libs/msm/doc/HTML/examples/SimpleTutorial2.cpp
// 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/row2.hpp> namespace msm = boost::msm; namespace mpl = boost::mpl; using namespace msm::front; namespace { // events struct play {}; struct end_pause {}; struct stop {}; struct pause {}; struct open_close {}; // 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_> { template <class Event,class FSM> void on_entry(Event const& ,FSM&) { std::cout << "entering: Player" << std::endl; } template <class Event,class FSM> void on_exit(Event const&,FSM& ) { std::cout << "leaving: Player" << std::endl; } // 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;} void open_drawer(open_close const&) { std::cout << "Empty::open_drawer\n"; } // actions for Empty's internal transitions void internal_action(cd_detected const&){ std::cout << "Empty::internal action\n"; } bool internal_guard(cd_detected const&) { std::cout << "Empty::internal guard\n"; return false; } }; struct Open : public msm::front::state<> { 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;} void close_drawer(open_close const&) { std::cout << "Open::close_drawer\n"; } void stop_and_open(open_close const&) { std::cout << "Open::stop_and_open\n"; } }; // 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; void start_playback(play const&) { std::cout << "Stopped::start_playback\n"; } void stop_playback(stop const&) { std::cout << "Stopped::stop_playback\n"; } }; struct Playing : public msm::front::state<> { 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;} // guard conditions // 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; } }; // state not defining any entry or exit struct Paused : public msm::front::state<> { void pause_playback(pause const&) { std::cout << "Paused::pause_playback\n"; } void resume_playback(end_pause const&) { std::cout << "Paused::resume_playback\n"; } }; // action void store_cd_info(cd_detected const&) { std::cout << "Player::store_cd_info\n"; } // guard 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; } // the initial state of the player SM. Must be defined typedef Empty initial_state; // Transition table for player struct transition_table : mpl::vector< // Start Event Next Action/Guard // +---------+-------------+---------+---------------------+----------------------+ a_row2 < Stopped , play , Playing , Stopped , &Stopped::start_playback >, a_row2 < Stopped , open_close , Open , Empty , &Empty::open_drawer >, _row < Stopped , stop , Stopped >, // +---------+-------------+---------+---------------------+----------------------+ a_row2 < Open , open_close , Empty , Open , &Open::close_drawer >, // +---------+-------------+---------+---------------------+----------------------+ a_row2 < Empty , open_close , Open , Empty ,&Empty::open_drawer >, row2 < Empty , cd_detected , Stopped , player_ ,&player_::store_cd_info , player_ ,&player_::good_disk_format >, row2 < Empty , cd_detected , Playing , player_ ,&player_::store_cd_info , Playing ,&Playing::auto_start >, // conflict with some internal rows irow2 < Empty , cd_detected , Empty ,&Empty::internal_action , Empty ,&Empty::internal_guard >, g_irow2 < Empty , cd_detected , Empty ,&Empty::internal_guard >, // +---------+-------------+---------+---------------------+----------------------+ a_row2 < Playing , stop , Stopped , Stopped ,&Stopped::stop_playback >, a_row2 < Playing , pause , Paused , Paused ,&Paused::pause_playback >, a_row2 < Playing , open_close , Open , Open ,&Open::stop_and_open >, // +---------+-------------+---------+---------------------+----------------------+ a_row2 < Paused , end_pause , Playing , Paused ,&Paused::resume_playback >, a_row2 < Paused , stop , Stopped , Stopped ,&Stopped::stop_playback >, a_row2 < Paused , open_close , Open , Open ,&Open::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(); // 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); // will be rejected, wrong disk type p.process_event( cd_detected("louie, louie",DISK_DVD)); pstate(p); p.process_event( cd_detected("louie, louie",DISK_CD)); pstate(p); p.process_event(play()); // at this point, Play is active p.process_event(pause()); pstate(p); // go back to Playing p.process_event(end_pause()); pstate(p); p.process_event(pause()); pstate(p); p.process_event(stop()); pstate(p); // event leading to the same state // no action method called as it is not present in the transition table p.process_event(stop()); pstate(p); std::cout << "stop fsm" << std::endl; p.stop(); } } int main() { test(); return 0; }