Chris@16: // Copyright 2008 Christophe Henry
Chris@16: // henry UNDERSCORE christophe AT hotmail DOT com
Chris@16: // This is an extended version of the state machine available in the boost::mpl library
Chris@16: // Distributed under the same license as the original.
Chris@16: // Copyright for the original version:
Chris@16: // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed
Chris@16: // under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_MSM_BACK_DISPATCH_TABLE_H
Chris@16: #define BOOST_MSM_BACK_DISPATCH_TABLE_H
Chris@16: 
Chris@16: #include <utility>
Chris@16: 
Chris@16: #include <boost/mpl/reverse_fold.hpp>
Chris@16: #include <boost/mpl/greater.hpp>
Chris@16: #include <boost/mpl/filter_view.hpp>
Chris@16: #include <boost/mpl/pop_front.hpp>
Chris@16: #include <boost/mpl/for_each.hpp>
Chris@16: #include <boost/mpl/advance.hpp>
Chris@16: 
Chris@16: #include <boost/type_traits/is_base_of.hpp>
Chris@16: #include <boost/type_traits/is_same.hpp>
Chris@16: 
Chris@16: #include <boost/msm/event_traits.hpp>
Chris@16: #include <boost/msm/back/metafunctions.hpp>
Chris@16: #include <boost/msm/back/common_types.hpp>
Chris@16: 
Chris@16: BOOST_MPL_HAS_XXX_TRAIT_DEF(is_frow)
Chris@16: 
Chris@16: namespace boost { namespace msm { namespace back 
Chris@16: {
Chris@16: 
Chris@16: // Generates a singleton runtime lookup table that maps current state
Chris@16: // to a function that makes the SM take its transition on the given
Chris@16: // Event type.
Chris@16: template <class Fsm,class Stt, class Event,class CompilePolicy>
Chris@16: struct dispatch_table
Chris@16: {
Chris@16:  private:
Chris@16:     // This is a table of these function pointers.
Chris@16:     typedef HandledEnum (*cell)(Fsm&, int,int,Event const&);
Chris@16:     typedef bool (*guard)(Fsm&, Event const&);
Chris@16: 
Chris@16:     // class used to build a chain (or sequence) of transitions for a given event and start state
Chris@16:     // (like an UML diamond). Allows transition conflicts.
Chris@16:     template< typename Seq,typename AnEvent,typename State >
Chris@16:     struct chain_row
Chris@16:     {
Chris@16:         typedef State   current_state_type;
Chris@16:         typedef AnEvent transition_event;
Chris@16: 
Chris@16:         // helper for building a disable/enable_if-controlled execute function
Chris@16:         struct execute_helper
Chris@16:         {
Chris@16:             template <class Sequence>
Chris@16:             static
Chris@16:             HandledEnum
Chris@16:             execute(Fsm& , int, int, Event const& , ::boost::mpl::true_ const & )
Chris@16:             {
Chris@16:                 // if at least one guard rejected, this will be ignored, otherwise will generate an error
Chris@16:                 return HANDLED_FALSE;
Chris@16:             }
Chris@16: 
Chris@16:             template <class Sequence>
Chris@16:             static
Chris@16:             HandledEnum
Chris@16:             execute(Fsm& fsm, int region_index , int state, Event const& evt,
Chris@16:                     ::boost::mpl::false_ const & )
Chris@16:             {
Chris@16:                  // try the first guard
Chris@16:                  typedef typename ::boost::mpl::front<Sequence>::type first_row;
Chris@16:                  HandledEnum res = first_row::execute(fsm,region_index,state,evt);
Chris@16:                  if (HANDLED_TRUE!=res && HANDLED_DEFERRED!=res)
Chris@16:                  {
Chris@16:                     // if the first rejected, move on to the next one
Chris@16:                     HandledEnum sub_res = 
Chris@16:                          execute<typename ::boost::mpl::pop_front<Sequence>::type>(fsm,region_index,state,evt,
Chris@16:                             ::boost::mpl::bool_<
Chris@16:                                 ::boost::mpl::empty<typename ::boost::mpl::pop_front<Sequence>::type>::type::value>());
Chris@16:                     // if at least one guards rejects, the event will not generate a call to no_transition
Chris@16:                     if ((HANDLED_FALSE==sub_res) && (HANDLED_GUARD_REJECT==res) )
Chris@16:                         return HANDLED_GUARD_REJECT;
Chris@16:                     else
Chris@16:                         return sub_res;
Chris@16:                  }
Chris@16:                  return res;
Chris@16:             }
Chris@16:         };
Chris@16:         // Take the transition action and return the next state.
