1// <tr1/shared_ptr.h> -*- C++ -*-
2
3// Copyright (C) 2007-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25// shared_count.hpp
26// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
27
28// shared_ptr.hpp
29// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
30// Copyright (C) 2001, 2002, 2003 Peter Dimov
31
32// weak_ptr.hpp
33// Copyright (C) 2001, 2002, 2003 Peter Dimov
34
35// enable_shared_from_this.hpp
36// Copyright (C) 2002 Peter Dimov
37
38// Distributed under the Boost Software License, Version 1.0. (See
39// accompanying file LICENSE_1_0.txt or copy at
40// http://www.boost.org/LICENSE_1_0.txt)
41
42// GCC Note: based on version 1.32.0 of the Boost library.
43
44/** @file tr1/shared_ptr.h
45 * This is an internal header file, included by other library headers.
46 * Do not attempt to use it directly. @headername{tr1/memory}
47 */
48
49#ifndef _TR1_SHARED_PTR_H
50#define _TR1_SHARED_PTR_H 1
51
52namespace std _GLIBCXX_VISIBILITY(default)
53{
54_GLIBCXX_BEGIN_NAMESPACE_VERSION
55
56namespace tr1
57{
58 /**
59 * @brief Exception possibly thrown by @c shared_ptr.
60 * @ingroup exceptions
61 */
62 class bad_weak_ptr : public std::exception
63 {
64 public:
65 virtual char const*
66 what() const throw()
67 { return "tr1::bad_weak_ptr"; }
68 };
69
70 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
71 inline void
72 __throw_bad_weak_ptr()
73 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
74
75 using __gnu_cxx::_Lock_policy;
76 using __gnu_cxx::__default_lock_policy;
77 using __gnu_cxx::_S_single;
78 using __gnu_cxx::_S_mutex;
79 using __gnu_cxx::_S_atomic;
80
81 // Empty helper class except when the template argument is _S_mutex.
82 template<_Lock_policy _Lp>
83 class _Mutex_base
84 {
85 protected:
86 // The atomic policy uses fully-fenced builtins, single doesn't care.
87 enum { _S_need_barriers = 0 };
88 };
89
90 template<>
91 class _Mutex_base<_S_mutex>
92 : public __gnu_cxx::__mutex
93 {
94 protected:
95 // This policy is used when atomic builtins are not available.
96 // The replacement atomic operations might not have the necessary
97 // memory barriers.
98 enum { _S_need_barriers = 1 };
99 };
100
101 template<_Lock_policy _Lp = __default_lock_policy>
102 class _Sp_counted_base
103 : public _Mutex_base<_Lp>
104 {
105 public:
106 _Sp_counted_base()
107 : _M_use_count(1), _M_weak_count(1) { }
108
109 virtual
110 ~_Sp_counted_base() // nothrow
111 { }
112
113 // Called when _M_use_count drops to zero, to release the resources
114 // managed by *this.
115 virtual void
116 _M_dispose() = 0; // nothrow
117
118 // Called when _M_weak_count drops to zero.
119 virtual void
120 _M_destroy() // nothrow
121 { delete this; }
122
123 virtual void*
124 _M_get_deleter(const std::type_info&) = 0;
125
126 void
127 _M_add_ref_copy()
128 { __gnu_cxx::__atomic_add_dispatch(mem: &_M_use_count, val: 1); }
129
130 void
131 _M_add_ref_lock();
132
133 void
134 _M_release() // nothrow
135 {
136 // Be race-detector-friendly. For more info see bits/c++config.
137 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
138 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: -1) == 1)
139 {
140 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
141 _M_dispose();
142 // There must be a memory barrier between dispose() and destroy()
143 // to ensure that the effects of dispose() are observed in the
144 // thread that runs destroy().
145 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
146 if (_Mutex_base<_Lp>::_S_need_barriers)
147 {
148 __atomic_thread_fence (__ATOMIC_ACQ_REL);
149 }
150
151 // Be race-detector-friendly. For more info see bits/c++config.
152 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
153 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_weak_count,
154 val: -1) == 1)
155 {
156 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
157 _M_destroy();
158 }
159 }
160 }
161
162 void
163 _M_weak_add_ref() // nothrow
164 { __gnu_cxx::__atomic_add_dispatch(mem: &_M_weak_count, val: 1); }
165
166 void
167 _M_weak_release() // nothrow
168 {
169 // Be race-detector-friendly. For more info see bits/c++config.
