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

   1 #include <vector>
   2 #include <iostream>
   3 // back-end
   4 #include <boost/msm/back/state_machine.hpp>
   5 // header for support of circular_buffer
   6 #include <boost/msm/back/queue_container_circular.hpp>
   7 //front-end
   8 #include <boost/msm/front/state_machine_def.hpp>
   9 // functors
  10 #include <boost/msm/front/functor_row.hpp>
  11 #include <boost/msm/front/euml/common.hpp>
  12 // for And_ operator
  13 #include <boost/msm/front/euml/operator.hpp>
  14
  15 using namespace std;
  16 namespace msm = boost::msm;
  17 namespace mpl = boost::mpl;
  18 using namespace msm::front;
  19 // for And_ operator
  20 using namespace msm::front::euml;
  21
  22 namespace  // Concrete FSM implementation
  23 {
  24     // events
  25     struct play {};
  26     struct end_pause {};
  27     struct stop {};
  28     struct pause {};
  29     struct open_close {};
  30
  31     // A "complicated" event type that carries some data.
  32         enum DiskTypeEnum
  33     {
  34         DISK_CD=0,
  35         DISK_DVD=1
  36     };
  37     struct cd_detected
  38     {
  39         cd_detected(std::string name, DiskTypeEnum diskType)
  40             : name(name),
  41             disc_type(diskType)
  42         {}
  43
  44         std::string name;
  45         DiskTypeEnum disc_type;
  46     };
  47
  48     // front-end: define the FSM structure
  49     struct player_ : public msm::front::state_machine_def<player_>
  50     {
  51         // The list of FSM states
  52         struct Empty : public msm::front::state<>
  53         {
  54             // every (optional) entry/exit methods get the event passed.
  55             template <class Event,class FSM>
  56             void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
  57             template <class Event,class FSM>
  58             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
  59         };
  60         struct Open : public msm::front::state<>
  61         {
  62             template <class Event,class FSM>
  63             void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;}
  64             template <class Event,class FSM>
  65             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
  66         };
  67
  68         struct Stopped : public msm::front::state<>
  69         {
  70             // when stopped, the CD is loaded
  71             template <class Event,class FSM>
  72             void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;}
  73             template <class Event,class FSM>
  74             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
  75         };
  76
  77         struct Playing : public msm::front::state<>
  78         {
  79             template <class Event,class FSM>
  80             void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
  81             template <class Event,class FSM>
  82             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
  83         };
  84
  85         // state not defining any entry or exit
  86         struct Paused : public msm::front::state<>
  87         {
  88         };
  89
  90         // the initial state of the player SM. Must be defined
  91         typedef Empty initial_state;
  92
  93         // transition actions
  94         // as the functors are generic on events, fsm and source/target state,
  95         // you can reuse them in another machine if you wish
  96         struct TestFct
  97         {
  98             template <class EVT,class FSM,class SourceState,class TargetState>
  99             void operator()(EVT const&, FSM&,SourceState& ,TargetState& )
 100             {
 101                 cout << "transition with event:" << typeid(EVT).name() << endl;
 102             }
 103         };
 104         struct start_playback
 105         {
 106             template <class EVT,class FSM,class SourceState,class TargetState>
 107             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 108             {
 109                 cout << "player::start_playback" << endl;
 110             }
 111         };
 112         struct open_drawer
 113         {
 114             template <class EVT,class FSM,class SourceState,class TargetState>
 115             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 116             {
 117                 cout << "player::open_drawer" << endl;
 118             }
 119         };
 120         struct close_drawer
 121         {
 122             template <class EVT,class FSM,class SourceState,class TargetState>
 123             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 124             {
 125                 cout << "player::close_drawer" << endl;
 126             }
 127         };
 128         struct store_cd_info
 129         {
 130             template <class EVT,class FSM,class SourceState,class TargetState>
 131             void operator()(EVT const&,FSM& fsm ,SourceState& ,TargetState& )
 132             {
 133                 cout << "player::store_cd_info" << endl;
 134                 fsm.process_event(play());
 135             }
 136         };
 137         struct stop_playback
 138         {
 139             template <class EVT,class FSM,class SourceState,class TargetState>
 140             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 141             {
 142                 cout << "player::stop_playback" << endl;
 143             }
 144         };
 145         struct pause_playback
 146         {
 147             template <class EVT,class FSM,class SourceState,class TargetState>
 148             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 149             {
 150                 cout << "player::pause_playback" << endl;
 151             }
 152         };
 153         struct resume_playback
 154         {
 155             template <class EVT,class FSM,class SourceState,class TargetState>
 156             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 157             {
 158                 cout << "player::resume_playback" << endl;
 159             }
 160         };
 161         struct stop_and_open
 162         {
 163             template <class EVT,class FSM,class SourceState,class TargetState>
 164             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 165             {
 166                 cout << "player::stop_and_open" << endl;
 167             }
 168         };
 169         struct stopped_again
 170         {
 171             template <class EVT,class FSM,class SourceState,class TargetState>
 172             void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
 173             {
 174                 cout << "player::stopped_again" << endl;
 175             }
 176         };
 177         // guard conditions
 178         struct DummyGuard
 179         {
 180             template <class EVT,class FSM,class SourceState,class TargetState>
 181             bool operator()(EVT const& evt,FSM& fsm,SourceState& src,TargetState& tgt)
 182             {
 183                 return true;
 184             }
 185         };
 186         struct good_disk_format
 187         {
 188             template <class EVT,class FSM,class SourceState,class TargetState>
 189             bool operator()(EVT const& evt ,FSM&,SourceState& ,TargetState& )
 190             {
 191                 // to test a guard condition, let's say we understand only CDs, not DVD
 192                 if (evt.disc_type != DISK_CD)
 193                 {
 194                     std::cout << "wrong disk, sorry" << std::endl;
 195                     return false;
 196                 }
 197                 return true;
 198             }
 199         };
 200         struct always_true
 201         {
 202             template <class EVT,class FSM,class SourceState,class TargetState>
 203             bool operator()(EVT const& evt ,FSM&,SourceState& ,TargetState& )
 204             {
 205                 return true;
 206             }
 207         };
 208         // we want to define one row with the classic look.
