1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___MEMORY_SHARED_PTR_H
11 #define _LIBCPP___MEMORY_SHARED_PTR_H
12 
13 #include <__availability>
14 #include <__config>
15 #include <__functional_base>
16 #include <__functional/binary_function.h>
17 #include <__functional/operations.h>
18 #include <__functional/reference_wrapper.h>
19 #include <__memory/addressof.h>
20 #include <__memory/allocation_guard.h>
21 #include <__memory/allocator_traits.h>
22 #include <__memory/allocator.h>
23 #include <__memory/compressed_pair.h>
24 #include <__memory/pointer_traits.h>
25 #include <__memory/unique_ptr.h>
26 #include <__utility/forward.h>
27 #include <cstddef>
28 #include <cstdlib> // abort
29 #include <iosfwd>
30 #include <stdexcept>
31 #include <typeinfo>
32 #include <type_traits>
33 #include <utility>
34 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
35 #  include <atomic>
36 #endif
37 
38 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
39 #   include <__memory/auto_ptr.h>
40 #endif
41 
42 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
43 #pragma GCC system_header
44 #endif
45 
46 _LIBCPP_PUSH_MACROS
47 #include <__undef_macros>
48 
49 _LIBCPP_BEGIN_NAMESPACE_STD
50 
51 template <class _Alloc>
52 class __allocator_destructor
53 {
54     typedef _LIBCPP_NODEBUG_TYPE allocator_traits<_Alloc> __alloc_traits;
55 public:
56     typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::pointer pointer;
57     typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::size_type size_type;
58 private:
59     _Alloc& __alloc_;
60     size_type __s_;
61 public:
__allocator_destructor(_Alloc & __a,size_type __s)62     _LIBCPP_INLINE_VISIBILITY __allocator_destructor(_Alloc& __a, size_type __s)
63              _NOEXCEPT
64         : __alloc_(__a), __s_(__s) {}
65     _LIBCPP_INLINE_VISIBILITY
operator()66     void operator()(pointer __p) _NOEXCEPT
67         {__alloc_traits::deallocate(__alloc_, __p, __s_);}
68 };
69 
70 // NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
71 // should be sufficient for thread safety.
72 // See https://llvm.org/PR22803
73 #if defined(__clang__) && __has_builtin(__atomic_add_fetch)          \
74                        && defined(__ATOMIC_RELAXED)                  \
75                        && defined(__ATOMIC_ACQ_REL)
76 #   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
77 #elif defined(_LIBCPP_COMPILER_GCC)
78 #   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
79 #endif
80 
81 template <class _ValueType>
82 inline _LIBCPP_INLINE_VISIBILITY
__libcpp_relaxed_load(_ValueType const * __value)83 _ValueType __libcpp_relaxed_load(_ValueType const* __value) {
84 #if !defined(_LIBCPP_HAS_NO_THREADS) && \
85     defined(__ATOMIC_RELAXED) &&        \
86     (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
87     return __atomic_load_n(__value, __ATOMIC_RELAXED);
88 #else
89     return *__value;
90 #endif
91 }
92 
93 template <class _ValueType>
94 inline _LIBCPP_INLINE_VISIBILITY
__libcpp_acquire_load(_ValueType const * __value)95 _ValueType __libcpp_acquire_load(_ValueType const* __value) {
96 #if !defined(_LIBCPP_HAS_NO_THREADS) && \
97     defined(__ATOMIC_ACQUIRE) &&        \
98     (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
99     return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
100 #else
101     return *__value;
102 #endif
103 }
104 
105 template <class _Tp>
106 inline _LIBCPP_INLINE_VISIBILITY _Tp
__libcpp_atomic_refcount_increment(_Tp & __t)107 __libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT
108 {
109 #if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
110     return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
111 #else
112     return __t += 1;
113 #endif
114 }
115 
116 template <class _Tp>
117 inline _LIBCPP_INLINE_VISIBILITY _Tp
__libcpp_atomic_refcount_decrement(_Tp & __t)118 __libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT
119 {
120 #if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
121     return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
122 #else
123     return __t -= 1;
124 #endif
125 }
126 
127 class _LIBCPP_EXCEPTION_ABI bad_weak_ptr
128     : public std::exception
129 {
130 public:
131     bad_weak_ptr() _NOEXCEPT = default;
132     bad_weak_ptr(const bad_weak_ptr&) _NOEXCEPT = default;
133     virtual ~bad_weak_ptr() _NOEXCEPT;
134     virtual const char* what() const  _NOEXCEPT;
135 };
136 
137 _LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
__throw_bad_weak_ptr()138 void __throw_bad_weak_ptr()
139 {
140 #ifndef _LIBCPP_NO_EXCEPTIONS
141     throw bad_weak_ptr();
142 #else
143     _VSTD::abort();
144 #endif
145 }
146 
147 template<class _Tp> class _LIBCPP_TEMPLATE_VIS weak_ptr;
148 
149 class _LIBCPP_TYPE_VIS __shared_count
150 {
151     __shared_count(const __shared_count&);
152     __shared_count& operator=(const __shared_count&);
153 
154 protected:
155     long __shared_owners_;
156     virtual ~__shared_count();
157 private:
158     virtual void __on_zero_shared() _NOEXCEPT = 0;
159 
160 public:
161     _LIBCPP_INLINE_VISIBILITY
162     explicit __shared_count(long __refs = 0) _NOEXCEPT
__shared_owners_(__refs)163         : __shared_owners_(__refs) {}
164 
165 #if defined(_LIBCPP_BUILDING_LIBRARY) && \
166     defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
167     void __add_shared() _NOEXCEPT;
168     bool __release_shared() _NOEXCEPT;
169 #else
170     _LIBCPP_INLINE_VISIBILITY
__add_shared()171     void __add_shared() _NOEXCEPT {
172       __libcpp_atomic_refcount_increment(__shared_owners_);
173     }
174     _LIBCPP_INLINE_VISIBILITY
__release_shared()175     bool __release_shared() _NOEXCEPT {
176       if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
177         __on_zero_shared();
178         return true;
179       }
180       return false;
181     }
182 #endif
183     _LIBCPP_INLINE_VISIBILITY
use_count()184     long use_count() const _NOEXCEPT {
185         return __libcpp_relaxed_load(&__shared_owners_) + 1;
186     }
187 };
188 
189 class _LIBCPP_TYPE_VIS __shared_weak_count
190     : private __shared_count
191 {
192     long __shared_weak_owners_;
193 
194 public:
195     _LIBCPP_INLINE_VISIBILITY
196     explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
__shared_count(__refs)197         : __shared_count(__refs),
198           __shared_weak_owners_(__refs) {}
199 protected:
200     virtual ~__shared_weak_count();
201 
202 public:
203 #if defined(_LIBCPP_BUILDING_LIBRARY) && \
204     defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
205     void __add_shared() _NOEXCEPT;
206     void __add_weak() _NOEXCEPT;
207     void __release_shared() _NOEXCEPT;
208 #else
209     _LIBCPP_INLINE_VISIBILITY
210     void __add_shared() _NOEXCEPT {
211       __shared_count::__add_shared();
212     }
213     _LIBCPP_INLINE_VISIBILITY
214     void __add_weak() _NOEXCEPT {
215       __libcpp_atomic_refcount_increment(__shared_weak_owners_);
216     }
217     _LIBCPP_INLINE_VISIBILITY
218     void __release_shared() _NOEXCEPT {
219       if (__shared_count::__release_shared())
220         __release_weak();
221     }
222 #endif
223     void __release_weak() _NOEXCEPT;
224     _LIBCPP_INLINE_VISIBILITY
use_count()225     long use_count() const _NOEXCEPT {return __shared_count::use_count();}
226     __shared_weak_count* lock() _NOEXCEPT;
227 
228     virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
229 private:
230     virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
231 };
232 
233 template <class _Tp, class _Dp, class _Alloc>
234 class __shared_ptr_pointer
235     : public __shared_weak_count
236 {
237     __compressed_pair<__compressed_pair<_Tp, _Dp>, _Alloc> __data_;
238 public:
239     _LIBCPP_INLINE_VISIBILITY
__shared_ptr_pointer(_Tp __p,_Dp __d,_Alloc __a)240     __shared_ptr_pointer(_Tp __p, _Dp __d, _Alloc __a)
241         :  __data_(__compressed_pair<_Tp, _Dp>(__p, _VSTD::move(__d)), _VSTD::move(__a)) {}
242 
243 #ifndef _LIBCPP_NO_RTTI
244     virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
