1#ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
2#define BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
3
4//
5// weak_ptr.hpp
6//
7// Copyright (c) 2001, 2002, 2003 Peter Dimov
8//
9// Distributed under the Boost Software License, Version 1.0. (See
10// accompanying file LICENSE_1_0.txt or copy at
11// http://www.boost.org/LICENSE_1_0.txt)
12//
13// See http://www.boost.org/libs/smart_ptr/ for documentation.
14//
15
16#include <boost/smart_ptr/detail/requires_cxx11.hpp>
17#include <boost/smart_ptr/detail/shared_count.hpp>
18#include <boost/smart_ptr/shared_ptr.hpp>
19#include <boost/smart_ptr/detail/sp_noexcept.hpp>
20#include <memory>
21#include <cstddef>
22
23namespace boost
24{
25
26template<class T> class weak_ptr
27{
28private:
29
30 // Borland 5.5.1 specific workarounds
31 typedef weak_ptr<T> this_type;
32
33public:
34
35 typedef typename boost::detail::sp_element< T >::type element_type;
36
37 BOOST_CONSTEXPR weak_ptr() BOOST_SP_NOEXCEPT : px(0), pn()
38 {
39 }
40
41// generated copy constructor, assignment, destructor are fine...
42
43#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
44
45// ... except in C++0x, move disables the implicit copy
46
47 weak_ptr( weak_ptr const & r ) BOOST_SP_NOEXCEPT : px( r.px ), pn( r.pn )
48 {
49 }
50
51 weak_ptr & operator=( weak_ptr const & r ) BOOST_SP_NOEXCEPT
52 {
53 px = r.px;
54 pn = r.pn;
55 return *this;
56 }
57
58#endif
59
60//
61// The "obvious" converting constructor implementation:
62//
63// template<class Y>
64// weak_ptr(weak_ptr<Y> const & r): px(r.px), pn(r.pn)
65// {
66// }
67//
68// has a serious problem.
69//
70// r.px may already have been invalidated. The px(r.px)
71// conversion may require access to *r.px (virtual inheritance).
72//
73// It is not possible to avoid spurious access violations since
74// in multithreaded programs r.px may be invalidated at any point.
75//
76
77 template<class Y>
78#if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
79
80 weak_ptr( weak_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
81
82#else
83
84 weak_ptr( weak_ptr<Y> const & r )
85
86#endif
87 BOOST_SP_NOEXCEPT : px(r.lock().get()), pn(r.pn)
88 {
89 boost::detail::sp_assert_convertible< Y, T >();
90 }
91
92#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
93
94 template<class Y>
95#if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
96
97 weak_ptr( weak_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
98
99#else
100
101 weak_ptr( weak_ptr<Y> && r )
102
103#endif
104 BOOST_SP_NOEXCEPT : px( r.lock().get() ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
105 {
106 boost::detail::sp_assert_convertible< Y, T >();
107 r.px = 0;
108 }
109
110 // for better efficiency in the T == Y case
111 weak_ptr( weak_ptr && r )
112 BOOST_SP_NOEXCEPT : px( r.px ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
113 {
114 r.px = 0;
115 }
116
117 // for better efficiency in the T == Y case
118 weak_ptr & operator=( weak_ptr && r ) BOOST_SP_NOEXCEPT
119 {
120 this_type( static_cast< weak_ptr && >( r ) ).swap( *this );
121 return *this;
122 }
123
124
125#endif
126
127 template<class Y>
128#if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
129
130 weak_ptr( shared_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
131
132#else
133
134 weak_ptr( shared_ptr<Y> const & r )
135
136#endif
137 BOOST_SP_NOEXCEPT : px( r.px ), pn( r.pn )
138 {
139 boost::detail::sp_assert_convertible< Y, T >();
140 }
141
142 // aliasing
143 template<class Y> weak_ptr(shared_ptr<Y> const & r, element_type * p) BOOST_SP_NOEXCEPT: px( p ), pn( r.pn )
144 {
145 }
146
147 template<class Y> weak_ptr(weak_ptr<Y> const & r, element_type * p) BOOST_SP_NOEXCEPT: px( p ), pn( r.pn )
148 {
149 }
150
151#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
152
153 template<class Y> weak_ptr(weak_ptr<Y> && r, element_type * p) BOOST_SP_NOEXCEPT: px( p ), pn( std::move( r.pn ) )
154 {
155 }
156
157#endif
158
159#if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1300)
160
