ceph/src/boost/libs/msm/doc/HTML/examples/Orthogonal-deferred2.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 <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 namespace mpl = boost::mpl;
  20 using namespace boost::msm::front;
  21
  22 namespace
  23 {
  24     // events
  25     struct play {};
  26     struct end_pause {};
  27     struct stop {};
  28     struct pause {};
  29     struct open_close {};
  30     struct NextSong {};
  31     struct PreviousSong {};
  32     struct error_found {};
  33     struct end_error {};
  34
  35     // Flags. Allow information about a property of the current state
  36     struct PlayingPaused{};
  37     struct CDLoaded {};
  38     struct FirstSongPlaying {};
  39
  40     // A "complicated" event type that carries some data.
  41     struct cd_detected
  42     {
  43         cd_detected(std::string name)
  44             : name(name)
  45         {}
  46
  47         std::string name;
  48     };
  49
  50     // front-end: define the FSM structure
  51     struct player_ : public msm::front::state_machine_def<player_>
  52     {
  53         // we want deferred events and no state requires deferred events (only the fsm in the
  54         // transition table), so the fsm does.
  55         typedef int activate_deferred_events;
  56         // The list of FSM states
  57         struct Empty : public msm::front::state<>
  58         {
  59             // every (optional) entry/exit methods get the event passed.
  60             template <class Event,class FSM>
  61             void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
  62             template <class Event,class FSM>
  63             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
  64         };
  65         struct Open : public msm::front::state<>
  66         {
  67             typedef mpl::vector1<CDLoaded>      flag_list;
  68             template <class Event,class FSM>
  69             void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;}
  70             template <class Event,class FSM>
  71             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
  72         };
  73
  74         struct Stopped : public msm::front::state<>
  75         {
  76             // when stopped, the CD is loaded
  77             typedef mpl::vector1<CDLoaded>      flag_list;
  78             template <class Event,class FSM>
  79             void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;}
  80             template <class Event,class FSM>
  81             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
  82         };
  83
  84         // the player state machine contains a state which is himself a state machine
  85         // as you see, no need to declare it anywhere so Playing can be developed separately
  86         // by another team in another module. For simplicity I just declare it inside player
  87         struct Playing_ : public msm::front::state_machine_def<Playing_>
  88         {
  89             // when playing, the CD is loaded and we are in either pause or playing (duh)
  90             typedef mpl::vector2<PlayingPaused,CDLoaded>        flag_list;
  91
  92             template <class Event,class FSM>
  93             void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
  94             template <class Event,class FSM>
  95             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
  96             // The list of FSM states
  97             struct Song1 : public msm::front::state<>
  98             {
  99                 typedef mpl::vector1<FirstSongPlaying>      flag_list;
 100                 template <class Event,class FSM>
 101                 void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
 102                 template <class Event,class FSM>
 103                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
 104             };
 105             struct Song2 : public msm::front::state<>
 106             {
 107                 template <class Event,class FSM>
 108                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
 109                 template <class Event,class FSM>
 110                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
 111             };
 112             struct Song3 : public msm::front::state<>
 113             {
 114                 template <class Event,class FSM>
 115                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
 116                 template <class Event,class FSM>
 117                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
 118             };
 119             // the initial state. Must be defined
 120             typedef Song1 initial_state;
 121             // transition actions
 122             void start_next_song(NextSong const&)       { std::cout << "Playing::start_next_song\n"; }
 123             void start_prev_song(PreviousSong const&)       { std::cout << "Playing::start_prev_song\n"; }
 124             // guard conditions
 125
 126             typedef Playing_ pl; // makes transition table cleaner
 127             // Transition table for Playing
 128             struct transition_table : mpl::vector4<
 129                 //      Start     Event         Next      Action               Guard
 130                 //    +---------+-------------+---------+---------------------+----------------------+
 131                 a_row < Song1   , NextSong    , Song2   , &pl::start_next_song                       >,
 132                 a_row < Song2   , PreviousSong, Song1   , &pl::start_prev_song                       >,
 133                 a_row < Song2   , NextSong    , Song3   , &pl::start_next_song                       >,
 134                 a_row < Song3   , PreviousSong, Song2   , &pl::start_prev_song                       >
 135                 //    +---------+-------------+---------+---------------------+----------------------+
 136             > {};
 137             // Replaces the default no-transition response.
