249 lines
9.9 KiB
C++
249 lines
9.9 KiB
C++
#include <iostream>
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// back-end
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#include <boost/msm/back/state_machine.hpp>
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//front-end
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#include <boost/msm/front/state_machine_def.hpp>
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// include headers that implement a archive in simple text format
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#include <boost/archive/text_oarchive.hpp>
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#include <boost/archive/text_iarchive.hpp>
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#include <boost/serialization/tracking.hpp>
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#include <fstream>
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namespace msm = boost::msm;
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namespace mpl = boost::mpl;
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namespace
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{
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// events
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struct play {};
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struct end_pause {};
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struct stop {};
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struct pause {};
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struct open_close {};
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// A "complicated" event type that carries some data.
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enum DiskTypeEnum
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{
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DISK_CD=0,
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DISK_DVD=1
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};
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struct cd_detected
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{
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cd_detected(std::string name, DiskTypeEnum diskType)
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: name(name),
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disc_type(diskType)
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{}
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std::string name;
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DiskTypeEnum disc_type;
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};
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// front-end: define the FSM structure
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struct player_ : public msm::front::state_machine_def<player_>
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{
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//we might want to serialize some data contained by the front-end
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int front_end_data;
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player_():front_end_data(0){}
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// to achieve this, ask for it
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typedef int do_serialize;
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// and provide a serialize
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template<class Archive>
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void serialize(Archive & ar, const unsigned int )
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{
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ar & front_end_data;
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}
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// The list of FSM states
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struct Empty : public msm::front::state<>
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{
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// we want Empty to be serialized
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typedef int do_serialize;
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template<class Archive>
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void serialize(Archive & ar, const unsigned int )
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{
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ar & some_dummy_data;
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}
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Empty():some_dummy_data(0){}
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// every (optional) entry/exit methods get the event passed.
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
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int some_dummy_data;
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};
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struct Open : public msm::front::state<>
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{
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template <class Event,class FSM>
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void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
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};
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// sm_ptr still supported but deprecated as functors are a much better way to do the same thing
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struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr>
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{
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template <class Event,class FSM>
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void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
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void set_sm_ptr(player_* pl)
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{
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m_player=pl;
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}
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player_* m_player;
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};
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struct Playing : public msm::front::state<>
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{
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template <class Event,class FSM>
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void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
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template <class Event,class FSM>
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void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
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};
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// state not defining any entry or exit
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struct Paused : public msm::front::state<>
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{
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};
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// the initial state of the player SM. Must be defined
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typedef Empty initial_state;
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// transition actions
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void start_playback(play const&) { std::cout << "player::start_playback\n"; }
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void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; }
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void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; }
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void store_cd_info(cd_detected const&) { std::cout << "player::store_cd_info\n"; }
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void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; }
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void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; }
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void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; }
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void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; }
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void stopped_again(stop const&) {std::cout << "player::stopped_again\n";}
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// guard conditions
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bool good_disk_format(cd_detected const& evt)
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{
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// to test a guard condition, let's say we understand only CDs, not DVD
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if (evt.disc_type != DISK_CD)
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{
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std::cout << "wrong disk, sorry" << std::endl;
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return false;
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}
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return true;
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}
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// used to show a transition conflict. This guard will simply deactivate one transition and thus
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// solve the conflict
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bool auto_start(cd_detected const&)
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{
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return false;
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}
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typedef player_ p; // makes transition table cleaner
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// Transition table for player
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struct transition_table : mpl::vector<
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// Start Event Next Action Guard
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Stopped , play , Playing , &p::start_playback >,
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a_row < Stopped , open_close , Open , &p::open_drawer >,
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_row < Stopped , stop , Stopped >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Open , open_close , Empty , &p::close_drawer >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Empty , open_close , Open , &p::open_drawer >,
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row < Empty , cd_detected , Stopped , &p::store_cd_info ,&p::good_disk_format >,
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row < Empty , cd_detected , Playing , &p::store_cd_info ,&p::auto_start >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Playing , stop , Stopped , &p::stop_playback >,
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a_row < Playing , pause , Paused , &p::pause_playback >,
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a_row < Playing , open_close , Open , &p::stop_and_open >,
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// +---------+-------------+---------+---------------------+----------------------+
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a_row < Paused , end_pause , Playing , &p::resume_playback >,
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a_row < Paused , stop , Stopped , &p::stop_playback >,
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a_row < Paused , open_close , Open , &p::stop_and_open >
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// +---------+-------------+---------+---------------------+----------------------+
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> {};
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// Replaces the default no-transition response.
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template <class FSM,class Event>
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void no_transition(Event const& e, FSM&,int state)
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{
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std::cout << "no transition from state " << state
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<< " on event " << typeid(e).name() << std::endl;
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}
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};
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// Pick a back-end
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typedef msm::back::state_machine<player_> player;
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//
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// Testing utilities.
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//
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static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
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void pstate(player const& p)
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{
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std::cout << " -> " << state_names[p.current_state()[0]] << std::endl;
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}
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void test()
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{
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player p;
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// needed to start the highest-level SM. This will call on_entry and mark the start of the SM
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p.start();
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p.get_state<player_::Empty&>().some_dummy_data=3;
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p.front_end_data=4;
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// go to Open, call on_exit on Empty, then action, then on_entry on Open
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p.process_event(open_close()); pstate(p);
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std::ofstream ofs("fsm.txt");
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// save fsm to archive (current state is Open)
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{
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boost::archive::text_oarchive oa(ofs);
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// write class instance to archive
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oa << p;
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}
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// reload fsm in state Open
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player p2;
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{
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// create and open an archive for input
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std::ifstream ifs("fsm.txt");
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boost::archive::text_iarchive ia(ifs);
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// read class state from archive
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ia >> p2;
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}
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// we now use p2 as it was loaded
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// check that we kept Empty's data value
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std::cout << "Empty's data should be 3:" << p2.get_state<player_::Empty&>().some_dummy_data << std::endl;
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std::cout << "front-end data should be 4:" << p2.front_end_data << std::endl;
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p2.process_event(open_close()); pstate(p2);
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// will be rejected, wrong disk type
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p2.process_event(
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cd_detected("louie, louie",DISK_DVD)); pstate(p2);
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p2.process_event(
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cd_detected("louie, louie",DISK_CD)); pstate(p2);
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p2.process_event(play());
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// at this point, Play is active
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p2.process_event(pause()); pstate(p2);
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// go back to Playing
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p2.process_event(end_pause()); pstate(p2);
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p2.process_event(pause()); pstate(p2);
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p2.process_event(stop()); pstate(p2);
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// event leading to the same state
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// no action method called as it is not present in the transition table
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p2.process_event(stop()); pstate(p2);
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}
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}
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// eliminate object tracking (even if serialized through a pointer)
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// at the risk of a programming error creating duplicate objects.
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// this is to get rid of warning because p is not const
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BOOST_CLASS_TRACKING(player, boost::serialization::track_never)
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int main()
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{
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test();
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return 0;
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}
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