptr's get_deleter() should use addressof()
486 return __ti == typeid(_Deleter)
487 ? std::__addressof(_M_impl._M_del())
488 : nullptr;
489#else
490 return nullptr;
491#endif
492 }
493
494 private:
495 _Impl _M_impl;
496 };
497
498 // helpers for make_shared / allocate_shared
499
500 struct _Sp_make_shared_tag { };
501
502 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
503 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
504 {
505 class _Impl : _Sp_ebo_helper<0, _Alloc>
506 {
507 typedef _Sp_ebo_helper<0, _Alloc> _A_base;
508
509 public:
510 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }
511
512 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }
513
514 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
515 };
516
517 public:
518 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>;
519
520 template<typename... _Args>
521 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
522 : _M_impl(__a)
523 {
524 // _GLIBCXX_RESOLVE_LIB_DEFECTS
525 // 2070. allocate_shared should use allocator_traits<A>::construct
526 allocator_traits<_Alloc>::construct(__a, _M_ptr(),
527 std::forward<_Args>(__args)...); // might throw
528 }
529
530 ~_Sp_counted_ptr_inplace() noexcept { }
531
532 virtual void
533 _M_dispose() noexcept
534 {
535 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
536 }
537
538 // Override because the allocator needs to know the dynamic type
539 virtual void
540 _M_destroy() noexcept
541 {
542 __allocator_type __a(_M_impl._M_alloc());
543 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
544 this->~_Sp_counted_ptr_inplace();
545 }
546
547 // Sneaky trick so __shared_ptr can get the managed pointer
548 virtual void*
549 _M_get_deleter(const std::type_info& __ti) noexcept
550 {
551#if __cpp_rtti
552 if (__ti == typeid(_Sp_make_shared_tag))
553 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
554#endif
555 return nullptr;
556 }
557
558 private:
559 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }
560
561 _Impl _M_impl;
562 };
563
564 // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>.
565 struct __sp_array_delete
566 {
567 template<typename _Yp>
568 void operator()(_Yp* __p) const { delete[] __p; }
569 };
570
571 template<_Lock_policy _Lp>
572 class __shared_count
573 {
574 public:
575 constexpr __shared_count() noexcept : _M_pi(0)
576 { }
577
578 template<typename _Ptr>
579 explicit
580 __shared_count(_Ptr __p) : _M_pi(0)
581 {
582 __try
583 {
584 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
585 }
586 __catch(...)
587 {
588 delete __p;
589 __throw_exception_again;
590 }
591 }
592
593 template<typename _Ptr>
594 __shared_count(_Ptr __p, /* is_array = */ false_type)
595 : __shared_count(__p)
596 { }
597
598 template<typename _Ptr>
599 __shared_count(_Ptr __p, /* is_array = */ true_type)
600 : __shared_count(__p, __sp_array_delete{}, allocator<void>())
601 { }
602
603 template<typename _Ptr, typename _Deleter>
604 __shared_count(_Ptr __p, _Deleter __d)
605 : __shared_count(__p, std::move(__d), allocator<void>())
606 { }
607
608 template<typename _Ptr, typename _Deleter, typename _Alloc>
609 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
610 {
611 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
612 __try
613 {
614 typename _Sp_cd_type::__allocator_type __a2(__a);
615 auto __guard = std::__allocate_guarded(__a2);
616 _Sp_cd_type* __mem = __guard.get();
617 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a));
618 _M_pi = __mem;
619 __guard = nullptr;
620 }
621 __catch(...)
622 {
623 __d(__p); // Call _Deleter on __p.
624 __throw_exception_again;
625 }
626 }
627
628 template<typename _Tp, typename _Alloc, typename... _Args>
629 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a,
630 _Args&&... __args)
631 : _M_pi(0)
632 {
633 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
634 typename _Sp_cp_type::__allocator_type __a2(__a);
635 auto __guard = std::__allocate_guarded(__a2);
636 _Sp_cp_type* __mem = __guard.get();
637 ::new (__mem) _Sp_cp_type(std::move(__a),
638 std::forward<_Args>(__args)...);
639 _M_pi = __mem;
640 __guard = nullptr;
641 }
642
643#if _GLIBCXX_USE_DEPRECATED
644 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
645 template<typename _Tp>
646 explicit
647 __shared_count(std::auto_ptr<_Tp>&& __r);
648#endif
649
650 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
651 template<typename _Tp, typename _Del>
652 explicit
653 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
654 {
655 // _GLIBCXX_RESOLVE_LIB_DEFECTS
656 // 2415. Inconsistency between unique_ptr and shared_ptr
657 if (__r.get() == nullptr)
658 return;
659
660 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
661 using _Del2 = typename conditional<is_reference<_Del>::value,
662 reference_wrapper<typename remove_reference<_Del>::type>,
663 _Del>::type;
664 using _Sp_cd_type
665 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
666 using _Alloc = allocator<_Sp_cd_type>;
667 using _Alloc_traits = allocator_traits<_Alloc>;
668 _Alloc __a;
669 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
670 _Alloc_traits::construct(__a, __mem, __r.release(),
671 __r.get_deleter()); // non-throwing
672 _M_pi = __mem;
673 }
674
675 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
676 explicit __shared_count(const __weak_count<_Lp>& __r);
677
678 // Does not throw if __r._M_get_use_count() == 0, caller must check.
