libstdc++
bits/shared_ptr.h
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1 // shared_ptr and weak_ptr implementation -*- C++ -*-
2 
3 // Copyright (C) 2007-2022 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
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 <iosfwd> // std::basic_ostream
53 #include <bits/shared_ptr_base.h>
54 
55 namespace std _GLIBCXX_VISIBILITY(default)
56 {
57 _GLIBCXX_BEGIN_NAMESPACE_VERSION
58 
59  /**
60  * @addtogroup pointer_abstractions
61  * @{
62  */
63 
64  // 20.7.2.2.11 shared_ptr I/O
65 
66  /// Write the stored pointer to an ostream.
67  /// @relates shared_ptr
68  template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
71  const __shared_ptr<_Tp, _Lp>& __p)
72  {
73  __os << __p.get();
74  return __os;
75  }
76 
77  template<typename _Del, typename _Tp, _Lock_policy _Lp>
78  inline _Del*
79  get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
80  {
81 #if __cpp_rtti
82  return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
83 #else
84  return 0;
85 #endif
86  }
87 
88  /// 20.7.2.2.10 shared_ptr get_deleter
89 
90  /// If `__p` has a deleter of type `_Del`, return a pointer to it.
91  /// @relates shared_ptr
92  template<typename _Del, typename _Tp>
93  inline _Del*
94  get_deleter(const shared_ptr<_Tp>& __p) noexcept
95  {
96 #if __cpp_rtti
97  return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
98 #else
99  return 0;
100 #endif
101  }
102 
103  /// @cond undocumented
104 
105  // Constraint for overloads taking non-array types.
106 #if __cpp_concepts && __cpp_lib_type_trait_variable_templates
107  template<typename _Tp>
108  requires (!is_array_v<_Tp>)
109  using _NonArray = _Tp;
110 #else
111  template<typename _Tp>
112  using _NonArray = __enable_if_t<!is_array<_Tp>::value, _Tp>;
113 #endif
114 
115 #if __cpp_lib_shared_ptr_arrays >= 201707L
116  // Constraint for overloads taking array types with unknown bound, U[].
117 #if __cpp_concepts
118  template<typename _Tp>
119  requires is_array_v<_Tp> && (extent_v<_Tp> == 0)
120  using _UnboundedArray = _Tp;
121 #else
122  template<typename _Tp>
123  using _UnboundedArray
124  = __enable_if_t<__is_array_unknown_bounds<_Tp>::value, _Tp>;
125 #endif
126 
127  // Constraint for overloads taking array types with known bound, U[N].
128 #if __cpp_concepts
129  template<typename _Tp>
130  requires (extent_v<_Tp> != 0)
131  using _BoundedArray = _Tp;
132 #else
133  template<typename _Tp>
134  using _BoundedArray
135  = __enable_if_t<__is_array_known_bounds<_Tp>::value, _Tp>;
136 #endif
137 
138 #if __cpp_lib_smart_ptr_for_overwrite
139  // Constraint for overloads taking either non-array or bounded array, U[N].
140 #if __cpp_concepts
141  template<typename _Tp>
142  requires (!is_array_v<_Tp>) || (extent_v<_Tp> != 0)
143  using _NotUnboundedArray = _Tp;
144 #else
145  template<typename _Tp>
146  using _NotUnboundedArray
147  = __enable_if_t<!__is_array_unknown_bounds<_Tp>::value, _Tp>;
148 #endif
149 #endif // smart_ptr_for_overwrite
150 #endif // shared_ptr_arrays
151 
152  /// @endcond
153 
154  /**
155  * @brief A smart pointer with reference-counted copy semantics.
156  * @headerfile memory
157  * @since C++11
158  *
159  * A `shared_ptr` object is either empty or _owns_ a pointer passed
160  * to the constructor. Copies of a `shared_ptr` share ownership of
161  * the same pointer. When the last `shared_ptr` that owns the pointer
162  * is destroyed or reset, the owned pointer is freed (either by `delete`
163  * or by invoking a custom deleter that was passed to the constructor).
164  *
165  * A `shared_ptr` also stores another pointer, which is usually
166  * (but not always) the same pointer as it owns. The stored pointer
167  * can be retrieved by calling the `get()` member function.
168  *
169  * The equality and relational operators for `shared_ptr` only compare
170  * the stored pointer returned by `get()`, not the owned pointer.
171  * To test whether two `shared_ptr` objects share ownership of the same
172  * pointer see `std::shared_ptr::owner_before` and `std::owner_less`.
173  */
174  template<typename _Tp>
175  class shared_ptr : public __shared_ptr<_Tp>
176  {
177  template<typename... _Args>
178  using _Constructible = typename enable_if<
179  is_constructible<__shared_ptr<_Tp>, _Args...>::value
180  >::type;
181 
182  template<typename _Arg>
183  using _Assignable = typename enable_if<
185  >::type;
186 
187  public:
188 
189  /// The type pointed to by the stored pointer, remove_extent_t<_Tp>
190  using element_type = typename __shared_ptr<_Tp>::element_type;
191 
192 #if __cplusplus >= 201703L
193 # define __cpp_lib_shared_ptr_weak_type 201606L
194  /// The corresponding weak_ptr type for this shared_ptr
195  /// @since C++17
197 #endif
198  /**
199  * @brief Construct an empty %shared_ptr.
200  * @post use_count()==0 && get()==0
201  */
202  constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }
203 
204  shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor
205 
206  /**
207  * @brief Construct a %shared_ptr that owns the pointer @a __p.
208  * @param __p A pointer that is convertible to element_type*.
209  * @post use_count() == 1 && get() == __p
210  * @throw std::bad_alloc, in which case @c delete @a __p is called.