170 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
171 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_weak_count, val: -1) == 1)
172 {
173 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
174 if (_Mutex_base<_Lp>::_S_need_barriers)
175 {
176 // See _M_release(),
177 // destroy() must observe results of dispose()
178 __atomic_thread_fence (__ATOMIC_ACQ_REL);
179 }
180 _M_destroy();
181 }
182 }
183
184 long
185 _M_get_use_count() const // nothrow
186 {
187 // No memory barrier is used here so there is no synchronization
188 // with other threads.
189 return const_cast<const volatile _Atomic_word&>(_M_use_count);
190 }
191
192 private:
193 _Sp_counted_base(_Sp_counted_base const&);
194 _Sp_counted_base& operator=(_Sp_counted_base const&);
195
196 _Atomic_word _M_use_count; // #shared
197 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
198 };
199
200 template<>
201 inline void
202 _Sp_counted_base<_S_single>::
203 _M_add_ref_lock()
204 {
205 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: 1) == 0)
206 {
207 _M_use_count = 0;
208 __throw_bad_weak_ptr();
209 }
210 }
211
212 template<>
213 inline void
214 _Sp_counted_base<_S_mutex>::
215 _M_add_ref_lock()
216 {
217 __gnu_cxx::__scoped_lock sentry(*this);
218 if (__gnu_cxx::__exchange_and_add_dispatch(mem: &_M_use_count, val: 1) == 0)
219 {
220 _M_use_count = 0;
221 __throw_bad_weak_ptr();
222 }
223 }
224
225 template<>
226 inline void
227 _Sp_counted_base<_S_atomic>::
228 _M_add_ref_lock()
229 {
230 // Perform lock-free add-if-not-zero operation.
231 _Atomic_word __count = _M_use_count;
232 do
233 {
234 if (__count == 0)
235 __throw_bad_weak_ptr();
236 // Replace the current counter value with the old value + 1, as
237 // long as it's not changed meanwhile.
238 }
239 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
240 true, __ATOMIC_ACQ_REL,
241 __ATOMIC_RELAXED));
242 }
243
244 template<typename _Ptr, typename _Deleter, _Lock_policy _Lp>
245 class _Sp_counted_base_impl
246 : public _Sp_counted_base<_Lp>
247 {
248 public:
249 // Precondition: __d(__p) must not throw.
250 _Sp_counted_base_impl(_Ptr __p, _Deleter __d)
251 : _M_ptr(__p), _M_del(__d) { }
252
253 virtual void
254 _M_dispose() // nothrow
255 { _M_del(_M_ptr); }
256
257 virtual void*
258 _M_get_deleter(const std::type_info& __ti)
259 {
260#if __cpp_rtti
261 return __ti == typeid(_Deleter) ? &_M_del : 0;
262#else
263 return 0;
264#endif
265 }
266
267 private:
268 _Sp_counted_base_impl(const _Sp_counted_base_impl&);
269 _Sp_counted_base_impl& operator=(const _Sp_counted_base_impl&);
270
271 _Ptr _M_ptr; // copy constructor must not throw
272 _Deleter _M_del; // copy constructor must not throw
273 };
274
275 template<_Lock_policy _Lp = __default_lock_policy>
276 class __weak_count;
277
278 template<typename _Tp>
279 struct _Sp_deleter
280 {
281 typedef void result_type;
282 typedef _Tp* argument_type;
283 void operator()(_Tp* __p) const { delete __p; }
284 };
285
286 template<_Lock_policy _Lp = __default_lock_policy>
287 class __shared_count
288 {
289 public:
290 __shared_count()
291 : _M_pi(0) // nothrow
292 { }
293
294 template<typename _Ptr>
295 __shared_count(_Ptr __p) : _M_pi(0)
296 {
297 __try
298 {
299 typedef typename std::tr1::remove_pointer<_Ptr>::type _Tp;
300 _M_pi = new _Sp_counted_base_impl<_Ptr, _Sp_deleter<_Tp>, _Lp>(
301 __p, _Sp_deleter<_Tp>());
302 }
303 __catch(...)
304 {
305 delete __p;
306 __throw_exception_again;
307 }
308 }
309
310 template<typename _Ptr, typename _Deleter>
311 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0)
312 {
313 __try
314 {
315 _M_pi = new _Sp_counted_base_impl<_Ptr, _Deleter, _Lp>(__p, __d);
316 }
317 __catch(...)
