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// 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 <iostream>
// back-end
#include <boost/msm/back11/state_machine.hpp>
//front-end
#include <boost/msm/front/state_machine_def.hpp>
namespace msm = boost::msm;
namespace mpl = boost::mpl;
namespace
{
// events
struct play {};
struct end_pause {};
struct stop {};
struct pause {};
struct open_close {};
// A "complicated" event type that carries some data.
enum DiskTypeEnum
{
DISK_CD=0,
DISK_DVD=1
};
struct cd_detected
{
cd_detected(std::string name, DiskTypeEnum diskType)
: name(name),
disc_type(diskType)
{}
std::string name;
DiskTypeEnum disc_type;
};
// front-end: define the FSM structure
struct player_ : public msm::front::state_machine_def<player_>
{
template <class Event,class FSM>
void on_entry(Event const& ,FSM&)
{
std::cout << "entering: Player" << std::endl;
}
template <class Event,class FSM>
void on_exit(Event const&,FSM& )
{
std::cout << "leaving: Player" << std::endl;
}
// The list of FSM states
struct Empty : public msm::front::state<>
{
// every (optional) entry/exit methods get the event passed.
template <class Event,class FSM>
void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;}
};
struct Open : public msm::front::state<>
{
template <class Event,class FSM>
void on_entry(Event const& ,FSM&) {std::cout << "entering: Open" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;}
};
// sm_ptr still supported but deprecated as functors are a much better way to do the same thing
struct Stopped : public msm::front::state<msm::front::default_base_state,msm::front::sm_ptr>
{
template <class Event,class FSM>
void on_entry(Event const& ,FSM&) {std::cout << "entering: Stopped" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;}
void set_sm_ptr(player_* pl)
{
m_player=pl;
}
player_* m_player;
};
struct Playing : public msm::front::state<>
{
template <class Event,class FSM>
void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;}
};
// state not defining any entry or exit
struct Paused : public msm::front::state<>
{
};
// the initial state of the player SM. Must be defined
typedef Empty initial_state;
// transition actions
void start_playback(play const&) { std::cout << "player::start_playback\n"; }
void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; }
void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; }
void store_cd_info(cd_detected const&) { std::cout << "player::store_cd_info\n"; }
void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; }
void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; }
void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; }
void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; }
void stopped_again(stop const&) {std::cout << "player::stopped_again\n";}
// guard conditions
bool good_disk_format(cd_detected const& evt)
{
// to test a guard condition, let's say we understand only CDs, not DVD
if (evt.disc_type != DISK_CD)
{
std::cout << "wrong disk, sorry" << std::endl;
return false;
}
return true;
}
// used to show a transition conflict. This guard will simply deactivate one transition and thus
// solve the conflict
bool auto_start(cd_detected const&)
{
return false;
}
typedef player_ p; // makes transition table cleaner
// Transition table for player
struct transition_table : mpl::vector<
// Start Event Next Action Guard
// +---------+-------------+---------+---------------------+----------------------+
a_row < Stopped , play , Playing , &p::start_playback >,
a_row < Stopped , open_close , Open , &p::open_drawer >,
_row < Stopped , stop , Stopped >,
// +---------+-------------+---------+---------------------+----------------------+
a_row < Open , open_close , Empty , &p::close_drawer >,
// +---------+-------------+---------+---------------------+----------------------+
a_row < Empty , open_close , Open , &p::open_drawer >,
row < Empty , cd_detected , Stopped , &p::store_cd_info ,&p::good_disk_format >,
row < Empty , cd_detected , Playing , &p::store_cd_info ,&p::auto_start >,
// +---------+-------------+---------+---------------------+----------------------+
a_row < Playing , stop , Stopped , &p::stop_playback >,
a_row < Playing , pause , Paused , &p::pause_playback >,
a_row < Playing , open_close , Open , &p::stop_and_open >,
// +---------+-------------+---------+---------------------+----------------------+
a_row < Paused , end_pause , Playing , &p::resume_playback >,
a_row < Paused , stop , Stopped , &p::stop_playback >,
a_row < Paused , open_close , Open , &p::stop_and_open >
// +---------+-------------+---------+---------------------+----------------------+
> {};
// Replaces the default no-transition response.
template <class FSM,class Event>
void no_transition(Event const& e, FSM&,int state)
{
std::cout << "no transition from state " << state
<< " on event " << typeid(e).name() << std::endl;
}
};
// Pick a back-end
typedef msm::back11::state_machine<player_> player;
//
// Testing utilities.
//
static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
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("louie, louie",DISK_DVD)); pstate(p);
p.process_event(
cd_detected("louie, louie",DISK_CD)); pstate(p);
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 it is not present in the transition table
p.process_event(stop()); pstate(p);
std::cout << "stop fsm" << std::endl;
p.stop();
}
}
int main()
{
test();
return 0;
}
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