211  */
212  template<typename _Yp, typename = _Constructible<_Yp*>>
213  explicit
214  shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { }
215 
216  /**
217  * @brief Construct a %shared_ptr that owns the pointer @a __p
218  * and the deleter @a __d.
219  * @param __p A pointer.
220  * @param __d A deleter.
221  * @post use_count() == 1 && get() == __p
222  * @throw std::bad_alloc, in which case @a __d(__p) is called.
223  *
224  * Requirements: _Deleter's copy constructor and destructor must
225  * not throw
226  *
227  * __shared_ptr will release __p by calling __d(__p)
228  */
229  template<typename _Yp, typename _Deleter,
230  typename = _Constructible<_Yp*, _Deleter>>
231  shared_ptr(_Yp* __p, _Deleter __d)
232  : __shared_ptr<_Tp>(__p, std::move(__d)) { }
233 
234  /**
235  * @brief Construct a %shared_ptr that owns a null pointer
236  * and the deleter @a __d.
237  * @param __p A null pointer constant.
238  * @param __d A deleter.
239  * @post use_count() == 1 && get() == __p
240  * @throw std::bad_alloc, in which case @a __d(__p) is called.
241  *
242  * Requirements: _Deleter's copy constructor and destructor must
243  * not throw
244  *
245  * The last owner will call __d(__p)
246  */
247  template<typename _Deleter>
248  shared_ptr(nullptr_t __p, _Deleter __d)
249  : __shared_ptr<_Tp>(__p, std::move(__d)) { }
250 
251  /**
252  * @brief Construct a %shared_ptr that owns the pointer @a __p
253  * and the deleter @a __d.
254  * @param __p A pointer.
255  * @param __d A deleter.
256  * @param __a An allocator.
257  * @post use_count() == 1 && get() == __p
258  * @throw std::bad_alloc, in which case @a __d(__p) is called.
259  *
260  * Requirements: _Deleter's copy constructor and destructor must
261  * not throw _Alloc's copy constructor and destructor must not
262  * throw.
263  *
264  * __shared_ptr will release __p by calling __d(__p)
265  */
266  template<typename _Yp, typename _Deleter, typename _Alloc,
267  typename = _Constructible<_Yp*, _Deleter, _Alloc>>
268  shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
269  : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
270 
271  /**
272  * @brief Construct a %shared_ptr that owns a null pointer
273  * and the deleter @a __d.
274  * @param __p A null pointer constant.
275  * @param __d A deleter.
276  * @param __a An allocator.
277  * @post use_count() == 1 && get() == __p
278  * @throw std::bad_alloc, in which case @a __d(__p) is called.
279  *
280  * Requirements: _Deleter's copy constructor and destructor must
281  * not throw _Alloc's copy constructor and destructor must not
282  * throw.
283  *
284  * The last owner will call __d(__p)
285  */
286  template<typename _Deleter, typename _Alloc>
287  shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
288  : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
289 
290  // Aliasing constructor
291 
292  /**
293  * @brief Constructs a `shared_ptr` instance that stores `__p`
294  * and shares ownership with `__r`.
295  * @param __r A `shared_ptr`.
296  * @param __p A pointer that will remain valid while `*__r` is valid.
297  * @post `get() == __p && use_count() == __r.use_count()`
298  *
299  * This can be used to construct a `shared_ptr` to a sub-object
300  * of an object managed by an existing `shared_ptr`. The complete
301  * object will remain valid while any `shared_ptr` owns it, even
302  * if they don't store a pointer to the complete object.
303  *
304  * @code
305  * shared_ptr<pair<int,int>> pii(new pair<int,int>());
306  * shared_ptr<int> pi(pii, &pii->first);
307  * assert(pii.use_count() == 2);
308  * @endcode
309  */
310  template<typename _Yp>
311  shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
312  : __shared_ptr<_Tp>(__r, __p) { }
313 
314 #if __cplusplus > 201703L
315  // _GLIBCXX_RESOLVE_LIB_DEFECTS
316  // 2996. Missing rvalue overloads for shared_ptr operations
317  /**
318  * @brief Constructs a `shared_ptr` instance that stores `__p`
319  * and shares ownership with `__r`.
320  * @param __r A `shared_ptr`.
321  * @param __p A pointer that will remain valid while `*__r` is valid.
322  * @post `get() == __p && !__r.use_count() && !__r.get()`
323  * @since C++17
324  *
325  * This can be used to construct a `shared_ptr` to a sub-object
326  * of an object managed by an existing `shared_ptr`. The complete
327  * object will remain valid while any `shared_ptr` owns it, even
328  * if they don't store a pointer to the complete object.
329  *
330  * @code
331  * shared_ptr<pair<int,int>> pii(new pair<int,int>());
332  * shared_ptr<int> pi1(pii, &pii->first);
333  * assert(pii.use_count() == 2);
334  * shared_ptr<int> pi2(std::move(pii), &pii->second);
335  * assert(pii.use_count() == 0);
336  * @endcode
337  */
338  template<typename _Yp>
340  : __shared_ptr<_Tp>(std::move(__r), __p) { }
341 #endif
342  /**
343  * @brief If @a __r is empty, constructs an empty %shared_ptr;
344  * otherwise construct a %shared_ptr that shares ownership
345  * with @a __r.
346  * @param __r A %shared_ptr.
347  * @post get() == __r.get() && use_count() == __r.use_count()
348  */
349  template<typename _Yp,
350  typename = _Constructible<const shared_ptr<_Yp>&>>
351  shared_ptr(const shared_ptr<_Yp>& __r) noexcept
352  : __shared_ptr<_Tp>(__r) { }
353 
354  /**
355  * @brief Move-constructs a %shared_ptr instance from @a __r.
356  * @param __r A %shared_ptr rvalue.
357  * @post *this contains the old value of @a __r, @a __r is empty.
