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