re PR libstdc++/59656 (weak_ptr::lock function crashes when compiling with -fno-excep...
[gcc.git] / libstdc++-v3 / include / bits / shared_ptr_base.h
1 // shared_ptr and weak_ptr implementation details -*- C++ -*-
2
3 // Copyright (C) 2007-2014 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 // GCC Note: Based on files from version 1.32.0 of the Boost library.
26
27 // shared_count.hpp
28 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
29
30 // shared_ptr.hpp
31 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32 // Copyright (C) 2001, 2002, 2003 Peter Dimov
33
34 // weak_ptr.hpp
35 // Copyright (C) 2001, 2002, 2003 Peter Dimov
36
37 // enable_shared_from_this.hpp
38 // Copyright (C) 2002 Peter Dimov
39
40 // Distributed under the Boost Software License, Version 1.0. (See
41 // accompanying file LICENSE_1_0.txt or copy at
42 // http://www.boost.org/LICENSE_1_0.txt)
43
44 /** @file bits/shared_ptr_base.h
45 * This is an internal header file, included by other library headers.
46 * Do not attempt to use it directly. @headername{memory}
47 */
48
49 #ifndef _SHARED_PTR_BASE_H
50 #define _SHARED_PTR_BASE_H 1
51
52 #include <ext/aligned_buffer.h>
53
54 namespace std _GLIBCXX_VISIBILITY(default)
55 {
56 _GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58 #if _GLIBCXX_USE_DEPRECATED
59 template<typename> class auto_ptr;
60 #endif
61
62 /**
63 * @brief Exception possibly thrown by @c shared_ptr.
64 * @ingroup exceptions
65 */
66 class bad_weak_ptr : public std::exception
67 {
68 public:
69 virtual char const*
70 what() const noexcept;
71
72 virtual ~bad_weak_ptr() noexcept;
73 };
74
75 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
76 inline void
77 __throw_bad_weak_ptr()
78 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
79
80 using __gnu_cxx::_Lock_policy;
81 using __gnu_cxx::__default_lock_policy;
82 using __gnu_cxx::_S_single;
83 using __gnu_cxx::_S_mutex;
84 using __gnu_cxx::_S_atomic;
85
86 // Empty helper class except when the template argument is _S_mutex.
87 template<_Lock_policy _Lp>
88 class _Mutex_base
89 {
90 protected:
91 // The atomic policy uses fully-fenced builtins, single doesn't care.
92 enum { _S_need_barriers = 0 };
93 };
94
95 template<>
96 class _Mutex_base<_S_mutex>
97 : public __gnu_cxx::__mutex
98 {
99 protected:
100 // This policy is used when atomic builtins are not available.
101 // The replacement atomic operations might not have the necessary
102 // memory barriers.
103 enum { _S_need_barriers = 1 };
104 };
105
106 template<_Lock_policy _Lp = __default_lock_policy>
107 class _Sp_counted_base
108 : public _Mutex_base<_Lp>
109 {
110 public:
111 _Sp_counted_base() noexcept
112 : _M_use_count(1), _M_weak_count(1) { }
113
114 virtual
115 ~_Sp_counted_base() noexcept
116 { }
117
118 // Called when _M_use_count drops to zero, to release the resources
119 // managed by *this.
120 virtual void
121 _M_dispose() noexcept = 0;
122
123 // Called when _M_weak_count drops to zero.
124 virtual void
125 _M_destroy() noexcept
126 { delete this; }
127
128 virtual void*
129 _M_get_deleter(const std::type_info&) noexcept = 0;
130
131 void
132 _M_add_ref_copy()
133 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
134
135 void
136 _M_add_ref_lock();
137
138 bool
139 _M_add_ref_lock_nothrow();
140
141 void
142 _M_release() noexcept
143 {
144 // Be race-detector-friendly. For more info see bits/c++config.
145 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
146 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
147 {
148 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
149 _M_dispose();
150 // There must be a memory barrier between dispose() and destroy()
151 // to ensure that the effects of dispose() are observed in the
152 // thread that runs destroy().
153 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
154 if (_Mutex_base<_Lp>::_S_need_barriers)
155 {
156 _GLIBCXX_READ_MEM_BARRIER;
157 _GLIBCXX_WRITE_MEM_BARRIER;
158 }
159
160 // Be race-detector-friendly. For more info see bits/c++config.
161 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
162 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
163 -1) == 1)
164 {
165 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
166 _M_destroy();
167 }
168 }
169 }
170
171 void
172 _M_weak_add_ref() noexcept
173 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
174
175 void
176 _M_weak_release() noexcept
177 {
178 // Be race-detector-friendly. For more info see bits/c++config.
179 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
180 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
181 {
182 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
183 if (_Mutex_base<_Lp>::_S_need_barriers)
184 {
185 // See _M_release(),
186 // destroy() must observe results of dispose()
187 _GLIBCXX_READ_MEM_BARRIER;
188 _GLIBCXX_WRITE_MEM_BARRIER;
189 }
190 _M_destroy();
191 }
192 }
193
194 long
195 _M_get_use_count() const noexcept
196 {
197 // No memory barrier is used here so there is no synchronization
198 // with other threads.
