boost/boost/statechart/transition.hpp

   1 #ifndef BOOST_STATECHART_TRANSITION_HPP_INCLUDED
   2 #define BOOST_STATECHART_TRANSITION_HPP_INCLUDED
   3 //////////////////////////////////////////////////////////////////////////////
   4 // Copyright 2002-2006 Andreas Huber Doenni
   5 // Distributed under the Boost Software License, Version 1.0. (See accompany-
   6 // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 //////////////////////////////////////////////////////////////////////////////
   8
   9
  10
  11 #include <boost/statechart/result.hpp>
  12
  13 #include <boost/mpl/if.hpp>
  14
  15 #include <boost/cast.hpp> // boost::polymorphic_downcast
  16 #include <boost/type_traits/is_same.hpp>
  17
  18
  19
  20 namespace boost
  21 {
  22 namespace statechart
  23 {
  24 namespace detail
  25 {
  26
  27
  28
  29 //////////////////////////////////////////////////////////////////////////////
  30 template< class Event >
  31 struct no_context
  32 {
  33   void no_function( const Event & );
  34 };
  35
  36
  37
  38 } // namespace detail
  39
  40
  41
  42 class event_base;
  43
  44 //////////////////////////////////////////////////////////////////////////////
  45 template< class Event, class Destination,
  46           class TransitionContext = detail::no_context< Event >,
  47           void ( TransitionContext::*pTransitionAction )( const Event & ) =
  48             &detail::no_context< Event >::no_function >
  49 class transition
  50 {
  51   private:
  52     //////////////////////////////////////////////////////////////////////////
  53     struct react_without_transition_action_impl
  54     {
  55       template< class State, class EventBase >
  56       static detail::reaction_result react( State & stt, const EventBase & )
  57       {
  58         return detail::result_utility::get_result(
  59           stt.template transit< Destination >() );
  60       }
  61     };
  62
  63     struct react_base_with_transition_action_impl
  64     {
  65       template< class State, class EventBase >
  66       static detail::reaction_result react(
  67         State & stt, const EventBase & toEvent )
  68       {
  69         return detail::result_utility::get_result(
  70           stt.template transit< Destination >( pTransitionAction, toEvent ) );
  71       }
  72     };
  73
  74     struct react_base
  75     {
  76       template< class State, class EventBase, class IdType >
  77       static detail::reaction_result react(
  78         State & stt, const EventBase & evt, const IdType & )
  79       {
  80         typedef typename mpl::if_<
  81           is_same< TransitionContext, detail::no_context< Event > >,
  82           react_without_transition_action_impl,
  83           react_base_with_transition_action_impl
  84         >::type impl;
  85         return impl::react( stt, evt );
  86       }
  87     };
  88
  89     struct react_derived_with_transition_action_impl
  90     {
  91       template< class State, class EventBase >
  92       static detail::reaction_result react(
  93         State & stt, const EventBase & toEvent )
  94       {
  95         return detail::result_utility::get_result(
  96           stt.template transit< Destination >(
  97             pTransitionAction,
  98             *polymorphic_downcast< const Event * >( &toEvent ) ) );
  99       }
 100     };
 101
 102     struct react_derived
 103     {
 104       template< class State, class EventBase, class IdType >
 105       static detail::reaction_result react(
 106         State & stt, const EventBase & evt, const IdType & eventType )
 107       {
 108         if ( eventType == Event::static_type() )
 109         {
 110           typedef typename mpl::if_<
 111             is_same< TransitionContext, detail::no_context< Event > >,
 112             react_without_transition_action_impl,
 113             react_derived_with_transition_action_impl
 114           >::type impl;
 115           return impl::react( stt, evt );
 116         }
 117         else
 118         {
 119           return detail::no_reaction;
 120         }
 121       }
 122     };
 123
 124   public:
 125     //////////////////////////////////////////////////////////////////////////
 126     // The following declarations should be private.
 127     // They are only public because many compilers lack template friends.
 128     //////////////////////////////////////////////////////////////////////////
 129     template< class State, class EventBase, class IdType >
 130     static detail::reaction_result react(
 131       State & stt, const EventBase & evt, const IdType & eventType )
 132     {
 133       typedef typename mpl::if_<
 134         is_same< Event, event_base >, react_base, react_derived
 135       >::type impl;
 136
 137       return impl::react( stt, evt, eventType );
 138     }
 139 };
 140
 141
 142
 143 } // namespace statechart
 144 } // namespace boost
 145
 146
 147
 148 #endif