Chris@16:         static HandledEnum execute(Fsm& fsm, int region_index, int state, Event const& evt)
Chris@16:         {
Chris@16:             // forward to helper
Chris@16:             return execute_helper::template execute<Seq>(fsm,region_index,state,evt,
Chris@16:                 ::boost::mpl::bool_< ::boost::mpl::empty<Seq>::type::value>());
Chris@16:         }
Chris@16:     };
Chris@16:     // nullary metafunction whose only job is to prevent early evaluation of _1
Chris@16:     template< typename Entry > 
Chris@16:     struct make_chain_row_from_map_entry
Chris@16:     { 
Chris@16:         // if we have more than one frow with the same state as source, remove the ones extra
Chris@16:         // note: we know the frow's are located at the beginning so we remove at the beginning (number of frows - 1) elements
Chris@16:         enum {number_frows = ::boost::mpl::count_if< typename Entry::second,has_is_frow< ::boost::mpl::placeholders::_1> >::value};
Chris@16: 
Chris@16:         //erases the first NumberToDelete rows
Chris@16:         template<class Sequence, int NumberToDelete>
Chris@16:         struct erase_first_rows
Chris@16:         {
Chris@16:             typedef typename ::boost::mpl::erase<
Chris@16:                 typename Entry::second,
Chris@16:                 typename ::boost::mpl::begin<Sequence>::type,
Chris@16:                 typename ::boost::mpl::advance<
Chris@16:                         typename ::boost::mpl::begin<Sequence>::type, 
Chris@16:                         ::boost::mpl::int_<NumberToDelete> >::type
Chris@16:             >::type type;
Chris@16:         };
Chris@16:         // if we have more than 1 frow with this event (not allowed), delete the spare
Chris@16:         typedef typename ::boost::mpl::eval_if<
Chris@16:             typename ::boost::mpl::bool_< number_frows >= 2 >::type,
Chris@16:             erase_first_rows<typename Entry::second,number_frows-1>,
Chris@16:             ::boost::mpl::identity<typename Entry::second>
Chris@16:         >::type filtered_stt;
Chris@16: 
Chris@16:         typedef chain_row<filtered_stt,Event,
Chris@16:             typename Entry::first > type;
Chris@16:     }; 
Chris@16:     // helper for lazy evaluation in eval_if of change_frow_event
Chris@16:     template <class Transition,class NewEvent>
Chris@16:     struct replace_event
Chris@16:     {
Chris@16:         typedef typename Transition::template replace_event<NewEvent>::type type;
Chris@16:     };
Chris@16:     // changes the event type for a frow to the event we are dispatching
Chris@16:     // this helps ensure that an event does not get processed more than once because of frows and base events.
Chris@16:     template <class FrowTransition>
Chris@16:     struct change_frow_event
Chris@16:     {
Chris@16:         typedef typename ::boost::mpl::eval_if<
Chris@16:             typename has_is_frow<FrowTransition>::type,
Chris@16:             replace_event<FrowTransition,Event>,
Chris@16:             boost::mpl::identity<FrowTransition>
Chris@16:         >::type type;
Chris@16:     };
Chris@16:     // Compute the maximum state value in the sm so we know how big
Chris@16:     // to make the table
Chris@16:     typedef typename generate_state_set<Stt>::type state_list;
Chris@16:     BOOST_STATIC_CONSTANT(int, max_state = ( ::boost::mpl::size<state_list>::value));
Chris@16: 
Chris@16:     template <class Transition>
Chris@16:     struct convert_event_and_forward
Chris@16:     {
Chris@16:         static HandledEnum execute(Fsm& fsm, int region_index, int state, Event const& evt)
Chris@16:         {
Chris@16:             typename Transition::transition_event forwarded(evt);
Chris@16:             return Transition::execute(fsm,region_index,state,forwarded);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     // A function object for use with mpl::for_each that stuffs
Chris@16:     // transitions into cells.