199 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED);
200 }
201
202 private:
203 _Sp_counted_base(_Sp_counted_base const&) = delete;
204 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete;
205
206 _Atomic_word _M_use_count; // #shared
207 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
208 };
209
210 template<>
211 inline void
212 _Sp_counted_base<_S_single>::
213 _M_add_ref_lock()
214 {
215 if (_M_use_count == 0)
216 __throw_bad_weak_ptr();
217 ++_M_use_count;
218 }
219
220 template<>
221 inline void
222 _Sp_counted_base<_S_mutex>::
223 _M_add_ref_lock()
224 {
225 __gnu_cxx::__scoped_lock sentry(*this);
226 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
227 {
228 _M_use_count = 0;
229 __throw_bad_weak_ptr();
230 }
231 }
232
233 template<>
234 inline void
235 _Sp_counted_base<_S_atomic>::
236 _M_add_ref_lock()
237 {
238 // Perform lock-free add-if-not-zero operation.
239 _Atomic_word __count = _M_get_use_count();
240 do
241 {
242 if (__count == 0)
243 __throw_bad_weak_ptr();
244 // Replace the current counter value with the old value + 1, as
245 // long as it's not changed meanwhile.
246 }
247 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
248 true, __ATOMIC_ACQ_REL,
249 __ATOMIC_RELAXED));
250 }
251
252 template<>
253 inline bool
254 _Sp_counted_base<_S_single>::
255 _M_add_ref_lock_nothrow()
256 {
257 if (_M_use_count == 0)
258 return false;
259 ++_M_use_count;
260 return true;
261 }
262
263 template<>
264 inline bool
265 _Sp_counted_base<_S_mutex>::
266 _M_add_ref_lock_nothrow()
267 {
268 __gnu_cxx::__scoped_lock sentry(*this);
269 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
270 {
271 _M_use_count = 0;
272 return false;
273 }
274 return true;
275 }
276
277 template<>
278 inline bool
279 _Sp_counted_base<_S_atomic>::
280 _M_add_ref_lock_nothrow()
281 {
282 // Perform lock-free add-if-not-zero operation.
283 _Atomic_word __count = _M_get_use_count();
284 do
285 {
286 if (__count == 0)
287 return false;
288 // Replace the current counter value with the old value + 1, as
289 // long as it's not changed meanwhile.
290 }
291 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
292 true, __ATOMIC_ACQ_REL,
293 __ATOMIC_RELAXED));
294 return true;
295 }
296
297 template<>
298 inline void
299 _Sp_counted_base<_S_single>::_M_add_ref_copy()
300 { ++_M_use_count; }
301
302 template<>
303 inline void
304 _Sp_counted_base<_S_single>::_M_release() noexcept
305 {
306 if (--_M_use_count == 0)
307 {
308 _M_dispose();
309 if (--_M_weak_count == 0)
310 _M_destroy();
311 }
312 }
313
314 template<>
315 inline void
316 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
317 { ++_M_weak_count; }
318
319 template<>
320 inline void
321 _Sp_counted_base<_S_single>::_M_weak_release() noexcept
322 {
323 if (--_M_weak_count == 0)
324 _M_destroy();
325 }
326
327 template<>
328 inline long
329 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
330 { return _M_use_count; }
331
332
333 // Forward declarations.
334 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
335 class __shared_ptr;
336
337 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
338 class __weak_ptr;
339
340 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
341 class __enable_shared_from_this;
342
343 template<typename _Tp>
344 class shared_ptr;
345
346 template<typename _Tp>
347 class weak_ptr;
348
349 template<typename _Tp>
350 struct owner_less;
351
352 template<typename _Tp>
353 class enable_shared_from_this;
354
355 template<_Lock_policy _Lp = __default_lock_policy>
356 class __weak_count;
357
358 template<_Lock_policy _Lp = __default_lock_policy>
359 class __shared_count;
360
361
362 // Counted ptr with no deleter or allocator support
363 template<typename _Ptr, _Lock_policy _Lp>
364 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
365 {
366 public:
367 explicit
368 _Sp_counted_ptr(_Ptr __p) noexcept
369 : _M_ptr(__p) { }
370
371 virtual void
372 _M_dispose() noexcept
373 { delete _M_ptr; }
374
375 virtual void
376 _M_destroy() noexcept
377 { delete this; }
378
379 virtual void*
380 _M_get_deleter(const std::type_info&) noexcept
381 { return nullptr; }
382
383 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
384 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
385
386 private:
387 _Ptr _M_ptr;
388 };
389
390 template<>
391 inline void
392 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }
393
394 template<>
395 inline void
396 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }
397
398 template<>
399 inline void
400 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }
401
402 template<int _Nm, typename _Tp,
403 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
404 struct _Sp_ebo_helper;
405
406 /// Specialization using EBO.
407 template<int _Nm, typename _Tp>
408 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
409 {
410 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
411
412 static _Tp&
413 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
414 };
415
416 /// Specialization not using EBO.
417 template<int _Nm, typename _Tp>
418 struct _Sp_ebo_helper<_Nm, _Tp, false>
419 {
420 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
421
422 static _Tp&
423 _S_get(_Sp_ebo_helper& __eboh)
424 { return __eboh._M_tp; }
425
426 private:
427 _Tp _M_tp;
428 };
429
430 // Support for custom deleter and/or allocator
431 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
432 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
433 {
434 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
435 {
436 typedef _Sp_ebo_helper<0, _Deleter> _Del_base;
437 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base;
438
439 public:
440 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
441 : _M_ptr(__p), _Del_base(__d), _Alloc_base(__a)
442 { }
443
444 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
445 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }
446
447 _Ptr _M_ptr;
448 };
449
450 public:
451 // __d(__p) must not throw.
