1 // shared_ptr and weak_ptr implementation -*- C++ -*-
2
3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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.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_H
50 #define _SHARED_PTR_H 1
51
52 #include <bits/shared_ptr_base.h>
53
_GLIBCXX_VISIBILITY(default)54 namespace std _GLIBCXX_VISIBILITY(default)
55 {
56 _GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58 /**
59 * @addtogroup pointer_abstractions
60 * @{
61 */
62
63 /// 2.2.3.7 shared_ptr I/O
64 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
65 inline std::basic_ostream<_Ch, _Tr>&
66 operator<<(std::basic_ostream<_Ch, _Tr>& __os,
67 const __shared_ptr<_Tp, _Lp>& __p)
68 {
69 __os << __p.get();
70 return __os;
71 }
72
73 /// 2.2.3.10 shared_ptr get_deleter (experimental)
74 template<typename _Del, typename _Tp, _Lock_policy _Lp>
75 inline _Del*
76 get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
77 {
78 #ifdef __GXX_RTTI
79 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
80 #else
81 return 0;
82 #endif
83 }
84
85
86 /**
87 * @brief A smart pointer with reference-counted copy semantics.
88 *
89 * The object pointed to is deleted when the last shared_ptr pointing to
90 * it is destroyed or reset.
91 */
92 template<typename _Tp>
93 class shared_ptr : public __shared_ptr<_Tp>
94 {
95 public:
96 /**
97 * @brief Construct an empty %shared_ptr.
98 * @post use_count()==0 && get()==0
99 */
100 constexpr shared_ptr() noexcept
101 : __shared_ptr<_Tp>() { }
102
103 shared_ptr(const shared_ptr&) noexcept = default;
104
105 /**
106 * @brief Construct a %shared_ptr that owns the pointer @a __p.
107 * @param __p A pointer that is convertible to element_type*.
108 * @post use_count() == 1 && get() == __p
109 * @throw std::bad_alloc, in which case @c delete @a __p is called.
110 */
111 template<typename _Tp1>
112 explicit shared_ptr(_Tp1* __p)
113 : __shared_ptr<_Tp>(__p) { }
114
115 /**
116 * @brief Construct a %shared_ptr that owns the pointer @a __p
117 * and the deleter @a __d.
118 * @param __p A pointer.
119 * @param __d A deleter.
120 * @post use_count() == 1 && get() == __p
121 * @throw std::bad_alloc, in which case @a __d(__p) is called.
122 *
123 * Requirements: _Deleter's copy constructor and destructor must
124 * not throw
125 *
126 * __shared_ptr will release __p by calling __d(__p)
127 */
128 template<typename _Tp1, typename _Deleter>
129 shared_ptr(_Tp1* __p, _Deleter __d)
130 : __shared_ptr<_Tp>(__p, __d) { }
131
132 /**
133 * @brief Construct a %shared_ptr that owns a null pointer
134 * and the deleter @a __d.
135 * @param __p A null pointer constant.
136 * @param __d A deleter.
137 * @post use_count() == 1 && get() == __p
138 * @throw std::bad_alloc, in which case @a __d(__p) is called.
139 *
140 * Requirements: _Deleter's copy constructor and destructor must
141 * not throw
142 *
143 * The last owner will call __d(__p)
144 */
145 template<typename _Deleter>
146 shared_ptr(nullptr_t __p, _Deleter __d)
147 : __shared_ptr<_Tp>(__p, __d) { }
148
149 /**
150 * @brief Construct a %shared_ptr that owns the pointer @a __p
151 * and the deleter @a __d.
152 * @param __p A pointer.
153 * @param __d A deleter.
154 * @param __a An allocator.
155 * @post use_count() == 1 && get() == __p
156 * @throw std::bad_alloc, in which case @a __d(__p) is called.
157 *
158 * Requirements: _Deleter's copy constructor and destructor must
159 * not throw _Alloc's copy constructor and destructor must not
160 * throw.
161 *
162 * __shared_ptr will release __p by calling __d(__p)
163 */
164 template<typename _Tp1, typename _Deleter, typename _Alloc>
165 shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
166 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
167
168 /**
169 * @brief Construct a %shared_ptr that owns a null pointer
170 * and the deleter @a __d.
171 * @param __p A null pointer constant.
172 * @param __d A deleter.
173 * @param __a An allocator.
174 * @post use_count() == 1 && get() == __p
175 * @throw std::bad_alloc, in which case @a __d(__p) is called.
176 *
177 * Requirements: _Deleter's copy constructor and destructor must
178 * not throw _Alloc's copy constructor and destructor must not
179 * throw.