Chris@16:     struct init_cell
Chris@16:     {
Chris@16:         init_cell(dispatch_table* self_)
Chris@16:           : self(self_)
Chris@16:         {}
Chris@16:         // version for transition event not base of our event
Chris@16:         // first for all transitions, then for internal ones of a fsm
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::disable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::true_ const &, ::boost::mpl::false_ const &) const
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = 
Chris@16:                 (get_state_id<stt,typename Transition::current_state_type>::value));
Chris@16:             self->entries[state_id+1] = reinterpret_cast<cell>(&Transition::execute);
Chris@16:         }
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::enable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::true_ const &, ::boost::mpl::false_ const &) const
Chris@16:         {
Chris@16:             self->entries[0] = reinterpret_cast<cell>(&Transition::execute);
Chris@16:         }
Chris@16: 
Chris@16:         // version for transition event is boost::any
Chris@16:         // first for all transitions, then for internal ones of a fsm
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::disable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::true_ const &) const
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = 
Chris@16:                 (get_state_id<stt,typename Transition::current_state_type>::value));
Chris@16:             self->entries[state_id+1] = &convert_event_and_forward<Transition>::execute;
Chris@16:         }
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::enable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::true_ const &) const
Chris@16:         {
Chris@16:             self->entries[0] = &convert_event_and_forward<Transition>::execute;
Chris@16:         }
Chris@16: 
Chris@16:         // version for transition event base of our event
Chris@16:         // first for all transitions, then for internal ones of a fsm
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::disable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::false_ const &) const
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = 
Chris@16:                 (get_state_id<stt,typename Transition::current_state_type>::value));
Chris@16:             self->entries[state_id+1] = &Transition::execute;
Chris@16:         }
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::enable_if<
Chris@16:             typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::false_ const &) const
Chris@16:         {
Chris@16:             self->entries[0] = &Transition::execute;
Chris@16:         }
Chris@16:         // Cell initializer function object, used with mpl::for_each
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::enable_if<typename has_not_real_row_tag<Transition>::type,void >::type
Chris@16:             operator()(Transition const&,boost::msm::back::dummy<0> = 0) const
Chris@16:         {
Chris@16:             // version for not real rows. No problem because irrelevant for process_event
Chris@16:         }
Chris@16:         template <class Transition>
Chris@16:         typename ::boost::disable_if<typename has_not_real_row_tag<Transition>::type,void >::type
Chris@16:         operator()(Transition const& tr,boost::msm::back::dummy<1> = 0) const
Chris@16:         {
Chris@16:             //only if the transition event is a base of our event is the reinterpret_case safe
Chris@16:             init_event_base_case(tr,
Chris@16:                 ::boost::mpl::bool_< 
Chris@16:                     ::boost::is_base_of<typename Transition::transition_event,Event>::type::value>(),
Chris@16:                 ::boost::mpl::bool_< 
Chris@16:                     ::boost::msm::is_kleene_event<typename Transition::transition_event>::type::value>());
Chris@16:         }
Chris@16:     
Chris@16:         dispatch_table* self;
Chris@16:     };
Chris@16: 
Chris@16:     // Cell default-initializer function object, used with mpl::for_each
Chris@16:     // initializes with call_no_transition, defer_transition or default_eventless_transition
Chris@16:     // variant for non-anonymous transitions
Chris@16:     template <class EventType,class Enable=void>
Chris@16:     struct default_init_cell
Chris@16:     {
Chris@16:         default_init_cell(dispatch_table* self_,cell* tofill_entries_)