452 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
453 : _M_impl(__p, __d, _Alloc()) { }
454
455 // __d(__p) must not throw.
456 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
457 : _M_impl(__p, __d, __a) { }
458
459 ~_Sp_counted_deleter() noexcept { }
460
461 virtual void
462 _M_dispose() noexcept
463 { _M_impl._M_del()(_M_impl._M_ptr); }
464
465 virtual void
466 _M_destroy() noexcept
467 {
468 typedef typename allocator_traits<_Alloc>::template
469 rebind_traits<_Sp_counted_deleter> _Alloc_traits;
470 typename _Alloc_traits::allocator_type __a(_M_impl._M_alloc());
471 _Alloc_traits::destroy(__a, this);
472 _Alloc_traits::deallocate(__a, this, 1);
473 }
474
475 virtual void*
476 _M_get_deleter(const std::type_info& __ti) noexcept
477 {
478 #ifdef __GXX_RTTI
479 return __ti == typeid(_Deleter) ? &_M_impl._M_del() : nullptr;
480 #else
481 return nullptr;
482 #endif
483 }
484
485 private:
486 _Impl _M_impl;
487 };
488
489 // helpers for make_shared / allocate_shared
490
491 struct _Sp_make_shared_tag { };
492
493 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
494 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
495 {
496 class _Impl : _Sp_ebo_helper<0, _Alloc>
497 {
498 typedef _Sp_ebo_helper<0, _Alloc> _A_base;
499
500 public:
501 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }
502
503 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }
504
505 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
506 };
507
508 public:
509 template<typename... _Args>
510 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
511 : _M_impl(__a)
512 {
513 // _GLIBCXX_RESOLVE_LIB_DEFECTS
514 // 2070. allocate_shared should use allocator_traits<A>::construct
515 allocator_traits<_Alloc>::construct(__a, _M_ptr(),
516 std::forward<_Args>(__args)...); // might throw
517 }
518
519 ~_Sp_counted_ptr_inplace() noexcept { }
520
521 virtual void
522 _M_dispose() noexcept
523 {
524 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
525 }
526
527 // Override because the allocator needs to know the dynamic type
528 virtual void
529 _M_destroy() noexcept
530 {
531 typedef typename allocator_traits<_Alloc>::template
532 rebind_traits<_Sp_counted_ptr_inplace> _Alloc_traits;
533 typename _Alloc_traits::allocator_type __a(_M_impl._M_alloc());
534 _Alloc_traits::destroy(__a, this);
535 _Alloc_traits::deallocate(__a, this, 1);
536 }
537
538 // Sneaky trick so __shared_ptr can get the managed pointer
539 virtual void*
540 _M_get_deleter(const std::type_info& __ti) noexcept
541 {
542 #ifdef __GXX_RTTI
543 if (__ti == typeid(_Sp_make_shared_tag))
544 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
545 #endif
546 return nullptr;
547 }
548
549 private:
550 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }
551
552 _Impl _M_impl;
553 };
554
555
556 template<_Lock_policy _Lp>
557 class __shared_count
558 {
559 public:
560 constexpr __shared_count() noexcept : _M_pi(0)
561 { }
562
563 template<typename _Ptr>
564 explicit
565 __shared_count(_Ptr __p) : _M_pi(0)
566 {
567 __try
568 {
569 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
570 }
571 __catch(...)
572 {
573 delete __p;
574 __throw_exception_again;
575 }
576 }
577
578 template<typename _Ptr, typename _Deleter>
579 __shared_count(_Ptr __p, _Deleter __d)
580 : __shared_count(__p, std::move(__d), allocator<void>())
581 { }
582
583 template<typename _Ptr, typename _Deleter, typename _Alloc>
584 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
585 {
586 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
587 typedef typename allocator_traits<_Alloc>::template
588 rebind_traits<_Sp_cd_type> _Alloc_traits;
589 typename _Alloc_traits::allocator_type __a2(__a);
590 _Sp_cd_type* __mem = 0;
591 __try
592 {
593 __mem = _Alloc_traits::allocate(__a2, 1);
594 _Alloc_traits::construct(__a2, __mem,
595 __p, std::move(__d), std::move(__a));
596 _M_pi = __mem;
597 }
598 __catch(...)
599 {
600 __d(__p); // Call _Deleter on __p.
601 if (__mem)
602 _Alloc_traits::deallocate(__a2, __mem, 1);
603 __throw_exception_again;
604 }
605 }
606
607 template<typename _Tp, typename _Alloc, typename... _Args>
608 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a,
609 _Args&&... __args)
610 : _M_pi(0)
611 {
612 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
613 typedef typename allocator_traits<_Alloc>::template
614 rebind_traits<_Sp_cp_type> _Alloc_traits;
615 typename _Alloc_traits::allocator_type __a2(__a);
616 _Sp_cp_type* __mem = _Alloc_traits::allocate(__a2, 1);
617 __try
618 {
619 _Alloc_traits::construct(__a2, __mem, std::move(__a),
620 std::forward<_Args>(__args)...);
621 _M_pi = __mem;
622 }
623 __catch(...)