 138             template <class FSM,class Event>
 139             void no_transition(Event const& e, FSM&,int state)
 140             {
 141                 std::cout << "no transition from state " << state
 142                     << " on event " << typeid(e).name() << std::endl;
 143             }
 144         };
 145         // back-end
 146         typedef msm::back::state_machine<Playing_> Playing;
 147
 148         // state not defining any entry or exit
 149         struct Paused : public msm::front::state<>
 150         {
 151             typedef mpl::vector2<PlayingPaused,CDLoaded>        flag_list;
 152         };
 153         struct AllOk : public msm::front::state<>
 154         {
 155             template <class Event,class FSM>
 156             void on_entry(Event const&,FSM& ) {std::cout << "starting: AllOk" << std::endl;}
 157             template <class Event,class FSM>
 158             void on_exit(Event const&,FSM& ) {std::cout << "finishing: AllOk" << std::endl;}
 159         };
 160         // this state is also made terminal so that all the events are blocked
 161         struct ErrorMode :  //public msm::front::terminate_state<> // ErrorMode terminates the state machine
 162             public msm::front::interrupt_state<end_error>   // ErroMode just interrupts. Will resume if
 163                                                             // the event end_error is generated
 164         {
 165             template <class Event,class FSM>
 166             void on_entry(Event const&,FSM& ) {std::cout << "starting: ErrorMode" << std::endl;}
 167             template <class Event,class FSM>
 168             void on_exit(Event const&,FSM& ) {std::cout << "finishing: ErrorMode" << std::endl;}
 169         };
 170         // the initial state of the player SM. Must be defined
 171         typedef mpl::vector<Empty,AllOk> initial_state;
 172
 173         // transition actions
 174         void start_playback(play const&)       { std::cout << "player::start_playback\n"; }
 175         void open_drawer(open_close const&)    { std::cout << "player::open_drawer\n"; }
 176         void close_drawer(open_close const&)   { std::cout << "player::close_drawer\n"; }
 177         void store_cd_info(cd_detected const& cd) {std::cout << "player::store_cd_info\n";}
 178         void stop_playback(stop const&)        { std::cout << "player::stop_playback\n"; }
 179         void pause_playback(pause const&)      { std::cout << "player::pause_playback\n"; }
 180         void resume_playback(end_pause const&)      { std::cout << "player::resume_playback\n"; }
 181         void stop_and_open(open_close const&)  { std::cout << "player::stop_and_open\n"; }
 182         void stopped_again(stop const&){std::cout << "player::stopped_again\n";}
 183         void report_error(error_found const&) {std::cout << "player::report_error\n";}
 184         void report_end_error(end_error const&) {std::cout << "player::report_end_error\n";}
 185
 186         // guard conditions
 187
 188         typedef player_ p; // makes transition table cleaner
 189
 190         // Transition table for player
 191         struct transition_table : mpl::vector<
 192             //      Start     Event         Next      Action               Guard
 193             //    +---------+-------------+---------+---------------------+----------------------+
 194             a_row < Stopped , play        , Playing , &p::start_playback                         >,
 195             a_row < Stopped , open_close  , Open    , &p::open_drawer                            >,
 196             a_row < Stopped , stop        , Stopped , &p::stopped_again                          >,
 197             //    +---------+-------------+---------+---------------------+----------------------+
 198             a_row < Open    , open_close  , Empty   , &p::close_drawer                           >,
 199             Row   < Open    , play        , none    , Defer               , none                 >,
 200             //    +---------+-------------+---------+---------------------+----------------------+
 201             a_row < Empty   , open_close  , Open    , &p::open_drawer                            >,
 202             a_row < Empty   , cd_detected , Stopped , &p::store_cd_info                          >,
 203             Row   < Empty   , play        , none    , Defer               , none                 >,
 204             //    +---------+-------------+---------+---------------------+----------------------+
 205             a_row < Playing , stop        , Stopped , &p::stop_playback                          >,
 206             a_row < Playing , pause       , Paused  , &p::pause_playback                         >,
 207             a_row < Playing , open_close  , Open    , &p::stop_and_open                          >,
 208             //    +---------+-------------+---------+---------------------+----------------------+
 209             a_row < Paused  , end_pause   , Playing , &p::resume_playback                        >,
 210             a_row < Paused  , stop        , Stopped , &p::stop_playback                          >,
 211             a_row < Paused  , open_close  , Open    , &p::stop_and_open                          >,
 212             //    +---------+-------------+---------+---------------------+----------------------+
 213             a_row < AllOk   , error_found ,ErrorMode, &p::report_error                           >,
 214             a_row <ErrorMode,end_error    ,AllOk    , &p::report_end_error                       >
 215             //    +---------+-------------+---------+---------------------+----------------------+
 216         > {};
 217
 218         // Replaces the default no-transition response.
