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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 | #include <boost/msm/front/functor_row.hpp> | |
17 | ||
18 | namespace msm = boost::msm; | |
19 | using namespace msm::front; | |
20 | ||
21 | namespace | |
22 | { | |
23 | // events | |
24 | struct play {}; | |
25 | struct end_pause {}; | |
26 | struct stop {}; | |
27 | struct pause {}; | |
28 | struct open_close {}; | |
29 | ||
30 | // A "complicated" event type that carries some data. | |
31 | enum DiskTypeEnum | |
32 | { | |
33 | DISK_CD=0, | |
34 | DISK_DVD=1 | |
35 | }; | |
36 | struct cd_detected | |
37 | { | |
38 | cd_detected(std::string name, DiskTypeEnum diskType) | |
39 | : name(name), | |
40 | disc_type(diskType) | |
41 | {} | |
42 | ||
43 | std::string name; | |
44 | DiskTypeEnum disc_type; | |
45 | }; | |
46 | ||
47 | // front-end: define the FSM structure | |
48 | struct player_ : public msm::front::state_machine_def<player_> | |
49 | { | |
50 | // actions for Empty's internal transitions | |
51 | void internal_action(cd_detected const&){ std::cout << "Empty::internal action\n"; } | |
52 | bool internal_guard(cd_detected const&) | |
53 | { | |
54 | std::cout << "Empty::internal guard\n"; | |
55 | return false; | |
56 | } | |
57 | struct internal_guard_fct | |
58 | { | |
59 | template <class EVT,class FSM,class SourceState,class TargetState> | |
60 | bool operator()(EVT const& evt ,FSM&,SourceState& ,TargetState& ) | |
61 | { | |
62 | std::cout << "Empty::internal guard functor\n"; | |
63 | return false; | |
64 | } | |
65 | }; | |
66 | struct internal_action_fct | |
67 | { | |
68 | template <class EVT,class FSM,class SourceState,class TargetState> | |
69 | void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& ) | |
70 | { | |
71 | std::cout << "Empty::internal action functor" << std::endl; | |
72 | } | |
73 | }; | |
74 | ||
75 | // The list of FSM states | |
76 | struct Empty : public msm::front::state<> | |
77 | { | |
78 | // every (optional) entry/exit methods get the event passed. | |
79 | template <class Event,class FSM> | |
80 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;} | |
81 | template <class Event,class FSM> | |
82 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;} | |
83 | ||
84 | // Transition table for Empty | |
85 | struct internal_transition_table : mpl::vector< | |
86 | // Start Event Next Action Guard | |
87 | Internal < cd_detected , internal_action_fct ,internal_guard_fct > | |
88 | // +---------+-------------+---------+---------------------+----------------------+ | |
89 | > {}; | |
90 | }; | |
91 | struct Open : public msm::front::state<> | |
92 | { | |
93 | template <class Event,class FSM> | |
94 | void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;} | |
95 | template <class Event,class FSM> | |
96 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;} | |
97 | }; | |
98 | ||
99 | // sm_ptr still supported but deprecated as functors are a much better way to do the same thing | |
100 | struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr> | |
101 | { | |
102 | template <class Event,class FSM> | |
103 | void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;} | |
104 | template <class Event,class FSM> | |
105 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;} | |
106 | void set_sm_ptr(player_* pl) | |
107 | { | |
108 | m_player=pl; | |
109 | } | |
110 | player_* m_player; | |
111 | }; | |
112 | ||
113 | struct Playing : public msm::front::state<> | |
114 | { | |
115 | template <class Event,class FSM> | |
116 | void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;} | |
117 | template <class Event,class FSM> | |
118 | void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;} | |
119 | }; | |
120 | ||
121 | // state not defining any entry or exit | |
122 | struct Paused : public msm::front::state<> | |
123 | { | |
124 | }; | |
125 | ||
126 | // the initial state of the player SM. Must be defined | |
127 | typedef Empty initial_state; | |
128 | ||
129 | // transition actions | |
130 | void start_playback(play const&) { std::cout << "player::start_playback\n"; } | |
131 | void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; } | |
132 | void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; } | |
133 | void store_cd_info(cd_detected const&) { std::cout << "player::store_cd_info\n"; } | |
134 | void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; } | |
