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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) | |
10 | ||
11 | #include <iostream> | |
12 | // back-end | |
13 | #include <boost/msm/back/state_machine.hpp> | |
14 | //front-end | |
15 | #include <boost/msm/front/state_machine_def.hpp> | |
16 | ||
17 | namespace msm = boost::msm; | |
18 | namespace mpl = boost::mpl; | |
19 | ||
20 | namespace | |
21 | { | |
22 | // events | |
23 | struct play {}; | |
24 | struct end_pause {}; | |
25 | struct stop {}; | |
26 | struct pause {}; | |
27 | struct open_close {}; | |
28 | struct NextSong {}; | |
29 | struct PreviousSong {}; | |
30 | struct error_found {}; | |
31 | struct end_error {}; | |
32 | struct end_error2 {}; | |
33 | ||
34 | // Flags. Allow information about a property of the current state | |
35 | struct PlayingPaused{}; | |
36 | struct CDLoaded {}; | |
37 | struct FirstSongPlaying {}; | |
38 | ||
39 | // A "complicated" event type that carries some data. | |
40 | struct cd_detected | |
41 | { | |
42 | cd_detected(std::string name) | |
43 | : name(name) | |
44 | {} | |
45 | ||
46 | std::string name; | |
47 | }; | |
48 | ||
49 | // front-end: define the FSM structure | |
50 | struct player_ : public msm::front::state_machine_def<player_> | |
51 | { | |
52 | template <class Event,class FSM> | |
53 | void on_entry(Event const& ,FSM&) | |
54 | { | |
55 | std::cout << "entering: Player" << std::endl; | |
56 | } | |
57 | template <class Event,class FSM> | |
58 | void on_exit(Event const&,FSM& ) | |
59 | { | |
60 | std::cout << "leaving: Player" << std::endl; | |
61 | } | |
62 | // The list of FSM states | |
63 | struct Empty : public msm::front::state<> | |
64 | { | |
65 | // if the play event arrives in this state, defer it until a state handles it or | |
66 | // rejects it | |
67 | typedef mpl::vector<play> deferred_events; | |
68 | // every (optional) entry/exit methods get the event passed. | |
69 | template <class Event,class FSM> | |
70 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;} | |
71 | template <class Event,class FSM> | |
72 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;} | |
73 | }; | |
74 | struct Open : public msm::front::state<> | |
75 | { | |
76 | // if the play event arrives in this state, defer it until a state handles it or | |
77 | // rejects it | |
78 | typedef mpl::vector<play> deferred_events; | |
79 | typedef mpl::vector1<CDLoaded> flag_list; | |
80 | template <class Event,class FSM> | |
81 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;} | |
82 | template <class Event,class FSM> | |
83 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;} | |
84 | }; | |
85 | ||
86 | struct Stopped : public msm::front::state<> | |
87 | { | |
88 | // when stopped, the CD is loaded | |
89 | typedef mpl::vector1<CDLoaded> flag_list; | |
90 | template <class Event,class FSM> | |
91 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;} | |
92 | template <class Event,class FSM> | |
93 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;} | |
94 | }; | |
95 | ||
96 | // the player state machine contains a state which is himself a state machine | |
97 | // as you see, no need to declare it anywhere so Playing can be developed separately | |
98 | // by another team in another module. For simplicity I just declare it inside player | |
99 | struct Playing_ : public msm::front::state_machine_def<Playing_> | |
100 | { | |
101 | // when playing, the CD is loaded and we are in either pause or playing (duh) | |
102 | typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list; | |
103 | ||
104 | template <class Event,class FSM> | |
105 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;} | |
106 | template <class Event,class FSM> | |
107 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;} | |
108 | // The list of FSM states | |
109 | struct Song1 : public msm::front::state<> | |
110 | { | |
111 | typedef mpl::vector1<FirstSongPlaying> flag_list; | |
112 | template <class Event,class FSM> | |
113 | void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;} | |
114 | template <class Event,class FSM> | |
115 | void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;} | |
116 | }; | |
117 | struct Song2 : public msm::front::state<> | |
118 | { | |
119 | template <class Event,class FSM> | |
120 | void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;} | |
121 | template <class Event,class FSM> | |
122 | void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;} | |
123 | }; | |
124 | struct Song3 : public msm::front::state<> | |
125 | { | |
126 | template <class Event,class FSM> | |
127 | void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;} | |
128 | template <class Event,class FSM> | |
129 | void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;} | |
