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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>
- namespace msm = boost::msm;
- namespace mpl = boost::mpl;
- 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;}
- };
- 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;}
- };
- // 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<>
- {
- 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;}
- };
- // 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()
- {
- 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;
- }
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