624 {
625 _Alloc_traits::deallocate(__a2, __mem, 1);
626 __throw_exception_again;
627 }
628 }
629
630 #if _GLIBCXX_USE_DEPRECATED
631 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
632 template<typename _Tp>
633 explicit
634 __shared_count(std::auto_ptr<_Tp>&& __r);
635 #endif
636
637 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
638 template<typename _Tp, typename _Del>
639 explicit
640 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
641 {
642 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
643 using _Del2 = typename conditional<is_reference<_Del>::value,
644 reference_wrapper<typename remove_reference<_Del>::type>,
645 _Del>::type;
646 using _Sp_cd_type
647 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
648 using _Alloc = allocator<_Sp_cd_type>;
649 using _Alloc_traits = allocator_traits<_Alloc>;
650 _Alloc __a;
651 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
652 _Alloc_traits::construct(__a, __mem, __r.release(),
653 __r.get_deleter()); // non-throwing
654 _M_pi = __mem;
655 }
656
657 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
658 explicit __shared_count(const __weak_count<_Lp>& __r);
659
660 // Does not throw if __r._M_get_use_count() == 0, caller must check.
661 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
662
663 ~__shared_count() noexcept
664 {
665 if (_M_pi != nullptr)
666 _M_pi->_M_release();
667 }
668
669 __shared_count(const __shared_count& __r) noexcept
670 : _M_pi(__r._M_pi)
671 {
672 if (_M_pi != 0)
673 _M_pi->_M_add_ref_copy();
674 }
675
676 __shared_count&
677 operator=(const __shared_count& __r) noexcept
678 {
679 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
680 if (__tmp != _M_pi)
681 {
682 if (__tmp != 0)
683 __tmp->_M_add_ref_copy();
684 if (_M_pi != 0)
685 _M_pi->_M_release();
686 _M_pi = __tmp;
687 }
688 return *this;
689 }
690
691 void
692 _M_swap(__shared_count& __r) noexcept
693 {
694 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
695 __r._M_pi = _M_pi;
696 _M_pi = __tmp;
697 }
698
699 long
700 _M_get_use_count() const noexcept
701 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
702
703 bool
704 _M_unique() const noexcept
705 { return this->_M_get_use_count() == 1; }
706
707 void*
708 _M_get_deleter(const std::type_info& __ti) const noexcept
709 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }
710
711 bool
712 _M_less(const __shared_count& __rhs) const noexcept
713 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
714
715 bool
716 _M_less(const __weak_count<_Lp>& __rhs) const noexcept
717 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
718
719 // Friend function injected into enclosing namespace and found by ADL
720 friend inline bool
721 operator==(const __shared_count& __a, const __shared_count& __b) noexcept
722 { return __a._M_pi == __b._M_pi; }
723
724 private:
725 friend class __weak_count<_Lp>;
726
727 _Sp_counted_base<_Lp>* _M_pi;
728 };
729
730
731 template<_Lock_policy _Lp>
732 class __weak_count
733 {
734 public:
735 constexpr __weak_count() noexcept : _M_pi(0)
736 { }
737
738 __weak_count(const __shared_count<_Lp>& __r) noexcept
739 : _M_pi(__r._M_pi)
740 {
741 if (_M_pi != 0)
742 _M_pi->_M_weak_add_ref();
743 }
744
745 __weak_count(const __weak_count<_Lp>& __r) noexcept
746 : _M_pi(__r._M_pi)
747 {
748 if (_M_pi != 0)
749 _M_pi->_M_weak_add_ref();
750 }
751
752 ~__weak_count() noexcept
753 {
754 if (_M_pi != 0)
755 _M_pi->_M_weak_release();
756 }
757
758 __weak_count<_Lp>&
759 operator=(const __shared_count<_Lp>& __r) noexcept
760 {
761 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
762 if (__tmp != 0)
763 __tmp->_M_weak_add_ref();
764 if (_M_pi != 0)
765 _M_pi->_M_weak_release();
766 _M_pi = __tmp;
767 return *this;
768 }
769
770 __weak_count<_Lp>&
771 operator=(const __weak_count<_Lp>& __r) noexcept
772 {
773 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
774 if (__tmp != 0)
775 __tmp->_M_weak_add_ref();
776 if (_M_pi != 0)
777 _M_pi->_M_weak_release();
778 _M_pi = __tmp;
779 return *this;
780 }
781
782 void
783 _M_swap(__weak_count<_Lp>& __r) noexcept
784 {
785 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
786 __r._M_pi = _M_pi;
787 _M_pi = __tmp;
788 }
789
790 long
791 _M_get_use_count() const noexcept
792 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
793
794 bool
795 _M_less(const __weak_count& __rhs) const noexcept
796 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
797
798 bool
799 _M_less(const __shared_count<_Lp>& __rhs) const noexcept
800 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
801
802 // Friend function injected into enclosing namespace and found by ADL
803 friend inline bool
804 operator==(const __weak_count& __a, const __weak_count& __b) noexcept
805 { return __a._M_pi == __b._M_pi; }
806
807 private:
808 friend class __shared_count<_Lp>;
809
810 _Sp_counted_base<_Lp>* _M_pi;
811 };
812
813 // Now that __weak_count is defined we can define this constructor:
814 template<_Lock_policy _Lp>
815 inline
816 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
817 : _M_pi(__r._M_pi)
818 {
819 if (_M_pi != nullptr)
820 _M_pi->_M_add_ref_lock();
821 else
822 __throw_bad_weak_ptr();
823 }
824
825 // Now that __weak_count is defined we can define this constructor:
826 template<_Lock_policy _Lp>
827 inline
828 __shared_count<_Lp>::
829 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
830 : _M_pi(__r._M_pi)
831 {
832 if (_M_pi != nullptr)
833 if (!_M_pi->_M_add_ref_lock_nothrow())
834 _M_pi = nullptr;
835 }
836
837 // Support for enable_shared_from_this.