180 *
181 * The last owner will call __d(__p)
182 */
183 template<typename _Deleter, typename _Alloc>
184 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
185 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
186
187 // Aliasing constructor
188
189 /**
190 * @brief Constructs a %shared_ptr instance that stores @a __p
191 * and shares ownership with @a __r.
192 * @param __r A %shared_ptr.
193 * @param __p A pointer that will remain valid while @a *__r is valid.
194 * @post get() == __p && use_count() == __r.use_count()
195 *
196 * This can be used to construct a @c shared_ptr to a sub-object
197 * of an object managed by an existing @c shared_ptr.
198 *
199 * @code
200 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
201 * shared_ptr<int> pi(pii, &pii->first);
202 * assert(pii.use_count() == 2);
203 * @endcode
204 */
205 template<typename _Tp1>
206 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p) noexcept
207 : __shared_ptr<_Tp>(__r, __p) { }
208
209 /**
210 * @brief If @a __r is empty, constructs an empty %shared_ptr;
211 * otherwise construct a %shared_ptr that shares ownership
212 * with @a __r.
213 * @param __r A %shared_ptr.
214 * @post get() == __r.get() && use_count() == __r.use_count()
215 */
216 template<typename _Tp1, typename = typename
217 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
218 shared_ptr(const shared_ptr<_Tp1>& __r) noexcept
219 : __shared_ptr<_Tp>(__r) { }
220
221 /**
222 * @brief Move-constructs a %shared_ptr instance from @a __r.
223 * @param __r A %shared_ptr rvalue.
224 * @post *this contains the old value of @a __r, @a __r is empty.
225 */
226 shared_ptr(shared_ptr&& __r) noexcept
227 : __shared_ptr<_Tp>(std::move(__r)) { }
228
229 /**
230 * @brief Move-constructs a %shared_ptr instance from @a __r.
231 * @param __r A %shared_ptr rvalue.
232 * @post *this contains the old value of @a __r, @a __r is empty.
233 */
234 template<typename _Tp1, typename = typename
235 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
236 shared_ptr(shared_ptr<_Tp1>&& __r) noexcept
237 : __shared_ptr<_Tp>(std::move(__r)) { }
238
239 /**
240 * @brief Constructs a %shared_ptr that shares ownership with @a __r
241 * and stores a copy of the pointer stored in @a __r.
242 * @param __r A weak_ptr.
243 * @post use_count() == __r.use_count()
244 * @throw bad_weak_ptr when __r.expired(),
245 * in which case the constructor has no effect.
246 */
247 template<typename _Tp1>
248 explicit shared_ptr(const weak_ptr<_Tp1>& __r)
249 : __shared_ptr<_Tp>(__r) { }
250
251 #if _GLIBCXX_USE_DEPRECATED
252 template<typename _Tp1>
253 shared_ptr(std::auto_ptr<_Tp1>&& __r)
254 : __shared_ptr<_Tp>(std::move(__r)) { }
255 #endif
256
257 template<typename _Tp1, typename _Del>
258 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
259 : __shared_ptr<_Tp>(std::move(__r)) { }
260
261 /**
262 * @brief Construct an empty %shared_ptr.
263 * @param __p A null pointer constant.
264 * @post use_count() == 0 && get() == nullptr
265 */
266 constexpr shared_ptr(nullptr_t __p) noexcept
267 : __shared_ptr<_Tp>(__p) { }
268
269 shared_ptr& operator=(const shared_ptr&) noexcept = default;
270
271 template<typename _Tp1>
272 shared_ptr&
273 operator=(const shared_ptr<_Tp1>& __r) noexcept
274 {
275 this->__shared_ptr<_Tp>::operator=(__r);
276 return *this;
277 }
278
279 #if _GLIBCXX_USE_DEPRECATED
280 template<typename _Tp1>
281 shared_ptr&
282 operator=(std::auto_ptr<_Tp1>&& __r)
283 {
284 this->__shared_ptr<_Tp>::operator=(std::move(__r));
285 return *this;
286 }
287 #endif
288
289 shared_ptr&
290 operator=(shared_ptr&& __r) noexcept
291 {
292 this->__shared_ptr<_Tp>::operator=(std::move(__r));
293 return *this;
294 }
295
296 template<class _Tp1>
297 shared_ptr&
298 operator=(shared_ptr<_Tp1>&& __r) noexcept
299 {
300 this->__shared_ptr<_Tp>::operator=(std::move(__r));
301 return *this;
302 }
303
304 template<typename _Tp1, typename _Del>
305 shared_ptr&
306 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
307 {
308 this->__shared_ptr<_Tp>::operator=(std::move(__r));
309 return *this;
310 }
311
312 private:
313 // This constructor is non-standard, it is used by allocate_shared.