 209         bool auto_start(cd_detected const& evt)
 210         {
 211             return false;
 212         }
 213
 214         typedef player_ p; // makes transition table cleaner
 215
 216         // Transition table for player
 217         struct transition_table : mpl::vector<
 218             //    Start     Event         Next      Action                                     Guard
 219             //  +---------+-------------+---------+---------------------------+----------------------+
 220             Row < Stopped , play        , Playing , ActionSequence_
 221                                                      <mpl::vector<
 222                                                      TestFct,start_playback> >
 223                                                                               , DummyGuard           >,
 224             Row < Stopped , open_close  , Open    , open_drawer               , none                 >,
 225             Row < Stopped , stop        , Stopped , none                      , none                 >,
 226             //  +---------+-------------+---------+---------------------------+----------------------+
 227             Row < Open    , open_close  , Empty   , close_drawer              , none                 >,
 228             //  +---------+-------------+---------+---------------------------+----------------------+
 229             Row < Empty   , open_close  , Open    , open_drawer               , none                 >,
 230             Row < Empty   , cd_detected , Stopped , store_cd_info             , And_<good_disk_format,
 231                                                                                      always_true>    >,
 232             // we here also mix with some "classical row"
 233           g_row < Empty   , cd_detected , Playing                             , &p::auto_start       >,
 234             //  +---------+-------------+---------+---------------------------+----------------------+
 235             Row < Playing , stop        , Stopped , stop_playback             , none                 >,
 236             Row < Playing , pause       , Paused  , pause_playback            , none                 >,
 237             Row < Playing , open_close  , Open    , stop_and_open             , none                 >,
 238             //  +---------+-------------+---------+---------------------------+----------------------+
 239             Row < Paused  , end_pause   , Playing , resume_playback           , none                 >,
 240             Row < Paused  , stop        , Stopped , stop_playback             , none                 >,
 241             Row < Paused  , open_close  , Open    , stop_and_open             , none                 >
 242             //  +---------+-------------+---------+---------------------------+----------------------+
 243         > {};
 244         // Replaces the default no-transition response.
 245         template <class FSM,class Event>
 246         void no_transition(Event const& e, FSM&,int state)
 247         {
 248             std::cout << "no transition from state " << state
 249                 << " on event " << typeid(e).name() << std::endl;
 250         }
 251     };
 252     // Pick a back-end
 253     typedef msm::back::state_machine<player_, msm::back::queue_container_circular> player;
 254
 255     //
 256     // Testing utilities.
 257     //
 258     static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
 259     void pstate(player const& p)
 260     {
 261         std::cout << " -> " << state_names[p.current_state()[0]] << std::endl;
 262     }
 263
 264     void test()
 265     {
 266                 player p;
 267         // we get the message queue and limit it to capacity 1
 268         // get_message_queue returns the queue container (in this case circular_buffer)
 269         p.get_message_queue().set_capacity(1);
 270         // needed to start the highest-level SM. This will call on_entry and mark the start of the SM
 271         p.start();
 272         // go to Open, call on_exit on Empty, then action, then on_entry on Open
 273         p.process_event(open_close()); pstate(p);
 274         p.process_event(open_close()); pstate(p);
 275         // will be rejected, wrong disk type
 276         p.process_event(
 277             cd_detected("louie, louie",DISK_DVD)); pstate(p);
 278         p.process_event(
 279             cd_detected("louie, louie",DISK_CD)); pstate(p);
 280         // no need to call play() as the previous event does it in its action method
 281                 //p.process_event(play());
 282
 283         // at this point, Play is active
 284         p.process_event(pause()); pstate(p);
 285         // go back to Playing
 286         p.process_event(end_pause());  pstate(p);
 287         p.process_event(pause()); pstate(p);
 288         p.process_event(stop());  pstate(p);
 289         // event leading to the same state
 290         // no action method called as it is not present in the transition table
 291         p.process_event(stop());  pstate(p);
 292     }
 293 }
 294
 295 int main()
 296 {
 297     test();
 298     return 0;
 299 }