245 #endif
246 
247 private:
248     virtual void __on_zero_shared() _NOEXCEPT;
249     virtual void __on_zero_shared_weak() _NOEXCEPT;
250 };
251 
252 #ifndef _LIBCPP_NO_RTTI
253 
254 template <class _Tp, class _Dp, class _Alloc>
255 const void*
__get_deleter(const type_info & __t)256 __shared_ptr_pointer<_Tp, _Dp, _Alloc>::__get_deleter(const type_info& __t) const _NOEXCEPT
257 {
258     return __t == typeid(_Dp) ? _VSTD::addressof(__data_.first().second()) : nullptr;
259 }
260 
261 #endif // _LIBCPP_NO_RTTI
262 
263 template <class _Tp, class _Dp, class _Alloc>
264 void
__on_zero_shared()265 __shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared() _NOEXCEPT
266 {
267     __data_.first().second()(__data_.first().first());
268     __data_.first().second().~_Dp();
269 }
270 
271 template <class _Tp, class _Dp, class _Alloc>
272 void
__on_zero_shared_weak()273 __shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
274 {
275     typedef typename __allocator_traits_rebind<_Alloc, __shared_ptr_pointer>::type _Al;
276     typedef allocator_traits<_Al> _ATraits;
277     typedef pointer_traits<typename _ATraits::pointer> _PTraits;
278 
279     _Al __a(__data_.second());
280     __data_.second().~_Alloc();
281     __a.deallocate(_PTraits::pointer_to(*this), 1);
282 }
283 
284 template <class _Tp, class _Alloc>
285 struct __shared_ptr_emplace
286     : __shared_weak_count
287 {
288     template<class ..._Args>
289     _LIBCPP_HIDE_FROM_ABI
__shared_ptr_emplace__shared_ptr_emplace290     explicit __shared_ptr_emplace(_Alloc __a, _Args&& ...__args)
291         : __storage_(_VSTD::move(__a))
292     {
293 #if _LIBCPP_STD_VER > 17
294         using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
295         _TpAlloc __tmp(*__get_alloc());
296         allocator_traits<_TpAlloc>::construct(__tmp, __get_elem(), _VSTD::forward<_Args>(__args)...);
297 #else
298         ::new ((void*)__get_elem()) _Tp(_VSTD::forward<_Args>(__args)...);
299 #endif
300     }
301 
302     _LIBCPP_HIDE_FROM_ABI
__get_alloc__shared_ptr_emplace303     _Alloc* __get_alloc() _NOEXCEPT { return __storage_.__get_alloc(); }
304 
305     _LIBCPP_HIDE_FROM_ABI
__get_elem__shared_ptr_emplace306     _Tp* __get_elem() _NOEXCEPT { return __storage_.__get_elem(); }
307 
308 private:
__on_zero_shared__shared_ptr_emplace309     virtual void __on_zero_shared() _NOEXCEPT {
310 #if _LIBCPP_STD_VER > 17
311         using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
312         _TpAlloc __tmp(*__get_alloc());
313         allocator_traits<_TpAlloc>::destroy(__tmp, __get_elem());
314 #else
315         __get_elem()->~_Tp();
316 #endif
317     }
318 
__on_zero_shared_weak__shared_ptr_emplace319     virtual void __on_zero_shared_weak() _NOEXCEPT {
320         using _ControlBlockAlloc = typename __allocator_traits_rebind<_Alloc, __shared_ptr_emplace>::type;
321         using _ControlBlockPointer = typename allocator_traits<_ControlBlockAlloc>::pointer;
322         _ControlBlockAlloc __tmp(*__get_alloc());
323         __storage_.~_Storage();
324         allocator_traits<_ControlBlockAlloc>::deallocate(__tmp,
325             pointer_traits<_ControlBlockPointer>::pointer_to(*this), 1);
326     }
327 
328     // This class implements the control block for non-array shared pointers created
329     // through `std::allocate_shared` and `std::make_shared`.
330     //
331     // In previous versions of the library, we used a compressed pair to store
332     // both the _Alloc and the _Tp. This implies using EBO, which is incompatible
333     // with Allocator construction for _Tp. To allow implementing P0674 in C++20,
334     // we now use a properly aligned char buffer while making sure that we maintain
335     // the same layout that we had when we used a compressed pair.
336     using _CompressedPair = __compressed_pair<_Alloc, _Tp>;
_ALIGNAS_TYPE__shared_ptr_emplace337     struct _ALIGNAS_TYPE(_CompressedPair) _Storage {
338         char __blob_[sizeof(_CompressedPair)];
339 
340         _LIBCPP_HIDE_FROM_ABI explicit _Storage(_Alloc&& __a) {
341             ::new ((void*)__get_alloc()) _Alloc(_VSTD::move(__a));
342         }
343         _LIBCPP_HIDE_FROM_ABI ~_Storage() {
344             __get_alloc()->~_Alloc();
345         }
346         _Alloc* __get_alloc() _NOEXCEPT {
347             _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
348             typename _CompressedPair::_Base1* __first = _CompressedPair::__get_first_base(__as_pair);
349             _Alloc *__alloc = reinterpret_cast<_Alloc*>(__first);
350             return __alloc;
351         }
352         _LIBCPP_NO_CFI _Tp* __get_elem() _NOEXCEPT {
353             _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
354             typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair);
355             _Tp *__elem = reinterpret_cast<_Tp*>(__second);
356             return __elem;
357         }
358     };
359 
360     static_assert(_LIBCPP_ALIGNOF(_Storage) == _LIBCPP_ALIGNOF(_CompressedPair), "");
361     static_assert(sizeof(_Storage) == sizeof(_CompressedPair), "");
362     _Storage __storage_;
363 };
364 
365 struct __shared_ptr_dummy_rebind_allocator_type;
366 template <>
367 class _LIBCPP_TEMPLATE_VIS allocator<__shared_ptr_dummy_rebind_allocator_type>
368 {
369 public:
370     template <class _Other>
371     struct rebind
372     {
373         typedef allocator<_Other> other;
374     };
375 };
376 
377 template<class _Tp> class _LIBCPP_TEMPLATE_VIS enable_shared_from_this;
378 
379 template<class _Tp, class _Up>
380 struct __compatible_with
381 #if _LIBCPP_STD_VER > 14
382     : is_convertible<remove_extent_t<_Tp>*, remove_extent_t<_Up>*> {};
383 #else
384     : is_convertible<_Tp*, _Up*> {};
385 #endif // _LIBCPP_STD_VER > 14
386 
387 template <class _Ptr, class = void>
388 struct __is_deletable : false_type { };
389 template <class _Ptr>
390 struct __is_deletable<_Ptr, decltype(delete declval<_Ptr>())> : true_type { };
391 
392 template <class _Ptr, class = void>
393 struct __is_array_deletable : false_type { };
394 template <class _Ptr>
395 struct __is_array_deletable<_Ptr, decltype(delete[] declval<_Ptr>())> : true_type { };
396 
397 template <class _Dp, class _Pt,
398     class = decltype(declval<_Dp>()(declval<_Pt>()))>
399 static true_type __well_formed_deleter_test(int);
400 
401 template <class, class>
402 static false_type __well_formed_deleter_test(...);
403 
404 template <class _Dp, class _Pt>
405 struct __well_formed_deleter : decltype(__well_formed_deleter_test<_Dp, _Pt>(0)) {};
406 
407 template<class _Dp, class _Tp, class _Yp>
408 struct __shared_ptr_deleter_ctor_reqs
409 {
410     static const bool value = __compatible_with<_Tp, _Yp>::value &&
411                               is_move_constructible<_Dp>::value &&
412                               __well_formed_deleter<_Dp, _Tp*>::value;
413 };
414 
415 #if defined(_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI)
416 #  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI __attribute__((trivial_abi))
417 #else
418 #  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI
419 #endif
420 
421 template<class _Tp>
422 class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr
423 {
424 public:
425 #if _LIBCPP_STD_VER > 14
426     typedef weak_ptr<_Tp> weak_type;
427     typedef remove_extent_t<_Tp> element_type;
428 #else
429     typedef _Tp element_type;
430 #endif
431 
432 private:
433     element_type*      __ptr_;
434     __shared_weak_count* __cntrl_;
435 
436     struct __nat {int __for_bool_;};
437 public:
438     _LIBCPP_INLINE_VISIBILITY
439     _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT;
440     _LIBCPP_INLINE_VISIBILITY
441     _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
442 
443     template<class _Yp, class = _EnableIf<
444         _And<
445             __compatible_with<_Yp, _Tp>
446             // In C++03 we get errors when trying to do SFINAE with the
447             // delete operator, so we always pretend that it's deletable.
