ceph/src/boost/libs/msm/doc/HTML/examples/SimpleTutorial.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
  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 }