318 {
319 __d(__p); // Call _Deleter on __p.
320 __throw_exception_again;
321 }
322 }
323
324#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
325#pragma GCC diagnostic push
326#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
327 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
328 template<typename _Tp>
329 explicit
330 __shared_count(std::auto_ptr<_Tp>& __r)
331 : _M_pi(new _Sp_counted_base_impl<_Tp*,
332 _Sp_deleter<_Tp>, _Lp >(__r.get(), _Sp_deleter<_Tp>()))
333 { __r.release(); }
334#pragma GCC diagnostic pop
335#endif
336
337 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
338 explicit
339 __shared_count(const __weak_count<_Lp>& __r);
340
341 ~__shared_count() // nothrow
342 {
343 if (_M_pi != 0)
344 _M_pi->_M_release();
345 }
346
347 __shared_count(const __shared_count& __r)
348 : _M_pi(__r._M_pi) // nothrow
349 {
350 if (_M_pi != 0)
351 _M_pi->_M_add_ref_copy();
352 }
353
354 __shared_count&
355 operator=(const __shared_count& __r) // nothrow
356 {
357 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
358 if (__tmp != _M_pi)
359 {
360 if (__tmp != 0)
361 __tmp->_M_add_ref_copy();
362 if (_M_pi != 0)
363 _M_pi->_M_release();
364 _M_pi = __tmp;
365 }
366 return *this;
367 }
368
369 void
370 _M_swap(__shared_count& __r) // nothrow
371 {
372 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
373 __r._M_pi = _M_pi;
374 _M_pi = __tmp;
375 }
376
377 long
378 _M_get_use_count() const // nothrow
379 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
380
381 bool
382 _M_unique() const // nothrow
383 { return this->_M_get_use_count() == 1; }
384
385 friend inline bool
386 operator==(const __shared_count& __a, const __shared_count& __b)
387 { return __a._M_pi == __b._M_pi; }
388
389 friend inline bool
390 operator<(const __shared_count& __a, const __shared_count& __b)
391 { return std::less<_Sp_counted_base<_Lp>*>()(__a._M_pi, __b._M_pi); }
392
393 void*
394 _M_get_deleter(const std::type_info& __ti) const
395 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; }
396
397 private:
398 friend class __weak_count<_Lp>;
399
400 _Sp_counted_base<_Lp>* _M_pi;
401 };
402
403
404 template<_Lock_policy _Lp>
405 class __weak_count
406 {
407 public:
408 __weak_count()
409 : _M_pi(0) // nothrow
410 { }
411
412 __weak_count(const __shared_count<_Lp>& __r)
413 : _M_pi(__r._M_pi) // nothrow
414 {
415 if (_M_pi != 0)
416 _M_pi->_M_weak_add_ref();
417 }
418
419 __weak_count(const __weak_count<_Lp>& __r)
420 : _M_pi(__r._M_pi) // nothrow
421 {
422 if (_M_pi != 0)
423 _M_pi->_M_weak_add_ref();
424 }
425
426 ~__weak_count() // nothrow
427 {
428 if (_M_pi != 0)
429 _M_pi->_M_weak_release();
430 }
431
432 __weak_count<_Lp>&
433 operator=(const __shared_count<_Lp>& __r) // nothrow
434 {
435 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
436 if (__tmp != 0)
437 __tmp->_M_weak_add_ref();
438 if (_M_pi != 0)
439 _M_pi->_M_weak_release();
440 _M_pi = __tmp;
441 return *this;
442 }
443
444 __weak_count<_Lp>&
445 operator=(const __weak_count<_Lp>& __r) // nothrow
446 {
447 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
448 if (__tmp != 0)
449 __tmp->_M_weak_add_ref();
450 if (_M_pi != 0)
451 _M_pi->_M_weak_release();
452 _M_pi = __tmp;
453 return *this;
454 }
455
456 void
457 _M_swap(__weak_count<_Lp>& __r) // nothrow
458 {
459 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
460 __r._M_pi = _M_pi;
461 _M_pi = __tmp;
462 }
463
464 long
465 _M_get_use_count() const // nothrow
466 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
467
468 friend inline bool
469 operator==(const __weak_count<_Lp>& __a, const __weak_count<_Lp>& __b)
470 { return __a._M_pi == __b._M_pi; }
471
472 friend inline bool
473 operator<(const __weak_count<_Lp>& __a, const __weak_count<_Lp>& __b)
474 { return std::less<_Sp_counted_base<_Lp>*>()(__a._M_pi, __b._M_pi); }
475
476 private:
477 friend class __shared_count<_Lp>;
478
479 _Sp_counted_base<_Lp>* _M_pi;
480 };
481
482 // now that __weak_count is defined we can define this constructor:
483 template<_Lock_policy _Lp>
484 inline
485 __shared_count<_Lp>::
486 __shared_count(const __weak_count<_Lp>& __r)
487 : _M_pi(__r._M_pi)
488 {
489 if (_M_pi != 0)
490 _M_pi->_M_add_ref_lock();
491 else
492 __throw_bad_weak_ptr();
493 }
494
495 // Forward declarations.
