ceph/src/boost/libs/msm/doc/PDF/examples/SimpleTutorialInternal2.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 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 }