libstdc++
shared_ptr.h
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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 
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>
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)
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()
101  : __shared_ptr<_Tp>() { }
102 
103  shared_ptr(const shared_ptr&) = default; // never throws
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)
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
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  */
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
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>
254  : __shared_ptr<_Tp>(std::move(__r)) { }
255 #endif
256 
257  template<typename _Tp1, typename _Del>
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)
267  : __shared_ptr<_Tp>(__p) { }
268 
269  shared_ptr& operator=(const shared_ptr&) = default;
270 
271  template<typename _Tp1>
272  shared_ptr&
273  operator=(const shared_ptr<_Tp1>& __r) // never throws
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)
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)
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, const shared_ptr<_Tp2>& __b)
329  { return __a.get() == __b.get(); }
330 
331  template<typename _Tp>
332  inline bool
333  operator==(const shared_ptr<_Tp>& __a, nullptr_t)
334  { return __a.get() == nullptr; }
335 
336  template<typename _Tp>
337  inline bool
338  operator==(nullptr_t, const shared_ptr<_Tp>& __b)
339  { return nullptr == __b.get(); }
340 
341  template<typename _Tp1, typename _Tp2>
342  inline bool
343  operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
344  { return __a.get() != __b.get(); }
345 
346  template<typename _Tp>
347  inline bool
348  operator!=(const shared_ptr<_Tp>& __a, nullptr_t)
349  { return __a.get() != nullptr; }
350 
351  template<typename _Tp>
352  inline bool
353  operator!=(nullptr_t, const shared_ptr<_Tp>& __b)
354  { return nullptr != __b.get(); }
355 
356  template<typename _Tp1, typename _Tp2>
357  inline bool
358  operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
359  { return __a.get() < __b.get(); }
360 
361  template<typename _Tp>
362  struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
363  { };
364 
365  // 20.8.13.2.9 shared_ptr specialized algorithms.
366  template<typename _Tp>
367  inline void
368  swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
369  { __a.swap(__b); }
370 
371  // 20.8.13.2.10 shared_ptr casts.
372  template<typename _Tp, typename _Tp1>
373  inline shared_ptr<_Tp>
374  static_pointer_cast(const shared_ptr<_Tp1>& __r)
375  { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
376 
377  template<typename _Tp, typename _Tp1>
378  inline shared_ptr<_Tp>
379  const_pointer_cast(const shared_ptr<_Tp1>& __r)
380  { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
381 
382  template<typename _Tp, typename _Tp1>
383  inline shared_ptr<_Tp>
384  dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
385  {
386  if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
387  return shared_ptr<_Tp>(__r, __p);
388  return shared_ptr<_Tp>();
389  }
390 
391 
392  /**
393  * @brief A smart pointer with weak semantics.
394  *
395  * With forwarding constructors and assignment operators.
396  */
397  template<typename _Tp>
398  class weak_ptr : public __weak_ptr<_Tp>
399  {
400  public:
401  constexpr weak_ptr()
402  : __weak_ptr<_Tp>() { }
403 
404  template<typename _Tp1, typename = typename
406  weak_ptr(const weak_ptr<_Tp1>& __r)
407  : __weak_ptr<_Tp>(__r) { }
408 
409  template<typename _Tp1, typename = typename
411  weak_ptr(const shared_ptr<_Tp1>& __r)
412  : __weak_ptr<_Tp>(__r) { }
413 
414  template<typename _Tp1>
415  weak_ptr&
416  operator=(const weak_ptr<_Tp1>& __r) // never throws
417  {
418  this->__weak_ptr<_Tp>::operator=(__r);
419  return *this;
420  }
421 
422  template<typename _Tp1>
423  weak_ptr&
424  operator=(const shared_ptr<_Tp1>& __r) // never throws
425  {
426  this->__weak_ptr<_Tp>::operator=(__r);
427  return *this;
428  }
429 
431  lock() const // never throws
432  {
433 #ifdef __GTHREADS
434  if (this->expired())
435  return shared_ptr<_Tp>();
436 
437  __try
438  {
439  return shared_ptr<_Tp>(*this);
440  }
441  __catch(const bad_weak_ptr&)
442  {
443  return shared_ptr<_Tp>();
444  }
445 #else
446  return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
447 #endif
448  }
449  };
450 
451  // 20.8.13.3.7 weak_ptr specialized algorithms.
452  template<typename _Tp>
453  inline void
454  swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
455  { __a.swap(__b); }
456 
457 
458  /// Primary template owner_less
459  template<typename _Tp>
460  struct owner_less;
461 
462  /// Partial specialization of owner_less for shared_ptr.
463  template<typename _Tp>
464  struct owner_less<shared_ptr<_Tp>>
465  : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
466  { };
467 
468  /// Partial specialization of owner_less for weak_ptr.
469  template<typename _Tp>
470  struct owner_less<weak_ptr<_Tp>>
471  : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
472  { };
473 
474  /**
475  * @brief Base class allowing use of member function shared_from_this.
476  */
477  template<typename _Tp>
479  {
480  protected:
481  constexpr enable_shared_from_this() { }
482 
484 
486  operator=(const enable_shared_from_this&)
487  { return *this; }
488 
490 
491  public:
493  shared_from_this()
494  { return shared_ptr<_Tp>(this->_M_weak_this); }
495 
497  shared_from_this() const
498  { return shared_ptr<const _Tp>(this->_M_weak_this); }
499 
500  private:
501  template<typename _Tp1>
502  void
503  _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
504  { _M_weak_this._M_assign(__p, __n); }
505 
506  template<typename _Tp1>
507  friend void
508  __enable_shared_from_this_helper(const __shared_count<>& __pn,
509  const enable_shared_from_this* __pe,
510  const _Tp1* __px)
511  {
512  if (__pe != 0)
513  __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
514  }
515 
516  mutable weak_ptr<_Tp> _M_weak_this;
517  };
518 
519  /**
520  * @brief Create an object that is owned by a shared_ptr.