838
839 // Friend of __enable_shared_from_this.
840 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2>
841 void
842 __enable_shared_from_this_helper(const __shared_count<_Lp>&,
843 const __enable_shared_from_this<_Tp1,
844 _Lp>*, const _Tp2*) noexcept;
845
846 // Friend of enable_shared_from_this.
847 template<typename _Tp1, typename _Tp2>
848 void
849 __enable_shared_from_this_helper(const __shared_count<>&,
850 const enable_shared_from_this<_Tp1>*,
851 const _Tp2*) noexcept;
852
853 template<_Lock_policy _Lp>
854 inline void
855 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept
856 { }
857
858
859 template<typename _Tp, _Lock_policy _Lp>
860 class __shared_ptr
861 {
862 public:
863 typedef _Tp element_type;
864
865 constexpr __shared_ptr() noexcept
866 : _M_ptr(0), _M_refcount()
867 { }
868
869 template<typename _Tp1>
870 explicit __shared_ptr(_Tp1* __p)
871 : _M_ptr(__p), _M_refcount(__p)
872 {
873 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
874 static_assert( !is_void<_Tp>::value, "incomplete type" );
875 static_assert( sizeof(_Tp1) > 0, "incomplete type" );
876 __enable_shared_from_this_helper(_M_refcount, __p, __p);
877 }
878
879 template<typename _Tp1, typename _Deleter>
880 __shared_ptr(_Tp1* __p, _Deleter __d)
881 : _M_ptr(__p), _M_refcount(__p, __d)
882 {
883 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
884 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
885 __enable_shared_from_this_helper(_M_refcount, __p, __p);
886 }
887
888 template<typename _Tp1, typename _Deleter, typename _Alloc>
889 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
890 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a))
891 {
892 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
893 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
894 __enable_shared_from_this_helper(_M_refcount, __p, __p);
895 }
896
897 template<typename _Deleter>
898 __shared_ptr(nullptr_t __p, _Deleter __d)
899 : _M_ptr(0), _M_refcount(__p, __d)
900 { }
901
902 template<typename _Deleter, typename _Alloc>
903 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
904 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a))
905 { }
906
907 template<typename _Tp1>
908 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) noexcept
909 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
910 { }
911
912 __shared_ptr(const __shared_ptr&) noexcept = default;
913 __shared_ptr& operator=(const __shared_ptr&) noexcept = default;
914 ~__shared_ptr() = default;
915
916 template<typename _Tp1, typename = typename
917 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
918 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
919 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
920 { }
921
922 __shared_ptr(__shared_ptr&& __r) noexcept
923 : _M_ptr(__r._M_ptr), _M_refcount()
924 {
925 _M_refcount._M_swap(__r._M_refcount);
926 __r._M_ptr = 0;
927 }
928
929 template<typename _Tp1, typename = typename
930 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
931 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept
932 : _M_ptr(__r._M_ptr), _M_refcount()
933 {
934 _M_refcount._M_swap(__r._M_refcount);
935 __r._M_ptr = 0;
936 }
937
938 template<typename _Tp1>
939 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
940 : _M_refcount(__r._M_refcount) // may throw
941 {
942 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
943
944 // It is now safe to copy __r._M_ptr, as
945 // _M_refcount(__r._M_refcount) did not throw.
946 _M_ptr = __r._M_ptr;
947 }
948
949 // If an exception is thrown this constructor has no effect.
950 template<typename _Tp1, typename _Del>
951 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
952 : _M_ptr(__r.get()), _M_refcount()
953 {
954 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
955 auto __raw = _S_raw_ptr(__r.get());
956 _M_refcount = __shared_count<_Lp>(std::move(__r));
957 __enable_shared_from_this_helper(_M_refcount, __raw, __raw);
958 }
959
960 #if _GLIBCXX_USE_DEPRECATED
961 // Postcondition: use_count() == 1 and __r.get() == 0
962 template<typename _Tp1>
963 __shared_ptr(std::auto_ptr<_Tp1>&& __r);
964 #endif
965
966 /* TODO: use delegating constructor */
967 constexpr __shared_ptr(nullptr_t) noexcept
968 : _M_ptr(0), _M_refcount()
969 { }
970
971 template<typename _Tp1>
972 __shared_ptr&
973 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
974 {
975 _M_ptr = __r._M_ptr;
976 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
977 return *this;
978 }
979
980 #if _GLIBCXX_USE_DEPRECATED
981 template<typename _Tp1>
982 __shared_ptr&
983 operator=(std::auto_ptr<_Tp1>&& __r)
984 {
985 __shared_ptr(std::move(__r)).swap(*this);
986 return *this;
987 }
988 #endif
989
990 __shared_ptr&
991 operator=(__shared_ptr&& __r) noexcept
992 {
993 __shared_ptr(std::move(__r)).swap(*this);
994 return *this;
995 }
996
997 template<class _Tp1>
998 __shared_ptr&
999 operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept
1000 {
1001 __shared_ptr(std::move(__r)).swap(*this);
1002 return *this;
1003 }
1004
1005 template<typename _Tp1, typename _Del>
1006 __shared_ptr&
1007 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
1008 {
1009 __shared_ptr(std::move(__r)).swap(*this);
1010 return *this;
1011 }
1012
1013 void
1014 reset() noexcept
1015 { __shared_ptr().swap(*this); }
1016
1017 template<typename _Tp1>
1018 void
1019 reset(_Tp1* __p) // _Tp1 must be complete.
