sl@0: #ifndef BOOST_STATECHART_RESULT_HPP_INCLUDED
sl@0: #define BOOST_STATECHART_RESULT_HPP_INCLUDED
sl@0: //////////////////////////////////////////////////////////////////////////////
sl@0: // Copyright 2002-2006 Andreas Huber Doenni
sl@0: // Distributed under the Boost Software License, Version 1.0. (See accompany-
sl@0: // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
sl@0: //////////////////////////////////////////////////////////////////////////////
sl@0: 
sl@0: 
sl@0: 
sl@0: #include <boost/assert.hpp>
sl@0: 
sl@0: 
sl@0: 
sl@0: namespace boost
sl@0: {
sl@0: namespace statechart
sl@0: {
sl@0: namespace detail
sl@0: {
sl@0: 
sl@0: 
sl@0: 
sl@0: //////////////////////////////////////////////////////////////////////////////
sl@0: enum reaction_result
sl@0: {
sl@0:   no_reaction,
sl@0:   do_forward_event,
sl@0:   do_discard_event,
sl@0:   do_defer_event,
sl@0:   consumed
sl@0: };
sl@0: 
sl@0: struct result_utility;
sl@0: 
sl@0: //////////////////////////////////////////////////////////////////////////////
sl@0: class safe_reaction_result
sl@0: {
sl@0:   public:
sl@0:     //////////////////////////////////////////////////////////////////////////
sl@0:     safe_reaction_result( const safe_reaction_result & other ) :
sl@0:       reactionResult( other.reactionResult )
sl@0:     {
sl@0:       // This assert fails when an attempt is made to make multiple copies of
sl@0:       // a result value. This makes little sense, given the requirement that
sl@0:       // an obtained result value must be returned out of the react function.
sl@0:       BOOST_ASSERT( reactionResult != consumed );
sl@0:       other.reactionResult = consumed;
sl@0:     }
sl@0: 
sl@0:     ~safe_reaction_result()
sl@0:     {
sl@0:       // This assert fails when an obtained result value is not returned out
sl@0:       // of the react() function. This can happen if the user accidentally
sl@0:       // makes more than one call to reaction functions inside react() or
sl@0:       // accidentally makes one or more calls to reaction functions outside
sl@0:       // react()
sl@0:       BOOST_ASSERT( reactionResult == consumed );
sl@0:     }
sl@0: 
sl@0:   private:
sl@0:     //////////////////////////////////////////////////////////////////////////
sl@0:     safe_reaction_result( reaction_result reactionResult ) :
sl@0:       reactionResult( reactionResult )
sl@0:     {
sl@0:     }
sl@0: 
sl@0:     operator reaction_result() const
sl@0:     {
sl@0:       const reaction_result val = reactionResult;
sl@0:       reactionResult = consumed;
sl@0:       return val;
sl@0:     }
sl@0: 
sl@0:     safe_reaction_result & operator=( const safe_reaction_result & );
sl@0: 
sl@0:     mutable reaction_result reactionResult;
sl@0: 
sl@0:     friend struct result_utility;
sl@0: };
sl@0: 
sl@0: 
sl@0: 
sl@0: } // namespace detail
sl@0: 
sl@0: 
sl@0: 
sl@0: #ifdef NDEBUG
sl@0:   typedef detail::reaction_result result;
sl@0: #else
sl@0:   typedef detail::safe_reaction_result result;
sl@0: #endif
sl@0: 
sl@0: 
sl@0: namespace detail
sl@0: {
sl@0: 
sl@0: 
sl@0: 
sl@0: //////////////////////////////////////////////////////////////////////////////
sl@0: struct result_utility
sl@0: {
sl@0:   static ::boost::statechart::result make_result( reaction_result value )
sl@0:   {
sl@0:     return value;
sl@0:   }
sl@0: 
sl@0:   static reaction_result get_result( ::boost::statechart::result value )
sl@0:   {
sl@0:     return value;
sl@0:   }
sl@0: };
sl@0: 
sl@0: 
sl@0: 
sl@0: } // namespace detail
sl@0: } // namespace statechart
sl@0: } // namespace boost
sl@0: 
sl@0: 
sl@0: 
sl@0: #endif