#ifndef BOOST_STATECHART_RESULT_HPP_INCLUDED

 #define BOOST_STATECHART_RESULT_HPP_INCLUDED

 //////////////////////////////////////////////////////////////////////////////

 // Copyright 2002-2006 Andreas Huber Doenni

 // Distributed under the Boost Software License, Version 1.0. (See accompany-

 // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

 //////////////////////////////////////////////////////////////////////////////

 #include <boost/assert.hpp>

 namespace boost

 {

 namespace statechart

 {

 namespace detail

 {

 //////////////////////////////////////////////////////////////////////////////

 enum reaction_result

 {

   no_reaction,

   do_forward_event,

   do_discard_event,

   do_defer_event,

   consumed

 };

 struct result_utility;

 //////////////////////////////////////////////////////////////////////////////

 class safe_reaction_result

 {

   public:

     //////////////////////////////////////////////////////////////////////////

     safe_reaction_result( const safe_reaction_result & other ) :

       reactionResult( other.reactionResult )

     {

       // This assert fails when an attempt is made to make multiple copies of

       // a result value. This makes little sense, given the requirement that

       // an obtained result value must be returned out of the react function.

       BOOST_ASSERT( reactionResult != consumed );

       other.reactionResult = consumed;

     }

     ~safe_reaction_result()

     {

       // This assert fails when an obtained result value is not returned out

       // of the react() function. This can happen if the user accidentally

       // makes more than one call to reaction functions inside react() or

       // accidentally makes one or more calls to reaction functions outside

       // react()

       BOOST_ASSERT( reactionResult == consumed );

     }

   private:

     //////////////////////////////////////////////////////////////////////////

     safe_reaction_result( reaction_result reactionResult ) :

       reactionResult( reactionResult )

     {

     }

     operator reaction_result() const

     {

       const reaction_result val = reactionResult;

       reactionResult = consumed;

       return val;

     }

     safe_reaction_result & operator=( const safe_reaction_result & );

     mutable reaction_result reactionResult;

     friend struct result_utility;

 };

 } // namespace detail

 #ifdef NDEBUG

   typedef detail::reaction_result result;

 #else

   typedef detail::safe_reaction_result result;

 #endif

 namespace detail

 {

 //////////////////////////////////////////////////////////////////////////////

 struct result_utility

 {

   static ::boost::statechart::result make_result( reaction_result value )

   {

     return value;

   }

   static reaction_result get_result( ::boost::statechart::result value )

   {

     return value;

   }

 };

 } // namespace detail

 } // namespace statechart

 } // namespace boost

 #endif