358  */
359  shared_ptr(shared_ptr&& __r) noexcept
360  : __shared_ptr<_Tp>(std::move(__r)) { }
361 
362  /**
363  * @brief Move-constructs a %shared_ptr instance from @a __r.
364  * @param __r A %shared_ptr rvalue.
365  * @post *this contains the old value of @a __r, @a __r is empty.
366  */
367  template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
368  shared_ptr(shared_ptr<_Yp>&& __r) noexcept
369  : __shared_ptr<_Tp>(std::move(__r)) { }
370 
371  /**
372  * @brief Constructs a %shared_ptr that shares ownership with @a __r
373  * and stores a copy of the pointer stored in @a __r.
374  * @param __r A weak_ptr.
375  * @post use_count() == __r.use_count()
376  * @throw bad_weak_ptr when __r.expired(),
377  * in which case the constructor has no effect.
378  */
379  template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
380  explicit shared_ptr(const weak_ptr<_Yp>& __r)
381  : __shared_ptr<_Tp>(__r) { }
382 
383 #if _GLIBCXX_USE_DEPRECATED
384 #pragma GCC diagnostic push
385 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
386  template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
387  shared_ptr(auto_ptr<_Yp>&& __r);
388 #pragma GCC diagnostic pop
389 #endif
390 
391  // _GLIBCXX_RESOLVE_LIB_DEFECTS
392  // 2399. shared_ptr's constructor from unique_ptr should be constrained
393  template<typename _Yp, typename _Del,
394  typename = _Constructible<unique_ptr<_Yp, _Del>>>
396  : __shared_ptr<_Tp>(std::move(__r)) { }
397 
398 #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
399  // This non-standard constructor exists to support conversions that
400  // were possible in C++11 and C++14 but are ill-formed in C++17.
401  // If an exception is thrown this constructor has no effect.
402  template<typename _Yp, typename _Del,
403  _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0>
404  shared_ptr(unique_ptr<_Yp, _Del>&& __r)
405  : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { }
406 #endif
407 
408  /**
409  * @brief Construct an empty %shared_ptr.
410  * @post use_count() == 0 && get() == nullptr
411  */
412  constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }
413 
414  shared_ptr& operator=(const shared_ptr&) noexcept = default;
415 
416  template<typename _Yp>
417  _Assignable<const shared_ptr<_Yp>&>
418  operator=(const shared_ptr<_Yp>& __r) noexcept
419  {
420  this->__shared_ptr<_Tp>::operator=(__r);
421  return *this;
422  }
423 
424 #if _GLIBCXX_USE_DEPRECATED
425 #pragma GCC diagnostic push
426 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
427  template<typename _Yp>
428  _Assignable<auto_ptr<_Yp>>
429  operator=(auto_ptr<_Yp>&& __r)
430  {
431  this->__shared_ptr<_Tp>::operator=(std::move(__r));
432  return *this;
433  }
434 #pragma GCC diagnostic pop
435 #endif
436 
437  shared_ptr&
438  operator=(shared_ptr&& __r) noexcept
439  {
440  this->__shared_ptr<_Tp>::operator=(std::move(__r));
441  return *this;
442  }
443 
444  template<class _Yp>
445  _Assignable<shared_ptr<_Yp>>
446  operator=(shared_ptr<_Yp>&& __r) noexcept
447  {
448  this->__shared_ptr<_Tp>::operator=(std::move(__r));
449  return *this;
450  }
451 
452  template<typename _Yp, typename _Del>
453  _Assignable<unique_ptr<_Yp, _Del>>
454  operator=(unique_ptr<_Yp, _Del>&& __r)
455  {
456  this->__shared_ptr<_Tp>::operator=(std::move(__r));
457  return *this;
458  }
459 
460  private:
461  // This constructor is non-standard, it is used by allocate_shared.
462  template<typename _Alloc, typename... _Args>
463  shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
464  : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...)
465  { }
466 
467  template<typename _Yp, typename _Alloc, typename... _Args>
468  friend shared_ptr<_NonArray<_Yp>>
469  allocate_shared(const _Alloc&, _Args&&...);
470 
471  template<typename _Yp, typename... _Args>
472  friend shared_ptr<_NonArray<_Yp>>
473  make_shared(_Args&&...);
474 
475 #if __cpp_lib_shared_ptr_arrays >= 201707L
476  // This constructor is non-standard, it is used by allocate_shared<T[]>.
477  template<typename _Alloc, typename _Init = const remove_extent_t<_Tp>*>
478  shared_ptr(const _Sp_counted_array_base<_Alloc>& __a,
479  _Init __init = nullptr)
480  : __shared_ptr<_Tp>(__a, __init)
481  { }
482 
483  template<typename _Yp, typename _Alloc>
484  friend shared_ptr<_UnboundedArray<_Yp>>
485  allocate_shared(const _Alloc&, size_t);
486 
487  template<typename _Yp>
488  friend shared_ptr<_UnboundedArray<_Yp>>
489  make_shared(size_t);
490 
491  template<typename _Yp, typename _Alloc>
492  friend shared_ptr<_UnboundedArray<_Yp>>
493  allocate_shared(const _Alloc&, size_t, const remove_extent_t<_Yp>&);
494 
495  template<typename _Yp>
496  friend shared_ptr<_UnboundedArray<_Yp>>
497  make_shared(size_t, const remove_extent_t<_Yp>&);
498 
499  template<typename _Yp, typename _Alloc>
500  friend shared_ptr<_BoundedArray<_Yp>>
501  allocate_shared(const _Alloc&);
502 
503  template<typename _Yp>
504  friend shared_ptr<_BoundedArray<_Yp>>
505  make_shared();
506 
507  template<typename _Yp, typename _Alloc>
508  friend shared_ptr<_BoundedArray<_Yp>>
509  allocate_shared(const _Alloc&, const remove_extent_t<_Yp>&);
510 
511  template<typename _Yp>
512  friend shared_ptr<_BoundedArray<_Yp>>
513  make_shared(const remove_extent_t<_Yp>&);
514 
515 #if __cpp_lib_smart_ptr_for_overwrite
516  template<typename _Yp, typename _Alloc>
517  friend shared_ptr<_NotUnboundedArray<_Yp>>
518  allocate_shared_for_overwrite(const _Alloc&);
519 
520  template<typename _Yp>
521  friend shared_ptr<_NotUnboundedArray<_Yp>>
522  make_shared_for_overwrite();
523 
524  template<typename _Yp, typename _Alloc>
525  friend shared_ptr<_UnboundedArray<_Yp>>
526  allocate_shared_for_overwrite(const _Alloc&, size_t);
527 
528  template<typename _Yp>
529  friend shared_ptr<_UnboundedArray<_Yp>>
530  make_shared_for_overwrite(size_t);
531 #endif
532 #endif
533 
534  // This constructor is non-standard, it is used by weak_ptr::lock().
