| // 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; |
| |
| struct SomeExternalContext |
| { |
| SomeExternalContext(int b):bla(b){} |
| int bla; |
| }; |
| |
| namespace |
| { |
| // events |
| struct play {}; |
| struct end_pause {}; |
| struct stop {}; |
| struct pause {}; |
| struct open_close {}; |
| struct NextSong {}; |
| struct PreviousSong {}; |
| |
| // A "complicated" event type that carries some data. |
| enum DiskTypeEnum |
| { |
| DISK_CD=0, |
| DISK_DVD=1 |
| }; |
| struct cd_detected |
| { |
| cd_detected(std::string name, DiskTypeEnum diskType) |
| : name(name), |
| disc_type(diskType) |
| {} |
| |
| std::string name; |
| DiskTypeEnum disc_type; |
| }; |
| |
| // front-end: define the FSM structure |
| struct player_ : public msm::front::state_machine_def<player_> |
| { |
| player_(SomeExternalContext& context,int someint) |
| :context_(context) |
| { |
| std::cout << "context value:" << context_.bla << " with value:" << someint << std::endl; |
| context.bla = 10; |
| } |
| |
| SomeExternalContext& context_; |
| |
| // The list of FSM states |
| struct Empty : public msm::front::state<> |
| { |
| int data_; |
| Empty():data_(0){} |
| Empty(int i):data_(i){} |
| // 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<> |
| { |
| int data_; |
| Open():data_(0){} |
| Open(int i):data_(i){} |
| |
| 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;} |
| }; |
| |
| // sm_ptr still supported but deprecated as functors are a much better way to do the same thing |
| struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr> |
| { |
| 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;} |
| void set_sm_ptr(player_* pl) |
| { |
| m_player=pl; |
| } |
| player_* m_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) |
| 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<> |
| { |
| int data_; |
| Song1():data_(0){} |
| Song1(int i):data_(i){} |
| |
| 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<> |
| { |
| }; |
| |
| // 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&) { 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 |
| bool good_disk_format(cd_detected const& evt) |
| { |
| // to test a guard condition, let's say we understand only CDs, not DVD |
| if (evt.disc_type != DISK_CD) |
| { |
| std::cout << "wrong disk, sorry" << std::endl; |
| return false; |
| } |
| return true; |
| } |
| // used to show a transition conflict. This guard will simply deactivate one transition and thus |
| // solve the conflict |
| bool auto_start(cd_detected const&) |
| { |
| return false; |
| } |
| |
| 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 >, |
| _row < Stopped , stop , Stopped >, |
| // +---------+-------------+---------+---------------------+----------------------+ |
| a_row < Open , open_close , Empty , &p::close_drawer >, |
| // +---------+-------------+---------+---------------------+----------------------+ |
| a_row < Empty , open_close , Open , &p::open_drawer >, |
| row < Empty , cd_detected , Stopped , &p::store_cd_info ,&p::good_disk_format >, |
| row < Empty , cd_detected , Playing , &p::store_cd_info ,&p::auto_start >, |
| // +---------+-------------+---------+---------------------+----------------------+ |
| 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() |
| { |
| SomeExternalContext ctx(3); |
| // example 1 |
| // create a player with an argument by reference and an int |
| // (go to the constructor front-end) |
| player p1(boost::ref(ctx),5); |
| |
| // example 2 |
| // create a player with a copy of an Empty state, an argument by reference and an int |
| // (last 2 go to the constructor front-end) |
| player p2(msm::back::states_ << player_::Empty(1),boost::ref(ctx),5); |
| std::cout << "Empty's data should be 1. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl; |
| |
| std::cout << "Set a new Empty state" << std::endl; |
| p2.set_states(msm::back::states_ << player_::Empty(5)); |
| std::cout << "Empty's data should be 5. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl; |
| |
| std::cout << "Set new Empty and Open states" << std::endl; |
| p2.set_states(msm::back::states_ << player_::Empty(7) << player_::Open(2)); |
| std::cout << "Empty's data should be 7. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl; |
| std::cout << "Open's data should be 2. Is: " << p2.get_state<player_::Open&>().data_ << std::endl; |
| |
| // example 3 |
| // create a player with a copy of an Empty state, a copy of a Playing submachine |
| // (which is itself created by a copy of Song1) |
| // an argument by reference and an int |
| // (last 2 go to the constructor front-end) |
| player p(msm::back::states_ << player_::Empty(1) |
| << player_::Playing(msm::back::states_ << player_::Playing_::Song1(8)), |
| boost::ref(ctx),5); |
| |
| std::cout << "Song1's data should be 8. Is: " |
| << p.get_state<player_::Playing&>().get_state<player_::Playing_::Song1&>().data_ << std::endl; |
| |
| |
| } |
| } |
| |
| int main() |
| { |
| test(); |
| return 0; |
| } |