1020 {
1021 // Catch self-reset errors.
1022 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr);
1023 __shared_ptr(__p).swap(*this);
1024 }
1025
1026 template<typename _Tp1, typename _Deleter>
1027 void
1028 reset(_Tp1* __p, _Deleter __d)
1029 { __shared_ptr(__p, __d).swap(*this); }
1030
1031 template<typename _Tp1, typename _Deleter, typename _Alloc>
1032 void
1033 reset(_Tp1* __p, _Deleter __d, _Alloc __a)
1034 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); }
1035
1036 // Allow class instantiation when _Tp is [cv-qual] void.
1037 typename std::add_lvalue_reference<_Tp>::type
1038 operator*() const noexcept
1039 {
1040 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
1041 return *_M_ptr;
1042 }
1043
1044 _Tp*
1045 operator->() const noexcept
1046 {
1047 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
1048 return _M_ptr;
1049 }
1050
1051 _Tp*
1052 get() const noexcept
1053 { return _M_ptr; }
1054
1055 explicit operator bool() const // never throws
1056 { return _M_ptr == 0 ? false : true; }
1057
1058 bool
1059 unique() const noexcept
1060 { return _M_refcount._M_unique(); }
1061
1062 long
1063 use_count() const noexcept
1064 { return _M_refcount._M_get_use_count(); }
1065
1066 void
1067 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
1068 {
1069 std::swap(_M_ptr, __other._M_ptr);
1070 _M_refcount._M_swap(__other._M_refcount);
1071 }
1072
1073 template<typename _Tp1>
1074 bool
1075 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const
1076 { return _M_refcount._M_less(__rhs._M_refcount); }
1077
1078 template<typename _Tp1>
1079 bool
1080 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const
1081 { return _M_refcount._M_less(__rhs._M_refcount); }
1082
1083 #ifdef __GXX_RTTI
1084 protected:
1085 // This constructor is non-standard, it is used by allocate_shared.
1086 template<typename _Alloc, typename... _Args>
1087 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1088 _Args&&... __args)
1089 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
1090 std::forward<_Args>(__args)...)
1091 {
1092 // _M_ptr needs to point to the newly constructed object.
1093 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
1094 void* __p = _M_refcount._M_get_deleter(typeid(__tag));
1095 _M_ptr = static_cast<_Tp*>(__p);
1096 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
1097 }
1098 #else
1099 template<typename _Alloc>
1100 struct _Deleter
1101 {
1102 void operator()(_Tp* __ptr)
1103 {
1104 typedef allocator_traits<_Alloc> _Alloc_traits;
1105 _Alloc_traits::destroy(_M_alloc, __ptr);
1106 _Alloc_traits::deallocate(_M_alloc, __ptr, 1);
1107 }
1108 _Alloc _M_alloc;
1109 };
1110
1111 template<typename _Alloc, typename... _Args>
1112 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1113 _Args&&... __args)
1114 : _M_ptr(), _M_refcount()
1115 {
1116 typedef typename _Alloc::template rebind<_Tp>::other _Alloc2;
1117 _Deleter<_Alloc2> __del = { _Alloc2(__a) };
1118 typedef allocator_traits<_Alloc2> __traits;
1119 _M_ptr = __traits::allocate(__del._M_alloc, 1);
1120 __try
1121 {
1122 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1123 // 2070. allocate_shared should use allocator_traits<A>::construct
1124 __traits::construct(__del._M_alloc, _M_ptr,
1125 std::forward<_Args>(__args)...);
1126 }
1127 __catch(...)
1128 {
1129 __traits::deallocate(__del._M_alloc, _M_ptr, 1);
1130 __throw_exception_again;
1131 }
1132 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc);
1133 _M_refcount._M_swap(__count);
1134 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
1135 }
1136 #endif
1137
1138 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
1139 typename... _Args>
1140 friend __shared_ptr<_Tp1, _Lp1>
1141 __allocate_shared(const _Alloc& __a, _Args&&... __args);
1142
1143 // This constructor is used by __weak_ptr::lock() and
1144 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
1145 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
1146 : _M_refcount(__r._M_refcount, std::nothrow)
1147 {
1148 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
1149 }
1150
1151 friend class __weak_ptr<_Tp, _Lp>;
1152
1153 private:
1154 void*
1155 _M_get_deleter(const std::type_info& __ti) const noexcept
1156 { return _M_refcount._M_get_deleter(__ti); }
1157
1158 template<typename _Tp1>
1159 static _Tp1*
1160 _S_raw_ptr(_Tp1* __ptr)
1161 { return __ptr; }
1162
1163 template<typename _Tp1>
1164 static auto
1165 _S_raw_ptr(_Tp1 __ptr) -> decltype(std::__addressof(*__ptr))
1166 { return std::__addressof(*__ptr); }
1167
1168 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1169 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1170
1171 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
1172 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;
1173
1174 _Tp* _M_ptr; // Contained pointer.
1175 __shared_count<_Lp> _M_refcount; // Reference counter.
