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- // Copyright 2010 Christophe Henry
- // henry UNDERSCORE christophe AT hotmail DOT com
- // This is an extended version of the state machine available in the boost::mpl library
- // Distributed under the same license as the original.
- // Copyright for the original version:
- // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed
- // under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- #include <iostream>
- // back-end
- #include <boost/msm/back/state_machine.hpp>
- //front-end
- #include <boost/msm/front/state_machine_def.hpp>
- #include <boost/msm/front/functor_row.hpp>
- namespace msm = boost::msm;
- namespace mpl = boost::mpl;
- using namespace boost::msm::front;
- namespace
- {
- // events
- struct play {};
- struct end_pause {};
- struct stop {};
- struct pause {};
- struct open_close {};
- struct NextSong {};
- struct PreviousSong {};
- struct error_found {};
- struct end_error {};
- // Flags. Allow information about a property of the current state
- struct PlayingPaused{};
- struct CDLoaded {};
- struct FirstSongPlaying {};
- // A "complicated" event type that carries some data.
- struct cd_detected
- {
- cd_detected(std::string name)
- : name(name)
- {}
- std::string name;
- };
- // front-end: define the FSM structure
- struct player_ : public msm::front::state_machine_def<player_>
- {
- // we want deferred events and no state requires deferred events (only the fsm in the
- // transition table), so the fsm does.
- typedef int activate_deferred_events;
- // The list of FSM states
- struct Empty : public msm::front::state<>
- {
- // every (optional) entry/exit methods get the event passed.
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
- };
- struct Open : public msm::front::state<>
- {
- typedef mpl::vector1<CDLoaded> flag_list;
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
- };
- struct Stopped : public msm::front::state<>
- {
- // when stopped, the CD is loaded
- typedef mpl::vector1<CDLoaded> flag_list;
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
- };
- // the player state machine contains a state which is himself a state machine
- // as you see, no need to declare it anywhere so Playing can be developed separately
- // by another team in another module. For simplicity I just declare it inside player
- struct Playing_ : public msm::front::state_machine_def<Playing_>
- {
- // when playing, the CD is loaded and we are in either pause or playing (duh)
- typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
- // The list of FSM states
- struct Song1 : public msm::front::state<>
- {
- typedef mpl::vector1<FirstSongPlaying> flag_list;
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
- };
- struct Song2 : public msm::front::state<>
- {
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
- };
- struct Song3 : public msm::front::state<>
- {
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
- };
- // the initial state. Must be defined
- typedef Song1 initial_state;
- // transition actions
- void start_next_song(NextSong const&) { std::cout << "Playing::start_next_song\n"; }
- void start_prev_song(PreviousSong const&) { std::cout << "Playing::start_prev_song\n"; }
- // guard conditions
- typedef Playing_ pl; // makes transition table cleaner
- // Transition table for Playing
- struct transition_table : mpl::vector4<
- // Start Event Next Action Guard
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Song1 , NextSong , Song2 , &pl::start_next_song >,
- a_row < Song2 , PreviousSong, Song1 , &pl::start_prev_song >,
- a_row < Song2 , NextSong , Song3 , &pl::start_next_song >,
- a_row < Song3 , PreviousSong, Song2 , &pl::start_prev_song >
- // +---------+-------------+---------+---------------------+----------------------+
- > {};
- // Replaces the default no-transition response.