Chris@16:             : self(self_),tofill_entries(tofill_entries_)
Chris@16:         {}
Chris@16:         template <class State>
Chris@16:         typename ::boost::enable_if<typename has_state_delayed_event<State,Event>::type,void>::type
Chris@16:         operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<0> = 0)
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value));
Chris@16:             cell call_no_transition = &Fsm::defer_transition;
Chris@16:             tofill_entries[state_id+1] = call_no_transition;
Chris@16:         }
Chris@16:         template <class State>
Chris@16:         typename ::boost::disable_if<
Chris@16:             typename ::boost::mpl::or_<
Chris@16:                 typename has_state_delayed_event<State,Event>::type,
Chris@16:                 typename ::boost::is_same<State,Fsm>::type
Chris@16:             >::type
Chris@16:         ,void >::type
Chris@16:         operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<1> = 0)
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value));
Chris@16:             cell call_no_transition = &Fsm::call_no_transition;
Chris@16:             tofill_entries[state_id+1] = call_no_transition;
Chris@16:         }
Chris@16:         // case for internal transitions of this fsm
Chris@16:         template <class State>
Chris@16:         typename ::boost::enable_if<
Chris@16:             typename ::boost::mpl::and_<
Chris@16:                 typename ::boost::mpl::not_<typename has_state_delayed_event<State,Event>::type>::type,
Chris@16:                 typename ::boost::is_same<State,Fsm>::type
Chris@16:             >::type
Chris@16:         ,void>::type
Chris@16:         operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<2> = 0)
Chris@16:         {
Chris@16:             cell call_no_transition = &Fsm::call_no_transition_internal;
Chris@16:             tofill_entries[0] = call_no_transition;
Chris@16:         }
Chris@16:         dispatch_table* self;
Chris@16:         cell* tofill_entries;
Chris@16:     };
Chris@16: 
Chris@16:     // variant for anonymous transitions
Chris@16:     template <class EventType>
Chris@16:     struct default_init_cell<EventType,
Chris@16:                              typename ::boost::enable_if<
Chris@16:                                 typename is_completion_event<EventType>::type>::type>
Chris@16:     {
Chris@16:         default_init_cell(dispatch_table* self_,cell* tofill_entries_)
Chris@16:             : self(self_),tofill_entries(tofill_entries_)
Chris@16:         {}
Chris@16: 
Chris@16:         // this event is a compound one (not a real one, just one for use in event-less transitions)
Chris@16:         // Note this event cannot be used as deferred!
Chris@16:         // case for internal transitions of this fsm 
Chris@16:         template <class State>
Chris@16:         typename ::boost::disable_if<
Chris@16:             typename ::boost::is_same<State,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<0> = 0)
Chris@16:         {
Chris@16:             typedef typename create_stt<Fsm>::type stt; 
Chris@16:             BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value));
Chris@16:             cell call_no_transition = &Fsm::default_eventless_transition;
Chris@16:             tofill_entries[state_id+1] = call_no_transition;
Chris@16:         }
Chris@16: 
Chris@16:         template <class State>
Chris@16:         typename ::boost::enable_if<
Chris@16:             typename ::boost::is_same<State,Fsm>::type
Chris@16:         ,void>::type
Chris@16:         operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<1> = 0)
Chris@16:         {
Chris@16:             cell call_no_transition = &Fsm::default_eventless_transition;
Chris@16:             tofill_entries[0] = call_no_transition;
Chris@16:         }
Chris@16:         dispatch_table* self;
Chris@16:         cell* tofill_entries;
Chris@16:     };
Chris@16: 
Chris@16:  public:
Chris@16:     // initialize the dispatch table for a given Event and Fsm
Chris@16:     dispatch_table()
Chris@16:     {
Chris@16:         // Initialize cells for no transition
Chris@16:         ::boost::mpl::for_each<typename generate_state_set<Stt>::type, 
Chris@16:                                boost::msm::wrap< ::boost::mpl::placeholders::_1> >
Chris@16:                         (default_init_cell<Event>(this,entries));
Chris@16: 