679 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
680
681 ~__shared_count() noexcept
682 {
683 if (_M_pi != nullptr)
684 _M_pi->_M_release();
685 }
686
687 __shared_count(const __shared_count& __r) noexcept
688 : _M_pi(__r._M_pi)
689 {
690 if (_M_pi != 0)
691 _M_pi->_M_add_ref_copy();
692 }
693
694 __shared_count&
695 operator=(const __shared_count& __r) noexcept
696 {
697 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
698 if (__tmp != _M_pi)
699 {
700 if (__tmp != 0)
701 __tmp->_M_add_ref_copy();
702 if (_M_pi != 0)
703 _M_pi->_M_release();
704 _M_pi = __tmp;
705 }
706 return *this;
707 }
708
709 void
710 _M_swap(__shared_count& __r) noexcept
711 {
712 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
713 __r._M_pi = _M_pi;
714 _M_pi = __tmp;
715 }
716
717 long
718 _M_get_use_count() const noexcept
719 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
720
721 bool
722 _M_unique() const noexcept
723 { return this->_M_get_use_count() == 1; }
724
725 void*
726 _M_get_deleter(const std::type_info& __ti) const noexcept
727 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }
728
729 bool
730 _M_less(const __shared_count& __rhs) const noexcept
731 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
732
733 bool
734 _M_less(const __weak_count<_Lp>& __rhs) const noexcept
735 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
736
737 // Friend function injected into enclosing namespace and found by ADL
738 friend inline bool
739 operator==(const __shared_count& __a, const __shared_count& __b) noexcept
740 { return __a._M_pi == __b._M_pi; }
741
742 private:
743 friend class __weak_count<_Lp>;
744
745 _Sp_counted_base<_Lp>* _M_pi;
746 };
747
748
749 template<_Lock_policy _Lp>
750 class __weak_count
751 {
752 public:
753 constexpr __weak_count() noexcept : _M_pi(nullptr)
754 { }
755
756 __weak_count(const __shared_count<_Lp>& __r) noexcept
757 : _M_pi(__r._M_pi)
758 {
759 if (_M_pi != nullptr)
760 _M_pi->_M_weak_add_ref();
761 }
762
763 __weak_count(const __weak_count& __r) noexcept
764 : _M_pi(__r._M_pi)
765 {
766 if (_M_pi != nullptr)
767 _M_pi->_M_weak_add_ref();
768 }
769
770 __weak_count(__weak_count&& __r) noexcept
771 : _M_pi(__r._M_pi)
772 { __r._M_pi = nullptr; }
773
774 ~__weak_count() noexcept
775 {
776 if (_M_pi != nullptr)
777 _M_pi->_M_weak_release();
778 }
779
780 __weak_count&
781 operator=(const __shared_count<_Lp>& __r) noexcept
782 {
783 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
784 if (__tmp != nullptr)
785 __tmp->_M_weak_add_ref();
786 if (_M_pi != nullptr)
787 _M_pi->_M_weak_release();
788 _M_pi = __tmp;
789 return *this;
790 }
791
792 __weak_count&
793 operator=(const __weak_count& __r) noexcept
794 {
795 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
796 if (__tmp != nullptr)
797 __tmp->_M_weak_add_ref();
798 if (_M_pi != nullptr)
799 _M_pi->_M_weak_release();
800 _M_pi = __tmp;
801 return *this;
802 }
803
804 __weak_count&
805 operator=(__weak_count&& __r) noexcept
806 {
807 if (_M_pi != nullptr)
808 _M_pi->_M_weak_release();
809 _M_pi = __r._M_pi;
810 __r._M_pi = nullptr;
811 return *this;
812 }
813
814 void
815 _M_swap(__weak_count& __r) noexcept
816 {
817 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
818 __r._M_pi = _M_pi;
819 _M_pi = __tmp;
820 }
821
822 long
823 _M_get_use_count() const noexcept
824 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; }
825
826 bool
827 _M_less(const __weak_count& __rhs) const noexcept
828 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
829
830 bool
831 _M_less(const __shared_count<_Lp>& __rhs) const noexcept
832 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
833
834 // Friend function injected into enclosing namespace and found by ADL
835 friend inline bool
836 operator==(const __weak_count& __a, const __weak_count& __b) noexcept
837 { return __a._M_pi == __b._M_pi; }
838
839 private:
840 friend class __shared_count<_Lp>;
841
842 _Sp_counted_base<_Lp>* _M_pi;
843 };
844
845 // Now that __weak_count is defined we can define this constructor:
846 template<_Lock_policy _Lp>
847 inline
848 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
849 : _M_pi(__r._M_pi)
850 {
851 if (_M_pi != nullptr)
852 _M_pi->_M_add_ref_lock();
853 else
854 __throw_bad_weak_ptr();
855 }
856
857 // Now that __weak_count is defined we can define this constructor:
858 template<_Lock_policy _Lp>
859 inline
860 __shared_count<_Lp>::
861 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
862 : _M_pi(__r._M_pi)
863 {
864 if (_M_pi != nullptr)
865 if (!_M_pi->_M_add_ref_lock_nothrow())
866 _M_pi = nullptr;
867 }
868
869#define __cpp_lib_shared_ptr_arrays 201603
870
871 // Helper traits for shared_ptr of array:
872
873 // A pointer type Y* is said to be compatible with a pointer type T* when
874 // either Y* is convertible to T* or Y is U[N] and T is U cv [].
