| // 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> |
| |
| namespace msm = boost::msm; |
| namespace mpl = boost::mpl; |
| |
| namespace // Concrete FSM implementation |
| { |
| // events |
| struct play {}; |
| struct end_pause {}; |
| struct stop {}; |
| struct pause {}; |
| struct open_close {}; |
| struct NextSong {}; |
| struct PreviousSong {}; |
| |
| // 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_> |
| { |
| // 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; |
| }; |
| |
| // the initial state of the player SM. Must be defined |
| typedef Empty 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";} |
| // 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 >, |
| // +---------+-------------+---------+---------------------+----------------------+ |
| a_row < Empty , open_close , Open , &p::open_drawer >, |
| a_row < Empty , cd_detected , Stopped , &p::store_cd_info >, |
| // +---------+-------------+---------+---------------------+----------------------+ |
| 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 > |
| // +---------+-------------+---------+---------------------+----------------------+ |
| > {}; |
| |
| // 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" }; |
| |
| void pstate(player const& p) |
| { |
| std::cout << " -> " << state_names[p.current_state()[0]] << 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(); |
| // 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")); |
| p.process_event(play()); |
| |
| // at this point, Play is active |
| 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 |
| |
| // event leading to the same state |
| p.process_event(stop()); pstate(p); |
| } |
| } |
| |
| int main() |
| { |
| test(); |
| return 0; |
| } |