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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;
- 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;
- }
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