875 template<typename _Yp_ptr, typename _Tp_ptr>
876 struct __sp_compatible_with
877 : false_type
878 { };
879
880 template<typename _Yp, typename _Tp>
881 struct __sp_compatible_with<_Yp*, _Tp*>
882 : is_convertible<_Yp*, _Tp*>::type
883 { };
884
885 template<typename _Up, size_t _Nm>
886 struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]>
887 : true_type
888 { };
889
890 template<typename _Up, size_t _Nm>
891 struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]>
892 : true_type
893 { };
894
895 template<typename _Up, size_t _Nm>
896 struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]>
897 : true_type
898 { };
899
900 template<typename _Up, size_t _Nm>
901 struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]>
902 : true_type
903 { };
904
905 // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N].
906 template<typename _Up, size_t _Nm, typename _Yp, typename = void>
907 struct __sp_is_constructible_arrN
908 : false_type
909 { };
910
911 template<typename _Up, size_t _Nm, typename _Yp>
912 struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>>
913 : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type
914 { };
915
916 // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[].
917 template<typename _Up, typename _Yp, typename = void>
918 struct __sp_is_constructible_arr
919 : false_type
920 { };
921
922 template<typename _Up, typename _Yp>
923 struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>>
924 : is_convertible<_Yp(*)[], _Up(*)[]>::type
925 { };
926
927 // Trait to check if shared_ptr<T> can be constructed from Y*.
928 template<typename _Tp, typename _Yp>
929 struct __sp_is_constructible;
930
931 // When T is U[N], Y(*)[N] shall be convertible to T*;
932 template<typename _Up, size_t _Nm, typename _Yp>
933 struct __sp_is_constructible<_Up[_Nm], _Yp>
934 : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type
935 { };
936
937 // when T is U[], Y(*)[] shall be convertible to T*;
938 template<typename _Up, typename _Yp>
939 struct __sp_is_constructible<_Up[], _Yp>
940 : __sp_is_constructible_arr<_Up, _Yp>::type
941 { };
942
943 // otherwise, Y* shall be convertible to T*.
944 template<typename _Tp, typename _Yp>
945 struct __sp_is_constructible
946 : is_convertible<_Yp*, _Tp*>::type
947 { };
948
949
950 // Define operator* and operator-> for shared_ptr<T>.
951 template<typename _Tp, _Lock_policy _Lp,
952 bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>
953 class __shared_ptr_access
954 {
955 public:
956 using element_type = _Tp;
957
958 element_type&
959 operator*() const noexcept
960 {
961 __glibcxx_assert(_M_get() != nullptr);
962 return *_M_get();
963 }
964
965 element_type*
966 operator->() const noexcept
967 {
968 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
969 return _M_get();
970 }
971
972 private:
973 element_type*
974 _M_get() const noexcept
975 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
976 };
977
978 // Define operator-> for shared_ptr<cv void>.
979 template<typename _Tp, _Lock_policy _Lp>
980 class __shared_ptr_access<_Tp, _Lp, false, true>
981 {
982 public:
983 using element_type = _Tp;
984
985 element_type*
986 operator->() const noexcept
987 {
988 auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get();
989 _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr);
990 return __ptr;
991 }
992 };
993
994 // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>.
