3rdparty/boost/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 signals2::connection &conn = signals2::connection(),
  26         bool initially_blocked = true):
  27         _weak_connection_body(conn._weak_connection_body)
  28       {
  29         if(initially_blocked) block();
  30       }
  31       void block()
  32       {
  33         if(blocking()) return;
  34         boost::shared_ptr<detail::connection_body_base> connection_body(_weak_connection_body.lock());
  35         if(connection_body == 0)
  36         {
  37           // Make _blocker non-empty so the blocking() method still returns the correct value
  38           // after the connection has expired.
  39           _blocker.reset(static_cast<int*>(0));
  40           return;
  41         }
  42         _blocker = connection_body->get_blocker();
  43       }
  44       void unblock()
  45       {
  46         _blocker.reset();
  47       }
  48       bool blocking() const
  49       {
  50         shared_ptr<void> empty;
  51         return _blocker < empty || empty < _blocker;
  52       }
  53       signals2::connection connection() const
  54       {
  55         return signals2::connection(_weak_connection_body);
  56       }
  57     private:
  58       boost::weak_ptr<detail::connection_body_base> _weak_connection_body;
  59       shared_ptr<void> _blocker;
  60     };
  61   }
  62 } // end namespace boost
  63
  64 #endif // BOOST_SIGNALS2_SHARED_CONNECTION_BLOCK_HPP