535  shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept
536  : __shared_ptr<_Tp>(__r, std::nothrow) { }
537 
538  friend class weak_ptr<_Tp>;
539  };
540 
541 #if __cpp_deduction_guides >= 201606
542  template<typename _Tp>
543  shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
544  template<typename _Tp, typename _Del>
545  shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>;
546 #endif
547 
548  // 20.7.2.2.7 shared_ptr comparisons
549 
550  /// @relates shared_ptr @{
551 
552  /// Equality operator for shared_ptr objects, compares the stored pointers
553  template<typename _Tp, typename _Up>
554  _GLIBCXX_NODISCARD inline bool
555  operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
556  { return __a.get() == __b.get(); }
557 
558  /// shared_ptr comparison with nullptr
559  template<typename _Tp>
560  _GLIBCXX_NODISCARD inline bool
561  operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
562  { return !__a; }
563 
564 #ifdef __cpp_lib_three_way_comparison
565  template<typename _Tp, typename _Up>
566  inline strong_ordering
567  operator<=>(const shared_ptr<_Tp>& __a,
568  const shared_ptr<_Up>& __b) noexcept
569  { return compare_three_way()(__a.get(), __b.get()); }
570 
571  template<typename _Tp>
572  inline strong_ordering
573  operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
574  {
575  using pointer = typename shared_ptr<_Tp>::element_type*;
576  return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
577  }
578 #else
579  /// shared_ptr comparison with nullptr
580  template<typename _Tp>
581  _GLIBCXX_NODISCARD inline bool
582  operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
583  { return !__a; }
584 
585  /// Inequality operator for shared_ptr objects, compares the stored pointers
586  template<typename _Tp, typename _Up>
587  _GLIBCXX_NODISCARD inline bool
588  operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
589  { return __a.get() != __b.get(); }
590 
591  /// shared_ptr comparison with nullptr
592  template<typename _Tp>
593  _GLIBCXX_NODISCARD inline bool
594  operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
595  { return (bool)__a; }
596 
597  /// shared_ptr comparison with nullptr
598  template<typename _Tp>
599  _GLIBCXX_NODISCARD inline bool
600  operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
601  { return (bool)__a; }
602 
603  /// Relational operator for shared_ptr objects, compares the stored pointers
604  template<typename _Tp, typename _Up>
605  _GLIBCXX_NODISCARD inline bool
606  operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
607  {
608  using _Tp_elt = typename shared_ptr<_Tp>::element_type;
609  using _Up_elt = typename shared_ptr<_Up>::element_type;
610  using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
611  return less<_Vp>()(__a.get(), __b.get());
612  }
613 
614  /// shared_ptr comparison with nullptr
615  template<typename _Tp>
616  _GLIBCXX_NODISCARD inline bool
617  operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
618  {
619  using _Tp_elt = typename shared_ptr<_Tp>::element_type;
620  return less<_Tp_elt*>()(__a.get(), nullptr);
621  }
622 
623  /// shared_ptr comparison with nullptr
624  template<typename _Tp>
625  _GLIBCXX_NODISCARD inline bool
626  operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
627  {
628  using _Tp_elt = typename shared_ptr<_Tp>::element_type;
629  return less<_Tp_elt*>()(nullptr, __a.get());
630  }
631 
632  /// Relational operator for shared_ptr objects, compares the stored pointers
633  template<typename _Tp, typename _Up>
634  _GLIBCXX_NODISCARD inline bool
635  operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
636  { return !(__b < __a); }
637 
638  /// shared_ptr comparison with nullptr
639  template<typename _Tp>
640  _GLIBCXX_NODISCARD inline bool
641  operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
642  { return !(nullptr < __a); }
643 
644  /// shared_ptr comparison with nullptr
645  template<typename _Tp>
646  _GLIBCXX_NODISCARD inline bool
647  operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
648  { return !(__a < nullptr); }
649 
650  /// Relational operator for shared_ptr objects, compares the stored pointers
651  template<typename _Tp, typename _Up>
652  _GLIBCXX_NODISCARD inline bool
653  operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
654  { return (__b < __a); }
655 
656  /// shared_ptr comparison with nullptr
657  template<typename _Tp>
658  _GLIBCXX_NODISCARD inline bool
659  operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
660  { return nullptr < __a; }
661 
662  /// shared_ptr comparison with nullptr
663  template<typename _Tp>
664  _GLIBCXX_NODISCARD inline bool
665  operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
666  { return __a < nullptr; }
667 
668  /// Relational operator for shared_ptr objects, compares the stored pointers
669  template<typename _Tp, typename _Up>
670  _GLIBCXX_NODISCARD inline bool
671  operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
672  { return !(__a < __b); }
673 
674  /// shared_ptr comparison with nullptr
675  template<typename _Tp>
676  _GLIBCXX_NODISCARD inline bool
677  operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
678  { return !(__a < nullptr); }
679 
680  /// shared_ptr comparison with nullptr
681  template<typename _Tp>
682  _GLIBCXX_NODISCARD inline bool
683  operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
684  { return !(nullptr < __a); }
685 #endif
686 
687  // 20.7.2.2.8 shared_ptr specialized algorithms.