995 template<typename _Tp, _Lock_policy _Lp>
996 class __shared_ptr_access<_Tp, _Lp, true, false>
997 {
998 public:
999 using element_type = typename remove_extent<_Tp>::type;
1000
1001#if __cplusplus <= 201402L
1002 [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]]
1003 element_type&
1004 operator*() const noexcept
1005 {
1006 __glibcxx_assert(_M_get() != nullptr);
1007 return *_M_get();
1008 }
1009
1010 [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]]
1011 element_type*
1012 operator->() const noexcept
1013 {
1014 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
1015 return _M_get();
1016 }
1017#endif
1018
1019 element_type&
1020 operator[](ptrdiff_t __i) const
1021 {
1022 __glibcxx_assert(_M_get() != nullptr);
1023 __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value);
1024 return _M_get()[__i];
1025 }
1026
1027 private:
1028 element_type*
1029 _M_get() const noexcept
1030 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
1031 };
1032
1033 template<typename _Tp, _Lock_policy _Lp>
1034 class __shared_ptr
1035 : public __shared_ptr_access<_Tp, _Lp>
1036 {
1037 public:
1038 using element_type = typename remove_extent<_Tp>::type;
1039
1040 private:
1041 // Constraint for taking ownership of a pointer of type _Yp*:
1042 template<typename _Yp>
1043 using _SafeConv
1044 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;
1045
1046 // Constraint for construction from shared_ptr and weak_ptr:
1047 template<typename _Yp, typename _Res = void>
1048 using _Compatible = typename
1049 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1050
1051 // Constraint for assignment from shared_ptr and weak_ptr:
1052 template<typename _Yp>
1053 using _Assignable = _Compatible<_Yp, __shared_ptr&>;
1054
1055 // Constraint for construction from unique_ptr:
1056 template<typename _Yp, typename _Del, typename _Res = void,
1057 typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>
1058 using _UniqCompatible = typename enable_if<__and_<
1059 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>
1060 >::value, _Res>::type;
1061
1062 // Constraint for assignment from unique_ptr:
1063 template<typename _Yp, typename _Del>
1064 using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;
1065
1066 public:
1067
1068#if __cplusplus > 201402L
1069 using weak_type = __weak_ptr<_Tp, _Lp>;
1070#endif
1071
1072 constexpr __shared_ptr() noexcept
1073 : _M_ptr(0), _M_refcount()
1074 { }
1075
1076 template<typename _Yp, typename = _SafeConv<_Yp>>
1077 explicit
1078 __shared_ptr(_Yp* __p)
1079 : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type())
1080 {
1081 static_assert( !is_void<_Yp>::value, "incomplete type" );
1082 static_assert( sizeof(_Yp) > 0, "incomplete type" );
1083 _M_enable_shared_from_this_with(__p);
1084 }
1085
1086 template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>
1087 __shared_ptr(_Yp* __p, _Deleter __d)
1088 : _M_ptr(__p), _M_refcount(__p, std::move(__d))
1089 {
1090 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1091 "deleter expression d(p) is well-formed");
1092 _M_enable_shared_from_this_with(__p);
1093 }
1094
1095 template<typename _Yp, typename _Deleter, typename _Alloc,
1096 typename = _SafeConv<_Yp>>
1097 __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
1098 : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a))
1099 {
1100 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
1101 "deleter expression d(p) is well-formed");
1102 _M_enable_shared_from_this_with(__p);
1103 }
1104
1105 template<typename _Deleter>
1106 __shared_ptr(nullptr_t __p, _Deleter __d)
1107 : _M_ptr(0), _M_refcount(__p, std::move(__d))
1108 { }
1109
1110 template<typename _Deleter, typename _Alloc>
1111 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
1112 : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a))
1113 { }
1114
1115 template<typename _Yp>
1116 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,
1117 element_type* __p) noexcept
1118 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
1119 { }
1120
1121 __shared_ptr(const __shared_ptr&) noexcept = default;
1122 __shared_ptr& operator=(const __shared_ptr&) noexcept = default;
1123 ~__shared_ptr() = default;
1124
1125 template<typename _Yp, typename = _Compatible<_Yp>>
1126 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1127 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1128 { }
1129
1130 __shared_ptr(__shared_ptr&& __r) noexcept
1131 : _M_ptr(__r._M_ptr), _M_refcount()
1132 {
1133 _M_refcount._M_swap(__r._M_refcount);
1134 __r._M_ptr = 0;
1135 }
1136
1137 template<typename _Yp, typename = _Compatible<_Yp>>
1138 __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1139 : _M_ptr(__r._M_ptr), _M_refcount()
1140 {
1141 _M_refcount._M_swap(__r._M_refcount);
1142 __r._M_ptr = 0;
1143 }
1144
1145 template<typename _Yp, typename = _Compatible<_Yp>>
1146 explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r)
1147 : _M_refcount(__r._M_refcount) // may throw
1148 {
1149 // It is now safe to copy __r._M_ptr, as
1150 // _M_refcount(__r._M_refcount) did not throw.
1151 _M_ptr = __r._M_ptr;
1152 }
1153
1154 // If an exception is thrown this constructor has no effect.
1155 template<typename _Yp, typename _Del,
1156 typename = _UniqCompatible<_Yp, _Del>>
1157 __shared_ptr(unique_ptr<_Yp, _Del>&& __r)
1158 : _M_ptr(__r.get()), _M_refcount()
1159 {
1160 auto __raw = _S_raw_ptr(__r.get());
1161 _M_refcount = __shared_count<_Lp>(std::move(__r));
1162 _M_enable_shared_from_this_with(__raw);
1163 }
1164
1165#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
1166 protected:
1167 // If an exception is thrown this constructor has no effect.