130 | }; | |
131 | // the initial state. Must be defined | |
132 | typedef Song1 initial_state; | |
133 | // transition actions | |
134 | void start_next_song(NextSong const&) { std::cout << "Playing::start_next_song\n"; } | |
135 | void start_prev_song(PreviousSong const&) { std::cout << "Playing::start_prev_song\n"; } | |
136 | // guard conditions | |
137 | ||
138 | typedef Playing_ pl; // makes transition table cleaner | |
139 | // Transition table for Playing | |
140 | struct transition_table : mpl::vector4< | |
141 | // Start Event Next Action Guard | |
142 | // +---------+-------------+---------+---------------------+----------------------+ | |
143 | a_row < Song1 , NextSong , Song2 , &pl::start_next_song >, | |
144 | a_row < Song2 , PreviousSong, Song1 , &pl::start_prev_song >, | |
145 | a_row < Song2 , NextSong , Song3 , &pl::start_next_song >, | |
146 | a_row < Song3 , PreviousSong, Song2 , &pl::start_prev_song > | |
147 | // +---------+-------------+---------+---------------------+----------------------+ | |
148 | > {}; | |
149 | // Replaces the default no-transition response. | |
150 | template <class FSM,class Event> | |
151 | void no_transition(Event const& e, FSM&,int state) | |
152 | { | |
153 | std::cout << "no transition from state " << state | |
154 | << " on event " << typeid(e).name() << std::endl; | |
155 | } | |
156 | }; | |
157 | // back-end | |
158 | typedef msm::back::state_machine<Playing_> Playing; | |
159 | ||
160 | // state not defining any entry or exit | |
161 | struct Paused : public msm::front::state<> | |
162 | { | |
163 | typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list; | |
164 | }; | |
165 | struct AllOk : public msm::front::state<> | |
166 | { | |
167 | template <class Event,class FSM> | |
168 | void on_entry(Event const&,FSM& ) {std::cout << "starting: AllOk" << std::endl;} | |
169 | template <class Event,class FSM> | |
170 | void on_exit(Event const&,FSM& ) {std::cout << "finishing: AllOk" << std::endl;} | |
171 | }; | |
172 | // this state is also made terminal so that all the events are blocked | |
173 | struct ErrorMode : //public msm::front::terminate_state<> // ErrorMode terminates the state machine | |
174 | public msm::front::interrupt_state<end_error/*mpl::vector<end_error,end_error2>*/ > // ErroMode just interrupts. Will resume if | |
175 | // the event end_error is generated | |
176 | { | |
177 | template <class Event,class FSM> | |
178 | void on_entry(Event const&,FSM& ) {std::cout << "starting: ErrorMode" << std::endl;} | |
179 | template <class Event,class FSM> | |
180 | void on_exit(Event const&,FSM& ) {std::cout << "finishing: ErrorMode" << std::endl;} | |
181 | }; | |
182 | // the initial state of the player SM. Must be defined | |
183 | typedef mpl::vector<Empty,AllOk> initial_state; | |
184 | ||
185 | // transition actions | |
186 | void start_playback(play const&) { std::cout << "player::start_playback\n"; } | |
187 | void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; } | |
188 | void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; } | |
189 | void store_cd_info(cd_detected const& cd) {std::cout << "player::store_cd_info\n";} | |
190 | void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; } | |
191 | void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; } | |
192 | void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; } | |
193 | void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; } | |
194 | void stopped_again(stop const&){std::cout << "player::stopped_again\n";} | |
195 | void report_error(error_found const&) {std::cout << "player::report_error\n";} | |
196 | void report_end_error(end_error const&) {std::cout << "player::report_end_error\n";} | |
197 | ||
198 | // guard conditions | |
199 | ||
200 | typedef player_ p; // makes transition table cleaner | |
201 | ||
202 | // Transition table for player | |
203 | struct transition_table : mpl::vector< | |
204 | // Start Event Next Action Guard | |
205 | // +---------+-------------+---------+---------------------+----------------------+ | |
206 | a_row < Stopped , play , Playing , &p::start_playback >, | |
207 | a_row < Stopped , open_close , Open , &p::open_drawer >, | |
208 | a_row < Stopped , stop , Stopped , &p::stopped_again >, | |
209 | // +---------+-------------+---------+---------------------+----------------------+ | |
210 | a_row < Open , open_close , Empty , &p::close_drawer >, | |
211 | // +---------+-------------+---------+---------------------+----------------------+ | |
212 | a_row < Empty , open_close , Open , &p::open_drawer >, | |
213 | a_row < Empty , cd_detected , Stopped , &p::store_cd_info >, | |
214 | // +---------+-------------+---------+---------------------+----------------------+ | |
215 | a_row < Playing , stop , Stopped , &p::stop_playback >, | |
