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

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