521  * @param __a An allocator.
522  * @param __args Arguments for the @a _Tp object's constructor.
523  * @return A shared_ptr that owns the newly created object.
524  * @throw An exception thrown from @a _Alloc::allocate or from the
525  * constructor of @a _Tp.
526  *
527  * A copy of @a __a will be used to allocate memory for the shared_ptr
528  * and the new object.
529  */
530  template<typename _Tp, typename _Alloc, typename... _Args>
531  inline shared_ptr<_Tp>
532  allocate_shared(const _Alloc& __a, _Args&&... __args)
533  {
534  return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
535  std::forward<_Args>(__args)...);
536  }
537 
538  /**
539  * @brief Create an object that is owned by a shared_ptr.
540  * @param __args Arguments for the @a _Tp object's constructor.
541  * @return A shared_ptr that owns the newly created object.
542  * @throw std::bad_alloc, or an exception thrown from the
543  * constructor of @a _Tp.
544  */
545  template<typename _Tp, typename... _Args>
546  inline shared_ptr<_Tp>
547  make_shared(_Args&&... __args)
548  {
549  typedef typename std::remove_const<_Tp>::type _Tp_nc;
550  return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
551  std::forward<_Args>(__args)...);
552  }
553 
554  /// std::hash specialization for shared_ptr.
555  template<typename _Tp>
556  struct hash<shared_ptr<_Tp>>
557  : public std::unary_function<shared_ptr<_Tp>, size_t>
558  {
559  size_t
560  operator()(const shared_ptr<_Tp>& __s) const
561  { return std::hash<_Tp*>()(__s.get()); }
562  };
563 
564  // @} group pointer_abstractions
565 
566 _GLIBCXX_END_NAMESPACE_VERSION
567 } // namespace
568 
569 #endif // _SHARED_PTR_H
shared_ptr(nullptr_t __p, _Deleter __d)
Construct a shared_ptr that owns a null pointer and the deleter __d.
Definition: shared_ptr.h:146
constexpr shared_ptr(nullptr_t __p)
Construct an empty shared_ptr.
Definition: shared_ptr.h:266
A simple smart pointer providing strict ownership semantics.
Definition: auto_ptr.h:87
Controlling output.This is the base class for all output streams. It provides text formatting of all ...
Definition: iosfwd:88
20.7.12.2 unique_ptr for single objects.
Definition: unique_ptr.h:88
Exception possibly thrown by shared_ptr.
shared_ptr< _Tp > make_shared(_Args &&...__args)
Create an object that is owned by a shared_ptr.
Definition: shared_ptr.h:547
shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns a null pointer and the deleter __d.
Definition: shared_ptr.h:184
shared_ptr(_Tp1 *__p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
Definition: shared_ptr.h:165
_Del * get_deleter(const __shared_ptr< _Tp, _Lp > &__p)
2.2.3.10 shared_ptr get_deleter (experimental)
Definition: shared_ptr.h:76
shared_ptr(const shared_ptr< _Tp1 > &__r)
If __r is empty, constructs an empty shared_ptr; otherwise construct a shared_ptr that shares ownersh...
Definition: shared_ptr.h:218
shared_ptr< _Tp > allocate_shared(const _Alloc &__a, _Args &&...__args)
Create an object that is owned by a shared_ptr.
Definition: shared_ptr.h:532
Partial specializations for pointer types.
A smart pointer with reference-counted copy semantics.
Definition: shared_ptr.h:93
Primary class template hash.
Definition: system_error:112
shared_ptr(const shared_ptr< _Tp1 > &__r, _Tp *__p)
Constructs a shared_ptr instance that stores __p and shares ownership with __r.
Definition: shared_ptr.h:206
Primary template owner_less.
Definition: shared_ptr.h:460
shared_ptr(const weak_ptr< _Tp1 > &__r)
Constructs a shared_ptr that shares ownership with __r and stores a copy of the pointer stored in __r...
Definition: shared_ptr.h:248
constexpr shared_ptr()
Construct an empty shared_ptr.
Definition: shared_ptr.h:100
friend shared_ptr< _Tp1 > allocate_shared(const _Alloc &__a, _Args &&...__args)
Create an object that is owned by a shared_ptr.
Definition: shared_ptr.h:532
A smart pointer with weak semantics.
Definition: shared_ptr.h:398
Base class allowing use of member function shared_from_this.
Definition: shared_ptr.h:478
shared_ptr(shared_ptr< _Tp1 > &&__r)
Move-constructs a shared_ptr instance from __r.
Definition: shared_ptr.h:236
shared_ptr(_Tp1 *__p)
Construct a shared_ptr that owns the pointer __p.
Definition: shared_ptr.h:112
enable_if
Definition: type_traits:836
shared_ptr(_Tp1 *__p, _Deleter __d)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
Definition: shared_ptr.h:129
shared_ptr(shared_ptr &&__r)
Move-constructs a shared_ptr instance from __r.
Definition: shared_ptr.h:226
_Tp && forward(typename std::remove_reference< _Tp >::type &__t)
forward (as per N3143)
Definition: move.h:62
The standard allocator, as per [20.4].Further details: http://gcc.gnu.org/onlinedocs/libstdc++/manual...
Definition: allocator.h:66