boost/signals2/shared_connection_block.hpp

   1 // Boost.Signals2 library
   2
   3 // Copyright Frank Mori Hess 2007-2008.
   4 // Use, modification and
   5 // distribution is subject to the Boost Software License, Version
   6 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8
   9 // For more information, see http://www.boost.org
  10
  11 #ifndef BOOST_SIGNALS2_SHARED_CONNECTION_BLOCK_HPP
  12 #define BOOST_SIGNALS2_SHARED_CONNECTION_BLOCK_HPP
  13
  14 #include <boost/shared_ptr.hpp>
  15 #include <boost/signals2/connection.hpp>
  16 #include <boost/weak_ptr.hpp>
  17
  18 namespace boost
  19 {
  20   namespace signals2
  21   {
  22     class shared_connection_block
  23     {
  24     public:
  25       shared_connection_block(const connection &conn):
  26         _weak_connection_body(conn._weak_connection_body)
  27       {
  28         block();
  29       }
  30       void block()
  31       {
  32         if(blocking()) return;
  33         boost::shared_ptr<detail::connection_body_base> connection_body(_weak_connection_body.lock());
  34         if(connection_body == 0)
  35         {
  36           // Make _blocker non-empty so the blocking() method still returns the correct value
  37           // after the connection has expired.
  38           _blocker.reset(static_cast<int*>(0));
  39           return;
  40         }
  41         _blocker = connection_body->get_blocker();
  42       }
  43       void unblock()
  44       {
  45         _blocker.reset();
  46       }
  47       bool blocking() const
  48       {
  49         shared_ptr<void> empty;
  50         return _blocker < empty || empty < _blocker;
  51       }
  52     private:
  53       boost::weak_ptr<detail::connection_body_base> _weak_connection_body;
  54       shared_ptr<void> _blocker;
  55     };
  56   }
  57 } // end namespace boost
  58
  59 #endif // BOOST_SIGNALS2_SHARED_CONNECTION_BLOCK_HPP