ceph/src/boost/libs/msm/doc/PDF/examples/Constructor.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 struct SomeExternalContext
  21 {
  22     SomeExternalContext(int b):bla(b){}
  23     int bla;
  24 };
  25
  26 namespace
  27 {
  28     // events
  29     struct play {};
  30     struct end_pause {};
  31     struct stop {};
  32     struct pause {};
  33     struct open_close {};
  34     struct NextSong {};
  35     struct PreviousSong {};
  36
  37     // A "complicated" event type that carries some data.
  38         enum DiskTypeEnum
  39     {
  40         DISK_CD=0,
  41         DISK_DVD=1
  42     };
  43     struct cd_detected
  44     {
  45         cd_detected(std::string name, DiskTypeEnum diskType)
  46             : name(name),
  47             disc_type(diskType)
  48         {}
  49
  50         std::string name;
  51         DiskTypeEnum disc_type;
  52     };
  53
  54     // front-end: define the FSM structure
  55     struct player_ : public msm::front::state_machine_def<player_>
  56     {
  57         player_(SomeExternalContext& context,int someint)
  58             :context_(context)
  59         {
  60             std::cout << "context value:" << context_.bla << " with value:" << someint << std::endl;
  61             context.bla = 10;
  62         }
  63
  64         SomeExternalContext& context_;
  65
  66         // The list of FSM states
  67         struct Empty : public msm::front::state<>
  68         {
  69             int data_;
  70             Empty():data_(0){}
  71             Empty(int i):data_(i){}
  72             // every (optional) entry/exit methods get the event passed.
  73             template <class Event,class FSM>
  74             void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
  75             template <class Event,class FSM>
  76             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
  77         };
  78         struct Open : public msm::front::state<>
  79         {
  80             int data_;
  81             Open():data_(0){}
  82             Open(int i):data_(i){}
  83
  84             template <class Event,class FSM>
  85             void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;}
  86             template <class Event,class FSM>
  87             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
  88         };
  89
  90         // sm_ptr still supported but deprecated as functors are a much better way to do the same thing
  91         struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr>
  92         {
  93             template <class Event,class FSM>
  94             void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;}
  95             template <class Event,class FSM>
  96             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
  97             void set_sm_ptr(player_* pl)
  98             {
  99                 m_player=pl;
 100             }
 101             player_* m_player;
 102         };
 103
 104         struct Playing_ : public msm::front::state_machine_def<Playing_>
 105         {
 106             // when playing, the CD is loaded and we are in either pause or playing (duh)
 107             template <class Event,class FSM>
 108             void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
 109             template <class Event,class FSM>
 110             void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
 111
 112             // The list of FSM states
 113             struct Song1 : public msm::front::state<>
 114             {
 115                 int data_;
 116                 Song1():data_(0){}
 117                 Song1(int i):data_(i){}
 118
 119                 template <class Event,class FSM>
 120                 void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
 121                 template <class Event,class FSM>
 122                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
 123
 124             };
 125             struct Song2 : public msm::front::state<>
 126             {
 127                 template <class Event,class FSM>
 128                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
 129                 template <class Event,class FSM>
 130                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
 131             };
 132             struct Song3 : public msm::front::state<>
 133             {
 134                 template <class Event,class FSM>
 135                 void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
 136                 template <class Event,class FSM>
 137                 void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
 138             };
 139             // the initial state. Must be defined
 140             typedef Song1 initial_state;
 141             // transition actions
 142             void start_next_song(NextSong const&)       { std::cout << "Playing::start_next_song\n"; }
 143             void start_prev_song(PreviousSong const&)       { std::cout << "Playing::start_prev_song\n"; }
 144             // guard conditions
 145
 146             typedef Playing_ pl; // makes transition table cleaner
 147             // Transition table for Playing
 148             struct transition_table : mpl::vector4<
 149                 //      Start     Event         Next      Action               Guard
 150                 //    +---------+-------------+---------+---------------------+----------------------+
 151                 a_row < Song1   , NextSong    , Song2   , &pl::start_next_song                       >,
 152                 a_row < Song2   , PreviousSong, Song1   , &pl::start_prev_song                       >,
 153                 a_row < Song2   , NextSong    , Song3   , &pl::start_next_song                       >,
 154                 a_row < Song3   , PreviousSong, Song2   , &pl::start_prev_song                       >
 155                 //    +---------+-------------+---------+---------------------+----------------------+
 156             > {};
 157             // Replaces the default no-transition response.