1168 template<typename _Tp1, typename _Del,
1169 typename enable_if<__and_<
1170 __not_<is_array<_Tp>>, is_array<_Tp1>,
1171 is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>
1172 >::value, bool>::type = true>
1173 __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
1174 : _M_ptr(__r.get()), _M_refcount()
1175 {
1176 auto __raw = _S_raw_ptr(__r.get());
1177 _M_refcount = __shared_count<_Lp>(std::move(__r));
1178 _M_enable_shared_from_this_with(__raw);
1179 }
1180 public:
1181#endif
1182
1183#if _GLIBCXX_USE_DEPRECATED
1184 // Postcondition: use_count() == 1 and __r.get() == 0
1185 template<typename _Yp, typename = _Compatible<_Yp>>
1186 __shared_ptr(auto_ptr<_Yp>&& __r);
1187#endif
1188
1189 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }
1190
1191 template<typename _Yp>
1192 _Assignable<_Yp>
1193 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1194 {
1195 _M_ptr = __r._M_ptr;
1196 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
1197 return *this;
1198 }
1199
1200#if _GLIBCXX_USE_DEPRECATED
1201 template<typename _Yp>
1202 _Assignable<_Yp>
1203 operator=(auto_ptr<_Yp>&& __r)
1204 {
1205 __shared_ptr(std::move(__r)).swap(*this);
1206 return *this;
1207 }
1208#endif
1209
1210 __shared_ptr&
1211 operator=(__shared_ptr&& __r) noexcept
1212 {
1213 __shared_ptr(std::move(__r)).swap(*this);
1214 return *this;
1215 }
1216
1217 template<class _Yp>
1218 _Assignable<_Yp>
1219 operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept
1220 {
1221 __shared_ptr(std::move(__r)).swap(*this);
1222 return *this;
1223 }
1224
1225 template<typename _Yp, typename _Del>
1226 _UniqAssignable<_Yp, _Del>
1227 operator=(unique_ptr<_Yp, _Del>&& __r)
1228 {
1229 __shared_ptr(std::move(__r)).swap(*this);
1230 return *this;
1231 }
1232
1233 void
1234 reset() noexcept
1235 { __shared_ptr().swap(*this); }
1236
1237 template<typename _Yp>
1238 _SafeConv<_Yp>
1239 reset(_Yp* __p) // _Yp must be complete.
1240 {
1241 // Catch self-reset errors.
1242 __glibcxx_assert(__p == 0 || __p != _M_ptr);
1243 __shared_ptr(__p).swap(*this);
1244 }
1245
1246 template<typename _Yp, typename _Deleter>
1247 _SafeConv<_Yp>
1248 reset(_Yp* __p, _Deleter __d)
1249 { __shared_ptr(__p, std::move(__d)).swap(*this); }
1250
1251 template<typename _Yp, typename _Deleter, typename _Alloc>
1252 _SafeConv<_Yp>
1253 reset(_Yp* __p, _Deleter __d, _Alloc __a)
1254 { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }
1255
1256 element_type*
1257 get() const noexcept
1258 { return _M_ptr; }
1259
1260 explicit operator bool() const // never throws
1261 { return _M_ptr == 0 ? false : true; }
1262
1263 bool
1264 unique() const noexcept
1265 { return _M_refcount._M_unique(); }
1266
1267 long
1268 use_count() const noexcept
1269 { return _M_refcount._M_get_use_count(); }
1270
1271 void
1272 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
1273 {
1274 std::swap(_M_ptr, __other._M_ptr);
1275 _M_refcount._M_swap(__other._M_refcount);
1276 }
1277
1278 template<typename _Tp1>
1279 bool
1280 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1281 { return _M_refcount._M_less(__rhs._M_refcount); }
1282
1283 template<typename _Tp1>
1284 bool
1285 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept
1286 { return _M_refcount._M_less(__rhs._M_refcount); }
1287
1288#if __cpp_rtti
1289 protected:
1290 // This constructor is non-standard, it is used by allocate_shared.
1291 template<typename _Alloc, typename... _Args>
1292 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1293 _Args&&... __args)
1294 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
1295 std::forward<_Args>(__args)...)
1296 {
1297 // _M_ptr needs to point to the newly constructed object.
1298 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
1299 void* __p = _M_refcount._M_get_deleter(typeid(__tag));
1300 _M_ptr = static_cast<_Tp*>(__p);
1301 _M_enable_shared_from_this_with(_M_ptr);
1302 }
1303#else
1304 template<typename _Alloc>
1305 struct _Deleter
1306 {
1307 void operator()(typename _Alloc::value_type* __ptr)
1308 {
1309 __allocated_ptr<_Alloc> __guard{ _M_alloc, __ptr };
1310 allocator_traits<_Alloc>::destroy(_M_alloc, __guard.get());
1311 }
1312 _Alloc _M_alloc;
1313 };
1314
1315 template<typename _Alloc, typename... _Args>
1316 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1317 _Args&&... __args)
1318 : _M_ptr(), _M_refcount()
1319 {
1320 typedef typename allocator_traits<_Alloc>::template
1321 rebind_traits<typename std::remove_cv<_Tp>::type> __traits;
1322 _Deleter<typename __traits::allocator_type> __del = { __a };
1323 auto __guard = std::__allocate_guarded(__del._M_alloc);
1324 auto __ptr = __guard.get();
1325 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1326 // 2070. allocate_shared should use allocator_traits<A>::construct
1327 __traits::construct(__del._M_alloc, __ptr,
1328 std::forward<_Args>(__args)...);
1329 __guard = nullptr;
1330 __shared_count<_Lp> __count(__ptr, __del, __del._M_alloc);
1331 _M_refcount._M_swap(__count);
1332 _M_ptr = __ptr;
1333 _M_enable_shared_from_this_with(_M_ptr);
1334 }
1335#endif
1336
1337 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
1338 typename... _Args>
1339 friend __shared_ptr<_Tp1, _Lp1>
1340 __allocate_shared(const _Alloc& __a, _Args&&... __args);
1341
1342 // This constructor is used by __weak_ptr::lock() and
1343 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
1344 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
1345 : _M_refcount(__r._M_refcount, std::nothrow)
1346 {
1347 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
1348 }
1349
1350 friend class __weak_ptr<_Tp, _Lp>;
1351
1352 private:
1353
1354 template<typename _Yp>
1355 using __esft_base_t = decltype(__enable_shared_from_this_base(
1356 std::declval<const __shared_count<_Lp>&>(),
1357 std::declval<_Yp*>()));
1358
1359 // Detect an accessible and unambiguous enable_shared_from_this base.
