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;
}