496 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
497 class __shared_ptr;
498
499 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
500 class __weak_ptr;
501
502 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
503 class __enable_shared_from_this;
504
505 template<typename _Tp>
506 class shared_ptr;
507
508 template<typename _Tp>
509 class weak_ptr;
510
511 template<typename _Tp>
512 class enable_shared_from_this;
513
514 // Support for enable_shared_from_this.
515
516 // Friend of __enable_shared_from_this.
517 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2>
518 void
519 __enable_shared_from_this_helper(const __shared_count<_Lp>&,
520 const __enable_shared_from_this<_Tp1,
521 _Lp>*, const _Tp2*);
522
523 // Friend of enable_shared_from_this.
524 template<typename _Tp1, typename _Tp2>
525 void
526 __enable_shared_from_this_helper(const __shared_count<>&,
527 const enable_shared_from_this<_Tp1>*,
528 const _Tp2*);
529
530 template<_Lock_policy _Lp>
531 inline void
532 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...)
533 { }
534
535
536 struct __static_cast_tag { };
537 struct __const_cast_tag { };
538 struct __dynamic_cast_tag { };
539
540 // A smart pointer with reference-counted copy semantics. The
541 // object pointed to is deleted when the last shared_ptr pointing to
542 // it is destroyed or reset.
543 template<typename _Tp, _Lock_policy _Lp>
544 class __shared_ptr
545 {
546 public:
547 typedef _Tp element_type;
548
549 __shared_ptr()
550 : _M_ptr(0), _M_refcount() // never throws
551 { }
552
553 template<typename _Tp1>
554 explicit
555 __shared_ptr(_Tp1* __p)
556 : _M_ptr(__p), _M_refcount(__p)
557 {
558 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
559 typedef int _IsComplete[sizeof(_Tp1)];
560 __enable_shared_from_this_helper(_M_refcount, __p, __p);
561 }
562
563 template<typename _Tp1, typename _Deleter>
564 __shared_ptr(_Tp1* __p, _Deleter __d)
565 : _M_ptr(__p), _M_refcount(__p, __d)
566 {
567 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
568 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
569 __enable_shared_from_this_helper(_M_refcount, __p, __p);
570 }
571
572 // generated copy constructor, assignment, destructor are fine.
573
574 template<typename _Tp1>
575 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
576 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
577 { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) }
578
579 template<typename _Tp1>
580 explicit
581 __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
582 : _M_refcount(__r._M_refcount) // may throw
583 {
584 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
585 // It is now safe to copy __r._M_ptr, as _M_refcount(__r._M_refcount)
586 // did not throw.
