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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 | ||
29 | // A "complicated" event type that carries some data. | |
30 | enum DiskTypeEnum | |
31 | { | |
32 | DISK_CD=0, | |
33 | DISK_DVD=1 | |
34 | }; | |
35 | struct cd_detected | |
36 | { | |
37 | cd_detected(std::string name, DiskTypeEnum diskType) | |
38 | : name(name), | |
39 | disc_type(diskType) | |
40 | {} | |
41 | ||
42 | std::string name; | |
43 | DiskTypeEnum disc_type; | |
44 | }; | |
45 | ||
46 | // front-end: define the FSM structure | |
47 | struct player_ : public msm::front::state_machine_def<player_> | |
48 | { | |
49 | template <class Event,class FSM> | |
50 | void on_entry(Event const& ,FSM&) | |
51 | { | |
52 | std::cout << "entering: Player" << std::endl; | |
53 | } | |
54 | template <class Event,class FSM> | |
55 | void on_exit(Event const&,FSM& ) | |
56 | { | |
57 | std::cout << "leaving: Player" << std::endl; | |
58 | } | |
59 | ||
60 | // The list of FSM states | |
61 | struct Empty : public msm::front::state<> | |
62 | { | |
63 | // every (optional) entry/exit methods get the event passed. | |
64 | template <class Event,class FSM> | |
65 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;} | |
66 | template <class Event,class FSM> | |
67 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;} | |
68 | }; | |
69 | struct Open : public msm::front::state<> | |
70 | { | |
71 | template <class Event,class FSM> | |
72 | void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;} | |
73 | template <class Event,class FSM> | |
74 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;} | |
75 | }; | |
76 | ||
77 | // sm_ptr still supported but deprecated as functors are a much better way to do the same thing | |
78 | struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr> | |
79 | { | |
80 | template <class Event,class FSM> | |
81 | void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;} | |
82 | template <class Event,class FSM> | |
83 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;} | |
84 | void set_sm_ptr(player_* pl) | |
85 | { | |
86 | m_player=pl; | |
87 | } | |
88 | player_* m_player; | |
89 | }; | |
90 | ||
91 | struct Playing : public msm::front::state<> | |
92 | { | |
93 | template <class Event,class FSM> | |
94 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;} | |
95 | template <class Event,class FSM> | |
96 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;} | |
97 | }; | |
98 | ||
99 | // state not defining any entry or exit | |
100 | struct Paused : public msm::front::state<> | |
101 | { | |
102 | }; | |
103 | ||
104 | // the initial state of the player SM. Must be defined | |
105 | typedef Empty initial_state; | |
106 | ||
107 | // transition actions | |
108 | void start_playback(play const&) { std::cout << "player::start_playback\n"; } | |
109 | void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; } | |
110 | void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; } | |
111 | void store_cd_info(cd_detected const&) { std::cout << "player::store_cd_info\n"; } | |
112 | void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; } | |
113 | void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; } | |
114 | void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; } | |
115 | void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; } | |
116 | void stopped_again(stop const&) {std::cout << "player::stopped_again\n";} | |
117 | // guard conditions | |
118 | bool good_disk_format(cd_detected const& evt) | |
119 | { | |
120 | // to test a guard condition, let's say we understand only CDs, not DVD | |
121 | if (evt.disc_type != DISK_CD) | |
122 | { | |
123 | std::cout << "wrong disk, sorry" << std::endl; | |
124 | return false; | |
125 | } | |
126 | return true; | |
127 | } | |
128 | // used to show a transition conflict. This guard will simply deactivate one transition and thus | |
129 | // solve the conflict | |
130 | bool auto_start(cd_detected const&) | |
131 | { | |
132 | return false; | |
133 | } | |
134 | ||
135 | typedef player_ p; // makes transition table cleaner | |
136 | ||
137 | // Transition table for player | |
138 | struct transition_table : mpl::vector< | |
139 | // Start Event Next Action Guard | |
140 | // +---------+-------------+---------+---------------------+----------------------+ | |
141 | a_row < Stopped , play , Playing , &p::start_playback >, | |
142 | a_row < Stopped , open_close , Open , &p::open_drawer >, | |
143 | _row < Stopped , stop , Stopped >, | |
144 | // +---------+-------------+---------+---------------------+----------------------+ | |
145 | a_row < Open , open_close , Empty , &p::close_drawer >, | |
146 | // +---------+-------------+---------+---------------------+----------------------+ | |
147 | a_row < Empty , open_close , Open , &p::open_drawer >, | |
148 | row < Empty , cd_detected , Stopped , &p::store_cd_info ,&p::good_disk_format >, | |
149 | row < Empty , cd_detected , Playing , &p::store_cd_info ,&p::auto_start >, | |
150 | // +---------+-------------+---------+---------------------+----------------------+ | |
151 | a_row < Playing , stop , Stopped , &p::stop_playback >, | |
152 | a_row < Playing , pause , Paused , &p::pause_playback >, | |
153 | a_row < Playing , open_close , Open , &p::stop_and_open >, | |
154 | // +---------+-------------+---------+---------------------+----------------------+ | |
155 | a_row < Paused , end_pause , Playing , &p::resume_playback >, | |
156 | a_row < Paused , stop , Stopped , &p::stop_playback >, | |
157 | a_row < Paused , open_close , Open , &p::stop_and_open > | |
158 | // +---------+-------------+---------+---------------------+----------------------+ | |
159 | > {}; | |
160 | // Replaces the default no-transition response. | |
161 | template <class FSM,class Event> | |
162 | void no_transition(Event const& e, FSM&,int state) | |
163 | { | |
164 | std::cout << "no transition from state " << state | |
165 | << " on event " << typeid(e).name() << std::endl; | |
166 | } | |
167 | }; | |
168 | // Pick a back-end | |
169 | typedef msm::back::state_machine<player_> player; | |
170 | ||
171 | // | |
172 | // Testing utilities. | |
173 | // | |
174 | static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" }; | |
175 | void pstate(player const& p) | |
176 | { | |
177 | std::cout << " -> " << state_names[p.current_state()[0]] << std::endl; | |
178 | } | |
179 | ||
180 | void test() | |
181 | { | |
182 | player p; | |
183 | // needed to start the highest-level SM. This will call on_entry and mark the start of the SM | |
184 | p.start(); | |
185 | // go to Open, call on_exit on Empty, then action, then on_entry on Open | |
186 | p.process_event(open_close()); pstate(p); | |
187 | p.process_event(open_close()); pstate(p); | |
188 | // will be rejected, wrong disk type | |
189 | p.process_event( | |
190 | cd_detected("louie, louie",DISK_DVD)); pstate(p); | |
191 | p.process_event( | |
192 | cd_detected("louie, louie",DISK_CD)); pstate(p); | |
193 | p.process_event(play()); | |
194 | ||
195 | // at this point, Play is active | |
196 | p.process_event(pause()); pstate(p); | |
197 | // go back to Playing | |
198 | p.process_event(end_pause()); pstate(p); | |
199 | p.process_event(pause()); pstate(p); | |
200 | p.process_event(stop()); pstate(p); | |
201 | // event leading to the same state | |
202 | // no action method called as it is not present in the transition table | |
203 | p.process_event(stop()); pstate(p); | |
204 | std::cout << "stop fsm" << std::endl; | |
205 | p.stop(); | |
206 | } | |
207 | } | |
208 | ||
209 | int main() | |
210 | { | |
211 | test(); | |
212 | return 0; | |
213 | } |