688 
689  /// Swap overload for shared_ptr
690  template<typename _Tp>
691  inline void
692  swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
693  { __a.swap(__b); }
694 
695  // 20.7.2.2.9 shared_ptr casts.
696 
697  /// Convert type of `shared_ptr`, via `static_cast`
698  template<typename _Tp, typename _Up>
699  inline shared_ptr<_Tp>
701  {
702  using _Sp = shared_ptr<_Tp>;
703  return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
704  }
705 
706  /// Convert type of `shared_ptr`, via `const_cast`
707  template<typename _Tp, typename _Up>
708  inline shared_ptr<_Tp>
709  const_pointer_cast(const shared_ptr<_Up>& __r) noexcept
710  {
711  using _Sp = shared_ptr<_Tp>;
712  return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
713  }
714 
715  /// Convert type of `shared_ptr`, via `dynamic_cast`
716  template<typename _Tp, typename _Up>
717  inline shared_ptr<_Tp>
719  {
720  using _Sp = shared_ptr<_Tp>;
721  if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
722  return _Sp(__r, __p);
723  return _Sp();
724  }
725 
726 #if __cplusplus >= 201703L
727  /// Convert type of `shared_ptr`, via `reinterpret_cast`
728  /// @since C++17
729  template<typename _Tp, typename _Up>
730  inline shared_ptr<_Tp>
732  {
733  using _Sp = shared_ptr<_Tp>;
734  return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
735  }
736 
737 #if __cplusplus > 201703L
738  // _GLIBCXX_RESOLVE_LIB_DEFECTS
739  // 2996. Missing rvalue overloads for shared_ptr operations
740 
741  /// Convert type of `shared_ptr` rvalue, via `static_cast`
742  /// @since C++20
743  template<typename _Tp, typename _Up>
744  inline shared_ptr<_Tp>
746  {
747  using _Sp = shared_ptr<_Tp>;
748  return _Sp(std::move(__r),
749  static_cast<typename _Sp::element_type*>(__r.get()));
750  }
751 
752  /// Convert type of `shared_ptr` rvalue, via `const_cast`
753  /// @since C++20
754  template<typename _Tp, typename _Up>
755  inline shared_ptr<_Tp>
757  {
758  using _Sp = shared_ptr<_Tp>;
759  return _Sp(std::move(__r),
760  const_cast<typename _Sp::element_type*>(__r.get()));
761  }
762 
763  /// Convert type of `shared_ptr` rvalue, via `dynamic_cast`
764  /// @since C++20
765  template<typename _Tp, typename _Up>
766  inline shared_ptr<_Tp>
768  {
769  using _Sp = shared_ptr<_Tp>;
770  if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
771  return _Sp(std::move(__r), __p);
772  return _Sp();
773  }
774 
775  /// Convert type of `shared_ptr` rvalue, via `reinterpret_cast`
776  /// @since C++20
777  template<typename _Tp, typename _Up>
778  inline shared_ptr<_Tp>
780  {
781  using _Sp = shared_ptr<_Tp>;
782  return _Sp(std::move(__r),
783  reinterpret_cast<typename _Sp::element_type*>(__r.get()));
784  }
785 #endif // C++20
786 #endif // C++17
787 
788  /// @}
789 
790  /**
791  * @brief A non-owning observer for a pointer owned by a shared_ptr
792  * @headerfile memory
793  * @since C++11
794  *
795  * A weak_ptr provides a safe alternative to a raw pointer when you want
796  * a non-owning reference to an object that is managed by a shared_ptr.
797  *
798  * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr
799  * that shares ownership with every other shared_ptr that already owns
800  * the pointer. In other words you can upgrade from a non-owning "weak"
801  * reference to an owning shared_ptr, without having access to any of
802  * the existing shared_ptr objects.
803  *
804  * Also unlike a raw pointer, a weak_ptr does not become "dangling" after
805  * the object it points to has been destroyed. Instead, a weak_ptr
806  * becomes _expired_ and can no longer be converted to a shared_ptr that
807  * owns the freed pointer, so you cannot accidentally access the pointed-to
808  * object after it has been destroyed.