135 | void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; } | |
136 | void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; } | |
137 | void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; } | |
138 | void stopped_again(stop const&) {std::cout << "player::stopped_again\n";} | |
139 | // guard conditions | |
140 | bool good_disk_format(cd_detected const& evt) | |
141 | { | |
142 | // to test a guard condition, let's say we understand only CDs, not DVD | |
143 | if (evt.disc_type != DISK_CD) | |
144 | { | |
145 | std::cout << "wrong disk, sorry" << std::endl; | |
146 | return false; | |
147 | } | |
148 | return true; | |
149 | } | |
150 | ||
151 | typedef player_ p; // makes transition table cleaner | |
152 | ||
153 | // Transition table for player | |
154 | struct transition_table : mpl::vector< | |
155 | // Start Event Next Action Guard | |
156 | // +---------+-------------+---------+---------------------+----------------------+ | |
157 | a_row < Stopped , play , Playing , &p::start_playback >, | |
158 | a_row < Stopped , open_close , Open , &p::open_drawer >, | |
159 | _row < Stopped , stop , Stopped >, | |
160 | // +---------+-------------+---------+---------------------+----------------------+ | |
161 | a_row < Open , open_close , Empty , &p::close_drawer >, | |
162 | // +---------+-------------+---------+---------------------+----------------------+ | |
163 | a_row < Empty , open_close , Open , &p::open_drawer >, | |
164 | // conflict between a normal and 2 internal transitions (irow/g_irow) | |
165 | row < Empty , cd_detected , Stopped , &p::store_cd_info ,&p::good_disk_format >, | |
166 | irow < Empty , cd_detected , &p::internal_action ,&p::internal_guard >, | |
167 | g_irow < Empty , cd_detected ,&p::internal_guard >, | |
168 | // +---------+-------------+---------+---------------------+----------------------+ | |
169 | a_row < Playing , stop , Stopped , &p::stop_playback >, | |
170 | a_row < Playing , pause , Paused , &p::pause_playback >, | |
171 | a_row < Playing , open_close , Open , &p::stop_and_open >, | |
172 | // +---------+-------------+---------+---------------------+----------------------+ | |
173 | a_row < Paused , end_pause , Playing , &p::resume_playback >, | |
174 | a_row < Paused , stop , Stopped , &p::stop_playback >, | |
175 | a_row < Paused , open_close , Open , &p::stop_and_open > | |
176 | // +---------+-------------+---------+---------------------+----------------------+ | |
177 | > {}; | |
178 | // Replaces the default no-transition response. | |
179 | template <class FSM,class Event> | |
180 | void no_transition(Event const& e, FSM&,int state) | |
181 | { | |
182 | std::cout << "no transition from state " << state | |
183 | << " on event " << typeid(e).name() << std::endl; | |
184 | } | |
185 | typedef int no_message_queue; | |
186 | ||
187 | }; | |
188 | // Pick a back-end | |
189 | typedef msm::back::state_machine<player_> player; | |
190 | ||
191 | // | |
192 | // Testing utilities. | |
193 | // | |
194 | static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" }; | |
195 | void pstate(player const& p) | |
196 | { | |
197 | std::cout << " -> " << state_names[p.current_state()[0]] << std::endl; | |
198 | } | |
199 | ||
200 | void test() | |
201 | { | |
202 | player p; | |
203 | // needed to start the highest-level SM. This will call on_entry and mark the start of the SM | |
204 | p.start(); | |
205 | // go to Open, call on_exit on Empty, then action, then on_entry on Open | |
206 | p.process_event(open_close()); pstate(p); | |
207 | p.process_event(open_close()); pstate(p); | |
208 | // will be rejected, wrong disk type | |
209 | p.process_event( | |
210 | cd_detected("louie, louie",DISK_DVD)); pstate(p); | |
211 | p.process_event( | |
212 | cd_detected("louie, louie",DISK_CD)); pstate(p); | |
213 | p.process_event(play()); | |
214 | ||
215 | // at this point, Play is active | |
216 | p.process_event(pause()); pstate(p); | |
217 | // go back to Playing | |
218 | p.process_event(end_pause()); pstate(p); | |
219 | p.process_event(pause()); pstate(p); | |
220 | p.process_event(stop()); pstate(p); | |
221 | // event leading to the same state | |
222 | // no action method called as it is not present in the transition table | |
223 | p.process_event(stop()); pstate(p); | |
224 | } | |
225 | } | |
226 | ||
227 | int main() | |
228 | { | |
229 | test(); | |
230 | return 0; | |
231 | } |