- template <class FSM,class Event>
- void no_transition(Event const& e, FSM&,int state)
- {
- std::cout << "no transition from state " << state
- << " on event " << typeid(e).name() << std::endl;
- }
- };
- // back-end
- typedef msm::back::state_machine<Playing_> Playing;
- // state not defining any entry or exit
- struct Paused : public msm::front::state<>
- {
- typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;
- };
- struct AllOk : public msm::front::state<>
- {
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "starting: AllOk" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "finishing: AllOk" << std::endl;}
- };
- // this state is also made terminal so that all the events are blocked
- struct ErrorMode : //public msm::front::terminate_state<> // ErrorMode terminates the state machine
- public msm::front::interrupt_state<end_error> // ErroMode just interrupts. Will resume if
- // the event end_error is generated
- {
- template <class Event,class FSM>
- void on_entry(Event const&,FSM& ) {std::cout << "starting: ErrorMode" << std::endl;}
- template <class Event,class FSM>
- void on_exit(Event const&,FSM& ) {std::cout << "finishing: ErrorMode" << std::endl;}
- };
- // the initial state of the player SM. Must be defined
- typedef mpl::vector<Empty,AllOk> initial_state;
- // transition actions
- void start_playback(play const&) { std::cout << "player::start_playback\n"; }
- void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; }
- void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; }
- void store_cd_info(cd_detected const& cd) {std::cout << "player::store_cd_info\n";}
- void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; }
- void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; }
- void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; }
- void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; }
- void stopped_again(stop const&){std::cout << "player::stopped_again\n";}
- void report_error(error_found const&) {std::cout << "player::report_error\n";}
- void report_end_error(end_error const&) {std::cout << "player::report_end_error\n";}
- // guard conditions
-
- typedef player_ p; // makes transition table cleaner
- // Transition table for player
- struct transition_table : mpl::vector<
- // Start Event Next Action Guard
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Stopped , play , Playing , &p::start_playback >,
- a_row < Stopped , open_close , Open , &p::open_drawer >,
- a_row < Stopped , stop , Stopped , &p::stopped_again >,
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Open , open_close , Empty , &p::close_drawer >,
- Row < Open , play , none , Defer , none >,
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Empty , open_close , Open , &p::open_drawer >,
- a_row < Empty , cd_detected , Stopped , &p::store_cd_info >,
- Row < Empty , play , none , Defer , none >,
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Playing , stop , Stopped , &p::stop_playback >,
- a_row < Playing , pause , Paused , &p::pause_playback >,
- a_row < Playing , open_close , Open , &p::stop_and_open >,
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < Paused , end_pause , Playing , &p::resume_playback >,
- a_row < Paused , stop , Stopped , &p::stop_playback >,
- a_row < Paused , open_close , Open , &p::stop_and_open >,
- // +---------+-------------+---------+---------------------+----------------------+
- a_row < AllOk , error_found ,ErrorMode, &p::report_error >,
- a_row <ErrorMode,end_error ,AllOk , &p::report_end_error >
- // +---------+-------------+---------+---------------------+----------------------+
- > {};
- // Replaces the default no-transition response.
- template <class FSM,class Event>
- void no_transition(Event const& e, FSM&,int state)
- {
- std::cout << "no transition from state " << state
- << " on event " << typeid(e).name() << std::endl;
- }
- };
- // Pick a back-end
- typedef msm::back::state_machine<player_> player;
- //
- // Testing utilities.
- //
- static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused","AllOk","ErrorMode" };
- void pstate(player const& p)
- {
- // we have now several active states, which we show
- for (unsigned int i=0;i<player::nr_regions::value;++i)
- {
- std::cout << " -> " << state_names[p.current_state()[i]] << std::endl;
- }
- }
- void test()
- {
- player p;
- // needed to start the highest-level SM. This will call on_entry and mark the start of the SM
- p.start();
- // test deferred event
- // deferred in Empty and Open, will be handled only after event cd_detected
- p.process_event(play());
- // tests some flags
- std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet)
- // go to Open, call on_exit on Empty, then action, then on_entry on Open
- p.process_event(open_close()); pstate(p);
- p.process_event(open_close()); pstate(p);
- p.process_event(cd_detected("louie, louie"));
- // at this point, Play is active (was deferred)
- std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
- std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true
- // make transition happen inside it. Player has no idea about this event but it's ok.
- p.process_event(NextSong());pstate(p); //2nd song active
- p.process_event(NextSong());pstate(p);//3rd song active
- p.process_event(PreviousSong());pstate(p);//2nd song active
- std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false
- std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
- p.process_event(pause()); pstate(p);
- std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
- // go back to Playing
- // as you see, it starts back from the original state
- p.process_event(end_pause()); pstate(p);
- p.process_event(pause()); pstate(p);
- p.process_event(stop()); pstate(p);
- std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false
- std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true
- // by default, the flags are OR'ed but you can also use AND. Then the flag must be present in
- // all of the active states
- std::cout << "CDLoaded active with AND:" << std::boolalpha << p.is_flag_active<CDLoaded,player::Flag_AND>() << std::endl;//=> false
- // event leading to the same state
- p.process_event(stop()); pstate(p);
- // event leading to a terminal/interrupt state
- p.process_event(error_found()); pstate(p);
- // try generating more events
- std::cout << "Trying to generate another event" << std::endl; // will not work, fsm is terminated or interrupted
- p.process_event(play());pstate(p);
- std::cout << "Trying to end the error" << std::endl; // will work only if ErrorMode is interrupt state
- p.process_event(end_error());pstate(p);
- std::cout << "Trying to generate another event" << std::endl; // will work only if ErrorMode is interrupt state
- p.process_event(play());pstate(p);
- }
- }
- int main()
- {
- test();
- return 0;
- }
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