1176 };
1177
1178
1179 // 20.7.2.2.7 shared_ptr comparisons
1180 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1181 inline bool
1182 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
1183 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1184 { return __a.get() == __b.get(); }
1185
1186 template<typename _Tp, _Lock_policy _Lp>
1187 inline bool
1188 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1189 { return !__a; }
1190
1191 template<typename _Tp, _Lock_policy _Lp>
1192 inline bool
1193 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1194 { return !__a; }
1195
1196 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1197 inline bool
1198 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
1199 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1200 { return __a.get() != __b.get(); }
1201
1202 template<typename _Tp, _Lock_policy _Lp>
1203 inline bool
1204 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1205 { return (bool)__a; }
1206
1207 template<typename _Tp, _Lock_policy _Lp>
1208 inline bool
1209 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1210 { return (bool)__a; }
1211
1212 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1213 inline bool
1214 operator<(const __shared_ptr<_Tp1, _Lp>& __a,
1215 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1216 {
1217 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT;
1218 return std::less<_CT>()(__a.get(), __b.get());
1219 }
1220
1221 template<typename _Tp, _Lock_policy _Lp>
1222 inline bool
1223 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1224 { return std::less<_Tp*>()(__a.get(), nullptr); }
1225
1226 template<typename _Tp, _Lock_policy _Lp>
1227 inline bool
1228 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1229 { return std::less<_Tp*>()(nullptr, __a.get()); }
1230
1231 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1232 inline bool
1233 operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
1234 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1235 { return !(__b < __a); }
1236
1237 template<typename _Tp, _Lock_policy _Lp>
1238 inline bool
1239 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1240 { return !(nullptr < __a); }
1241
1242 template<typename _Tp, _Lock_policy _Lp>
1243 inline bool
1244 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1245 { return !(__a < nullptr); }
1246
1247 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1248 inline bool
1249 operator>(const __shared_ptr<_Tp1, _Lp>& __a,
1250 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1251 { return (__b < __a); }
1252
1253 template<typename _Tp, _Lock_policy _Lp>
1254 inline bool
1255 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1256 { return std::less<_Tp*>()(nullptr, __a.get()); }
1257
1258 template<typename _Tp, _Lock_policy _Lp>
1259 inline bool
1260 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1261 { return std::less<_Tp*>()(__a.get(), nullptr); }
1262
1263 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1264 inline bool
1265 operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
1266 const __shared_ptr<_Tp2, _Lp>& __b) noexcept
1267 { return !(__a < __b); }
1268
1269 template<typename _Tp, _Lock_policy _Lp>
1270 inline bool
1271 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
1272 { return !(__a < nullptr); }
1273
1274 template<typename _Tp, _Lock_policy _Lp>
1275 inline bool
1276 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
1277 { return !(nullptr < __a); }
1278
1279 template<typename _Sp>
1280 struct _Sp_less : public binary_function<_Sp, _Sp, bool>
1281 {
1282 bool
1283 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept
1284 {
1285 typedef typename _Sp::element_type element_type;
1286 return std::less<element_type*>()(__lhs.get(), __rhs.get());
1287 }
1288 };
1289
1290 template<typename _Tp, _Lock_policy _Lp>
1291 struct less<__shared_ptr<_Tp, _Lp>>
1292 : public _Sp_less<__shared_ptr<_Tp, _Lp>>
1293 { };
1294
1295 // 20.7.2.2.8 shared_ptr specialized algorithms.
1296 template<typename _Tp, _Lock_policy _Lp>
1297 inline void
1298 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
1299 { __a.swap(__b); }
1300
1301 // 20.7.2.2.9 shared_ptr casts
1302
1303 // The seemingly equivalent code:
1304 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
1305 // will eventually result in undefined behaviour, attempting to
1306 // delete the same object twice.
1307 /// static_pointer_cast
1308 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1309 inline __shared_ptr<_Tp, _Lp>
1310 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1311 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); }
1312
1313 // The seemingly equivalent code:
1314 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
1315 // will eventually result in undefined behaviour, attempting to
1316 // delete the same object twice.
1317 /// const_pointer_cast
1318 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1319 inline __shared_ptr<_Tp, _Lp>
1320 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1321 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); }
1322
1323 // The seemingly equivalent code:
1324 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
1325 // will eventually result in undefined behaviour, attempting to
1326 // delete the same object twice.
1327 /// dynamic_pointer_cast
1328 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1329 inline __shared_ptr<_Tp, _Lp>
1330 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1331 {
1332 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
1333 return __shared_ptr<_Tp, _Lp>(__r, __p);
1334 return __shared_ptr<_Tp, _Lp>();
1335 }
1336
1337
1338 template<typename _Tp, _Lock_policy _Lp>
1339 class __weak_ptr
1340 {
1341 public:
1342 typedef _Tp element_type;
1343
1344 constexpr __weak_ptr() noexcept
1345 : _M_ptr(0), _M_refcount()
1346 { }
1347
1348 __weak_ptr(const __weak_ptr&) noexcept = default;
1349 __weak_ptr& operator=(const __weak_ptr&) noexcept = default;
1350 ~__weak_ptr() = default;
1351
1352 // The "obvious" converting constructor implementation:
1353 //
1354 // template<typename _Tp1>
1355 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1356 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1357 // { }
1358 //
1359 // has a serious problem.
1360 //
1361 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1362 // conversion may require access to *__r._M_ptr (virtual inheritance).