448             // The same happens on GCC.
449 #if !defined(_LIBCPP_CXX03_LANG) && !defined(_LIBCPP_COMPILER_GCC)
450             , _If<is_array<_Tp>::value, __is_array_deletable<_Yp*>, __is_deletable<_Yp*> >
451 #endif
452         >::value
453     > >
454     explicit shared_ptr(_Yp* __p) : __ptr_(__p) {
455         unique_ptr<_Yp> __hold(__p);
456         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
457         typedef __shared_ptr_pointer<_Yp*, __shared_ptr_default_delete<_Tp, _Yp>, _AllocT > _CntrlBlk;
458         __cntrl_ = new _CntrlBlk(__p, __shared_ptr_default_delete<_Tp, _Yp>(), _AllocT());
459         __hold.release();
460         __enable_weak_this(__p, __p);
461     }
462 
463     template<class _Yp, class _Dp>
464         shared_ptr(_Yp* __p, _Dp __d,
465                    typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
466     template<class _Yp, class _Dp, class _Alloc>
467         shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
468                    typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
469     template <class _Dp> shared_ptr(nullptr_t __p, _Dp __d);
470     template <class _Dp, class _Alloc> shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a);
471     template<class _Yp> _LIBCPP_INLINE_VISIBILITY shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) _NOEXCEPT;
472     _LIBCPP_INLINE_VISIBILITY
473     shared_ptr(const shared_ptr& __r) _NOEXCEPT;
474     template<class _Yp>
475         _LIBCPP_INLINE_VISIBILITY
476         shared_ptr(const shared_ptr<_Yp>& __r,
477                    typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
478                        _NOEXCEPT;
479     _LIBCPP_INLINE_VISIBILITY
480     shared_ptr(shared_ptr&& __r) _NOEXCEPT;
481     template<class _Yp> _LIBCPP_INLINE_VISIBILITY  shared_ptr(shared_ptr<_Yp>&& __r,
482                    typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
483                        _NOEXCEPT;
484     template<class _Yp> explicit shared_ptr(const weak_ptr<_Yp>& __r,
485                    typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type= __nat());
486 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
487     template<class _Yp>
488         shared_ptr(auto_ptr<_Yp>&& __r,
489                    typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type = __nat());
490 #endif
491     template <class _Yp, class _Dp>
492         shared_ptr(unique_ptr<_Yp, _Dp>&&,
493                    typename enable_if
494                    <
495                        !is_lvalue_reference<_Dp>::value &&
496                        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
497                        __nat
498                    >::type = __nat());
499     template <class _Yp, class _Dp>
500         shared_ptr(unique_ptr<_Yp, _Dp>&&,
501                    typename enable_if
502                    <
503                        is_lvalue_reference<_Dp>::value &&
504                        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
505                        __nat
506                    >::type = __nat());
507 
508     ~shared_ptr();
509 
510     _LIBCPP_INLINE_VISIBILITY
511     shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT;
512     template<class _Yp>
513         typename enable_if
514         <
515             __compatible_with<_Yp, element_type>::value,
516             shared_ptr&
517         >::type
518         _LIBCPP_INLINE_VISIBILITY
519         operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
520     _LIBCPP_INLINE_VISIBILITY
521     shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
522     template<class _Yp>
523         typename enable_if
524         <
525             __compatible_with<_Yp, element_type>::value,
526             shared_ptr&
527         >::type
528         _LIBCPP_INLINE_VISIBILITY
529         operator=(shared_ptr<_Yp>&& __r);
530 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
531     template<class _Yp>
532         _LIBCPP_INLINE_VISIBILITY
533         typename enable_if
534         <
535             !is_array<_Yp>::value &&
536             is_convertible<_Yp*, element_type*>::value,
537             shared_ptr
538         >::type&
539         operator=(auto_ptr<_Yp>&& __r);
540 #endif
541     template <class _Yp, class _Dp>
542         typename enable_if
543         <
544             is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
545             shared_ptr&
546         >::type
547         _LIBCPP_INLINE_VISIBILITY
548         operator=(unique_ptr<_Yp, _Dp>&& __r);
549 
550     _LIBCPP_INLINE_VISIBILITY
551     void swap(shared_ptr& __r) _NOEXCEPT;
552     _LIBCPP_INLINE_VISIBILITY
553     void reset() _NOEXCEPT;
554     template<class _Yp>
555         typename enable_if
556         <
557             __compatible_with<_Yp, element_type>::value,
558             void
559         >::type
560         _LIBCPP_INLINE_VISIBILITY
561         reset(_Yp* __p);
562     template<class _Yp, class _Dp>
563         typename enable_if
564         <
565             __compatible_with<_Yp, element_type>::value,
566             void
567         >::type
568         _LIBCPP_INLINE_VISIBILITY
569         reset(_Yp* __p, _Dp __d);
570     template<class _Yp, class _Dp, class _Alloc>
571         typename enable_if
572         <
573             __compatible_with<_Yp, element_type>::value,
574             void
575         >::type
576         _LIBCPP_INLINE_VISIBILITY
577         reset(_Yp* __p, _Dp __d, _Alloc __a);
578 
579     _LIBCPP_INLINE_VISIBILITY
580     element_type* get() const _NOEXCEPT {return __ptr_;}
581     _LIBCPP_INLINE_VISIBILITY
582     typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
583         {return *__ptr_;}
584     _LIBCPP_INLINE_VISIBILITY
585     element_type* operator->() const _NOEXCEPT
586     {
587         static_assert(!is_array<_Tp>::value,
588                       "std::shared_ptr<T>::operator-> is only valid when T is not an array type.");
589         return __ptr_;
590     }
591     _LIBCPP_INLINE_VISIBILITY
592     long use_count() const _NOEXCEPT {return __cntrl_ ? __cntrl_->use_count() : 0;}
593     _LIBCPP_INLINE_VISIBILITY
594     bool unique() const _NOEXCEPT {return use_count() == 1;}
595     _LIBCPP_INLINE_VISIBILITY
596     explicit operator bool() const _NOEXCEPT {return get() != nullptr;}
597     template <class _Up>
598         _LIBCPP_INLINE_VISIBILITY
599         bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
600         {return __cntrl_ < __p.__cntrl_;}
601     template <class _Up>
602         _LIBCPP_INLINE_VISIBILITY
603         bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
604         {return __cntrl_ < __p.__cntrl_;}
605     _LIBCPP_INLINE_VISIBILITY
606     bool
607     __owner_equivalent(const shared_ptr& __p) const
608         {return __cntrl_ == __p.__cntrl_;}
609 
610 #if _LIBCPP_STD_VER > 14
611     typename add_lvalue_reference<element_type>::type
612     _LIBCPP_INLINE_VISIBILITY
613     operator[](ptrdiff_t __i) const
614     {