 219         template <class FSM,class Event>
 220         void no_transition(Event const& e, FSM&,int state)
 221         {
 222             std::cout << "no transition from state " << state
 223                 << " on event " << typeid(e).name() << std::endl;
 224         }
 225     };
 226     // Pick a back-end
 227     typedef msm::back::state_machine<player_> player;
 228
 229     //
 230     // Testing utilities.
 231     //
 232     static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused","AllOk","ErrorMode" };
 233
 234     void pstate(player const& p)
 235     {
 236         // we have now several active states, which we show
 237         for (unsigned int i=0;i<player::nr_regions::value;++i)
 238         {
 239             std::cout << " -> " << state_names[p.current_state()[i]] << std::endl;
 240         }
 241     }
 242
 243     void test()
 244     {
 245         player p;
 246         // needed to start the highest-level SM. This will call on_entry and mark the start of the SM
 247         p.start();
 248         // test deferred event
 249         // deferred in Empty and Open, will be handled only after event cd_detected
 250         p.process_event(play());
 251
 252         // tests some flags
 253         std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet)
 254         // go to Open, call on_exit on Empty, then action, then on_entry on Open
 255         p.process_event(open_close()); pstate(p);
 256         p.process_event(open_close()); pstate(p);
 257         p.process_event(cd_detected("louie, louie"));
 258
 259         // at this point, Play is active (was deferred)
 260         std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
 261         std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true
 262
 263         // make transition happen inside it. Player has no idea about this event but it's ok.
 264         p.process_event(NextSong());pstate(p); //2nd song active
 265         p.process_event(NextSong());pstate(p);//3rd song active
 266         p.process_event(PreviousSong());pstate(p);//2nd song active
 267         std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false
 268
 269         std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
 270         p.process_event(pause()); pstate(p);
 271         std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true
 272         // go back to Playing
 273         // as you see, it starts back from the original state
 274         p.process_event(end_pause());  pstate(p);
 275         p.process_event(pause()); pstate(p);
 276         p.process_event(stop());  pstate(p);
 277         std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false
 278         std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true
 279         // by default, the flags are OR'ed but you can also use AND. Then the flag must be present in
 280         // all of the active states
 281         std::cout << "CDLoaded active with AND:" << std::boolalpha << p.is_flag_active<CDLoaded,player::Flag_AND>() << std::endl;//=> false
 282
 283         // event leading to the same state
 284         p.process_event(stop());  pstate(p);
 285
 286         // event leading to a terminal/interrupt state
 287         p.process_event(error_found());  pstate(p);
 288         // try generating more events
 289         std::cout << "Trying to generate another event" << std::endl; // will not work, fsm is terminated or interrupted
 290         p.process_event(play());pstate(p);
 291         std::cout << "Trying to end the error" << std::endl; // will work only if ErrorMode is interrupt state
 292         p.process_event(end_error());pstate(p);
 293         std::cout << "Trying to generate another event" << std::endl; // will work only if ErrorMode is interrupt state
 294         p.process_event(play());pstate(p);
 295
 296     }
 297 }
 298
 299 int main()
 300 {
 301     test();
 302     return 0;
 303 }