libs/msm/doc/HTML/examples/SimplePhoenix.cpp
// Copyright 2010 Christophe Henry // henry UNDERSCORE christophe AT hotmail DOT com // This is an extended version of the state machine available in the boost::mpl library // Distributed under the same license as the original. // Copyright for the original version: // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed // under the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include <vector> #include <iostream> #include <boost/phoenix/phoenix.hpp> // add phoenix support in eUML #define BOOST_MSM_EUML_PHOENIX_SUPPORT #include <boost/msm/back/state_machine.hpp> #include <boost/msm/front/euml/euml.hpp> using namespace std; using namespace boost::msm::front::euml; namespace msm = boost::msm; using namespace boost::phoenix; // entry/exit/action/guard logging functors #include "logging_functors.h" namespace // Concrete FSM implementation { // events BOOST_MSM_EUML_EVENT(end_pause) BOOST_MSM_EUML_EVENT(stop) BOOST_MSM_EUML_EVENT(pause) BOOST_MSM_EUML_EVENT(open_close) struct play_event : boost::msm::front::euml::euml_event<play_event> { }; play_event play; enum DiskTypeEnum { DISK_CD=0, DISK_DVD=1 }; // A "complicated" event type that carries some data. struct cd_detected_event : boost::msm::front::euml::euml_event<cd_detected_event> { cd_detected_event(){} cd_detected_event(std::string const& name,DiskTypeEnum disk):cd_name(name),cd_type(disk){} std::string cd_name; DiskTypeEnum cd_type; }; // define an instance for a nicer transition table cd_detected_event cd_detected; // Concrete FSM implementation // The list of FSM states // state not needing any entry or exit BOOST_MSM_EUML_STATE((),Paused) // states with standard eUML actions BOOST_MSM_EUML_STATE(( Stopped_Entry,Stopped_Exit ),Stopped) BOOST_MSM_EUML_STATE(( Playing_Entry,Playing_Exit ),Playing) // a "standard" msm state struct Empty_impl : public msm::front::state<> , public euml_state<Empty_impl> { // this allows us to add some functions void foo() {std::cout << "Empty::foo " << std::endl;} // standard entry behavior template <class Event,class FSM> void on_entry(Event const& evt,FSM& fsm) { std::cout << "entering: Empty" << std::endl; } template <class Event,class FSM> void on_exit(Event const& evt,FSM& fsm) { std::cout << "leaving: Empty" << std::endl; } }; //instance for use in the transition table Empty_impl const Empty; // entry and exit actions as phoenix functions struct open_entry_impl { typedef void result_type; void operator()() { cout << "entering: Open" << endl; } }; boost::phoenix::function<open_entry_impl> open_entry; struct open_exit_impl { typedef void result_type; void operator()() { cout << "leaving: Open" << endl; } }; boost::phoenix::function<open_exit_impl> open_exit; // a state using phoenix for entry/exit actions BOOST_MSM_EUML_STATE(( open_entry(),open_exit() ),Open) // actions and guards using boost::phoenix struct start_playback_impl { typedef void result_type; void operator()() { cout << "calling: start_playback" << endl; } }; boost::phoenix::function<start_playback_impl> start_playback; // a guard taking the event as argument struct good_disk_format_impl { typedef bool result_type; template <class Event> bool operator()(Event const& evt) { // to test a guard condition, let's say we understand only CDs, not DVD if (evt.cd_type!=DISK_CD) { std::cout << "wrong disk, sorry" << std::endl; return false; } std::cout << "good disk" << std::endl; return true; } }; boost::phoenix::function<good_disk_format_impl> good_disk_format; // a simple action struct store_cd_info_impl { typedef void result_type; void operator()() { cout << "calling: store_cd_info" << endl; } }; boost::phoenix::function<store_cd_info_impl> store_cd_info; // an action taking the fsm as argument and sending it a new event struct process_play_impl { typedef void result_type; template <class Fsm> void operator()(Fsm& fsm) { cout << "queuing a play event" << endl; fsm.process_event(play); } }; // it is also possible to use BOOST_PHOENIX_ADAPT_CALLABLE to avoid defining a global variable BOOST_PHOENIX_ADAPT_CALLABLE(process_play, process_play_impl, 1) // transition table. Actions and guards are written as phoenix functions BOOST_MSM_EUML_TRANSITION_TABLE(( //an action without arguments Playing == Stopped + play / start_playback() , Playing == Paused + end_pause , // +------------------------------------------------------------------------------+ Empty == Open + open_close , // +------------------------------------------------------------------------------+ Open == Empty + open_close , Open == Paused + open_close , Open == Stopped + open_close , Open == Playing + open_close , // +------------------------------------------------------------------------------+ Paused == Playing + pause , // +------------------------------------------------------------------------------+ Stopped == Playing + stop , Stopped == Paused + stop , // a guard taking the event as argument // and an action made of a phoenix expression of 2 actions // _event is a placeholder for the current event // _fsm is a placeholder for the current state machine Stopped == Empty + cd_detected [good_disk_format(_event)] / (store_cd_info(),process_play(_fsm)), Stopped == Stopped + stop // +------------------------------------------------------------------------------+ ),transition_table) // create a state machine "on the fly" BOOST_MSM_EUML_DECLARE_STATE_MACHINE(( transition_table, //STT init_ << Empty, // Init State no_action, // Entry no_action, // Exit attributes_ << no_attributes_, // Attributes configure_ << no_configure_, // configuration Log_No_Transition // no_transition handler ), player_) //fsm name // or simply, if no no_transition handler needed: //BOOST_MSM_EUML_DECLARE_STATE_MACHINE(( transition_table, //STT // Empty // Init State // ),player_) // choice of back-end typedef msm::back::state_machine<player_> player; // // Testing utilities. // static char const* const state_names[] = { "Stopped", "Paused", "Open", "Empty", "Playing" }; void pstate(player const& p) { std::cout << " -> " << state_names[p.current_state()[0]] << std::endl; } void test() { player p; // needed to start the highest-level SM. This will call on_entry and mark the start of the SM p.start(); // go to Open, call on_exit on Empty, then action, then on_entry on Open p.process_event(open_close); pstate(p); p.process_event(open_close); pstate(p); // will be rejected, wrong disk type p.process_event( cd_detected_event("louie, louie",DISK_DVD)); pstate(p); p.process_event( cd_detected_event("louie, louie",DISK_CD)); pstate(p); // no need to call play as the previous event does it in its action method //p.process_event(play); // at this point, Play is active p.process_event(pause); pstate(p); // go back to Playing p.process_event(end_pause); pstate(p); p.process_event(pause); pstate(p); p.process_event(stop); pstate(p); // event leading to the same state // no action method called as none is defined in the transition table p.process_event(stop); pstate(p); // test call to no_transition p.process_event(pause); pstate(p); } } int main() { test(); return 0; }