615             static_assert(is_array<_Tp>::value,
616                           "std::shared_ptr<T>::operator[] is only valid when T is an array type.");
617             return __ptr_[__i];
618     }
619 #endif
620 
621 #ifndef _LIBCPP_NO_RTTI
622     template <class _Dp>
623         _LIBCPP_INLINE_VISIBILITY
624         _Dp* __get_deleter() const _NOEXCEPT
625             {return static_cast<_Dp*>(__cntrl_
626                     ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp)))
627                       : nullptr);}
628 #endif // _LIBCPP_NO_RTTI
629 
630     template<class _Yp, class _CntrlBlk>
631     static shared_ptr<_Tp>
632     __create_with_control_block(_Yp* __p, _CntrlBlk* __cntrl) _NOEXCEPT
633     {
634         shared_ptr<_Tp> __r;
635         __r.__ptr_ = __p;
636         __r.__cntrl_ = __cntrl;
637         __r.__enable_weak_this(__r.__ptr_, __r.__ptr_);
638         return __r;
639     }
640 
641 private:
642     template <class _Yp, bool = is_function<_Yp>::value>
643         struct __shared_ptr_default_allocator
644         {
645             typedef allocator<_Yp> type;
646         };
647 
648     template <class _Yp>
649         struct __shared_ptr_default_allocator<_Yp, true>
650         {
651             typedef allocator<__shared_ptr_dummy_rebind_allocator_type> type;
652         };
653 
654     template <class _Yp, class _OrigPtr>
655         _LIBCPP_INLINE_VISIBILITY
656         typename enable_if<is_convertible<_OrigPtr*,
657                                           const enable_shared_from_this<_Yp>*
658         >::value,
659             void>::type
660         __enable_weak_this(const enable_shared_from_this<_Yp>* __e,
661                            _OrigPtr* __ptr) _NOEXCEPT
662         {
663             typedef typename remove_cv<_Yp>::type _RawYp;
664             if (__e && __e->__weak_this_.expired())
665             {
666                 __e->__weak_this_ = shared_ptr<_RawYp>(*this,
667                     const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr)));
668             }
669         }
670 
671     _LIBCPP_INLINE_VISIBILITY void __enable_weak_this(...) _NOEXCEPT {}
672 
673     template <class, class _Yp>
674         struct __shared_ptr_default_delete
675             : default_delete<_Yp> {};
676 
677     template <class _Yp, class _Un, size_t _Sz>
678         struct __shared_ptr_default_delete<_Yp[_Sz], _Un>
679             : default_delete<_Yp[]> {};
680 
681     template <class _Yp, class _Un>
682         struct __shared_ptr_default_delete<_Yp[], _Un>
683             : default_delete<_Yp[]> {};
684 
685     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
686     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
687 };
688 
689 #ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
690 template<class _Tp>
691 shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
692 template<class _Tp, class _Dp>
693 shared_ptr(unique_ptr<_Tp, _Dp>) -> shared_ptr<_Tp>;
694 #endif
695 
696 template<class _Tp>
697 inline
698 _LIBCPP_CONSTEXPR
699 shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
700     : __ptr_(nullptr),
701       __cntrl_(nullptr)
702 {
703 }
704 
705 template<class _Tp>
706 inline
707 _LIBCPP_CONSTEXPR
708 shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
709     : __ptr_(nullptr),
710       __cntrl_(nullptr)
711 {
712 }
713 
714 template<class _Tp>
715 template<class _Yp, class _Dp>
716 shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
717                             typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
718     : __ptr_(__p)
719 {
720 #ifndef _LIBCPP_NO_EXCEPTIONS
721     try
722     {
723 #endif // _LIBCPP_NO_EXCEPTIONS
724         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
725         typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
726 #ifndef _LIBCPP_CXX03_LANG
727         __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
728 #else
729         __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
730 #endif // not _LIBCPP_CXX03_LANG
731         __enable_weak_this(__p, __p);
732 #ifndef _LIBCPP_NO_EXCEPTIONS
733     }
734     catch (...)
735     {
736         __d(__p);
737         throw;
738     }
739 #endif // _LIBCPP_NO_EXCEPTIONS
740 }
741 
742 template<class _Tp>
743 template<class _Dp>
744 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
745     : __ptr_(nullptr)
746 {
747 #ifndef _LIBCPP_NO_EXCEPTIONS
748     try
749     {
750 #endif // _LIBCPP_NO_EXCEPTIONS
751         typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
752         typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
753 #ifndef _LIBCPP_CXX03_LANG
754         __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
755 #else
756         __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
757 #endif // not _LIBCPP_CXX03_LANG
758 #ifndef _LIBCPP_NO_EXCEPTIONS
759     }
760     catch (...)
761     {
762         __d(__p);
763         throw;
764     }
765 #endif // _LIBCPP_NO_EXCEPTIONS
766 }
767 
768 template<class _Tp>
769 template<class _Yp, class _Dp, class _Alloc>
770 shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
771                             typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
772     : __ptr_(__p)
773 {
774 #ifndef _LIBCPP_NO_EXCEPTIONS
775     try
776     {
777 #endif // _LIBCPP_NO_EXCEPTIONS
778         typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
779         typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
780         typedef __allocator_destructor<_A2> _D2;
781         _A2 __a2(__a);
782         unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
783         ::new ((void*)_VSTD::addressof(*__hold2.get()))
784 #ifndef _LIBCPP_CXX03_LANG
785             _CntrlBlk(__p, _VSTD::move(__d), __a);
786 #else
787             _CntrlBlk(__p, __d, __a);
788 #endif // not _LIBCPP_CXX03_LANG
789         __cntrl_ = _VSTD::addressof(*__hold2.release());
790         __enable_weak_this(__p, __p);
791 #ifndef _LIBCPP_NO_EXCEPTIONS
792     }
793     catch (...)
794     {
795         __d(__p);
796         throw;
797     }
798 #endif // _LIBCPP_NO_EXCEPTIONS
799 }
800 
801 template<class _Tp>
802 template<class _Dp, class _Alloc>
803 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
804     : __ptr_(nullptr)
805 {
806 #ifndef _LIBCPP_NO_EXCEPTIONS
807     try
808     {
809 #endif // _LIBCPP_NO_EXCEPTIONS
810         typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
811         typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
812         typedef __allocator_destructor<_A2> _D2;
813         _A2 __a2(__a);
814         unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
815         ::new ((void*)_VSTD::addressof(*__hold2.get()))
816 #ifndef _LIBCPP_CXX03_LANG
817             _CntrlBlk(__p, _VSTD::move(__d), __a);
818 #else
819             _CntrlBlk(__p, __d, __a);
820 #endif // not _LIBCPP_CXX03_LANG
821         __cntrl_ = _VSTD::addressof(*__hold2.release());
822 #ifndef _LIBCPP_NO_EXCEPTIONS
823     }
824     catch (...)