1360 template<typename _Yp, typename = void>
1361 struct __has_esft_base
1362 : false_type { };
1363
1364 template<typename _Yp>
1365 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
1366 : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays
1367
1368 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1369 typename enable_if<__has_esft_base<_Yp2>::value>::type
1370 _M_enable_shared_from_this_with(_Yp* __p) noexcept
1371 {
1372 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))
1373 __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);
1374 }
1375
1376 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
1377 typename enable_if<!__has_esft_base<_Yp2>::value>::type
1378 _M_enable_shared_from_this_with(_Yp*) noexcept
1379 { }
1380
1381 void*
1382 _M_get_deleter(const std::type_info& __ti) const noexcept
1383 { return _M_refcount._M_get_deleter(__ti); }
1384
1385 template<typename _Tp1>
1386 static _Tp1*
1387 _S_raw_ptr(_Tp1* __ptr)
1388 { return __ptr; }
1389
1390 template<typename _Tp1>
1391 static auto
1392 _S_raw_ptr(_Tp1 __ptr) -> decltype(std::__addressof(*__ptr))
1393 { return std::__addressof(*__ptr); }
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 element_type* _M_ptr; // Contained pointer.
1402 __shared_count<_Lp> _M_refcount; // Reference counter.
1403 };
1404
1405
1406 // 20.7.2.2.7 shared_ptr comparisons
1407 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1408 inline bool
1409 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
1410 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1411 { return __a.get() == __b.get(); }
1412
1413 template<typename _Tp, _Lock_policy _Lp>
1414 inline bool
1415 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1416 { return !__a; }
1417
1418 template<typename _Tp, _Lock_policy _Lp>
1419 inline bool
1420 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1421 { return !__a; }
1422
1423 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1424 inline bool
1425 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
1426 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1427 { return __a.get() != __b.get(); }
1428
1429 template<typename _Tp, _Lock_policy _Lp>
1430 inline bool
1431 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1432 { return (bool)__a; }
1433
1434 template<typename _Tp, _Lock_policy _Lp>
1435 inline bool
1436 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1437 { return (bool)__a; }
1438
1439 template<typename _Tp, typename _Up, _Lock_policy _Lp>
1440 inline bool
1441 operator<(const __shared_ptr<_Tp, _Lp>& __a,
1442 const __shared_ptr<_Up, _Lp>& __b) noexcept
1443 {
1444 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1445 using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type;
1446 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
1447 return less<_Vp>()(__a.get(), __b.get());
1448 }
1449
1450 template<typename _Tp, _Lock_policy _Lp>
1451 inline bool
1452 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1453 {
1454 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1455 return less<_Tp_elt*>()(__a.get(), nullptr);
1456 }
1457
1458 template<typename _Tp, _Lock_policy _Lp>
1459 inline bool
1460 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1461 {
1462 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
1463 return less<_Tp_elt*>()(nullptr, __a.get());
1464 }
1465
1466 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1467 inline bool
1468 operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
1469 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1470 { return !(__b < __a); }
1471
1472 template<typename _Tp, _Lock_policy _Lp>
1473 inline bool
1474 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1475 { return !(nullptr < __a); }
1476
1477 template<typename _Tp, _Lock_policy _Lp>
1478 inline bool
1479 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1480 { return !(__a < nullptr); }
1481
1482 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1483 inline bool
1484 operator>(const __shared_ptr<_Tp1, _Lp>& __a,
1485 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1486 { return (__b < __a); }
1487
1488 template<typename _Tp, _Lock_policy _Lp>
1489 inline bool
1490 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1491 { return nullptr < __a; }
1492
1493 template<typename _Tp, _Lock_policy _Lp>
1494 inline bool
1495 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1496 { return __a < nullptr; }
1497
1498 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1499 inline bool
1500 operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
1501 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1502 { return !(__a < __b); }
1503
1504 template<typename _Tp, _Lock_policy _Lp>
1505 inline bool
1506 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1507 { return !(__a < nullptr); }
1508
1509 template<typename _Tp, _Lock_policy _Lp>
1510 inline bool
1511 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1512 { return !(nullptr < __a); }
1513
1514 template<typename _Sp>
1515 struct _Sp_less : public binary_function<_Sp, _Sp, bool>
1516 {
1517 bool
1518 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept
1519 {
1520 typedef typename _Sp::element_type element_type;
1521 return std::less<element_type*>()(__lhs.get(), __rhs.get());
1522 }
1523 };
1524
1525 template<typename _Tp, _Lock_policy _Lp>
1526 struct less<__shared_ptr<_Tp, _Lp>>
1527 : public _Sp_less<__shared_ptr<_Tp, _Lp>>
1528 { };
1529
1530 // 20.7.2.2.8 shared_ptr specialized algorithms.