587 _M_ptr = __r._M_ptr;
588 }
589
590#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
591#pragma GCC diagnostic push
592#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
593 // Postcondition: use_count() == 1 and __r.get() == 0
594 template<typename _Tp1>
595 explicit
596 __shared_ptr(std::auto_ptr<_Tp1>& __r)
597 : _M_ptr(__r.get()), _M_refcount()
598 { // TODO requries delete __r.release() well-formed
599 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
600 typedef int _IsComplete[sizeof(_Tp1)];
601 _Tp1* __tmp = __r.get();
602 _M_refcount = __shared_count<_Lp>(__r);
603 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
604 }
605#pragma GCC diagnostic pop
606#endif
607
608 template<typename _Tp1>
609 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __static_cast_tag)
610 : _M_ptr(static_cast<element_type*>(__r._M_ptr)),
611 _M_refcount(__r._M_refcount)
612 { }
613
614 template<typename _Tp1>
615 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __const_cast_tag)
616 : _M_ptr(const_cast<element_type*>(__r._M_ptr)),
617 _M_refcount(__r._M_refcount)
618 { }
619
620 template<typename _Tp1>
621 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __dynamic_cast_tag)
622 : _M_ptr(dynamic_cast<element_type*>(__r._M_ptr)),
623 _M_refcount(__r._M_refcount)
624 {
625 if (_M_ptr == 0) // need to allocate new counter -- the cast failed
626 _M_refcount = __shared_count<_Lp>();
627 }
628
629 template<typename _Tp1>
630 __shared_ptr&
631 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
632 {
633 _M_ptr = __r._M_ptr;
634 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
635 return *this;
636 }
637
638#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
639#pragma GCC diagnostic push
640#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
641 template<typename _Tp1>
642 __shared_ptr&
643 operator=(std::auto_ptr<_Tp1>& __r)
644 {
645 __shared_ptr(__r).swap(*this);
646 return *this;
647 }
648#pragma GCC diagnostic pop
649#endif
650
651 void
652 reset() // never throws
653 { __shared_ptr().swap(*this); }
654
655 template<typename _Tp1>
656 void
657 reset(_Tp1* __p) // _Tp1 must be complete.
658 {
659 // Catch self-reset errors.
660 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr);
661 __shared_ptr(__p).swap(*this);
662 }
663
664 template<typename _Tp1, typename _Deleter>
665 void
666 reset(_Tp1* __p, _Deleter __d)
667 { __shared_ptr(__p, __d).swap(*this); }
668
669 // Allow class instantiation when _Tp is [cv-qual] void.
670 typename std::tr1::add_reference<_Tp>::type
671 operator*() const // never throws
672 {
673 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
674 return *_M_ptr;
675 }
676
677 _Tp*
678 operator->() const // never throws
679 {
680 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
681 return _M_ptr;
682 }
683
684 _Tp*
685 get() const // never throws
686 { return _M_ptr; }
687
688 // Implicit conversion to "bool"
689 private:
690 typedef _Tp* __shared_ptr::*__unspecified_bool_type;
691
692 public:
693 operator __unspecified_bool_type() const // never throws
694 { return _M_ptr == 0 ? 0 : &__shared_ptr::_M_ptr; }
695
696 bool
697 unique() const // never throws
698 { return _M_refcount._M_unique(); }
699
700 long
701 use_count() const // never throws
702 { return _M_refcount._M_get_use_count(); }
703
704 void
705 swap(__shared_ptr<_Tp, _Lp>& __other) // never throws
706 {
707 std::swap(_M_ptr, __other._M_ptr);
708 _M_refcount._M_swap(__other._M_refcount);
709 }
710
711 private:
712 void*
713 _M_get_deleter(const std::type_info& __ti) const
714 { return _M_refcount._M_get_deleter(__ti); }
715
716 template<typename _Tp1, _Lock_policy _Lp1>
717 bool
718 _M_less(const __shared_ptr<_Tp1, _Lp1>& __rhs) const
719 { return _M_refcount < __rhs._M_refcount; }
720
721 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
722 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
723
724 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
725 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&);
726
727 // Friends injected into enclosing namespace and found by ADL:
728 template<typename _Tp1>
729 friend inline bool
730 operator==(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b)
731 { return __a.get() == __b.get(); }
732
733 template<typename _Tp1>
734 friend inline bool
735 operator!=(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b)
736 { return __a.get() != __b.get(); }
737
738 template<typename _Tp1>
739 friend inline bool
740 operator<(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b)
741 { return __a._M_less(__b); }
742
743 _Tp* _M_ptr; // Contained pointer.
744 __shared_count<_Lp> _M_refcount; // Reference counter.
745 };
746
747 // 2.2.3.8 shared_ptr specialized algorithms.
748 template<typename _Tp, _Lock_policy _Lp>
749 inline void
750 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b)
751 { __a.swap(__b); }
752
753 // 2.2.3.9 shared_ptr casts
754 /* The seemingly equivalent
755 * shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
756 * will eventually result in undefined behaviour,
757 * attempting to delete the same object twice.
758 */
759 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
760 inline __shared_ptr<_Tp, _Lp>
761 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
762 { return __shared_ptr<_Tp, _Lp>(__r, __static_cast_tag()); }
763
764 /* The seemingly equivalent
765 * shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
766 * will eventually result in undefined behaviour,
767 * attempting to delete the same object twice.