Chris@16:         // build chaining rows for rows coming from the same state and the current event
Chris@16:         // first we build a map of sequence for every source
Chris@16:         // in reverse order so that the frow's are handled first (UML priority)
Chris@16:         typedef typename ::boost::mpl::reverse_fold<
Chris@16:                         // filter on event
Chris@16:                         ::boost::mpl::filter_view
Chris@16:                             <Stt, boost::mpl::or_<
Chris@16:                                     ::boost::is_base_of<transition_event< ::boost::mpl::placeholders::_>, Event>,
Chris@16:                                     ::boost::msm::is_kleene_event<transition_event< ::boost::mpl::placeholders::_> >
Chris@16:                                     >
Chris@16:                             >,
Chris@16:                         // build a map
Chris@16:                         ::boost::mpl::map<>,
Chris@16:                         ::boost::mpl::if_<
Chris@16:                             // if we already have a row on this source state
Chris@16:                             ::boost::mpl::has_key< ::boost::mpl::placeholders::_1,
Chris@16:                                                    transition_source_type< ::boost::mpl::placeholders::_2> >,
Chris@16:                             // insert a new element in the value type
Chris@16:                             ::boost::mpl::insert< 
Chris@16:                                 ::boost::mpl::placeholders::_1,
Chris@16:                                 ::boost::mpl::pair<transition_source_type< ::boost::mpl::placeholders::_2>,
Chris@16:                                                    ::boost::mpl::push_back< 
Chris@16:                                                         ::boost::mpl::at< ::boost::mpl::placeholders::_1,
Chris@16:                                                         transition_source_type< ::boost::mpl::placeholders::_2> >,
Chris@16:                                                         change_frow_event< ::boost::mpl::placeholders::_2 > > 
Chris@16:                                                    > >,
Chris@16:                             // first row on this source state, make a vector with 1 element
Chris@16:                             ::boost::mpl::insert< 
Chris@16:                                         ::boost::mpl::placeholders::_1,
Chris@16:                                         ::boost::mpl::pair<transition_source_type< ::boost::mpl::placeholders::_2>,
Chris@16:                                         make_vector< change_frow_event< ::boost::mpl::placeholders::_2> > > >
Chris@16:                                >
Chris@16:                        >::type map_of_row_seq;
Chris@16:         // and then build chaining rows for all source states having more than 1 row
Chris@16:         typedef typename ::boost::mpl::fold<
Chris@16:             map_of_row_seq,::boost::mpl::vector0<>,
Chris@16:             ::boost::mpl::if_<
Chris@16:                      ::boost::mpl::greater< ::boost::mpl::size< 
Chris@16:                                                     ::boost::mpl::second< ::boost::mpl::placeholders::_2> >,
Chris@16:                                             ::boost::mpl::int_<1> >,
Chris@16:                      // we need row chaining
Chris@16:                      ::boost::mpl::push_back< ::boost::mpl::placeholders::_1, 
Chris@16:                                     make_chain_row_from_map_entry< ::boost::mpl::placeholders::_2> >,
Chris@16:                      // just one row, no chaining, we rebuild the row like it was before
Chris@16:                      ::boost::mpl::push_back< ::boost::mpl::placeholders::_1, 
Chris@16:                                               get_first_element_pair_second< ::boost::mpl::placeholders::_2> > 
Chris@16:              > >::type chained_rows; 
Chris@16:         // Go back and fill in cells for matching transitions.
Chris@16:         ::boost::mpl::for_each<chained_rows>(init_cell(this));
Chris@16:     }
Chris@16: 
Chris@16:     // The singleton instance.
Chris@16:     static const dispatch_table instance;
Chris@16: 
Chris@16:  public: // data members
Chris@16:      // +1 => 0 is reserved for this fsm (internal transitions)
Chris@16:     cell entries[max_state+1];
Chris@16: };
Chris@16: 
Chris@16: }}} // boost::msm::back
Chris@16: 
Chris@16: 
Chris@16: #endif //BOOST_MSM_BACK_DISPATCH_TABLE_H
Chris@16: