ceph/src/boost/libs/msm/doc/HTML/examples/BoostCon09Full.cpp

   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 <vector>
  12 #include <iostream>
  13 #include <boost/mpl/vector/vector50.hpp>
  14 #include <boost/msm/back/state_machine.hpp>
  15 #include <boost/msm/front/state_machine_def.hpp>
  16 #include <boost/msm/back/tools.hpp>
  17
  18 namespace msm = boost::msm;
  19 namespace mpl = boost::mpl;
  20
  21 namespace  // Concrete FSM implementation
  22 {
  23     // events
  24     struct play {};
  25     struct end_pause {};
  26     struct stop {};
  27     struct pause {};
  28     struct open_close {};
  29     struct NextSong {};
  30     // event which every other event can convert to
  31     struct AllSongsPlayed
  32     {
  33         template <class Event>
  34         AllSongsPlayed(Event const&){}
  35     };
  36     struct PreviousSong {};
  37     struct error_found {};
  38     struct end_error {};
  39
  40     // Flags. Allow information about a property of the current state
  41     struct CDLoaded {};
  42     struct FirstSongPlaying {};
  43
  44     // A "complicated" event type that carries some data.
  45     enum DiskTypeEnum
  46     {
  47         DISK_CD=0,
  48         DISK_DVD=1
  49     };
  50     struct cd_detected
  51     {
  52         cd_detected(DiskTypeEnum diskType): disc_type(diskType) {}
  53         DiskTypeEnum disc_type;
  54     };
  55
  56     // Concrete FSM implementation
  57     struct player_ : public msm::front::state_machine_def<player_>
  58     {
  59         // The list of FSM states
  60         struct Empty : public msm::front::state<>
  61         {
  62             typedef mpl::vector<play> deferred_events;
  63             // every (optional) entry/exit methods get the event packed as boost::any. Not useful very often.
  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             typedef mpl::vector1<CDLoaded>  flag_list;
  72             typedef mpl::vector<play>       deferred_events;
  73             template <class Event,class FSM>
  74             void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;}
  75             template <class Event,class FSM>
  76             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
  77         };
  78         // a state needing a pointer to the containing state machine
  79         // and using for this the non-default policy
  80         // if policy used, set_sm_ptr is needed
  81         struct Stopped : public msm::front::state<default_base_state,msm::front::sm_ptr>
  82         {
  83             // when stopped, the CD is loaded
  84             typedef mpl::vector1<CDLoaded>  flag_list;
  85             template <class Event,class FSM>
  86             void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;}
  87             template <class Event,class FSM>
  88             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
  89             void set_sm_ptr(player_* pl){m_player=pl;}
  90             player_* m_player;
  91         };
  92         // the player state machine contains a state which is himself a state machine
  93         // it demonstrates Shallow History: if the state gets activated with end_pause
  94         // then it will remember the last active state and reactivate it
  95         // also possible: AlwaysHistory, the last active state will always be reactivated
  96         // or NoHistory, always restart from the initial state
  97         struct Playing_ : public msm::front::state_machine_def<Playing_>
  98         {
  99             // when playing, the CD is loaded and we are in either pause or playing (duh)
 100             typedef mpl::vector<CDLoaded>       flag_list;
 101             template <class Event,class FSM>
 102             void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
 103             template <class Event,class FSM>
 104             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
 105
 106             // The list of FSM states
 107             struct Song1 : public msm::front::state<>
 108             {
 109                 typedef mpl::vector1<FirstSongPlaying>      flag_list;
 110                 template <class Event,class FSM>
 111                 void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
 112                 template <class Event,class FSM>
 113                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
 114             };
 115             struct Song2 : public msm::front::state<>
 116             {
 117                 template <class Event,class FSM>
 118                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
 119                 template <class Event,class FSM>
 120                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
 121             };
 122             struct Song3 : public msm::front::state<>
 123             {
 124                 template <class Event,class FSM>
 125                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
 126                 template <class Event,class FSM>
 127                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
 128             };
 129             struct CDFinished : public msm::front::exit_pseudo_state<AllSongsPlayed>
 130             {
 131                 template <class Event,class FSM>
 132                 void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing::CDFinished" << std::endl;}
 133                 template <class Event,class FSM>
 134                 void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing::CDFinished" << std::endl;}
 135             };
 136             // the initial state. Must be defined
 137             typedef Song1 initial_state;
 138             // transition actions
 139             void start_next_song(NextSong const&)       { std::cout << "Playing::start_next_song\n"; }
 140             void start_prev_song(PreviousSong const&)       { std::cout << "Playing::start_prev_song\n"; }
 141             void all_songs_played(NextSong const&)       { std::cout << "Playing::all_songs_played\n"; }
 142            // guard conditions
 143
 144             typedef Playing_ pl; // makes transition table cleaner
 145             // Transition table for Playing
 146             struct transition_table : mpl::vector<
 147                 //    Start     Event           Next         Action               Guard
 148                 //  +---------+---------------+------------+---------------------+----------------------+
 149                 a_row < Song1   , NextSong    , Song2      , &pl::start_next_song                      >,
 150                 a_row < Song2   , PreviousSong, Song1      , &pl::start_prev_song                      >,
 151                 a_row < Song2   , NextSong    , Song3      , &pl::start_next_song                      >,
 152                 a_row < Song3   , PreviousSong, Song2      , &pl::start_prev_song                      >,
 153                 a_row < Song3   , NextSong    , CDFinished , &pl::all_songs_played                     >
 154                 //  +---------+---------------+---------+---------------------+----------------------+
 155             > {};
 156             // Replaces the default no-transition response.
 157             template <class FSM,class Event>
 158             void no_transition(Event const& e, FSM&,int state)
 159             {
 160                 std::cout << "no transition from state " << state
 161                     << " on event " << typeid(e).name() << std::endl;
 162             }
 163         };
 164         typedef msm::back::state_machine<Playing_,msm::back::ShallowHistory<mpl::vector<end_pause> > > Playing;
 165
 166         // the player state machine contains a state which is himself a state machine (2 of them, Playing and Paused)
 167         struct Paused : public msm::front::state<>
 168         {
 169             typedef mpl::vector<CDLoaded>       flag_list;
 170             template <class Event,class FSM>
 171             void on_entry(Event const&,FSM& ) {std::cout << "entering: Paused" << std::endl;}
 172             template <class Event,class FSM>
 173             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Paused" << std::endl;}
 174         };
 175
 176         struct AllOk : public msm::front::state<>
 177         {
 178             template <class Event,class FSM>
 179             void on_entry(Event const&,FSM& ) {std::cout << "starting: AllOk" << std::endl;}
 180             template <class Event,class FSM>
 181             void on_exit(Event const&,FSM& ) {std::cout << "finishing: AllOk" << std::endl;}
 182         };
 183         struct ErrorMode : //public msm::front::terminate_state<>
 184             public msm::front::interrupt_state<end_error>
 185         {
 186             template <class Event,class FSM>
 187             void on_entry(Event const&,FSM& ) {std::cout << "starting: ErrorMode" << std::endl;}
 188             template <class Event,class FSM>
 189             void on_exit(Event const&,FSM& ) {std::cout << "finishing: ErrorMode" << std::endl;}
 190         };
 191
 192         // the initial state of the player SM. Must be defined
 193         typedef mpl::vector<Empty,AllOk> initial_state;
 194
 195         // transition actions
 196         void start_playback(play const&)       { std::cout << "player::start_playback\n"; }
 197         void open_drawer(open_close const&)    { std::cout << "player::open_drawer\n"; }
 198         void close_drawer(open_close const&)   { std::cout << "player::close_drawer\n"; }
 199         void store_cd_info(cd_detected const&)
 200         {
 201             std::cout << "player::store_cd_info\n";
 202             // generate another event to test the queue
 203             //cd.m_player.process_event(play());
 204         }
 205         void stop_playback(stop const&)        { std::cout << "player::stop_playback\n"; }
 206         void end_playback (AllSongsPlayed const&)   { std::cout << "player::end_playback\n"; }
 207         void pause_playback(pause const&)      { std::cout << "player::pause_playback\n"; }
 208         void resume_playback(end_pause const&)      { std::cout << "player::resume_playback\n"; }
 209         void stop_and_open(open_close const&)  { std::cout << "player::stop_and_open\n"; }
 210         void stopped_again(stop const&){std::cout << "player::stopped_again\n";}
 211         void report_error(error_found const&) {std::cout << "player::report_error\n";}
 212         void report_end_error(end_error const&) {std::cout << "player::report_end_error\n";}
 213         // guard conditions
 214         bool good_disk_format(cd_detected const& evt)
 215         {
 216             // to test a guard condition, let's say we understand only CDs, not DVD
 217             if (evt.disc_type != DISK_CD)
 218             {
 219                 std::cout << "wrong disk, sorry" << std::endl;
 220                 return false;
 221             }
 222             return true;
 223         }
 224
 225         typedef player_ p; // makes transition table cleaner
 226
 227         // Transition table for player
 228         struct transition_table : mpl::vector<
 229           //    Start         Event           Next      Action              Guard
 230           //  +-------------+---------------+---------+---------------------+----------------------+
 231          a_row < Stopped    , play          , Playing , &p::start_playback                        >,
 232          a_row < Stopped    , open_close    , Open    , &p::open_drawer                           >,
 233          a_row < Stopped    , stop          , Stopped , &p::stopped_again                         >,
 234           //  +-------------+---------------+---------+---------------------+----------------------+
 235          a_row < Open       , open_close    , Empty   , &p::close_drawer                          >,
 236           //  +-------------+---------------+---------+---------------------+----------------------+
 237          a_row < Empty      , open_close    , Open    , &p::open_drawer                           >,
 238            row < Empty      , cd_detected   , Stopped , &p::store_cd_info   ,&p::good_disk_format >,
 239           //  +-------------+---------------+---------+---------------------+----------------------+
 240          a_row < Playing    , stop          , Stopped , &p::stop_playback                         >,
 241          a_row < Playing    , pause         , Paused  , &p::pause_playback                        >,
 242          a_row < Playing    , open_close    , Open    , &p::stop_and_open                         >,
 243          a_row < Playing::exit_pt<
 244                  Playing_::CDFinished> , AllSongsPlayed, Stopped , &p::end_playback                          >,
 245           //  +-------------+---------------+---------+---------------------+----------------------+
 246          a_row < Paused     , end_pause     , Playing , &p::resume_playback                       >,
 247          a_row < Paused     , stop          , Stopped , &p::stop_playback                         >,
 248          a_row < Paused     , open_close    , Open    , &p::stop_and_open                         >,
 249           //  +-------------+---------------+---------+---------------------+----------------------+
 250          a_row < AllOk      , error_found   ,ErrorMode, &p::report_error                          >,
 251          a_row < ErrorMode  ,end_error      ,AllOk    , &p::report_end_error                      >
 252           //  +-------------+---------------+---------+---------------------+----------------------+
 253         > {};
 254
 255
 256         // Replaces the default no-transition response.
 257         template <class FSM,class Event>
 258         void no_transition(Event const& e, FSM&,int state)
 259         {
 260             std::cout << "no transition from state " << state
 261                 << " on event " << typeid(e).name() << std::endl;
 262         }
 263     };
 264     typedef msm::back::state_machine<player_> player;
 265
 266     //
 267     // Testing utilities.