768 */
769 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
770 inline __shared_ptr<_Tp, _Lp>
771 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
772 { return __shared_ptr<_Tp, _Lp>(__r, __const_cast_tag()); }
773
774 /* The seemingly equivalent
775 * shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
776 * will eventually result in undefined behaviour,
777 * attempting to delete the same object twice.
778 */
779 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
780 inline __shared_ptr<_Tp, _Lp>
781 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
782 { return __shared_ptr<_Tp, _Lp>(__r, __dynamic_cast_tag()); }
783
784 // 2.2.3.7 shared_ptr I/O
785 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
786 std::basic_ostream<_Ch, _Tr>&
787 operator<<(std::basic_ostream<_Ch, _Tr>& __os,
788 const __shared_ptr<_Tp, _Lp>& __p)
789 {
790 __os << __p.get();
791 return __os;
792 }
793
794 // 2.2.3.10 shared_ptr get_deleter (experimental)
795 template<typename _Del, typename _Tp, _Lock_policy _Lp>
796 inline _Del*
797 get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
798 {
799#if __cpp_rtti
800 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
801#else
802 return 0;
803#endif
804 }
805
806
807 template<typename _Tp, _Lock_policy _Lp>
808 class __weak_ptr
809 {
810 public:
811 typedef _Tp element_type;
812
813 __weak_ptr()
814 : _M_ptr(0), _M_refcount() // never throws
815 { }
816
817 // Generated copy constructor, assignment, destructor are fine.
818
819 // The "obvious" converting constructor implementation:
820 //
821 // template<typename _Tp1>
822 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
823 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
824 // { }
825 //
826 // has a serious problem.
827 //
828 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
829 // conversion may require access to *__r._M_ptr (virtual inheritance).
830 //
831 // It is not possible to avoid spurious access violations since
832 // in multithreaded programs __r._M_ptr may be invalidated at any point.
833 template<typename _Tp1>
834 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
835 : _M_refcount(__r._M_refcount) // never throws
836 {
837 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
838 _M_ptr = __r.lock().get();
839 }
840
841 template<typename _Tp1>
842 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
843 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
844 { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) }
845
846 template<typename _Tp1>
847 __weak_ptr&
848 operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws
849 {
850 _M_ptr = __r.lock().get();
851 _M_refcount = __r._M_refcount;
852 return *this;
853 }
854
855 template<typename _Tp1>
856 __weak_ptr&
857 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
858 {
859 _M_ptr = __r._M_ptr;
860 _M_refcount = __r._M_refcount;
861 return *this;
862 }
863
864 __shared_ptr<_Tp, _Lp>
865 lock() const // never throws
866 {
867#ifdef __GTHREADS
868 // Optimization: avoid throw overhead.
869 if (expired())
870 return __shared_ptr<element_type, _Lp>();
871
872 __try
873 {
874 return __shared_ptr<element_type, _Lp>(*this);
875 }
876 __catch(const bad_weak_ptr&)
877 {
878 // Q: How can we get here?
879 // A: Another thread may have invalidated r after the
880 // use_count test above.
881 return __shared_ptr<element_type, _Lp>();
882 }
883
884#else
885 // Optimization: avoid try/catch overhead when single threaded.
886 return expired() ? __shared_ptr<element_type, _Lp>()
887 : __shared_ptr<element_type, _Lp>(*this);
888
889#endif
890 } // XXX MT
891
892 long
893 use_count() const // never throws
894 { return _M_refcount._M_get_use_count(); }
895
896 bool
897 expired() const // never throws
898 { return _M_refcount._M_get_use_count() == 0; }
899
900 void
901 reset() // never throws
902 { __weak_ptr().swap(*this); }
903
904 void
905 swap(__weak_ptr& __s) // never throws
906 {
907 std::swap(_M_ptr, __s._M_ptr);
908 _M_refcount._M_swap(__s._M_refcount);
909 }
910
911 private:
912 // Used by __enable_shared_from_this.
913 void
914 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount)
915 {
916 _M_ptr = __ptr;
917 _M_refcount = __refcount;
918 }
919
920 template<typename _Tp1>
921 bool
922 _M_less(const __weak_ptr<_Tp1, _Lp>& __rhs) const
923 { return _M_refcount < __rhs._M_refcount; }
924
925 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
926 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
927 friend class __enable_shared_from_this<_Tp, _Lp>;
928 friend class enable_shared_from_this<_Tp>;
929
930 // Friend injected into namespace and found by ADL.