314 template<typename _Alloc, typename... _Args>
315 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
316 _Args&&... __args)
317 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
318 { }
319
320 template<typename _Tp1, typename _Alloc, typename... _Args>
321 friend shared_ptr<_Tp1>
322 allocate_shared(const _Alloc& __a, _Args&&... __args);
323 };
324
325 // 20.8.13.2.7 shared_ptr comparisons
326 template<typename _Tp1, typename _Tp2>
327 inline bool
328 operator==(const shared_ptr<_Tp1>& __a,
329 const shared_ptr<_Tp2>& __b) noexcept
330 { return __a.get() == __b.get(); }
331
332 template<typename _Tp>
333 inline bool
334 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
335 { return !__a; }
336
337 template<typename _Tp>
338 inline bool
339 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
340 { return !__a; }
341
342 template<typename _Tp1, typename _Tp2>
343 inline bool
344 operator!=(const shared_ptr<_Tp1>& __a,
345 const shared_ptr<_Tp2>& __b) noexcept
346 { return __a.get() != __b.get(); }
347
348 template<typename _Tp>
349 inline bool
350 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
351 { return (bool)__a; }
352
353 template<typename _Tp>
354 inline bool
355 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
356 { return (bool)__a; }
357
358 template<typename _Tp1, typename _Tp2>
359 inline bool
360 operator<(const shared_ptr<_Tp1>& __a,
361 const shared_ptr<_Tp2>& __b) noexcept
362 {
363 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT;
364 return std::less<_CT>()(__a.get(), __b.get());
365 }
366
367 template<typename _Tp>
368 inline bool
369 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
370 { return std::less<_Tp*>()(__a.get(), nullptr); }
371
372 template<typename _Tp>
373 inline bool
374 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
375 { return std::less<_Tp*>()(nullptr, __a.get()); }
376
377 template<typename _Tp1, typename _Tp2>
378 inline bool
379 operator<=(const shared_ptr<_Tp1>& __a,
380 const shared_ptr<_Tp2>& __b) noexcept
381 { return !(__b < __a); }
382
383 template<typename _Tp>
384 inline bool
385 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
386 { return !(nullptr < __a); }
387
388 template<typename _Tp>
389 inline bool
390 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
391 { return !(__a < nullptr); }
392
393 template<typename _Tp1, typename _Tp2>
394 inline bool
395 operator>(const shared_ptr<_Tp1>& __a,
396 const shared_ptr<_Tp2>& __b) noexcept
397 { return (__b < __a); }
398
399 template<typename _Tp>
400 inline bool
401 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
402 { return std::less<_Tp*>()(nullptr, __a.get()); }
403
404 template<typename _Tp>
405 inline bool
406 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
407 { return std::less<_Tp*>()(__a.get(), nullptr); }
408
409 template<typename _Tp1, typename _Tp2>
410 inline bool
411 operator>=(const shared_ptr<_Tp1>& __a,
412 const shared_ptr<_Tp2>& __b) noexcept
413 { return !(__a < __b); }
414
415 template<typename _Tp>
416 inline bool
417 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
418 { return !(__a < nullptr); }
419
420 template<typename _Tp>
421 inline bool
422 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
423 { return !(nullptr < __a); }
424
425 template<typename _Tp>
426 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
427 { };
428
429 // 20.8.13.2.9 shared_ptr specialized algorithms.
430 template<typename _Tp>
431 inline void
432 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
433 { __a.swap(__b); }
434
435 // 20.8.13.2.10 shared_ptr casts.
436 template<typename _Tp, typename _Tp1>
437 inline shared_ptr<_Tp>
438 static_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
439 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
440
441 template<typename _Tp, typename _Tp1>
442 inline shared_ptr<_Tp>
443 const_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
444 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
445
446 template<typename _Tp, typename _Tp1>
447 inline shared_ptr<_Tp>
448 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
449 {
450 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
451 return shared_ptr<_Tp>(__r, __p);
452 return shared_ptr<_Tp>();
453 }
454
455
456 /**
457 * @brief A smart pointer with weak semantics.
458 *
459 * With forwarding constructors and assignment operators.