 268     //
 269
 270     void pstate(player const& p)
 271     {
 272         typedef player::stt Stt;
 273         typedef msm::back::generate_state_set<Stt>::type all_states;
 274         static char const* state_names[mpl::size<all_states>::value];
 275         // fill the names of the states defined in the state machine
 276         mpl::for_each<all_states,boost::msm::wrap<mpl::placeholders::_1> >
 277             (msm::back::fill_state_names<Stt>(state_names));
 278
 279         for (unsigned int i=0;i<player::nr_regions::value;++i)
 280         {
 281             std::cout << " -> " << state_names[p.current_state()[i]] << std::endl;
 282         }
 283     }
 284
 285     void test()
 286     {
 287         player p;
 288         // needed to start the highest-level SM. This will call on_entry and mark the start of the SM
 289         p.start();
 290         std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet)
 291
 292         // test deferred event
 293         // deferred in Empty and Open, will be handled only after event cd_detected
 294         std::cout << "play is not handled in the current state but is marked as delayed" << std::endl;
 295         p.process_event(play()); pstate(p);
 296         std::cout << "cd_detected will cause play to be handled also" << std::endl;
 297         // will be rejected, wrong disk type
 298         p.process_event(cd_detected(DISK_DVD)); pstate(p);
 299         // will be accepted, wrong disk type
 300         p.process_event(cd_detected(DISK_CD)); pstate(p);
 301
 302         std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl; //=> true
 303         p.process_event(NextSong());pstate(p);
 304         // We are now in second song, Flag inactive
 305         std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false
 306         p.process_event(NextSong());pstate(p);
 307         // 2nd song active
 308         p.process_event(PreviousSong());pstate(p);
 309         // Pause
 310         p.process_event(pause()); pstate(p);
 311         // go back to Playing
 312         // but end_pause is an event activating the History
 313         // => keep the last active State (SecondSong)
 314         p.process_event(end_pause());  pstate(p);
 315         // force an exit by listening all the songs
 316         p.process_event(NextSong());
 317         p.process_event(NextSong());pstate(p);
 318
 319         std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true
 320         std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false
 321
 322         // go back to Playing
 323         // but play is not leading to Shallow History => do not remember the last active State (SecondSong)
 324         // and activate again FirstSong and LightOn
 325         p.process_event(play());  pstate(p);
 326         p.process_event(error_found());  pstate(p);
 327
 328         // try generating more events
 329         std::cout << "Trying to generate another event" << std::endl; // will not work, fsm is terminated or interrupted
 330         p.process_event(NextSong());pstate(p);
 331
 332         std::cout << "Trying to end the error" << std::endl; // will work only if ErrorMode is interrupt state
 333         p.process_event(end_error());pstate(p);
 334         std::cout << "Trying to generate another event" << std::endl; // will work only if ErrorMode is interrupt state
 335         p.process_event(NextSong());pstate(p);
 336
 337         // the states and events of the higher level FSM (player)
 338         typedef player::stt Stt;
 339         typedef msm::back::generate_state_set<Stt>::type simple_states;
 340
 341         std::cout << "the state list:" << std::endl;
 342         mpl::for_each<simple_states,boost::msm::wrap<mpl::placeholders::_1> >(msm::back::display_type ());
 343
 344         std::cout << "the event list:" << std::endl;
 345         typedef msm::back::generate_event_set<Stt>::type event_list;
 346         mpl::for_each<event_list,boost::msm::wrap<mpl::placeholders::_1> >(msm::back::display_type ());
 347         std::cout << std::endl;
 348
 349         // the states and events recursively searched
 350         typedef msm::back::recursive_get_transition_table<player>::type recursive_stt;
 351
 352         std::cout << "the state list (including sub-SMs):" << std::endl;
 353
 354         typedef msm::back::generate_state_set<recursive_stt>::type all_states;
 355         mpl::for_each<all_states,boost::msm::wrap<mpl::placeholders::_1> >(msm::back::display_type ());
 356
 357         std::cout << "the event list (including sub-SMs):" << std::endl;
 358         typedef msm::back::generate_event_set<recursive_stt>::type all_events;
 359         mpl::for_each<all_events,boost::msm::wrap<mpl::placeholders::_1> >(msm::back::display_type ());
 360
 361     }
 362 }
 363
 364 int main()
 365 {
 366     test();
 367     return 0;
 368 }
 369
 370