931 template<typename _Tp1>
932 friend inline bool
933 operator<(const __weak_ptr& __lhs, const __weak_ptr<_Tp1, _Lp>& __rhs)
934 { return __lhs._M_less(__rhs); }
935
936 _Tp* _M_ptr; // Contained pointer.
937 __weak_count<_Lp> _M_refcount; // Reference counter.
938 };
939
940 // 2.2.4.7 weak_ptr specialized algorithms.
941 template<typename _Tp, _Lock_policy _Lp>
942 inline void
943 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b)
944 { __a.swap(__b); }
945
946
947 template<typename _Tp, _Lock_policy _Lp>
948 class __enable_shared_from_this
949 {
950 protected:
951 __enable_shared_from_this() { }
952
953 __enable_shared_from_this(const __enable_shared_from_this&) { }
954
955 __enable_shared_from_this&
956 operator=(const __enable_shared_from_this&)
957 { return *this; }
958
959 ~__enable_shared_from_this() { }
960
961 public:
962 __shared_ptr<_Tp, _Lp>
963 shared_from_this()
964 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
965
966 __shared_ptr<const _Tp, _Lp>
967 shared_from_this() const
968 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
969
970 private:
971 template<typename _Tp1>
972 void
973 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const
974 { _M_weak_this._M_assign(__p, __n); }
975
976 template<typename _Tp1>
977 friend void
978 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn,
979 const __enable_shared_from_this* __pe,
980 const _Tp1* __px)
981 {
982 if (__pe != 0)
983 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
984 }
985
986 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
987 };
988
989
990 // The actual shared_ptr, with forwarding constructors and
991 // assignment operators.
992 template<typename _Tp>
993 class shared_ptr
994 : public __shared_ptr<_Tp>
995 {
996 public:
997 shared_ptr()
998 : __shared_ptr<_Tp>() { }
999
1000 template<typename _Tp1>
1001 explicit
1002 shared_ptr(_Tp1* __p)
1003 : __shared_ptr<_Tp>(__p) { }
1004
1005 template<typename _Tp1, typename _Deleter>
1006 shared_ptr(_Tp1* __p, _Deleter __d)
1007 : __shared_ptr<_Tp>(__p, __d) { }
1008
1009 template<typename _Tp1>
1010 shared_ptr(const shared_ptr<_Tp1>& __r)
1011 : __shared_ptr<_Tp>(__r) { }
1012
1013 template<typename _Tp1>
1014 explicit
1015 shared_ptr(const weak_ptr<_Tp1>& __r)
1016 : __shared_ptr<_Tp>(__r) { }
1017
1018#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
1019#pragma GCC diagnostic push
1020#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1021 template<typename _Tp1>
1022 explicit
1023 shared_ptr(std::auto_ptr<_Tp1>& __r)
1024 : __shared_ptr<_Tp>(__r) { }
1025#pragma GCC diagnostic pop
1026#endif
1027
1028 template<typename _Tp1>
1029 shared_ptr(const shared_ptr<_Tp1>& __r, __static_cast_tag)
1030 : __shared_ptr<_Tp>(__r, __static_cast_tag()) { }
1031
1032 template<typename _Tp1>
1033 shared_ptr(const shared_ptr<_Tp1>& __r, __const_cast_tag)
1034 : __shared_ptr<_Tp>(__r, __const_cast_tag()) { }
1035
1036 template<typename _Tp1>
1037 shared_ptr(const shared_ptr<_Tp1>& __r, __dynamic_cast_tag)
1038 : __shared_ptr<_Tp>(__r, __dynamic_cast_tag()) { }
1039
1040 template<typename _Tp1>
1041 shared_ptr&
1042 operator=(const shared_ptr<_Tp1>& __r) // never throws
1043 {
1044 this->__shared_ptr<_Tp>::operator=(__r);
1045 return *this;
1046 }
1047
1048#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
1049#pragma GCC diagnostic push
1050#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
1051 template<typename _Tp1>
1052 shared_ptr&
1053 operator=(std::auto_ptr<_Tp1>& __r)
1054 {
1055 this->__shared_ptr<_Tp>::operator=(__r);
1056 return *this;
1057 }
1058#pragma GCC diagnostic pop
1059#endif
1060 };
1061
1062 // 2.2.3.8 shared_ptr specialized algorithms.