161 template<class Y>
162 weak_ptr & operator=( weak_ptr<Y> const & r ) BOOST_SP_NOEXCEPT
163 {
164 boost::detail::sp_assert_convertible< Y, T >();
165
166 px = r.lock().get();
167 pn = r.pn;
168
169 return *this;
170 }
171
172#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
173
174 template<class Y>
175 weak_ptr & operator=( weak_ptr<Y> && r ) BOOST_SP_NOEXCEPT
176 {
177 this_type( static_cast< weak_ptr<Y> && >( r ) ).swap( *this );
178 return *this;
179 }
180
181#endif
182
183 template<class Y>
184 weak_ptr & operator=( shared_ptr<Y> const & r ) BOOST_SP_NOEXCEPT
185 {
186 boost::detail::sp_assert_convertible< Y, T >();
187
188 px = r.px;
189 pn = r.pn;
190
191 return *this;
192 }
193
194#endif
195
196 shared_ptr<T> lock() const BOOST_SP_NOEXCEPT
197 {
198 return shared_ptr<T>( *this, boost::detail::sp_nothrow_tag() );
199 }
200
201 long use_count() const BOOST_SP_NOEXCEPT
202 {
203 return pn.use_count();
204 }
205
206 bool expired() const BOOST_SP_NOEXCEPT
207 {
208 return pn.use_count() == 0;
209 }
210
211 bool _empty() const BOOST_SP_NOEXCEPT // extension, not in std::weak_ptr
212 {
213 return pn.empty();
214 }
215
216 bool empty() const BOOST_SP_NOEXCEPT // extension, not in std::weak_ptr
217 {
218 return pn.empty();
219 }
220
221 void reset() BOOST_SP_NOEXCEPT
222 {
223 this_type().swap(*this);
224 }
225
226 void swap(this_type & other) BOOST_SP_NOEXCEPT
227 {
228 std::swap(px, other.px);
229 pn.swap(r&: other.pn);
230 }
231
232 template<class Y> bool owner_before( weak_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
233 {
234 return pn < rhs.pn;
235 }
236
237 template<class Y> bool owner_before( shared_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
238 {
239 return pn < rhs.pn;
240 }
241
242 template<class Y> bool owner_equals( weak_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
243 {
244 return pn == rhs.pn;
245 }
246
247 template<class Y> bool owner_equals( shared_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
248 {
249 return pn == rhs.pn;
250 }
251
252 std::size_t owner_hash_value() const BOOST_SP_NOEXCEPT
253 {
254 return pn.hash_value();
255 }
256
257// Tasteless as this may seem, making all members public allows member templates
258// to work in the absence of member template friends. (Matthew Langston)
259
260#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
261
262private:
263
264 template<class Y> friend class weak_ptr;
265 template<class Y> friend class shared_ptr;
266
267#endif
268
269 element_type * px; // contained pointer
270 boost::detail::weak_count pn; // reference counter
271
272}; // weak_ptr
273
274template<class T, class U> inline bool operator<(weak_ptr<T> const & a, weak_ptr<U> const & b) BOOST_SP_NOEXCEPT
275{
276 return a.owner_before( b );
277}
278
279template<class T> void swap(weak_ptr<T> & a, weak_ptr<T> & b) BOOST_SP_NOEXCEPT
280{
281 a.swap(b);
282}
283
284#if defined(__cpp_deduction_guides)
285
286template<class T> weak_ptr( shared_ptr<T> ) -> weak_ptr<T>;
287
288#endif
289
290// hash_value
291
292template< class T > std::size_t hash_value( boost::weak_ptr<T> const & p ) BOOST_SP_NOEXCEPT
293{
294 return p.owner_hash_value();
295}
296
297} // namespace boost
298
299// std::hash, std::equal_to
300
301namespace std
302{
303
304#if !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
305
306template<class T> struct hash< ::boost::weak_ptr<T> >
307{
308 std::size_t operator()( ::boost::weak_ptr<T> const & p ) const BOOST_SP_NOEXCEPT
309 {
310 return p.owner_hash_value();
311 }
312};
313
314#endif // #if !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
315
316template<class T> struct equal_to< ::boost::weak_ptr<T> >
317{
318 bool operator()( ::boost::weak_ptr<T> const & a, ::boost::weak_ptr<T> const & b ) const BOOST_SP_NOEXCEPT
319 {
320 return a.owner_equals( b );
321 }
322};
323
324} // namespace std
325
326#endif // #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
327

source code of boost/libs/smart_ptr/include/boost/smart_ptr/weak_ptr.hpp