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 // http://www.boost.org/libs/smart_ptr/enable_shared_from_this.html 14 // 15 16 #include <boost/smart_ptr/weak_ptr.hpp> 17 #include <boost/smart_ptr/shared_ptr.hpp> 18 #include <boost/assert.hpp> 19 #include <boost/config.hpp> 20 21 namespace boost 22 { 23 24 template<class T> class enable_shared_from_this 25 { 26 protected: 27 enable_shared_from_this()28 enable_shared_from_this() BOOST_NOEXCEPT 29 { 30 } 31 enable_shared_from_this(enable_shared_from_this const &)32 enable_shared_from_this(enable_shared_from_this const &) BOOST_NOEXCEPT 33 { 34 } 35 operator =(enable_shared_from_this const &)36 enable_shared_from_this & operator=(enable_shared_from_this const &) BOOST_NOEXCEPT 37 { 38 return *this; 39 } 40 ~enable_shared_from_this()41 ~enable_shared_from_this() BOOST_NOEXCEPT // ~weak_ptr<T> newer throws, so this call also must not throw 42 { 43 } 44 45 public: 46 shared_from_this()47 shared_ptr<T> shared_from_this() 48 { 49 shared_ptr<T> p( weak_this_ ); 50 BOOST_ASSERT( p.get() == this ); 51 return p; 52 } 53 shared_from_this() const54 shared_ptr<T const> shared_from_this() const 55 { 56 shared_ptr<T const> p( weak_this_ ); 57 BOOST_ASSERT( p.get() == this ); 58 return p; 59 } 60 weak_from_this()61 weak_ptr<T> weak_from_this() BOOST_NOEXCEPT 62 { 63 return weak_this_; 64 } 65 weak_from_this() const66 weak_ptr<T const> weak_from_this() const BOOST_NOEXCEPT 67 { 68 return weak_this_; 69 } 70 71 public: // actually private, but avoids compiler template friendship issues 72 73 // Note: invoked automatically by shared_ptr; do not call _internal_accept_owner(shared_ptr<X> const * ppx,Y * py) const74 template<class X, class Y> void _internal_accept_owner( shared_ptr<X> const * ppx, Y * py ) const 75 { 76 if( weak_this_.expired() ) 77 { 78 weak_this_ = shared_ptr<T>( *ppx, py ); 79 } 80 } 81 82 private: 83 84 mutable weak_ptr<T> weak_this_; 85 }; 86 87 } // namespace boost 88 89 #endif // #ifndef BOOST_SMART_PTR_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED 90