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1 // Copyright 2010 Christophe Henry
2 // henry UNDERSCORE christophe AT hotmail DOT com
3 // This is an extended version of the state machine available in the boost::mpl library
4 // Distributed under the same license as the original.
5 // Copyright for the original version:
6 // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed
7 // under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
13 #include <boost/msm/back/state_machine.hpp>
15 #include <boost/msm/front/state_machine_def.hpp>
17 namespace msm
= boost::msm
;
18 namespace mpl
= boost::mpl
;
29 struct PreviousSong
{};
31 // A "complicated" event type that carries some data.
34 cd_detected(std::string name
)
41 // front-end: define the FSM structure
42 struct player_
: public msm::front::state_machine_def
<player_
>
44 // The list of FSM states
45 struct Empty
: public msm::front::state
<>
47 // every (optional) entry/exit methods get the event passed
48 template <class Event
,class FSM
>
49 void on_entry(Event
const&,FSM
& ) {std::cout
<< "entering: Empty" << std::endl
;}
50 template <class Event
,class FSM
>
51 void on_exit(Event
const&,FSM
& ) {std::cout
<< "leaving: Empty" << std::endl
;}
53 struct Open
: public msm::front::state
<>
55 template <class Event
,class FSM
>
56 void on_entry(Event
const&,FSM
& ) {std::cout
<< "entering: Open" << std::endl
;}
57 template <class Event
,class FSM
>
58 void on_exit(Event
const&,FSM
& ) {std::cout
<< "leaving: Open" << std::endl
;}
61 struct Stopped
: public msm::front::state
<>
63 // when stopped, the CD is loaded
64 template <class Event
,class FSM
>
65 void on_entry(Event
const&,FSM
& ) {std::cout
<< "entering: Stopped" << std::endl
;}
66 template <class Event
,class FSM
>
67 void on_exit(Event
const&,FSM
& ) {std::cout
<< "leaving: Stopped" << std::endl
;}
70 struct Playing_
: public msm::front::state_machine_def
<Playing_
>
72 // when playing, the CD is loaded and we are in either pause or playing (duh)
73 template <class Event
,class FSM
>
74 void on_entry(Event
const&,FSM
& ) {std::cout
<< "entering: Playing" << std::endl
;}
75 template <class Event
,class FSM
>
76 void on_exit(Event
const&,FSM
& ) {std::cout
<< "leaving: Playing" << std::endl
;}
78 // The list of FSM states
79 struct Song1
: public msm::front::state
<>
81 template <class Event
,class FSM
>
82 void on_entry(Event
const&,FSM
& ) {std::cout
<< "starting: First song" << std::endl
;}
83 template <class Event
,class FSM
>
84 void on_exit(Event
const&,FSM
& ) {std::cout
<< "finishing: First Song" << std::endl
;}
86 struct Song2
: public msm::front::state
<>
88 template <class Event
,class FSM
>
89 void on_entry(Event
const&,FSM
& ) {std::cout
<< "starting: Second song" << std::endl
;}
90 template <class Event
,class FSM
>
91 void on_exit(Event
const&,FSM
& ) {std::cout
<< "finishing: Second Song" << std::endl
;}
93 struct Song3
: public msm::front::state
<>
95 template <class Event
,class FSM
>
96 void on_entry(Event
const&,FSM
& ) {std::cout
<< "starting: Third song" << std::endl
;}
97 template <class Event
,class FSM
>
98 void on_exit(Event
const&,FSM
& ) {std::cout
<< "finishing: Third Song" << std::endl
;}
100 // the initial state. Must be defined
101 typedef Song1 initial_state
;
102 // transition actions
103 void start_next_song(NextSong
const&) { std::cout
<< "Playing::start_next_song\n"; }
104 void start_prev_song(PreviousSong
const&) { std::cout
<< "Playing::start_prev_song\n"; }
107 typedef Playing_ pl
; // makes transition table cleaner
108 // Transition table for Playing
109 struct transition_table
: mpl::vector4
<
110 // Start Event Next Action Guard
111 // +---------+-------------+---------+---------------------+----------------------+
112 a_row
< Song1
, NextSong
, Song2
, &pl::start_next_song
>,
113 a_row
< Song2
, PreviousSong
, Song1
, &pl::start_prev_song
>,
114 a_row
< Song2
, NextSong
, Song3
, &pl::start_next_song
>,
115 a_row
< Song3
, PreviousSong
, Song2
, &pl::start_prev_song
>
116 // +---------+-------------+---------+---------------------+----------------------+
118 // Replaces the default no-transition response.