825     {
826         __d(__p);
827         throw;
828     }
829 #endif // _LIBCPP_NO_EXCEPTIONS
830 }
831 
832 template<class _Tp>
833 template<class _Yp>
834 inline
835 shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
836     : __ptr_(__p),
837       __cntrl_(__r.__cntrl_)
838 {
839     if (__cntrl_)
840         __cntrl_->__add_shared();
841 }
842 
843 template<class _Tp>
844 inline
845 shared_ptr<_Tp>::shared_ptr(const shared_ptr& __r) _NOEXCEPT
846     : __ptr_(__r.__ptr_),
847       __cntrl_(__r.__cntrl_)
848 {
849     if (__cntrl_)
850         __cntrl_->__add_shared();
851 }
852 
853 template<class _Tp>
854 template<class _Yp>
855 inline
856 shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r,
857                             typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
858          _NOEXCEPT
859     : __ptr_(__r.__ptr_),
860       __cntrl_(__r.__cntrl_)
861 {
862     if (__cntrl_)
863         __cntrl_->__add_shared();
864 }
865 
866 template<class _Tp>
867 inline
868 shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
869     : __ptr_(__r.__ptr_),
870       __cntrl_(__r.__cntrl_)
871 {
872     __r.__ptr_ = nullptr;
873     __r.__cntrl_ = nullptr;
874 }
875 
876 template<class _Tp>
877 template<class _Yp>
878 inline
879 shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
880                             typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
881          _NOEXCEPT
882     : __ptr_(__r.__ptr_),
883       __cntrl_(__r.__cntrl_)
884 {
885     __r.__ptr_ = nullptr;
886     __r.__cntrl_ = nullptr;
887 }
888 
889 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
890 template<class _Tp>
891 template<class _Yp>
892 shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp>&& __r,
893                             typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
894     : __ptr_(__r.get())
895 {
896     typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
897     __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
898     __enable_weak_this(__r.get(), __r.get());
899     __r.release();
900 }
901 #endif
902 
903 template<class _Tp>
904 template <class _Yp, class _Dp>
905 shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
906                             typename enable_if
907                             <
908                                 !is_lvalue_reference<_Dp>::value &&
909                                 is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
910                                 __nat
911                             >::type)
912     : __ptr_(__r.get())
913 {
914 #if _LIBCPP_STD_VER > 11
915     if (__ptr_ == nullptr)
916         __cntrl_ = nullptr;
917     else
918 #endif
919     {
920         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
921         typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT > _CntrlBlk;
922         __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
923         __enable_weak_this(__r.get(), __r.get());
924     }
925     __r.release();
926 }
927 
928 template<class _Tp>
929 template <class _Yp, class _Dp>
930 shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
931                             typename enable_if
932                             <
933                                 is_lvalue_reference<_Dp>::value &&
934                                 is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
935                                 __nat
936                             >::type)
937     : __ptr_(__r.get())
938 {
939 #if _LIBCPP_STD_VER > 11
940     if (__ptr_ == nullptr)
941         __cntrl_ = nullptr;
942     else
943 #endif
944     {
945         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
946         typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer,
947                                      reference_wrapper<typename remove_reference<_Dp>::type>,
948                                      _AllocT > _CntrlBlk;
949         __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
950         __enable_weak_this(__r.get(), __r.get());
951     }
952     __r.release();
953 }
954 
955 template<class _Tp>
956 shared_ptr<_Tp>::~shared_ptr()
957 {
958     if (__cntrl_)
959         __cntrl_->__release_shared();
960 }
961 
962 template<class _Tp>
963 inline
964 shared_ptr<_Tp>&
965 shared_ptr<_Tp>::operator=(const shared_ptr& __r) _NOEXCEPT
966 {
967     shared_ptr(__r).swap(*this);
968     return *this;
969 }
970 
971 template<class _Tp>
972 template<class _Yp>
973 inline
974 typename enable_if
975 <
976     __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
977     shared_ptr<_Tp>&
978 >::type
979 shared_ptr<_Tp>::operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
980 {
981     shared_ptr(__r).swap(*this);
982     return *this;
983 }
984 
985 template<class _Tp>
986 inline
987 shared_ptr<_Tp>&
988 shared_ptr<_Tp>::operator=(shared_ptr&& __r) _NOEXCEPT
989 {
990     shared_ptr(_VSTD::move(__r)).swap(*this);
991     return *this;
992 }
993 
994 template<class _Tp>
995 template<class _Yp>
996 inline
997 typename enable_if
998 <
999     __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
1000     shared_ptr<_Tp>&
1001 >::type
1002 shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
1003 {
1004     shared_ptr(_VSTD::move(__r)).swap(*this);
1005     return *this;
1006 }
1007 
1008 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
1009 template<class _Tp>
1010 template<class _Yp>
1011 inline
1012 typename enable_if
1013 <
1014     !is_array<_Yp>::value &&
1015     is_convertible<_Yp*, typename shared_ptr<_Tp>::element_type*>::value,
1016     shared_ptr<_Tp>
1017 >::type&
1018 shared_ptr<_Tp>::operator=(auto_ptr<_Yp>&& __r)
1019 {
1020     shared_ptr(_VSTD::move(__r)).swap(*this);
1021     return *this;
1022 }
1023 #endif
1024 
1025 template<class _Tp>
1026 template <class _Yp, class _Dp>
1027 inline
1028 typename enable_if
1029 <
1030     is_convertible<typename unique_ptr<_Yp, _Dp>::pointer,
1031                    typename shared_ptr<_Tp>::element_type*>::value,
1032     shared_ptr<_Tp>&
1033 >::type
1034 shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
1035 {
1036     shared_ptr(_VSTD::move(__r)).swap(*this);
1037     return *this;
1038 }
1039 
1040 template<class _Tp>
1041 inline
1042 void
1043 shared_ptr<_Tp>::swap(shared_ptr& __r) _NOEXCEPT
1044 {
1045     _VSTD::swap(__ptr_, __r.__ptr_);
1046     _VSTD::swap(__cntrl_, __r.__cntrl_);
1047 }
1048 
1049 template<class _Tp>
1050 inline
1051 void
1052 shared_ptr<_Tp>::reset() _NOEXCEPT
1053 {
1054     shared_ptr().swap(*this);
1055 }
1056 
1057 template<class _Tp>
1058 template<class _Yp>
1059 inline
1060 typename enable_if
1061 <
1062     __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
1063     void
1064 >::type
1065 shared_ptr<_Tp>::reset(_Yp* __p)
1066 {
1067     shared_ptr(__p).swap(*this);
1068 }
1069 
1070 template<class _Tp>
1071 template<class _Yp, class _Dp>
1072 inline
1073 typename enable_if
1074 <
1075     __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
1076     void
1077 >::type
1078 shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d)
1079 {
1080     shared_ptr(__p, __d).swap(*this);
1081 }
1082 
1083 template<class _Tp>
1084 template<class _Yp, class _Dp, class _Alloc>
1085 inline
1086 typename enable_if
1087 <
1088     __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
1089     void
1090 >::type
1091 shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d, _Alloc __a)
1092 {
1093     shared_ptr(__p, __d, __a).swap(*this);
1094 }
1095 
1096 //
1097 // std::allocate_shared and std::make_shared
1098 //
1099 template<class _Tp, class _Alloc, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
1100 _LIBCPP_HIDE_FROM_ABI
1101 shared_ptr<_Tp> allocate_shared(const _Alloc& __a, _Args&& ...__args)
1102 {
1103     using _ControlBlock = __shared_ptr_emplace<_Tp, _Alloc>;
1104     using _ControlBlockAllocator = typename __allocator_traits_rebind<_Alloc, _ControlBlock>::type;
