255 lines
12 KiB
C++
255 lines
12 KiB
C++
// Copyright 2010 Christophe Henry
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// henry UNDERSCORE christophe AT hotmail DOT com
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// This is an extended version of the state machine available in the boost::mpl library
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// Distributed under the same license as the original.
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// Copyright for the original version:
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// Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed
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// under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <iostream>
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// back-end
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#include <boost/msm/back/state_machine.hpp>
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//front-end
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#include <boost/msm/front/state_machine_def.hpp>
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namespace msm = boost::msm;
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namespace mpl = boost::mpl;
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namespace // Concrete FSM implementation
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{
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// events
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struct play {};
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struct end_pause {};
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struct stop {};
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struct pause {};
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struct open_close {};
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struct NextSong {};
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struct PreviousSong {};
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// Flags. Allow information about a property of the current state
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struct PlayingPaused{};
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struct CDLoaded {};
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struct FirstSongPlaying {};
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// A "complicated" event type that carries some data.
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struct cd_detected
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{
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cd_detected(std::string name)
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: name(name)
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{}
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std::string name;
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};
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// front-end: define the FSM structure
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struct player_ : public msm::front::state_machine_def<player_>
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{
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// The list of FSM states
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struct Empty : public msm::front::state<>
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{
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// every (optional) entry/exit methods get the event passed.
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
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};
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struct Open : public msm::front::state<>
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{
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typedef mpl::vector1<CDLoaded> flag_list;
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
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};
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struct Stopped : public msm::front::state<>
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{
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// when stopped, the CD is loaded
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typedef mpl::vector1<CDLoaded> flag_list;
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
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};
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// the player state machine contains a state which is himself a state machine
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// as you see, no need to declare it anywhere so Playing can be developed separately
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// by another team in another module. For simplicity I just declare it inside player
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struct Playing_ : public msm::front::state_machine_def<Playing_>
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{
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// when playing, the CD is loaded and we are in either pause or playing (duh)
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typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
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// The list of FSM states
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struct Song1 : public msm::front::state<>
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{
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typedef mpl::vector1<FirstSongPlaying> flag_list;
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
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};
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struct Song2 : public msm::front::state<>
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{
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
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};
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struct Song3 : public msm::front::state<>
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{
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
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};
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// the initial state. Must be defined
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typedef Song1 initial_state;
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// transition actions
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void start_next_song(NextSong const&) { std::cout << "Playing::start_next_song\n"; }
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void start_prev_song(PreviousSong const&) { std::cout << "Playing::start_prev_song\n"; }
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// guard conditions
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typedef Playing_ pl; // makes transition table cleaner
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// Transition table for Playing
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struct transition_table : mpl::vector4<
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// Start Event Next Action Guard
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Song1 , NextSong , Song2 , &pl::start_next_song >,
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a_row < Song2 , PreviousSong, Song1 , &pl::start_prev_song >,
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a_row < Song2 , NextSong , Song3 , &pl::start_next_song >,
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a_row < Song3 , PreviousSong, Song2 , &pl::start_prev_song >
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// +---------+-------------+---------+---------------------+----------------------+
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> {};
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// Replaces the default no-transition response.
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template <class FSM,class Event>
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void no_transition(Event const& e, FSM&,int state)
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{
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std::cout << "no transition from state " << state
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<< " on event " << typeid(e).name() << std::endl;
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}
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};
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// back-end
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typedef msm::back::state_machine<Playing_> Playing;
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// state not defining any entry or exit
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struct Paused : public msm::front::state<>
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{
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typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;
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};
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// the initial state of the player SM. Must be defined
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typedef Empty initial_state;
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// transition actions
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void start_playback(play const&) { std::cout << "player::start_playback\n"; }
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void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; }
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void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; }
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void store_cd_info(cd_detected const& cd) {std::cout << "player::store_cd_info\n";}
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void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; }
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void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; }
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void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; }
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void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; }
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void stopped_again(stop const&){std::cout << "player::stopped_again\n";}
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// guard conditions
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typedef player_ p; // makes transition table cleaner
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// Transition table for player
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struct transition_table : mpl::vector<
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// Start Event Next Action Guard
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Stopped , play , Playing , &p::start_playback >,
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a_row < Stopped , open_close , Open , &p::open_drawer >,
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a_row < Stopped , stop , Stopped , &p::stopped_again >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Open , open_close , Empty , &p::close_drawer >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Empty , open_close , Open , &p::open_drawer >,
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a_row < Empty , cd_detected , Stopped , &p::store_cd_info >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Playing , stop , Stopped , &p::stop_playback >,
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a_row < Playing , pause , Paused , &p::pause_playback >,
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a_row < Playing , open_close , Open , &p::stop_and_open >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Paused , end_pause , Playing , &p::resume_playback >,
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a_row < Paused , stop , Stopped , &p::stop_playback >,
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a_row < Paused , open_close , Open , &p::stop_and_open >
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// +---------+-------------+---------+---------------------+----------------------+
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> {};
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// Replaces the default no-transition response.
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template <class FSM,class Event>
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void no_transition(Event const& e, FSM&,int state)
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{
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std::cout << "no transition from state " << state
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<< " on event " << typeid(e).name() << std::endl;
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}
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};
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// Pick a back-end
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typedef msm::back::state_machine<player_> player;
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//
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// Testing utilities.
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//
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static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
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void pstate(player const& p)
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{
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std::cout << " -> " << state_names[p.current_state()[0]] << std::endl;
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}
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void test()
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{
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player p;
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// needed to start the highest-level SM. This will call on_entry and mark the start of the SM
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p.start();
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// tests some flags
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std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet)
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// go to Open, call on_exit on Empty, then action, then on_entry on Open
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p.process_event(open_close()); pstate(p);
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p.process_event(open_close()); pstate(p);
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p.process_event(cd_detected("louie, louie"));
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p.process_event(play());
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// at this point, Play is active
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std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
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std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true
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// make transition happen inside it. Player has no idea about this event but it's ok.
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p.process_event(NextSong());pstate(p); //2nd song active
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p.process_event(NextSong());pstate(p);//3rd song active
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p.process_event(PreviousSong());pstate(p);//2nd song active
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std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false
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std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
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p.process_event(pause()); pstate(p);
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std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
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// go back to Playing
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// as you see, it starts back from the original state
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p.process_event(end_pause()); pstate(p);
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p.process_event(pause()); pstate(p);
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p.process_event(stop()); pstate(p);
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std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false
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std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true
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// event leading to the same state
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p.process_event(stop()); pstate(p);
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}
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}
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int main()
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{
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test();
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return 0;
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}
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