809  */
810  template<typename _Tp>
811  class weak_ptr : public __weak_ptr<_Tp>
812  {
813  template<typename _Arg>
814  using _Constructible = typename enable_if<
816  >::type;
817 
818  template<typename _Arg>
819  using _Assignable = typename enable_if<
820  is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr&
821  >::type;
822 
823  public:
824  constexpr weak_ptr() noexcept = default;
825 
826  template<typename _Yp,
827  typename = _Constructible<const shared_ptr<_Yp>&>>
828  weak_ptr(const shared_ptr<_Yp>& __r) noexcept
829  : __weak_ptr<_Tp>(__r) { }
830 
831  weak_ptr(const weak_ptr&) noexcept = default;
832 
833  template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
834  weak_ptr(const weak_ptr<_Yp>& __r) noexcept
835  : __weak_ptr<_Tp>(__r) { }
836 
837  weak_ptr(weak_ptr&&) noexcept = default;
838 
839  template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>>
840  weak_ptr(weak_ptr<_Yp>&& __r) noexcept
841  : __weak_ptr<_Tp>(std::move(__r)) { }
842 
843  weak_ptr&
844  operator=(const weak_ptr& __r) noexcept = default;
845 
846  template<typename _Yp>
847  _Assignable<const weak_ptr<_Yp>&>
848  operator=(const weak_ptr<_Yp>& __r) noexcept
849  {
850  this->__weak_ptr<_Tp>::operator=(__r);
851  return *this;
852  }
853 
854  template<typename _Yp>
855  _Assignable<const shared_ptr<_Yp>&>
856  operator=(const shared_ptr<_Yp>& __r) noexcept
857  {
858  this->__weak_ptr<_Tp>::operator=(__r);
859  return *this;
860  }
861 
862  weak_ptr&
863  operator=(weak_ptr&& __r) noexcept = default;
864 
865  template<typename _Yp>
866  _Assignable<weak_ptr<_Yp>>
867  operator=(weak_ptr<_Yp>&& __r) noexcept
868  {
869  this->__weak_ptr<_Tp>::operator=(std::move(__r));
870  return *this;
871  }
872 
874  lock() const noexcept
875  { return shared_ptr<_Tp>(*this, std::nothrow); }
876  };
877 
878 #if __cpp_deduction_guides >= 201606
879  template<typename _Tp>
881 #endif
882 
883  // 20.7.2.3.6 weak_ptr specialized algorithms.
884  /// Swap overload for weak_ptr
885  /// @relates weak_ptr
886  template<typename _Tp>
887  inline void
888  swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
889  { __a.swap(__b); }
890 
891 
892  /// Primary template owner_less
893  template<typename _Tp = void>
894  struct owner_less;
895 
896  /// Void specialization of owner_less compares either shared_ptr or weak_ptr
897  template<>
898  struct owner_less<void> : _Sp_owner_less<void, void>
899  { };
900 
901  /// Partial specialization of owner_less for shared_ptr.
902  template<typename _Tp>
903  struct owner_less<shared_ptr<_Tp>>
904  : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
905  { };
906 
907  /// Partial specialization of owner_less for weak_ptr.
908  template<typename _Tp>
909  struct owner_less<weak_ptr<_Tp>>
910  : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
911  { };
912 
913  /**
914  * @brief Base class allowing use of the member function `shared_from_this`.
915  * @headerfile memory
916  * @since C++11
917  */
918  template<typename _Tp>
920  {
921  protected:
922  constexpr enable_shared_from_this() noexcept { }
923 
925 
927  operator=(const enable_shared_from_this&) noexcept
928  { return *this; }
929 
931 
932  public:
934  shared_from_this()
935  { return shared_ptr<_Tp>(this->_M_weak_this); }
936 
938  shared_from_this() const
939  { return shared_ptr<const _Tp>(this->_M_weak_this); }
940 
941 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
942 #define __cpp_lib_enable_shared_from_this 201603L
943  /** @{
944  * Get a `weak_ptr` referring to the object that has `*this` as its base.
945  * @since C++17
946  */
948  weak_from_this() noexcept
949  { return this->_M_weak_this; }
950 
952  weak_from_this() const noexcept
953  { return this->_M_weak_this; }
954  /// @}
955 #endif
956 
957  private:
958  template<typename _Tp1>
959  void
960  _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
961  { _M_weak_this._M_assign(__p, __n); }
962 
963  // Found by ADL when this is an associated class.
964  friend const enable_shared_from_this*
965  __enable_shared_from_this_base(const __shared_count<>&,
966  const enable_shared_from_this* __p)
967  { return __p; }
968 
969  template<typename, _Lock_policy>
970  friend class __shared_ptr;
971 
972  mutable weak_ptr<_Tp> _M_weak_this;
973  };
974 
975  /// @relates shared_ptr @{
976 
977  /**
978  * @brief Create an object that is owned by a shared_ptr.
979  * @param __a An allocator.
980  * @param __args Arguments for the @a _Tp object's constructor.
981  * @return A shared_ptr that owns the newly created object.
982  * @throw An exception thrown from @a _Alloc::allocate or from the
983  * constructor of @a _Tp.
984  *
985  * A copy of @a __a will be used to allocate memory for the shared_ptr
986  * and the new object.
987  */
988  template<typename _Tp, typename _Alloc, typename... _Args>
989  inline shared_ptr<_NonArray<_Tp>>
990  allocate_shared(const _Alloc& __a, _Args&&... __args)
991  {
992  return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a},
993  std::forward<_Args>(__args)...);
994  }
995 
996  /**
997  * @brief Create an object that is owned by a shared_ptr.
998  * @param __args Arguments for the @a _Tp object's constructor.
999  * @return A shared_ptr that owns the newly created object.
1000  * @throw std::bad_alloc, or an exception thrown from the
1001  * constructor of @a _Tp.