119 template <class FSM
,class Event
>
120 void no_transition(Event
const& e
, FSM
&,int state
)
122 std::cout
<< "no transition from state " << state
123 << " on event " << typeid(e
).name() << std::endl
;
128 // demonstrates Shallow History: if the state gets activated with end_pause
129 // then it will remember the last active state and reactivate it
130 // also possible: AlwaysHistory, the last active state will always be reactivated
131 // or NoHistory, always restart from the initial state
132 typedef msm::back::state_machine
<Playing_
,msm::back::ShallowHistory
<mpl::vector
<end_pause
> > > Playing
;
134 // state not defining any entry or exit
135 struct Paused
: public msm::front::state
<>
137 template <class Event
,class FSM
>
138 void on_entry(Event
const&,FSM
& ) {std::cout
<< "entering: Paused" << std::endl
;}
139 template <class Event
,class FSM
>
140 void on_exit(Event
const&,FSM
& ) {std::cout
<< "leaving: Paused" << std::endl
;}
143 // the initial state of the player SM. Must be defined
144 typedef Empty initial_state
;
146 // transition actions
147 void start_playback(play
const&) { std::cout
<< "player::start_playback\n"; }
148 void open_drawer(open_close
const&) { std::cout
<< "player::open_drawer\n"; }
149 void close_drawer(open_close
const&) { std::cout
<< "player::close_drawer\n"; }
150 void store_cd_info(cd_detected
const& cd
) {std::cout
<< "player::store_cd_info\n";}
151 void stop_playback(stop
const&) { std::cout
<< "player::stop_playback\n"; }
152 void pause_playback(pause
const&) { std::cout
<< "player::pause_playback\n"; }
153 void resume_playback(end_pause
const&) { std::cout
<< "player::resume_playback\n"; }
154 void stop_and_open(open_close
const&) { std::cout
<< "player::stop_and_open\n"; }
155 void stopped_again(stop
const&){std::cout
<< "player::stopped_again\n";}
158 typedef player_ p
; // makes transition table cleaner
160 // Transition table for player
161 struct transition_table
: mpl::vector
<
162 // Start Event Next Action Guard
163 // +---------+-------------+---------+---------------------+----------------------+
164 a_row
< Stopped
, play
, Playing
, &p::start_playback
>,
165 a_row
< Stopped
, open_close
, Open
, &p::open_drawer
>,
166 a_row
< Stopped
, stop
, Stopped
, &p::stopped_again
>,
167 // +---------+-------------+---------+---------------------+----------------------+
168 a_row
< Open
, open_close
, Empty
, &p::close_drawer
>,
169 // +---------+-------------+---------+---------------------+----------------------+
170 a_row
< Empty
, open_close
, Open
, &p::open_drawer
>,
171 a_row
< Empty
, cd_detected
, Stopped
, &p::store_cd_info
>,
172 // +---------+-------------+---------+---------------------+----------------------+
173 a_row
< Playing
, stop
, Stopped
, &p::stop_playback
>,
174 a_row
< Playing
, pause
, Paused
, &p::pause_playback
>,
175 a_row
< Playing
, open_close
, Open
, &p::stop_and_open
>,
176 // +---------+-------------+---------+---------------------+----------------------+
177 a_row
< Paused
, end_pause
, Playing
, &p::resume_playback
>,
178 a_row
< Paused
, stop
, Stopped
, &p::stop_playback
>,
179 a_row
< Paused
, open_close
, Open
, &p::stop_and_open
>
180 // +---------+-------------+---------+---------------------+----------------------+
183 // Replaces the default no-transition response.
184 template <class FSM
,class Event
>
185 void no_transition(Event
const& e
, FSM
&,int state
)
187 std::cout
<< "no transition from state " << state
188 << " on event " << typeid(e
).name() << std::endl
;
193 typedef msm::back::state_machine
<player_
> player
;
196 // Testing utilities.
198 static char const* const state_names
[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
200 void pstate(player
const& p
)
202 std::cout
<< " -> " << state_names
[p
.current_state()[0]] << std::endl
;
209 // needed to start the highest-level SM. This will call on_entry and mark the start of the SM
211 // go to Open, call on_exit on Empty, then action, then on_entry on Open
212 p
.process_event(open_close()); pstate(p
);
213 p
.process_event(open_close()); pstate(p
);
214 p
.process_event(cd_detected("louie, louie"));
215 p
.process_event(play());
217 // at this point, Play is active
218 // make transition happen inside it. Player has no idea about this event but it's ok.
219 p
.process_event(NextSong());pstate(p
); //2nd song active
220 p
.process_event(NextSong());pstate(p
);//3rd song active
221 p
.process_event(PreviousSong());pstate(p
);//2nd song active
223 p
.process_event(pause()); pstate(p
);
224 // go back to Playing
225 // as you see, remembers the original state as end_pause is an history trigger
226 p
.process_event(end_pause()); pstate(p
);
227 p
.process_event(pause()); pstate(p
);
228 p
.process_event(stop()); pstate(p
);
229 // event leading to the same state
230 p
.process_event(stop()); pstate(p
);
231 // play does not trigger shallow history => start back from 1st song
232 p
.process_event(play()); pstate(p
);