1363 //
1364 // It is not possible to avoid spurious access violations since
1365 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1366 template<typename _Tp1, typename = typename
1367 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
1368 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept
1369 : _M_refcount(__r._M_refcount)
1370 { _M_ptr = __r.lock().get(); }
1371
1372 template<typename _Tp1, typename = typename
1373 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
1374 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1375 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
1376 { }
1377
1378 template<typename _Tp1>
1379 __weak_ptr&
1380 operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept
1381 {
1382 _M_ptr = __r.lock().get();
1383 _M_refcount = __r._M_refcount;
1384 return *this;
1385 }
1386
1387 template<typename _Tp1>
1388 __weak_ptr&
1389 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
1390 {
1391 _M_ptr = __r._M_ptr;
1392 _M_refcount = __r._M_refcount;
1393 return *this;
1394 }
1395
1396 __shared_ptr<_Tp, _Lp>
1397 lock() const noexcept
1398 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
1399
1400 long
1401 use_count() const noexcept
1402 { return _M_refcount._M_get_use_count(); }
1403
1404 bool
1405 expired() const noexcept
1406 { return _M_refcount._M_get_use_count() == 0; }
1407
1408 template<typename _Tp1>
1409 bool
1410 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const
1411 { return _M_refcount._M_less(__rhs._M_refcount); }
1412
1413 template<typename _Tp1>
1414 bool
1415 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const
1416 { return _M_refcount._M_less(__rhs._M_refcount); }
1417
1418 void
1419 reset() noexcept
1420 { __weak_ptr().swap(*this); }
1421
1422 void
1423 swap(__weak_ptr& __s) noexcept
1424 {
1425 std::swap(_M_ptr, __s._M_ptr);
1426 _M_refcount._M_swap(__s._M_refcount);
1427 }
1428
1429 private:
1430 // Used by __enable_shared_from_this.
1431 void
1432 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
1433 {
1434 _M_ptr = __ptr;
1435 _M_refcount = __refcount;
1436 }
1437
1438 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1439 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1440 friend class __enable_shared_from_this<_Tp, _Lp>;
1441 friend class enable_shared_from_this<_Tp>;
1442
1443 _Tp* _M_ptr; // Contained pointer.
1444 __weak_count<_Lp> _M_refcount; // Reference counter.
1445 };
1446
1447 // 20.7.2.3.6 weak_ptr specialized algorithms.
1448 template<typename _Tp, _Lock_policy _Lp>
1449 inline void
1450 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
1451 { __a.swap(__b); }
1452
1453 template<typename _Tp, typename _Tp1>
1454 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1455 {
1456 bool
1457 operator()(const _Tp& __lhs, const _Tp& __rhs) const
1458 { return __lhs.owner_before(__rhs); }
1459
1460 bool
1461 operator()(const _Tp& __lhs, const _Tp1& __rhs) const
1462 { return __lhs.owner_before(__rhs); }
1463
1464 bool
1465 operator()(const _Tp1& __lhs, const _Tp& __rhs) const
1466 { return __lhs.owner_before(__rhs); }
1467 };
1468
1469 template<typename _Tp, _Lock_policy _Lp>
1470 struct owner_less<__shared_ptr<_Tp, _Lp>>
1471 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1472 { };
1473
1474 template<typename _Tp, _Lock_policy _Lp>
1475 struct owner_less<__weak_ptr<_Tp, _Lp>>
1476 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1477 { };
1478
1479
1480 template<typename _Tp, _Lock_policy _Lp>
1481 class __enable_shared_from_this
1482 {
1483 protected:
1484 constexpr __enable_shared_from_this() noexcept { }
1485
1486 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { }
1487
1488 __enable_shared_from_this&
1489 operator=(const __enable_shared_from_this&) noexcept
1490 { return *this; }
1491
1492 ~__enable_shared_from_this() { }
1493
1494 public:
1495 __shared_ptr<_Tp, _Lp>
1496 shared_from_this()
1497 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1498
1499 __shared_ptr<const _Tp, _Lp>
1500 shared_from_this() const
1501 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1502
1503 private:
1504 template<typename _Tp1>
1505 void
1506 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
1507 { _M_weak_this._M_assign(__p, __n); }
1508
1509 template<typename _Tp1>
1510 friend void
1511 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn,
1512 const __enable_shared_from_this* __pe,
1513 const _Tp1* __px) noexcept
1514 {
1515 if (__pe != 0)
1516 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
1517 }
1518
1519 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1520 };
1521
1522
1523 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
1524 inline __shared_ptr<_Tp, _Lp>
1525 __allocate_shared(const _Alloc& __a, _Args&&... __args)
1526 {
1527 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a,
1528 std::forward<_Args>(__args)...);
1529 }
1530
1531 template<typename _Tp, _Lock_policy _Lp, typename... _Args>
1532 inline __shared_ptr<_Tp, _Lp>
1533 __make_shared(_Args&&... __args)
1534 {
1535 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1536 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1537 std::forward<_Args>(__args)...);
1538 }
1539
1540 /// std::hash specialization for __shared_ptr.
1541 template<typename _Tp, _Lock_policy _Lp>
1542 struct hash<__shared_ptr<_Tp, _Lp>>
1543 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
1544 {
1545 size_t
1546 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
1547 { return std::hash<_Tp*>()(__s.get()); }
1548 };
1549
1550 _GLIBCXX_END_NAMESPACE_VERSION
1551 } // namespace
1552
1553 #endif // _SHARED_PTR_BASE_H