460 */
461 template<typename _Tp>
462 class weak_ptr : public __weak_ptr<_Tp>
463 {
464 public:
465 constexpr weak_ptr() noexcept
466 : __weak_ptr<_Tp>() { }
467
468 template<typename _Tp1, typename = typename
469 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
470 weak_ptr(const weak_ptr<_Tp1>& __r) noexcept
471 : __weak_ptr<_Tp>(__r) { }
472
473 template<typename _Tp1, typename = typename
474 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
475 weak_ptr(const shared_ptr<_Tp1>& __r) noexcept
476 : __weak_ptr<_Tp>(__r) { }
477
478 template<typename _Tp1>
479 weak_ptr&
480 operator=(const weak_ptr<_Tp1>& __r) noexcept
481 {
482 this->__weak_ptr<_Tp>::operator=(__r);
483 return *this;
484 }
485
486 template<typename _Tp1>
487 weak_ptr&
488 operator=(const shared_ptr<_Tp1>& __r) noexcept
489 {
490 this->__weak_ptr<_Tp>::operator=(__r);
491 return *this;
492 }
493
494 shared_ptr<_Tp>
495 lock() const noexcept
496 {
497 #ifdef __GTHREADS
498 if (this->expired())
499 return shared_ptr<_Tp>();
500
501 __try
502 {
503 return shared_ptr<_Tp>(*this);
504 }
505 __catch(const bad_weak_ptr&)
506 {
507 return shared_ptr<_Tp>();
508 }
509 #else
510 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
511 #endif
512 }
513 };
514
515 // 20.8.13.3.7 weak_ptr specialized algorithms.
516 template<typename _Tp>
517 inline void
518 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
519 { __a.swap(__b); }
520
521
522 /// Primary template owner_less
523 template<typename _Tp>
524 struct owner_less;
525
526 /// Partial specialization of owner_less for shared_ptr.
527 template<typename _Tp>
528 struct owner_less<shared_ptr<_Tp>>
529 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
530 { };
531
532 /// Partial specialization of owner_less for weak_ptr.
533 template<typename _Tp>
534 struct owner_less<weak_ptr<_Tp>>
535 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
536 { };
537
538 /**
539 * @brief Base class allowing use of member function shared_from_this.
540 */
541 template<typename _Tp>
542 class enable_shared_from_this
543 {
544 protected:
545 constexpr enable_shared_from_this() noexcept { }
546
547 enable_shared_from_this(const enable_shared_from_this&) noexcept { }
548
549 enable_shared_from_this&
550 operator=(const enable_shared_from_this&) noexcept
551 { return *this; }
552
553 ~enable_shared_from_this() { }
554
555 public:
556 shared_ptr<_Tp>
557 shared_from_this()
558 { return shared_ptr<_Tp>(this->_M_weak_this); }
559
560 shared_ptr<const _Tp>
561 shared_from_this() const
562 { return shared_ptr<const _Tp>(this->_M_weak_this); }
563
564 private:
565 template<typename _Tp1>
566 void
567 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
568 { _M_weak_this._M_assign(__p, __n); }
569
570 template<typename _Tp1>
571 friend void
572 __enable_shared_from_this_helper(const __shared_count<>& __pn,
573 const enable_shared_from_this* __pe,
574 const _Tp1* __px) noexcept
575 {
576 if (__pe != 0)
577 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
578 }
579
580 mutable weak_ptr<_Tp> _M_weak_this;
581 };
582
583 /**
584 * @brief Create an object that is owned by a shared_ptr.
585 * @param __a An allocator.
586 * @param __args Arguments for the @a _Tp object's constructor.
587 * @return A shared_ptr that owns the newly created object.
588 * @throw An exception thrown from @a _Alloc::allocate or from the
589 * constructor of @a _Tp.
590 *
591 * A copy of @a __a will be used to allocate memory for the shared_ptr
592 * and the new object.
593 */
594 template<typename _Tp, typename _Alloc, typename... _Args>
595 inline shared_ptr<_Tp>
596 allocate_shared(const _Alloc& __a, _Args&&... __args)
597 {
598 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
599 std::forward<_Args>(__args)...);
600 }
601
602 /**
603 * @brief Create an object that is owned by a shared_ptr.
604 * @param __args Arguments for the @a _Tp object's constructor.
605 * @return A shared_ptr that owns the newly created object.
606 * @throw std::bad_alloc, or an exception thrown from the
607 * constructor of @a _Tp.
608 */
609 template<typename _Tp, typename... _Args>
610 inline shared_ptr<_Tp>
611 make_shared(_Args&&... __args)
612 {
613 typedef typename std::remove_const<_Tp>::type _Tp_nc;
614 return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
615 std::forward<_Args>(__args)...);
616 }
617
618 /// std::hash specialization for shared_ptr.
619 template<typename _Tp>
620 struct hash<shared_ptr<_Tp>>
621 : public __hash_base<size_t, shared_ptr<_Tp>>
622 {
623 size_t
624 operator()(const shared_ptr<_Tp>& __s) const noexcept
625 { return std::hash<_Tp*>()(__s.get()); }
626 };
627
628 // @} group pointer_abstractions
629
630 _GLIBCXX_END_NAMESPACE_VERSION
631 } // namespace
632
633 #endif // _SHARED_PTR_H
634