1063 template<typename _Tp>
1064 inline void
1065 swap(__shared_ptr<_Tp>& __a, __shared_ptr<_Tp>& __b)
1066 { __a.swap(__b); }
1067
1068 template<typename _Tp, typename _Tp1>
1069 inline shared_ptr<_Tp>
1070 static_pointer_cast(const shared_ptr<_Tp1>& __r)
1071 { return shared_ptr<_Tp>(__r, __static_cast_tag()); }
1072
1073 template<typename _Tp, typename _Tp1>
1074 inline shared_ptr<_Tp>
1075 const_pointer_cast(const shared_ptr<_Tp1>& __r)
1076 { return shared_ptr<_Tp>(__r, __const_cast_tag()); }
1077
1078 template<typename _Tp, typename _Tp1>
1079 inline shared_ptr<_Tp>
1080 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
1081 { return shared_ptr<_Tp>(__r, __dynamic_cast_tag()); }
1082
1083
1084 // The actual weak_ptr, with forwarding constructors and
1085 // assignment operators.
1086 template<typename _Tp>
1087 class weak_ptr
1088 : public __weak_ptr<_Tp>
1089 {
1090 public:
1091 weak_ptr()
1092 : __weak_ptr<_Tp>() { }
1093
1094 template<typename _Tp1>
1095 weak_ptr(const weak_ptr<_Tp1>& __r)
1096 : __weak_ptr<_Tp>(__r) { }
1097
1098 template<typename _Tp1>
1099 weak_ptr(const shared_ptr<_Tp1>& __r)
1100 : __weak_ptr<_Tp>(__r) { }
1101
1102 template<typename _Tp1>
1103 weak_ptr&
1104 operator=(const weak_ptr<_Tp1>& __r) // never throws
1105 {
1106 this->__weak_ptr<_Tp>::operator=(__r);
1107 return *this;
1108 }
1109
1110 template<typename _Tp1>
1111 weak_ptr&
1112 operator=(const shared_ptr<_Tp1>& __r) // never throws
1113 {
1114 this->__weak_ptr<_Tp>::operator=(__r);
1115 return *this;
1116 }
1117
1118 shared_ptr<_Tp>
1119 lock() const // never throws
1120 {
1121#ifdef __GTHREADS
1122 if (this->expired())
1123 return shared_ptr<_Tp>();
1124
1125 __try
1126 {
1127 return shared_ptr<_Tp>(*this);
1128 }
1129 __catch(const bad_weak_ptr&)
1130 {
1131 return shared_ptr<_Tp>();
1132 }
1133#else
1134 return this->expired() ? shared_ptr<_Tp>()
1135 : shared_ptr<_Tp>(*this);
1136#endif
1137 }
1138 };
1139
1140 template<typename _Tp>
1141 class enable_shared_from_this
1142 {
1143 protected:
1144 enable_shared_from_this() { }
1145
1146 enable_shared_from_this(const enable_shared_from_this&) { }
1147
1148 enable_shared_from_this&
1149 operator=(const enable_shared_from_this&)
1150 { return *this; }
1151
1152 ~enable_shared_from_this() { }
1153
1154 public:
1155 shared_ptr<_Tp>
1156 shared_from_this()
1157 { return shared_ptr<_Tp>(this->_M_weak_this); }
1158
1159 shared_ptr<const _Tp>
1160 shared_from_this() const
1161 { return shared_ptr<const _Tp>(this->_M_weak_this); }
1162
1163 private:
1164 template<typename _Tp1>
1165 void
1166 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
1167 { _M_weak_this._M_assign(__p, __n); }
1168
1169 template<typename _Tp1>
1170 friend void
1171 __enable_shared_from_this_helper(const __shared_count<>& __pn,
1172 const enable_shared_from_this* __pe,
1173 const _Tp1* __px)
1174 {
1175 if (__pe != 0)
1176 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
1177 }
1178
1179 mutable weak_ptr<_Tp> _M_weak_this;
1180 };
1181}
1182
1183_GLIBCXX_END_NAMESPACE_VERSION
1184}
1185
1186#endif // _TR1_SHARED_PTR_H
1187

source code of include/c++/11/tr1/shared_ptr.h