1531 template<typename _Tp, _Lock_policy _Lp>
1532 inline void
1533 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
1534 { __a.swap(__b); }
1535
1536 // 20.7.2.2.9 shared_ptr casts
1537
1538 // The seemingly equivalent code:
1539 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
1540 // will eventually result in undefined behaviour, attempting to
1541 // delete the same object twice.
1542 /// static_pointer_cast
1543 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1544 inline __shared_ptr<_Tp, _Lp>
1545 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1546 {
1547 using _Sp = __shared_ptr<_Tp, _Lp>;
1548 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
1549 }
1550
1551 // The seemingly equivalent code:
1552 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
1553 // will eventually result in undefined behaviour, attempting to
1554 // delete the same object twice.
1555 /// const_pointer_cast
1556 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1557 inline __shared_ptr<_Tp, _Lp>
1558 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1559 {
1560 using _Sp = __shared_ptr<_Tp, _Lp>;
1561 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
1562 }
1563
1564 // The seemingly equivalent code:
1565 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
1566 // will eventually result in undefined behaviour, attempting to
1567 // delete the same object twice.
1568 /// dynamic_pointer_cast
1569 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1570 inline __shared_ptr<_Tp, _Lp>
1571 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1572 {
1573 using _Sp = __shared_ptr<_Tp, _Lp>;
1574 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
1575 return _Sp(__r, __p);
1576 return _Sp();
1577 }
1578
1579#if __cplusplus > 201402L
1580 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1581 inline __shared_ptr<_Tp, _Lp>
1582 reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1583 {
1584 using _Sp = __shared_ptr<_Tp, _Lp>;
1585 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
1586 }
1587#endif
1588
1589 template<typename _Tp, _Lock_policy _Lp>
1590 class __weak_ptr
1591 {
1592 template<typename _Yp, typename _Res = void>
1593 using _Compatible = typename
1594 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
1595
1596 // Constraint for assignment from shared_ptr and weak_ptr:
1597 template<typename _Yp>
1598 using _Assignable = _Compatible<_Yp, __weak_ptr&>;
1599
1600 public:
1601 using element_type = typename remove_extent<_Tp>::type;
1602
1603 constexpr __weak_ptr() noexcept
1604 : _M_ptr(nullptr), _M_refcount()
1605 { }
1606
1607 __weak_ptr(const __weak_ptr&) noexcept = default;
1608
1609 ~__weak_ptr() = default;
1610
1611 // The "obvious" converting constructor implementation:
1612 //
1613 // template<typename _Tp1>
1614 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1615 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1616 // { }
1617 //
1618 // has a serious problem.
1619 //
1620 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1621 // conversion may require access to *__r._M_ptr (virtual inheritance).
1622 //
1623 // It is not possible to avoid spurious access violations since
1624 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1625 template<typename _Yp, typename = _Compatible<_Yp>>
1626 __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1627 : _M_refcount(__r._M_refcount)
1628 { _M_ptr = __r.lock().get(); }
1629
1630 template<typename _Yp, typename = _Compatible<_Yp>>
1631 __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1632 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1633 { }
1634
1635 __weak_ptr(__weak_ptr&& __r) noexcept
1636 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount))
1637 { __r._M_ptr = nullptr; }
1638
1639 template<typename _Yp, typename = _Compatible<_Yp>>
1640 __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1641 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount))
1642 { __r._M_ptr = nullptr; }
1643
1644 __weak_ptr&
1645 operator=(const __weak_ptr& __r) noexcept = default;
1646
1647 template<typename _Yp>
1648 _Assignable<_Yp>
1649 operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept
1650 {
1651 _M_ptr = __r.lock().get();
1652 _M_refcount = __r._M_refcount;
1653 return *this;
1654 }
1655
1656 template<typename _Yp>
1657 _Assignable<_Yp>
1658 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
1659 {
1660 _M_ptr = __r._M_ptr;
1661 _M_refcount = __r._M_refcount;
1662 return *this;
1663 }
1664
1665 __weak_ptr&
1666 operator=(__weak_ptr&& __r) noexcept
1667 {
1668 _M_ptr = __r._M_ptr;
1669 _M_refcount = std::move(__r._M_refcount);
1670 __r._M_ptr = nullptr;
1671 return *this;
1672 }
1673
1674 template<typename _Yp>
1675 _Assignable<_Yp>
1676 operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept
1677 {
1678 _M_ptr = __r.lock().get();
1679 _M_refcount = std::move(__r._M_refcount);
1680 __r._M_ptr = nullptr;
1681 return *this;
1682 }
1683
1684 __shared_ptr<_Tp, _Lp>
1685 lock() const noexcept
1686 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
1687
1688 long
1689 use_count() const noexcept
1690 { return _M_refcount._M_get_use_count(); }
1691
1692 bool
1693 expired() const noexcept
1694 { return _M_refcount._M_get_use_count() == 0; }
1695
1696 template<typename _Tp1>
1697 bool
1698 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept
1699 { return _M_refcount._M_less(__rhs._M_refcount); }
1700
1701 template<typename _Tp1>
1702 bool
1703 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept
1704 { return _M_refcount._M_less(__rhs._M_refcount); }
1705
1706 void
1707 reset() noexcept
1708 { __weak_ptr().swap(*this); }
1709
1710 void
1711 swap(__weak_ptr& __s) noexcept
1712 {
1713 std::swap(_M_ptr, __s._M_ptr);
1714 _M_refcount._M_swap(__s._M_refcount);
1715 }
1716
1717 private:
1718 // Used by __enable_shared_from_this.
