1 #ifndef BOOST_ENABLE_SHARED_FROM_RAW_HPP_INCLUDED
2 #define BOOST_ENABLE_SHARED_FROM_RAW_HPP_INCLUDED
3
4 //
5 // enable_shared_from_raw.hpp
6 //
7 // Copyright 2002, 2009, 2014 Peter Dimov
8 // Copyright 2008-2009 Frank Mori Hess
9 //
10 // Distributed under the Boost Software License, Version 1.0.
11 // See accompanying file LICENSE_1_0.txt or copy at
12 // http://www.boost.org/LICENSE_1_0.txt
13 //
14
15 #include <boost/config.hpp>
16 #include <boost/shared_ptr.hpp>
17 #include <boost/weak_ptr.hpp>
18 #include <boost/assert.hpp>
19 #include <boost/detail/workaround.hpp>
20
21 namespace boost
22 {
23 template<typename T> boost::shared_ptr<T> shared_from_raw(T *);
24 template<typename T> boost::weak_ptr<T> weak_from_raw(T *);
25
26 namespace detail
27 {
28 template< class X, class Y > inline void sp_enable_shared_from_this( boost::shared_ptr<X> * ppx, Y const * py, boost::enable_shared_from_raw const * pe );
29
30 } // namespace detail
31
32 class enable_shared_from_raw
33 {
34 protected:
35
enable_shared_from_raw()36 enable_shared_from_raw()
37 {
38 }
39
enable_shared_from_raw(enable_shared_from_raw const &)40 enable_shared_from_raw( enable_shared_from_raw const & )
41 {
42 }
43
operator =(enable_shared_from_raw const &)44 enable_shared_from_raw & operator=( enable_shared_from_raw const & )
45 {
46 return *this;
47 }
48
~enable_shared_from_raw()49 ~enable_shared_from_raw()
50 {
51 BOOST_ASSERT( shared_this_.use_count() <= 1 ); // make sure no dangling shared_ptr objects exist
52 }
53
54 private:
55
init_if_expired() const56 void init_if_expired() const
57 {
58 if( weak_this_.expired() )
59 {
60 shared_this_.reset( static_cast<void*>(0), detail::esft2_deleter_wrapper() );
61 weak_this_ = shared_this_;
62 }
63 }
64
init_if_empty() const65 void init_if_empty() const
66 {
67 if( weak_this_._empty() )
68 {
69 shared_this_.reset( static_cast<void*>(0), detail::esft2_deleter_wrapper() );
70 weak_this_ = shared_this_;
71 }
72 }
73
74 #ifdef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
75 public:
76 #else
77 private:
78 template<class Y> friend class shared_ptr;
79 template<typename T> friend boost::shared_ptr<T> shared_from_raw(T *);
80 template<typename T> friend boost::weak_ptr<T> weak_from_raw(T *);
81 template< class X, class Y > friend inline void detail::sp_enable_shared_from_this( boost::shared_ptr<X> * ppx, Y const * py, boost::enable_shared_from_raw const * pe );
82 #endif
83
shared_from_this() const84 shared_ptr<void const volatile> shared_from_this() const
85 {
86 init_if_expired();
87 return shared_ptr<void const volatile>( weak_this_ );
88 }
89
shared_from_this() const90 shared_ptr<void const volatile> shared_from_this() const volatile
91 {
92 return const_cast< enable_shared_from_raw const * >( this )->shared_from_this();
93 }
94
weak_from_this() const95 weak_ptr<void const volatile> weak_from_this() const
96 {
97 init_if_empty();
98 return weak_this_;
99 }
100
weak_from_this() const101 weak_ptr<void const volatile> weak_from_this() const volatile
102 {
103 return const_cast< enable_shared_from_raw const * >( this )->weak_from_this();
104 }
105
106 // Note: invoked automatically by shared_ptr; do not call
_internal_accept_owner(shared_ptr<X> * ppx,Y *) const107 template<class X, class Y> void _internal_accept_owner( shared_ptr<X> * ppx, Y * ) const
108 {
109 BOOST_ASSERT( ppx != 0 );
110
111 if( weak_this_.expired() )
112 {
113 weak_this_ = *ppx;
114 }
115 else if( shared_this_.use_count() != 0 )
116 {
117 BOOST_ASSERT( ppx->unique() ); // no weak_ptrs should exist either, but there's no way to check that
118
119 detail::esft2_deleter_wrapper * pd = boost::get_deleter<detail::esft2_deleter_wrapper>( shared_this_ );
120 BOOST_ASSERT( pd != 0 );
121
122 pd->set_deleter( *ppx );
123
124 ppx->reset( shared_this_, ppx->get() );
125 shared_this_.reset();
126 }
127 }
128
129 mutable weak_ptr<void const volatile> weak_this_;
130
131 private:
132
133 mutable shared_ptr<void const volatile> shared_this_;
134 };
135
136 template<typename T>
shared_from_raw(T * p)137 boost::shared_ptr<T> shared_from_raw(T *p)
138 {
139 BOOST_ASSERT(p != 0);
140 return boost::shared_ptr<T>(p->enable_shared_from_raw::shared_from_this(), p);
141 }
142
143 template<typename T>
weak_from_raw(T * p)144 boost::weak_ptr<T> weak_from_raw(T *p)
145 {
146 BOOST_ASSERT(p != 0);
147 boost::weak_ptr<T> result;
148 result._internal_aliasing_assign(p->enable_shared_from_raw::weak_from_this(), p);
149 return result;
150 }
151
152 namespace detail
153 {
sp_enable_shared_from_this(boost::shared_ptr<X> * ppx,Y const * py,boost::enable_shared_from_raw const * pe)154 template< class X, class Y > inline void sp_enable_shared_from_this( boost::shared_ptr<X> * ppx, Y const * py, boost::enable_shared_from_raw const * pe )
155 {
156 if( pe != 0 )
157 {
158 pe->_internal_accept_owner( ppx, const_cast< Y* >( py ) );
159 }
160 }
161 } // namepsace detail
162
163 } // namespace boost
164
165 #endif // #ifndef BOOST_ENABLE_SHARED_FROM_RAW_HPP_INCLUDED
166