1105     __allocation_guard<_ControlBlockAllocator> __guard(__a, 1);
1106     ::new ((void*)_VSTD::addressof(*__guard.__get())) _ControlBlock(__a, _VSTD::forward<_Args>(__args)...);
1107     auto __control_block = __guard.__release_ptr();
1108     return shared_ptr<_Tp>::__create_with_control_block((*__control_block).__get_elem(), _VSTD::addressof(*__control_block));
1109 }
1110 
1111 template<class _Tp, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
1112 _LIBCPP_HIDE_FROM_ABI
1113 shared_ptr<_Tp> make_shared(_Args&& ...__args)
1114 {
1115     return _VSTD::allocate_shared<_Tp>(allocator<_Tp>(), _VSTD::forward<_Args>(__args)...);
1116 }
1117 
1118 template<class _Tp, class _Up>
1119 inline _LIBCPP_INLINE_VISIBILITY
1120 bool
1121 operator==(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1122 {
1123     return __x.get() == __y.get();
1124 }
1125 
1126 template<class _Tp, class _Up>
1127 inline _LIBCPP_INLINE_VISIBILITY
1128 bool
1129 operator!=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1130 {
1131     return !(__x == __y);
1132 }
1133 
1134 template<class _Tp, class _Up>
1135 inline _LIBCPP_INLINE_VISIBILITY
1136 bool
1137 operator<(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1138 {
1139 #if _LIBCPP_STD_VER <= 11
1140     typedef typename common_type<_Tp*, _Up*>::type _Vp;
1141     return less<_Vp>()(__x.get(), __y.get());
1142 #else
1143     return less<>()(__x.get(), __y.get());
1144 #endif
1145 
1146 }
1147 
1148 template<class _Tp, class _Up>
1149 inline _LIBCPP_INLINE_VISIBILITY
1150 bool
1151 operator>(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1152 {
1153     return __y < __x;
1154 }
1155 
1156 template<class _Tp, class _Up>
1157 inline _LIBCPP_INLINE_VISIBILITY
1158 bool
1159 operator<=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1160 {
1161     return !(__y < __x);
1162 }
1163 
1164 template<class _Tp, class _Up>
1165 inline _LIBCPP_INLINE_VISIBILITY
1166 bool
1167 operator>=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
1168 {
1169     return !(__x < __y);
1170 }
1171 
1172 template<class _Tp>
1173 inline _LIBCPP_INLINE_VISIBILITY
1174 bool
1175 operator==(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1176 {
1177     return !__x;
1178 }
1179 
1180 template<class _Tp>
1181 inline _LIBCPP_INLINE_VISIBILITY
1182 bool
1183 operator==(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1184 {
1185     return !__x;
1186 }
1187 
1188 template<class _Tp>
1189 inline _LIBCPP_INLINE_VISIBILITY
1190 bool
1191 operator!=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1192 {
1193     return static_cast<bool>(__x);
1194 }
1195 
1196 template<class _Tp>
1197 inline _LIBCPP_INLINE_VISIBILITY
1198 bool
1199 operator!=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1200 {
1201     return static_cast<bool>(__x);
1202 }
1203 
1204 template<class _Tp>
1205 inline _LIBCPP_INLINE_VISIBILITY
1206 bool
1207 operator<(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1208 {
1209     return less<_Tp*>()(__x.get(), nullptr);
1210 }
1211 
1212 template<class _Tp>
1213 inline _LIBCPP_INLINE_VISIBILITY
1214 bool
1215 operator<(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1216 {
1217     return less<_Tp*>()(nullptr, __x.get());
1218 }
1219 
1220 template<class _Tp>
1221 inline _LIBCPP_INLINE_VISIBILITY
1222 bool
1223 operator>(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1224 {
1225     return nullptr < __x;
1226 }
1227 
1228 template<class _Tp>
1229 inline _LIBCPP_INLINE_VISIBILITY
1230 bool
1231 operator>(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1232 {
1233     return __x < nullptr;
1234 }
1235 
1236 template<class _Tp>
1237 inline _LIBCPP_INLINE_VISIBILITY
1238 bool
1239 operator<=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1240 {
1241     return !(nullptr < __x);
1242 }
1243 
1244 template<class _Tp>
1245 inline _LIBCPP_INLINE_VISIBILITY
1246 bool
1247 operator<=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1248 {
1249     return !(__x < nullptr);
1250 }
1251 
1252 template<class _Tp>
1253 inline _LIBCPP_INLINE_VISIBILITY
1254 bool
1255 operator>=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
1256 {
1257     return !(__x < nullptr);
1258 }
1259 
1260 template<class _Tp>
1261 inline _LIBCPP_INLINE_VISIBILITY
1262 bool
1263 operator>=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
1264 {
1265     return !(nullptr < __x);
1266 }
1267 
1268 template<class _Tp>
1269 inline _LIBCPP_INLINE_VISIBILITY
1270 void
1271 swap(shared_ptr<_Tp>& __x, shared_ptr<_Tp>& __y) _NOEXCEPT
1272 {
1273     __x.swap(__y);
1274 }
1275 
1276 template<class _Tp, class _Up>
1277 inline _LIBCPP_INLINE_VISIBILITY
1278 shared_ptr<_Tp>
1279 static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
1280 {
1281     return shared_ptr<_Tp>(__r,
1282                            static_cast<
1283                                typename shared_ptr<_Tp>::element_type*>(__r.get()));
1284 }
1285 
1286 template<class _Tp, class _Up>
1287 inline _LIBCPP_INLINE_VISIBILITY
1288 shared_ptr<_Tp>
1289 dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
1290 {
1291     typedef typename shared_ptr<_Tp>::element_type _ET;
1292     _ET* __p = dynamic_cast<_ET*>(__r.get());
1293     return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>();
1294 }
1295 
1296 template<class _Tp, class _Up>
1297 shared_ptr<_Tp>
1298 const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
1299 {
1300     typedef typename shared_ptr<_Tp>::element_type _RTp;
1301     return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get()));
1302 }
1303 
1304 template<class _Tp, class _Up>
1305 shared_ptr<_Tp>
1306 reinterpret_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
1307 {
1308     return shared_ptr<_Tp>(__r,
1309                            reinterpret_cast<
1310                                typename shared_ptr<_Tp>::element_type*>(__r.get()));
1311 }
1312 
1313 #ifndef _LIBCPP_NO_RTTI
1314 
1315 template<class _Dp, class _Tp>
1316 inline _LIBCPP_INLINE_VISIBILITY
1317 _Dp*
1318 get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT
1319 {
1320     return __p.template __get_deleter<_Dp>();
1321 }
1322 
1323 #endif // _LIBCPP_NO_RTTI
1324 
1325 template<class _Tp>
1326 class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS weak_ptr
1327 {
1328 public:
1329     typedef _Tp element_type;
1330 private:
1331     element_type*        __ptr_;
1332     __shared_weak_count* __cntrl_;
1333 
1334 public:
1335     _LIBCPP_INLINE_VISIBILITY
1336     _LIBCPP_CONSTEXPR weak_ptr() _NOEXCEPT;
1337     template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(shared_ptr<_Yp> const& __r,
1338                    typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
1339                         _NOEXCEPT;
1340     _LIBCPP_INLINE_VISIBILITY
1341     weak_ptr(weak_ptr const& __r) _NOEXCEPT;
1342     template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp> const& __r,
1343                    typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
1344                          _NOEXCEPT;
1345 
1346     _LIBCPP_INLINE_VISIBILITY
1347     weak_ptr(weak_ptr&& __r) _NOEXCEPT;
1348     template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp>&& __r,
1349                    typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
1350                          _NOEXCEPT;
1351     ~weak_ptr();
1352 
1353     _LIBCPP_INLINE_VISIBILITY
1354     weak_ptr& operator=(weak_ptr const& __r) _NOEXCEPT;
1355     template<class _Yp>
1356         typename enable_if
1357         <
1358             is_convertible<_Yp*, element_type*>::value,
1359             weak_ptr&
1360         >::type
1361         _LIBCPP_INLINE_VISIBILITY
1362         operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT;
1363 
1364     _LIBCPP_INLINE_VISIBILITY
1365     weak_ptr& operator=(weak_ptr&& __r) _NOEXCEPT;
1366     template<class _Yp>
1367         typename enable_if
1368         <
