1#ifndef BOOST_SMART_PTR_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED
2#define BOOST_SMART_PTR_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED
3
4//
5// enable_shared_from_this.hpp
6//
7// Copyright 2002, 2009 Peter Dimov
8//
9// Distributed under the Boost Software License, Version 1.0.
10// See 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/weak_ptr.hpp>
17#include <boost/smart_ptr/shared_ptr.hpp>
18#include <boost/smart_ptr/detail/sp_noexcept.hpp>
19#include <boost/assert.hpp>
20#include <boost/config.hpp>
21
22namespace boost
23{
24
25template<class T> class enable_shared_from_this
26{
27protected:
28
29 BOOST_CONSTEXPR enable_shared_from_this() BOOST_SP_NOEXCEPT
30 {
31 }
32
33 BOOST_CONSTEXPR enable_shared_from_this(enable_shared_from_this const &) BOOST_SP_NOEXCEPT
34 {
35 }
36
37 enable_shared_from_this & operator=(enable_shared_from_this const &) BOOST_SP_NOEXCEPT
38 {
39 return *this;
40 }
41
42 ~enable_shared_from_this() BOOST_SP_NOEXCEPT // ~weak_ptr<T> newer throws, so this call also must not throw
43 {
44 }
45
46public:
47
48 shared_ptr<T> shared_from_this()
49 {
50 shared_ptr<T> p( weak_this_ );
51 BOOST_ASSERT( p.get() == this );
52 return p;
53 }
54
55 shared_ptr<T const> shared_from_this() const
56 {
57 shared_ptr<T const> p( weak_this_ );
58 BOOST_ASSERT( p.get() == this );
59 return p;
60 }
61
62 weak_ptr<T> weak_from_this() BOOST_SP_NOEXCEPT
63 {
64 return weak_this_;
65 }
66
67 weak_ptr<T const> weak_from_this() const BOOST_SP_NOEXCEPT
68 {
69 return weak_this_;
70 }
71
72public: // actually private, but avoids compiler template friendship issues
73
74 // Note: invoked automatically by shared_ptr; do not call
75 template<class X, class Y> void _internal_accept_owner( shared_ptr<X> const * ppx, Y * py ) const BOOST_SP_NOEXCEPT
76 {
77 if( weak_this_.expired() )
78 {
79 weak_this_ = shared_ptr<T>( *ppx, py );
80 }
81 }
82
83private:
84
85 mutable weak_ptr<T> weak_this_;
86};
87
88} // namespace boost
89
90#endif // #ifndef BOOST_SMART_PTR_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED
91