 158             template <class FSM,class Event>
 159             void no_transition(Event const& e, FSM&,int state)
 160             {
 161                 std::cout << "no transition from state " << state
 162                     << " on event " << typeid(e).name() << std::endl;
 163             }
 164         };
 165         // back-end
 166         typedef msm::back::state_machine<Playing_> Playing;
 167
 168         // state not defining any entry or exit
 169         struct Paused : public msm::front::state<>
 170         {
 171         };
 172
 173         // the initial state of the player SM. Must be defined
 174         typedef Empty initial_state;
 175
 176         // transition actions
 177         void start_playback(play const&)       { std::cout << "player::start_playback\n"; }
 178         void open_drawer(open_close const&)    { std::cout << "player::open_drawer\n"; }
 179         void close_drawer(open_close const&)   { std::cout << "player::close_drawer\n"; }
 180         void store_cd_info(cd_detected const&) { std::cout << "player::store_cd_info\n"; }
 181         void stop_playback(stop const&)        { std::cout << "player::stop_playback\n"; }
 182         void pause_playback(pause const&)      { std::cout << "player::pause_playback\n"; }
 183         void resume_playback(end_pause const&)      { std::cout << "player::resume_playback\n"; }
 184         void stop_and_open(open_close const&)  { std::cout << "player::stop_and_open\n"; }
 185         void stopped_again(stop const&) {std::cout << "player::stopped_again\n";}
 186         // guard conditions
 187         bool good_disk_format(cd_detected const& evt)
 188         {
 189             // to test a guard condition, let's say we understand only CDs, not DVD
 190             if (evt.disc_type != DISK_CD)
 191             {
 192                 std::cout << "wrong disk, sorry" << std::endl;
 193                 return false;
 194             }
 195             return true;
 196         }
 197         // used to show a transition conflict. This guard will simply deactivate one transition and thus
 198         // solve the conflict
 199         bool auto_start(cd_detected const&)
 200         {
 201             return false;
 202         }
 203
 204         typedef player_ p; // makes transition table cleaner
 205
 206         // Transition table for player
 207         struct transition_table : mpl::vector<
 208             //    Start     Event         Next      Action                               Guard
 209             //  +---------+-------------+---------+---------------------+----------------------+
 210           a_row < Stopped , play        , Playing , &p::start_playback                         >,
 211           a_row < Stopped , open_close  , Open    , &p::open_drawer                            >,
 212            _row < Stopped , stop        , Stopped                                              >,
 213             //  +---------+-------------+---------+---------------------+----------------------+
 214           a_row < Open    , open_close  , Empty   , &p::close_drawer                           >,
 215             //  +---------+-------------+---------+---------------------+----------------------+
 216           a_row < Empty   , open_close  , Open    , &p::open_drawer                            >,
 217             row < Empty   , cd_detected , Stopped , &p::store_cd_info   ,&p::good_disk_format  >,
 218             row < Empty   , cd_detected , Playing , &p::store_cd_info   ,&p::auto_start        >,
 219             //  +---------+-------------+---------+---------------------+----------------------+
 220           a_row < Playing , stop        , Stopped , &p::stop_playback                          >,
 221           a_row < Playing , pause       , Paused  , &p::pause_playback                         >,
 222           a_row < Playing , open_close  , Open    , &p::stop_and_open                          >,
 223             //  +---------+-------------+---------+---------------------+----------------------+
 224           a_row < Paused  , end_pause   , Playing , &p::resume_playback                        >,
 225           a_row < Paused  , stop        , Stopped , &p::stop_playback                          >,
 226           a_row < Paused  , open_close  , Open    , &p::stop_and_open                          >
 227             //  +---------+-------------+---------+---------------------+----------------------+
 228         > {};
 229         // Replaces the default no-transition response.
 230         template <class FSM,class Event>
 231         void no_transition(Event const& e, FSM&,int state)
 232         {
 233             std::cout << "no transition from state " << state
 234                 << " on event " << typeid(e).name() << std::endl;
 235         }
 236     };
 237     // Pick a back-end
 238     typedef msm::back::state_machine<player_> player;
 239
 240     //
 241     // Testing utilities.
 242     //
 243     static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
 244     void pstate(player const& p)
 245     {
 246         std::cout << " -> " << state_names[p.current_state()[0]] << std::endl;
 247     }
 248
 249     void test()
 250     {
 251         SomeExternalContext ctx(3);
 252         // example 1
 253         // create a player with an argument by reference and an int
 254         // (go to the constructor front-end)
 255         player p1(boost::ref(ctx),5);
 256
 257         // example 2
 258         // create a player with a copy of an Empty state, an argument by reference and an int
 259         // (last 2 go to the constructor front-end)
 260         player p2(msm::back::states_ << player_::Empty(1),boost::ref(ctx),5);
 261         std::cout << "Empty's data should be 1. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
 262
 263         std::cout << "Set a new Empty state" << std::endl;
 264         p2.set_states(msm::back::states_ << player_::Empty(5));
 265         std::cout << "Empty's data should be 5. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
 266
 267         std::cout << "Set new Empty and Open states" << std::endl;
 268         p2.set_states(msm::back::states_ << player_::Empty(7) << player_::Open(2));
 269         std::cout << "Empty's data should be 7. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
 270         std::cout << "Open's data should be 2. Is: " << p2.get_state<player_::Open&>().data_ << std::endl;
 271
 272         // example 3
 273         // create a player with a copy of an Empty state, a copy of a Playing submachine
 274         // (which is itself created by a copy of Song1)
 275         // an argument by reference and an int
 276         // (last 2 go to the constructor front-end)
 277         player p(msm::back::states_ << player_::Empty(1)
 278                                     << player_::Playing(msm::back::states_ << player_::Playing_::Song1(8)),
 279                  boost::ref(ctx),5);
 280
 281         std::cout << "Song1's data should be 8. Is: "
 282                   << p.get_state<player_::Playing&>().get_state<player_::Playing_::Song1&>().data_ << std::endl;
 283
 284
 285     }
 286 }
 287
 288 int main()
 289 {
 290     test();
 291     return 0;
 292 }