1369             is_convertible<_Yp*, element_type*>::value,
1370             weak_ptr&
1371         >::type
1372         _LIBCPP_INLINE_VISIBILITY
1373         operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT;
1374 
1375     template<class _Yp>
1376         typename enable_if
1377         <
1378             is_convertible<_Yp*, element_type*>::value,
1379             weak_ptr&
1380         >::type
1381         _LIBCPP_INLINE_VISIBILITY
1382         operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT;
1383 
1384     _LIBCPP_INLINE_VISIBILITY
1385     void swap(weak_ptr& __r) _NOEXCEPT;
1386     _LIBCPP_INLINE_VISIBILITY
1387     void reset() _NOEXCEPT;
1388 
1389     _LIBCPP_INLINE_VISIBILITY
1390     long use_count() const _NOEXCEPT
1391         {return __cntrl_ ? __cntrl_->use_count() : 0;}
1392     _LIBCPP_INLINE_VISIBILITY
1393     bool expired() const _NOEXCEPT
1394         {return __cntrl_ == nullptr || __cntrl_->use_count() == 0;}
1395     shared_ptr<_Tp> lock() const _NOEXCEPT;
1396     template<class _Up>
1397         _LIBCPP_INLINE_VISIBILITY
1398         bool owner_before(const shared_ptr<_Up>& __r) const _NOEXCEPT
1399         {return __cntrl_ < __r.__cntrl_;}
1400     template<class _Up>
1401         _LIBCPP_INLINE_VISIBILITY
1402         bool owner_before(const weak_ptr<_Up>& __r) const _NOEXCEPT
1403         {return __cntrl_ < __r.__cntrl_;}
1404 
1405     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
1406     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
1407 };
1408 
1409 #ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
1410 template<class _Tp>
1411 weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>;
1412 #endif
1413 
1414 template<class _Tp>
1415 inline
1416 _LIBCPP_CONSTEXPR
1417 weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
1418     : __ptr_(nullptr),
1419       __cntrl_(nullptr)
1420 {
1421 }
1422 
1423 template<class _Tp>
1424 inline
1425 weak_ptr<_Tp>::weak_ptr(weak_ptr const& __r) _NOEXCEPT
1426     : __ptr_(__r.__ptr_),
1427       __cntrl_(__r.__cntrl_)
1428 {
1429     if (__cntrl_)
1430         __cntrl_->__add_weak();
1431 }
1432 
1433 template<class _Tp>
1434 template<class _Yp>
1435 inline
1436 weak_ptr<_Tp>::weak_ptr(shared_ptr<_Yp> const& __r,
1437                         typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
1438                          _NOEXCEPT
1439     : __ptr_(__r.__ptr_),
1440       __cntrl_(__r.__cntrl_)
1441 {
1442     if (__cntrl_)
1443         __cntrl_->__add_weak();
1444 }
1445 
1446 template<class _Tp>
1447 template<class _Yp>
1448 inline
1449 weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp> const& __r,
1450                         typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
1451          _NOEXCEPT
1452     : __ptr_(__r.__ptr_),
1453       __cntrl_(__r.__cntrl_)
1454 {
1455     if (__cntrl_)
1456         __cntrl_->__add_weak();
1457 }
1458 
1459 template<class _Tp>
1460 inline
1461 weak_ptr<_Tp>::weak_ptr(weak_ptr&& __r) _NOEXCEPT
1462     : __ptr_(__r.__ptr_),
1463       __cntrl_(__r.__cntrl_)
1464 {
1465     __r.__ptr_ = nullptr;
1466     __r.__cntrl_ = nullptr;
1467 }
1468 
1469 template<class _Tp>
1470 template<class _Yp>
1471 inline
1472 weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp>&& __r,
1473                         typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
1474          _NOEXCEPT
1475     : __ptr_(__r.__ptr_),
1476       __cntrl_(__r.__cntrl_)
1477 {
1478     __r.__ptr_ = nullptr;
1479     __r.__cntrl_ = nullptr;
1480 }
1481 
1482 template<class _Tp>
1483 weak_ptr<_Tp>::~weak_ptr()
1484 {
1485     if (__cntrl_)
1486         __cntrl_->__release_weak();
1487 }
1488 
1489 template<class _Tp>
1490 inline
1491 weak_ptr<_Tp>&
1492 weak_ptr<_Tp>::operator=(weak_ptr const& __r) _NOEXCEPT
1493 {
1494     weak_ptr(__r).swap(*this);
1495     return *this;
1496 }
1497 
1498 template<class _Tp>
1499 template<class _Yp>
1500 inline
1501 typename enable_if
1502 <
1503     is_convertible<_Yp*, _Tp*>::value,
1504     weak_ptr<_Tp>&
1505 >::type
1506 weak_ptr<_Tp>::operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT
1507 {
1508     weak_ptr(__r).swap(*this);
1509     return *this;
1510 }
1511 
1512 template<class _Tp>
1513 inline
1514 weak_ptr<_Tp>&
1515 weak_ptr<_Tp>::operator=(weak_ptr&& __r) _NOEXCEPT
1516 {
1517     weak_ptr(_VSTD::move(__r)).swap(*this);
1518     return *this;
1519 }
1520 
1521 template<class _Tp>
1522 template<class _Yp>
1523 inline
1524 typename enable_if
1525 <
1526     is_convertible<_Yp*, _Tp*>::value,
1527     weak_ptr<_Tp>&
1528 >::type
1529 weak_ptr<_Tp>::operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT
1530 {
1531     weak_ptr(_VSTD::move(__r)).swap(*this);
1532     return *this;
1533 }
1534 
1535 template<class _Tp>
1536 template<class _Yp>
1537 inline
1538 typename enable_if
1539 <
1540     is_convertible<_Yp*, _Tp*>::value,
1541     weak_ptr<_Tp>&
1542 >::type
1543 weak_ptr<_Tp>::operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT
1544 {
1545     weak_ptr(__r).swap(*this);
1546     return *this;
1547 }
1548 
1549 template<class _Tp>
1550 inline
1551 void
1552 weak_ptr<_Tp>::swap(weak_ptr& __r) _NOEXCEPT
1553 {
1554     _VSTD::swap(__ptr_, __r.__ptr_);
1555     _VSTD::swap(__cntrl_, __r.__cntrl_);
1556 }
1557 
1558 template<class _Tp>
1559 inline _LIBCPP_INLINE_VISIBILITY
1560 void
1561 swap(weak_ptr<_Tp>& __x, weak_ptr<_Tp>& __y) _NOEXCEPT
1562 {
1563     __x.swap(__y);
1564 }
1565 
1566 template<class _Tp>
1567 inline
1568 void
1569 weak_ptr<_Tp>::reset() _NOEXCEPT
1570 {
1571     weak_ptr().swap(*this);
1572 }
1573 
1574 template<class _Tp>
1575 template<class _Yp>
1576 shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
1577                             typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
1578     : __ptr_(__r.__ptr_),
1579       __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
1580 {
1581     if (__cntrl_ == nullptr)
1582         __throw_bad_weak_ptr();
1583 }
1584 
1585 template<class _Tp>
1586 shared_ptr<_Tp>
1587 weak_ptr<_Tp>::lock() const _NOEXCEPT
1588 {
1589     shared_ptr<_Tp> __r;
1590     __r.__cntrl_ = __cntrl_ ? __cntrl_->lock() : __cntrl_;
1591     if (__r.__cntrl_)
1592         __r.__ptr_ = __ptr_;
1593     return __r;
1594 }
1595 
1596 #if _LIBCPP_STD_VER > 14
1597 template <class _Tp = void> struct owner_less;
1598 #else
1599 template <class _Tp> struct owner_less;
1600 #endif
1601 
1602 
1603 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
1604 template <class _Tp>
1605 struct _LIBCPP_TEMPLATE_VIS owner_less<shared_ptr<_Tp> >
1606 #if !defined(_LIBCPP_ABI_NO_BINDER_BASES)
1607     : binary_function<shared_ptr<_Tp>, shared_ptr<_Tp>, bool>
1608 #endif
1609 {
1610 _LIBCPP_SUPPRESS_DEPRECATED_POP
1611 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS)
1612     _LIBCPP_DEPRECATED_IN_CXX17 typedef bool result_type;
1613     _LIBCPP_DEPRECATED_IN_CXX17 typedef shared_ptr<_Tp> first_argument_type;
1614     _LIBCPP_DEPRECATED_IN_CXX17 typedef shared_ptr<_Tp> second_argument_type;
1615 #endif
1616     _LIBCPP_INLINE_VISIBILITY
1617     bool operator()(shared_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
1618         {return __x.owner_before(__y);}
1619     _LIBCPP_INLINE_VISIBILITY
1620     bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
1621         {return __x.owner_before(__y);}
1622     _LIBCPP_INLINE_VISIBILITY
1623     bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
1624         {return __x.owner_before(__y);}
1625 };
1626 
1627 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
1628 template <class _Tp>
1629 struct _LIBCPP_TEMPLATE_VIS owner_less<weak_ptr<_Tp> >
1630 #if !defined(_LIBCPP_ABI_NO_BINDER_BASES)
1631     : binary_function<weak_ptr<_Tp>, weak_ptr<_Tp>, bool>
1632 #endif
1633 {
1634 _LIBCPP_SUPPRESS_DEPRECATED_POP
1635 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS)