216 | a_row < Playing , pause , Paused , &p::pause_playback >, | |
217 | a_row < Playing , open_close , Open , &p::stop_and_open >, | |
218 | // +---------+-------------+---------+---------------------+----------------------+ | |
219 | a_row < Paused , end_pause , Playing , &p::resume_playback >, | |
220 | a_row < Paused , stop , Stopped , &p::stop_playback >, | |
221 | a_row < Paused , open_close , Open , &p::stop_and_open >, | |
222 | // +---------+-------------+---------+---------------------+----------------------+ | |
223 | a_row < AllOk , error_found ,ErrorMode, &p::report_error >, | |
224 | a_row <ErrorMode,end_error ,AllOk , &p::report_end_error > | |
225 | // +---------+-------------+---------+---------------------+----------------------+ | |
226 | > {}; | |
227 | ||
228 | // Replaces the default no-transition response. | |
229 | template <class FSM,class Event> | |
230 | void no_transition(Event const& e, FSM&,int state) | |
231 | { | |
232 | std::cout << "no transition from state " << state | |
233 | << " on event " << typeid(e).name() << std::endl; | |
234 | } | |
235 | }; | |
236 | // Pick a back-end | |
237 | typedef msm::back::state_machine<player_> player; | |
238 | ||
239 | // | |
240 | // Testing utilities. | |
241 | // | |
242 | static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused","AllOk","ErrorMode" }; | |
243 | ||
244 | void pstate(player const& p) | |
245 | { | |
246 | // we have now several active states, which we show | |
247 | for (unsigned int i=0;i<player::nr_regions::value;++i) | |
248 | { | |
249 | std::cout << " -> " << state_names[p.current_state()[i]] << std::endl; | |
250 | } | |
251 | } | |
252 | ||
253 | void test() | |
254 | { | |
255 | player p; | |
256 | // needed to start the highest-level SM. This will call on_entry and mark the start of the SM | |
257 | p.start(); | |
258 | // test deferred event | |
259 | // deferred in Empty and Open, will be handled only after event cd_detected | |
260 | p.process_event(play()); | |
261 | ||
262 | // tests some flags | |
263 | std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet) | |
264 | // go to Open, call on_exit on Empty, then action, then on_entry on Open | |
265 | p.process_event(open_close()); pstate(p); | |
266 | p.process_event(open_close()); pstate(p); | |
267 | p.process_event(cd_detected("louie, louie")); | |
268 | ||
269 | // at this point, Play is active (was deferred) | |
270 | std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true | |
271 | std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true | |
272 | ||
273 | // make transition happen inside it. Player has no idea about this event but it's ok. | |
274 | p.process_event(NextSong());pstate(p); //2nd song active | |
275 | p.process_event(NextSong());pstate(p);//3rd song active | |
276 | p.process_event(PreviousSong());pstate(p);//2nd song active | |
277 | std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false | |
278 | ||
279 | std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true | |
280 | p.process_event(pause()); pstate(p); | |
281 | std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true | |
282 | // go back to Playing | |
283 | // as you see, it starts back from the original state | |
284 | p.process_event(end_pause()); pstate(p); | |
285 | p.process_event(pause()); pstate(p); | |
286 | p.process_event(stop()); pstate(p); | |
287 | std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false | |
288 | std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true | |
289 | // by default, the flags are OR'ed but you can also use AND. Then the flag must be present in | |
290 | // all of the active states | |
291 | std::cout << "CDLoaded active with AND:" << std::boolalpha << p.is_flag_active<CDLoaded,player::Flag_AND>() << std::endl;//=> false | |
292 | ||
293 | // event leading to the same state | |
294 | p.process_event(stop()); pstate(p); | |
295 | ||
296 | // event leading to a terminal/interrupt state | |
297 | p.process_event(error_found()); pstate(p); | |
298 | // try generating more events | |
299 | std::cout << "Trying to generate another event" << std::endl; // will not work, fsm is terminated or interrupted | |
300 | p.process_event(play());pstate(p); | |
301 | std::cout << "Trying to end the error" << std::endl; // will work only if ErrorMode is interrupt state | |
302 | p.process_event(end_error());pstate(p); | |
303 | std::cout << "Trying to generate another event" << std::endl; // will work only if ErrorMode is interrupt state | |
304 | p.process_event(play());pstate(p); | |
305 | std::cout << "stop fsm" << std::endl; | |
306 | p.stop(); | |
307 | ||
308 | } | |
309 | } | |
310 | ||
311 | int main() | |
312 | { | |
313 | test(); | |
314 | return 0; | |
315 | } |