1719 void
1720 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
1721 {
1722 if (use_count() == 0)
1723 {
1724 _M_ptr = __ptr;
1725 _M_refcount = __refcount;
1726 }
1727 }
1728
1729 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1730 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1731 friend class __enable_shared_from_this<_Tp, _Lp>;
1732 friend class enable_shared_from_this<_Tp>;
1733
1734 element_type* _M_ptr; // Contained pointer.
1735 __weak_count<_Lp> _M_refcount; // Reference counter.
1736 };
1737
1738 // 20.7.2.3.6 weak_ptr specialized algorithms.
1739 template<typename _Tp, _Lock_policy _Lp>
1740 inline void
1741 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
1742 { __a.swap(__b); }
1743
1744 template<typename _Tp, typename _Tp1>
1745 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1746 {
1747 bool
1748 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept
1749 { return __lhs.owner_before(__rhs); }
1750
1751 bool
1752 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept
1753 { return __lhs.owner_before(__rhs); }
1754
1755 bool
1756 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept
1757 { return __lhs.owner_before(__rhs); }
1758 };
1759
1760 template<>
1761 struct _Sp_owner_less<void, void>
1762 {
1763 template<typename _Tp, typename _Up>
1764 auto
1765 operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept
1766 -> decltype(__lhs.owner_before(__rhs))
1767 { return __lhs.owner_before(__rhs); }
1768
1769 using is_transparent = void;
1770 };
1771
1772 template<typename _Tp, _Lock_policy _Lp>
1773 struct owner_less<__shared_ptr<_Tp, _Lp>>
1774 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1775 { };
1776
1777 template<typename _Tp, _Lock_policy _Lp>
1778 struct owner_less<__weak_ptr<_Tp, _Lp>>
1779 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1780 { };
1781
1782
1783 template<typename _Tp, _Lock_policy _Lp>
1784 class __enable_shared_from_this
1785 {
1786 protected:
1787 constexpr __enable_shared_from_this() noexcept { }
1788
1789 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { }
1790
1791 __enable_shared_from_this&
1792 operator=(const __enable_shared_from_this&) noexcept
1793 { return *this; }
1794
1795 ~__enable_shared_from_this() { }
1796
1797 public:
1798 __shared_ptr<_Tp, _Lp>
1799 shared_from_this()
1800 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1801
1802 __shared_ptr<const _Tp, _Lp>
1803 shared_from_this() const
1804 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1805
1806#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
1807 __weak_ptr<_Tp, _Lp>
1808 weak_from_this() noexcept
1809 { return this->_M_weak_this; }
1810
1811 __weak_ptr<const _Tp, _Lp>
1812 weak_from_this() const noexcept
1813 { return this->_M_weak_this; }
1814#endif
1815
1816 private:
1817 template<typename _Tp1>
1818 void
1819 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
1820 { _M_weak_this._M_assign(__p, __n); }
1821
1822 friend const __enable_shared_from_this*
1823 __enable_shared_from_this_base(const __shared_count<_Lp>&,
1824 const __enable_shared_from_this* __p)
1825 { return __p; }
1826
1827 template<typename, _Lock_policy>
1828 friend class __shared_ptr;
1829
1830 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1831 };
1832
1833 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
1834 inline __shared_ptr<_Tp, _Lp>
1835 __allocate_shared(const _Alloc& __a, _Args&&... __args)
1836 {
1837 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a,
1838 std::forward<_Args>(__args)...);
1839 }
1840
1841 template<typename _Tp, _Lock_policy _Lp, typename... _Args>
1842 inline __shared_ptr<_Tp, _Lp>
1843 __make_shared(_Args&&... __args)
1844 {
1845 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1846 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1847 std::forward<_Args>(__args)...);
1848 }
1849
1850 /// std::hash specialization for __shared_ptr.
1851 template<typename _Tp, _Lock_policy _Lp>
1852 struct hash<__shared_ptr<_Tp, _Lp>>
1853 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
1854 {
1855 size_t
1856 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
1857 {
1858 return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()(
1859 __s.get());
1860 }
1861 };
1862
1863_GLIBCXX_END_NAMESPACE_VERSION
1864} // namespace
1865
1866#endif // _SHARED_PTR_BASE_H
1867