1636     _LIBCPP_DEPRECATED_IN_CXX17 typedef bool result_type;
1637     _LIBCPP_DEPRECATED_IN_CXX17 typedef weak_ptr<_Tp> first_argument_type;
1638     _LIBCPP_DEPRECATED_IN_CXX17 typedef weak_ptr<_Tp> second_argument_type;
1639 #endif
1640     _LIBCPP_INLINE_VISIBILITY
1641     bool operator()(  weak_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
1642         {return __x.owner_before(__y);}
1643     _LIBCPP_INLINE_VISIBILITY
1644     bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
1645         {return __x.owner_before(__y);}
1646     _LIBCPP_INLINE_VISIBILITY
1647     bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
1648         {return __x.owner_before(__y);}
1649 };
1650 
1651 #if _LIBCPP_STD_VER > 14
1652 template <>
1653 struct _LIBCPP_TEMPLATE_VIS owner_less<void>
1654 {
1655     template <class _Tp, class _Up>
1656     _LIBCPP_INLINE_VISIBILITY
1657     bool operator()( shared_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
1658         {return __x.owner_before(__y);}
1659     template <class _Tp, class _Up>
1660     _LIBCPP_INLINE_VISIBILITY
1661     bool operator()( shared_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
1662         {return __x.owner_before(__y);}
1663     template <class _Tp, class _Up>
1664     _LIBCPP_INLINE_VISIBILITY
1665     bool operator()(   weak_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
1666         {return __x.owner_before(__y);}
1667     template <class _Tp, class _Up>
1668     _LIBCPP_INLINE_VISIBILITY
1669     bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
1670         {return __x.owner_before(__y);}
1671     typedef void is_transparent;
1672 };
1673 #endif
1674 
1675 template<class _Tp>
1676 class _LIBCPP_TEMPLATE_VIS enable_shared_from_this
1677 {
1678     mutable weak_ptr<_Tp> __weak_this_;
1679 protected:
1680     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1681     enable_shared_from_this() _NOEXCEPT {}
1682     _LIBCPP_INLINE_VISIBILITY
1683     enable_shared_from_this(enable_shared_from_this const&) _NOEXCEPT {}
1684     _LIBCPP_INLINE_VISIBILITY
1685     enable_shared_from_this& operator=(enable_shared_from_this const&) _NOEXCEPT
1686         {return *this;}
1687     _LIBCPP_INLINE_VISIBILITY
1688     ~enable_shared_from_this() {}
1689 public:
1690     _LIBCPP_INLINE_VISIBILITY
1691     shared_ptr<_Tp> shared_from_this()
1692         {return shared_ptr<_Tp>(__weak_this_);}
1693     _LIBCPP_INLINE_VISIBILITY
1694     shared_ptr<_Tp const> shared_from_this() const
1695         {return shared_ptr<const _Tp>(__weak_this_);}
1696 
1697 #if _LIBCPP_STD_VER > 14
1698     _LIBCPP_INLINE_VISIBILITY
1699     weak_ptr<_Tp> weak_from_this() _NOEXCEPT
1700        { return __weak_this_; }
1701 
1702     _LIBCPP_INLINE_VISIBILITY
1703     weak_ptr<const _Tp> weak_from_this() const _NOEXCEPT
1704         { return __weak_this_; }
1705 #endif // _LIBCPP_STD_VER > 14
1706 
1707     template <class _Up> friend class shared_ptr;
1708 };
1709 
1710 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
1711 
1712 template <class _Tp>
1713 struct _LIBCPP_TEMPLATE_VIS hash<shared_ptr<_Tp> >
1714 {
1715 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS)
1716     _LIBCPP_DEPRECATED_IN_CXX17 typedef shared_ptr<_Tp> argument_type;
1717     _LIBCPP_DEPRECATED_IN_CXX17 typedef size_t          result_type;
1718 #endif
1719 
1720     _LIBCPP_INLINE_VISIBILITY
1721     size_t operator()(const shared_ptr<_Tp>& __ptr) const _NOEXCEPT
1722     {
1723         return hash<typename shared_ptr<_Tp>::element_type*>()(__ptr.get());
1724     }
1725 };
1726 
1727 template<class _CharT, class _Traits, class _Yp>
1728 inline _LIBCPP_INLINE_VISIBILITY
1729 basic_ostream<_CharT, _Traits>&
1730 operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
1731 
1732 
1733 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
1734 
1735 class _LIBCPP_TYPE_VIS __sp_mut
1736 {
1737     void* __lx;
1738 public:
1739     void lock() _NOEXCEPT;
1740     void unlock() _NOEXCEPT;
1741 
1742 private:
1743     _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
1744     __sp_mut(const __sp_mut&);
1745     __sp_mut& operator=(const __sp_mut&);
1746 
1747     friend _LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
1748 };
1749 
1750 _LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1751 __sp_mut& __get_sp_mut(const void*);
1752 
1753 template <class _Tp>
1754 inline _LIBCPP_INLINE_VISIBILITY
1755 bool
1756 atomic_is_lock_free(const shared_ptr<_Tp>*)
1757 {
1758     return false;
1759 }
1760 
1761 template <class _Tp>
1762 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1763 shared_ptr<_Tp>
1764 atomic_load(const shared_ptr<_Tp>* __p)
1765 {
1766     __sp_mut& __m = __get_sp_mut(__p);
1767     __m.lock();
1768     shared_ptr<_Tp> __q = *__p;
1769     __m.unlock();
1770     return __q;
1771 }
1772 
1773 template <class _Tp>
1774 inline _LIBCPP_INLINE_VISIBILITY
1775 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1776 shared_ptr<_Tp>
1777 atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
1778 {
1779     return atomic_load(__p);
1780 }
1781 
1782 template <class _Tp>
1783 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1784 void
1785 atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
1786 {
1787     __sp_mut& __m = __get_sp_mut(__p);
1788     __m.lock();
1789     __p->swap(__r);
1790     __m.unlock();
1791 }
1792 
1793 template <class _Tp>
1794 inline _LIBCPP_INLINE_VISIBILITY
1795 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1796 void
1797 atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
1798 {
1799     atomic_store(__p, __r);
1800 }
1801 
1802 template <class _Tp>
1803 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1804 shared_ptr<_Tp>
1805 atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
1806 {
1807     __sp_mut& __m = __get_sp_mut(__p);
1808     __m.lock();
1809     __p->swap(__r);
1810     __m.unlock();
1811     return __r;
1812 }
1813 
1814 template <class _Tp>
1815 inline _LIBCPP_INLINE_VISIBILITY
1816 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1817 shared_ptr<_Tp>
1818 atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
1819 {
1820     return atomic_exchange(__p, __r);
1821 }
1822 
1823 template <class _Tp>
1824 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1825 bool
1826 atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
1827 {
1828     shared_ptr<_Tp> __temp;
1829     __sp_mut& __m = __get_sp_mut(__p);
1830     __m.lock();
1831     if (__p->__owner_equivalent(*__v))
1832     {
1833         _VSTD::swap(__temp, *__p);
1834         *__p = __w;
1835         __m.unlock();
1836         return true;
1837     }
1838     _VSTD::swap(__temp, *__v);
1839     *__v = *__p;
1840     __m.unlock();
1841     return false;
1842 }
1843 
1844 template <class _Tp>
1845 inline _LIBCPP_INLINE_VISIBILITY
1846 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1847 bool
1848 atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
1849 {
1850     return atomic_compare_exchange_strong(__p, __v, __w);
1851 }
1852 
1853 template <class _Tp>
1854 inline _LIBCPP_INLINE_VISIBILITY
1855 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1856 bool
1857 atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
1858                                         shared_ptr<_Tp> __w, memory_order, memory_order)
1859 {
1860     return atomic_compare_exchange_strong(__p, __v, __w);
1861 }
1862 
1863 template <class _Tp>
1864 inline _LIBCPP_INLINE_VISIBILITY
1865 _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
1866 bool
1867 atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
1868                                       shared_ptr<_Tp> __w, memory_order, memory_order)
1869 {
1870     return atomic_compare_exchange_weak(__p, __v, __w);
1871 }
1872 
1873 #endif // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
1874 
1875 _LIBCPP_END_NAMESPACE_STD
1876 
1877 _LIBCPP_POP_MACROS
1878 
1879 #endif // _LIBCPP___MEMORY_SHARED_PTR_H
1880