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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 | ||
31 | // A "complicated" event type that carries some data. | |
32 | struct cd_detected | |
33 | { | |
34 | cd_detected(std::string name) | |
35 | : name(name) | |
36 | {} | |
37 | ||
38 | std::string name; | |
39 | }; | |
40 | ||
41 | // front-end: define the FSM structure | |
42 | struct player_ : public msm::front::state_machine_def<player_> | |
43 | { | |
44 | // The list of FSM states | |
45 | struct Empty : public msm::front::state<> | |
46 | { | |
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;} | |
52 | }; | |
53 | struct Open : public msm::front::state<> | |
54 | { | |
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;} | |
59 | }; | |
60 | ||
61 | struct Stopped : public msm::front::state<> | |
62 | { | |
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;} | |
68 | }; | |
69 | ||
70 | struct Playing_ : public msm::front::state_machine_def<Playing_> | |
71 | { | |
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;} | |
77 | ||
78 | // The list of FSM states | |
79 | struct Song1 : public msm::front::state<> | |
80 | { | |
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;} | |
85 | }; | |
86 | struct Song2 : public msm::front::state<> | |
87 | { | |
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;} | |
92 | }; | |
93 | struct Song3 : public msm::front::state<> | |
94 | { | |
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;} | |
99 | }; | |
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"; } | |
105 | // guard conditions | |
106 | ||
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 | // +---------+-------------+---------+---------------------+----------------------+ | |
117 | > {}; | |
118 | // Replaces the default no-transition response. | |
119 | template <class FSM,class Event> | |
120 | void no_transition(Event const& e, FSM&,int state) | |
121 | { | |
122 | std::cout << "no transition from state " << state | |
123 | << " on event " << typeid(e).name() << std::endl; | |
124 | } | |
125 | ||
126 | }; | |
127 | // back-end | |
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; | |
133 | ||
134 | // state not defining any entry or exit | |
135 | struct Paused : public msm::front::state<> | |
136 | { | |
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;} | |
141 | }; | |
142 | ||
143 | // the initial state of the player SM. Must be defined | |
144 | typedef Empty initial_state; | |
145 | ||
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";} | |
156 | // guard conditions | |
157 | ||
158 | typedef player_ p; // makes transition table cleaner | |
159 | ||
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 | // +---------+-------------+---------+---------------------+----------------------+ | |
181 | > {}; | |
182 | ||
183 | // Replaces the default no-transition response. | |
184 | template <class FSM,class Event> | |
185 | void no_transition(Event const& e, FSM&,int state) | |
186 | { | |
187 | std::cout << "no transition from state " << state | |
188 | << " on event " << typeid(e).name() << std::endl; | |
189 | } | |
190 | ||
191 | }; | |
192 | // Pick a back-end | |
193 | typedef msm::back::state_machine<player_> player; | |
194 | ||
195 | // | |
196 | // Testing utilities. | |
197 | // | |
198 | static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" }; | |
199 | ||
200 | void pstate(player const& p) | |
201 | { | |
202 | std::cout << " -> " << state_names[p.current_state()[0]] << std::endl; | |
203 | } | |
204 | ||
205 | void test() | |
206 | { | |
207 | player p; | |
208 | ||
209 | // needed to start the highest-level SM. This will call on_entry and mark the start of the SM | |
210 | p.start(); | |
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()); | |
216 | ||
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 | |
222 | ||
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); | |
233 | } | |
234 | } | |
235 | ||
236 | int main() | |
237 | { | |
238 | test(); | |
239 | return 0; | |
240 | } |