1002  */
1003  template<typename _Tp, typename... _Args>
1005  make_shared(_Args&&... __args)
1006  {
1007  using _Alloc = allocator<void>;
1008  _Alloc __a;
1009  return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a},
1010  std::forward<_Args>(__args)...);
1011  }
1012 
1013 #if __cpp_lib_shared_ptr_arrays >= 201707L
1014  /// @cond undocumented
1015  template<typename _Tp, typename _Alloc = allocator<void>>
1016  auto
1017  __make_shared_arr_tag(size_t __n, const _Alloc& __a = _Alloc()) noexcept
1018  {
1019  using _Up = remove_all_extents_t<_Tp>;
1020  using _UpAlloc = __alloc_rebind<_Alloc, _Up>;
1021  size_t __s = sizeof(remove_extent_t<_Tp>) / sizeof(_Up);
1022  if (__builtin_mul_overflow(__s, __n, &__n))
1023  std::__throw_bad_array_new_length();
1024  return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n};
1025  }
1026  /// @endcond
1027 
1028  template<typename _Tp, typename _Alloc>
1029  inline shared_ptr<_UnboundedArray<_Tp>>
1030  allocate_shared(const _Alloc& __a, size_t __n)
1031  {
1032  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a));
1033  }
1034 
1035  template<typename _Tp>
1037  make_shared(size_t __n)
1038  {
1039  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n));
1040  }
1041 
1042  template<typename _Tp, typename _Alloc>
1043  inline shared_ptr<_UnboundedArray<_Tp>>
1044  allocate_shared(const _Alloc& __a, size_t __n,
1045  const remove_extent_t<_Tp>& __u)
1046  {
1047  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a),
1048  std::__addressof(__u));
1049  }
1050 
1051  template<typename _Tp>
1052  inline shared_ptr<_UnboundedArray<_Tp>>
1053  make_shared(size_t __n, const remove_extent_t<_Tp>& __u)
1054  {
1055  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n),
1056  std::__addressof(__u));
1057  }
1058 
1059  /// @cond undocumented
1060  template<typename _Tp, typename _Alloc = allocator<void>>
1061  auto
1062  __make_shared_arrN_tag(const _Alloc& __a = _Alloc()) noexcept
1063  {
1064  using _Up = remove_all_extents_t<_Tp>;
1065  using _UpAlloc = __alloc_rebind<_Alloc, _Up>;
1066  size_t __n = sizeof(_Tp) / sizeof(_Up);
1067  return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n};
1068  }
1069  /// @endcond
1070 
1071  template<typename _Tp, typename _Alloc>
1072  inline shared_ptr<_BoundedArray<_Tp>>
1073  allocate_shared(const _Alloc& __a)
1074  {
1075  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a));
1076  }
1077 
1078  template<typename _Tp>
1080  make_shared()
1081  {
1082  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>());
1083  }
1084 
1085  template<typename _Tp, typename _Alloc>
1086  inline shared_ptr<_BoundedArray<_Tp>>
1087  allocate_shared(const _Alloc& __a, const remove_extent_t<_Tp>& __u)
1088  {
1089  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a),
1090  std::__addressof(__u));
1091  }
1092 
1093  template<typename _Tp>
1094  inline shared_ptr<_BoundedArray<_Tp>>
1095  make_shared(const remove_extent_t<_Tp>& __u)
1096  {
1097  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(),
1098  std::__addressof(__u));
1099  }
1100 
1101 #if __cpp_lib_smart_ptr_for_overwrite
1102  template<typename _Tp, typename _Alloc>
1103  inline shared_ptr<_NotUnboundedArray<_Tp>>
1104  allocate_shared_for_overwrite(const _Alloc& __a)
1105  {
1106  if constexpr (is_array_v<_Tp>)
1107  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a),
1108  _Sp_overwrite_tag{});
1109  else
1110  {
1111  // Rebind the allocator to _Sp_overwrite_tag, so that the
1112  // relevant _Sp_counted_ptr_inplace specialization is used.
1113  using _Alloc2 = __alloc_rebind<_Alloc, _Sp_overwrite_tag>;
1114  _Alloc2 __a2 = __a;
1115  return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc2>{__a2});
1116  }
1117  }
1118 
1119  template<typename _Tp>
1120  inline shared_ptr<_NotUnboundedArray<_Tp>>
1121  make_shared_for_overwrite()
1122  {
1123  if constexpr (is_array_v<_Tp>)
1124  return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(),
1125  _Sp_overwrite_tag{});
1126  else
1127  {
1128  using _Alloc = allocator<_Sp_overwrite_tag>;
1129  return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{{}});
1130  }
1131  }
1132 
1133  template<typename _Tp, typename _Alloc>
1134  inline shared_ptr<_UnboundedArray<_Tp>>
1135  allocate_shared_for_overwrite(const _Alloc& __a, size_t __n)
1136  {
1137  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a),
1138  _Sp_overwrite_tag{});
1139  }
1140 
1141  template<typename _Tp>
1142  inline shared_ptr<_UnboundedArray<_Tp>>
1143  make_shared_for_overwrite(size_t __n)
1144  {
1145  return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n),
1146  _Sp_overwrite_tag{});
1147  }
1148 #endif // smart_ptr_for_overwrite
1149 #endif // shared_ptr_arrays
1150 
1151  /// std::hash specialization for shared_ptr.
1152  template<typename _Tp>
1153  struct hash<shared_ptr<_Tp>>
1154  : public __hash_base<size_t, shared_ptr<_Tp>>
1155  {
1156  size_t
1157  operator()(const shared_ptr<_Tp>& __s) const noexcept
1158  {
1160  }
1161  };
1162 
1163  /// @} relates shared_ptr
1164  /// @} group pointer_abstractions
1165 
1166 #if __cplusplus >= 201703L
1167  namespace __detail::__variant
1168  {
1169  template<typename> struct _Never_valueless_alt; // see <variant>
1170 
1171  // Provide the strong exception-safety guarantee when emplacing a
1172  // shared_ptr into a variant.
1173  template<typename _Tp>
1174  struct _Never_valueless_alt<std::shared_ptr<_Tp>>
1175  : std::true_type
1176  { };
1177 
1178  // Provide the strong exception-safety guarantee when emplacing a
1179  // weak_ptr into a variant.
