boost/signals2/trackable.hpp

0001 // Boost.Signals2 library
0002
0003 // Copyright Frank Mori Hess 2007,2009.
0004 // Copyright Timmo Stange 2007.
0005 // Copyright Douglas Gregor 2001-2004. Use, modification and
0006 // distribution is subject to the Boost Software License, Version
0007 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0008 // http://www.boost.org/LICENSE_1_0.txt)
0009
0010 // Compatibility class to ease porting from the original
0011 // Boost.Signals library.  However,
0012 // boost::signals2::trackable is NOT thread-safe.
0013
0014 // For more information, see http://www.boost.org
0015
0016 #ifndef BOOST_SIGNALS2_TRACKABLE_HPP
0017 #define BOOST_SIGNALS2_TRACKABLE_HPP
0018
0019 #include <boost/assert.hpp>
0020 #include <boost/shared_ptr.hpp>
0021 #include <boost/weak_ptr.hpp>
0022
0023 namespace boost {
0024   namespace signals2 {
0025     namespace detail
0026     {
0027         class tracked_objects_visitor;
0028
0029         // trackable_pointee is used to identify the tracked shared_ptr
0030         // originating from the signals2::trackable class.  These tracked
0031         // shared_ptr are special in that we shouldn't bother to
0032         // increment their use count during signal invocation, since
0033         // they don't actually control the lifetime of the
0034         // signals2::trackable object they are associated with.
0035         class trackable_pointee
0036         {};
0037     }
0038     class trackable {
0039     protected:
0040       trackable(): _tracked_ptr(static_cast<detail::trackable_pointee*>(0)) {}
0041       trackable(const trackable &): _tracked_ptr(static_cast<detail::trackable_pointee*>(0)) {}
0042       trackable& operator=(const trackable &)
0043       {
0044           return *this;
0045       }
0046       ~trackable() {}
0047     private:
0048       friend class detail::tracked_objects_visitor;
0049       weak_ptr<detail::trackable_pointee> get_weak_ptr() const
0050       {
0051           return _tracked_ptr;
0052       }
0053
0054       shared_ptr<detail::trackable_pointee> _tracked_ptr;
0055     };
0056   } // end namespace signals2
0057 } // end namespace boost
0058
0059 #endif // BOOST_SIGNALS2_TRACKABLE_HPP