1180  template<typename _Tp>
1181  struct _Never_valueless_alt<std::weak_ptr<_Tp>>
1182  : std::true_type
1183  { };
1184  } // namespace __detail::__variant
1185 #endif // C++17
1186 
1187 _GLIBCXX_END_NAMESPACE_VERSION
1188 } // namespace
1189 
1190 #endif // _SHARED_PTR_H
shared_ptr< _BoundedArray< _Tp > > allocate_shared(const _Alloc &__a)
Create an object that is owned by a shared_ptr.
bool operator!=(nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
bool operator>(const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
bool operator==(const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
shared_ptr< _NonArray< _Tp > > make_shared(_Args &&... __args)
Create an object that is owned by a shared_ptr.
bool operator==(nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
shared_ptr< _Tp > static_pointer_cast(const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via static_cast
bool operator!=(const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Inequality operator for shared_ptr objects, compares the stored pointers.
shared_ptr< _Tp > const_pointer_cast(shared_ptr< _Up > &&__r) noexcept
Convert type of shared_ptr rvalue, via const_cast
_Del * get_deleter(const shared_ptr< _Tp > &__p) noexcept
20.7.2.2.10 shared_ptr get_deleter
bool operator==(const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
shared_ptr< _Tp > static_pointer_cast(shared_ptr< _Up > &&__r) noexcept
Convert type of shared_ptr rvalue, via static_cast
shared_ptr< _Tp > reinterpret_pointer_cast(const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via reinterpret_cast
shared_ptr< _NonArray< _Tp > > allocate_shared(const _Alloc &__a, _Args &&... __args)
Create an object that is owned by a shared_ptr.
bool operator>=(const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
void swap(weak_ptr< _Tp > &__a, weak_ptr< _Tp > &__b) noexcept
Swap overload for weak_ptr.
shared_ptr< _Tp > reinterpret_pointer_cast(shared_ptr< _Up > &&__r) noexcept
Convert type of shared_ptr rvalue, via reinterpret_cast
bool operator>(nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
bool operator>=(nullptr_t, const shared_ptr< _Tp > &__a) noexcept
shared_ptr comparison with nullptr
shared_ptr< _Tp > dynamic_pointer_cast(const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via dynamic_cast
shared_ptr< _Tp > const_pointer_cast(const shared_ptr< _Up > &__r) noexcept
Convert type of shared_ptr, via const_cast
bool operator>(const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
bool operator>=(const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
Relational operator for shared_ptr objects, compares the stored pointers.
bool operator!=(const shared_ptr< _Tp > &__a, nullptr_t) noexcept
shared_ptr comparison with nullptr
void swap(shared_ptr< _Tp > &__a, shared_ptr< _Tp > &__b) noexcept
Swap overload for shared_ptr.
shared_ptr< _UnboundedArray< _Tp > > allocate_shared(const _Alloc &__a, size_t __n)
Create an object that is owned by a shared_ptr.
shared_ptr< _Tp > dynamic_pointer_cast(shared_ptr< _Up > &&__r) noexcept
Convert type of shared_ptr rvalue, via dynamic_cast
typename remove_all_extents< _Tp >::type remove_all_extents_t
Alias template for remove_all_extents.
Definition: type_traits:2047
typename remove_extent< _Tp >::type remove_extent_t
Alias template for remove_extent.
Definition: type_traits:2043
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
ISO C++ entities toplevel namespace is std.
std::basic_ostream< _CharT, _Traits > & operator<<(std::basic_ostream< _CharT, _Traits > &__os, const bitset< _Nb > &__x)
Global I/O operators for bitsets.
Definition: bitset:1540
Template class basic_ostream.
Definition: ostream:59
Primary class template hash.
integral_constant
Definition: type_traits:63
is_constructible
Definition: type_traits:979
is_assignable
Definition: type_traits:1113
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:2229
common_type
Definition: type_traits:2265
allocator<void> specialization.
Definition: allocator.h:73
A smart pointer with reference-counted copy semantics.
typename __shared_ptr< _Tp >::element_type element_type
The type pointed to by the stored pointer, remove_extent_t<_Tp>
shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns a null pointer and the deleter __d.
shared_ptr(const shared_ptr< _Yp > &__r) noexcept
If __r is empty, constructs an empty shared_ptr; otherwise construct a shared_ptr that shares ownersh...
shared_ptr(shared_ptr< _Yp > &&__r) noexcept
Move-constructs a shared_ptr instance from __r.
weak_ptr< _Tp > weak_type
The corresponding weak_ptr type for this shared_ptr.
shared_ptr(_Yp *__p, _Deleter __d, _Alloc __a)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
constexpr shared_ptr() noexcept
Construct an empty shared_ptr.
shared_ptr(const shared_ptr &) noexcept=default
Copy constructor.
shared_ptr(shared_ptr &&__r) noexcept
Move-constructs a shared_ptr instance from __r.
shared_ptr(_Yp *__p)
Construct a shared_ptr that owns the pointer __p.
shared_ptr(nullptr_t __p, _Deleter __d)
Construct a shared_ptr that owns a null pointer and the deleter __d.
shared_ptr(_Yp *__p, _Deleter __d)
Construct a shared_ptr that owns the pointer __p and the deleter __d.
shared_ptr(const shared_ptr< _Yp > &__r, element_type *__p) noexcept
Constructs a shared_ptr instance that stores __p and shares ownership with __r.
shared_ptr(const weak_ptr< _Yp > &__r)
Constructs a shared_ptr that shares ownership with __r and stores a copy of the pointer stored in __r...
constexpr shared_ptr(nullptr_t) noexcept
Construct an empty shared_ptr.
shared_ptr(shared_ptr< _Yp > &&__r, element_type *__p) noexcept
Constructs a shared_ptr instance that stores __p and shares ownership with __r.
A non-owning observer for a pointer owned by a shared_ptr.
Primary template owner_less.
Base class allowing use of the member function shared_from_this.
weak_ptr< const _Tp > weak_from_this() const noexcept
weak_ptr< _Tp > weak_from_this() noexcept
A simple smart pointer providing strict ownership semantics.
Definition: auto_ptr.h:90
One of the comparison functors.
Definition: stl_function.h:404
A move-only smart pointer that manages unique ownership of a resource.
Definition: unique_ptr.h:270