libs/msm/doc/HTML/examples/Constructor.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 <iostream>
// back-end
#include <boost/msm/back/state_machine.hpp>
//front-end
#include <boost/msm/front/state_machine_def.hpp>
namespace msm = boost::msm;
namespace mpl = boost::mpl;
struct SomeExternalContext
{
SomeExternalContext(int b):bla(b){}
int bla;
};
namespace
{
// events
struct play {};
struct end_pause {};
struct stop {};
struct pause {};
struct open_close {};
struct NextSong {};
struct PreviousSong {};
// 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_>
{
player_(SomeExternalContext& context,int someint)
:context_(context)
{
std::cout << "context value:" << context_.bla << " with value:" << someint << std::endl;
context.bla = 10;
}
SomeExternalContext& context_;
// The list of FSM states
struct Empty : public msm::front::state<>
{
int data_;
Empty():data_(0){}
Empty(int i):data_(i){}
// 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<>
{
int data_;
Open():data_(0){}
Open(int i):data_(i){}
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_machine_def<Playing_>
{
// when playing, the CD is loaded and we are in either pause or playing (duh)
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;}
// The list of FSM states
struct Song1 : public msm::front::state<>
{
int data_;
Song1():data_(0){}
Song1(int i):data_(i){}
template <class Event,class FSM>
void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;}
};
struct Song2 : public msm::front::state<>
{
template <class Event,class FSM>
void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;}
};
struct Song3 : public msm::front::state<>
{
template <class Event,class FSM>
void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;}
template <class Event,class FSM>
void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;}
};
// the initial state. Must be defined
typedef Song1 initial_state;
// transition actions
void start_next_song(NextSong const&) { std::cout << "Playing::start_next_song\n"; }
void start_prev_song(PreviousSong const&) { std::cout << "Playing::start_prev_song\n"; }
// guard conditions
typedef Playing_ pl; // makes transition table cleaner
// Transition table for Playing
struct transition_table : mpl::vector4<
// Start Event Next Action Guard
// +---------+-------------+---------+---------------------+----------------------+
a_row < Song1 , NextSong , Song2 , &pl::start_next_song >,
a_row < Song2 , PreviousSong, Song1 , &pl::start_prev_song >,
a_row < Song2 , NextSong , Song3 , &pl::start_next_song >,
a_row < Song3 , PreviousSong, Song2 , &pl::start_prev_song >
// +---------+-------------+---------+---------------------+----------------------+
> {};
// 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;
}
};
// back-end
typedef msm::back::state_machine<Playing_> Playing;
// 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::back::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()
{
SomeExternalContext ctx(3);
// example 1
// create a player with an argument by reference and an int
// (go to the constructor front-end)
player p1(boost::ref(ctx),5);
// example 2
// create a player with a copy of an Empty state, an argument by reference and an int
// (last 2 go to the constructor front-end)
player p2(msm::back::states_ << player_::Empty(1),boost::ref(ctx),5);
std::cout << "Empty's data should be 1. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
std::cout << "Set a new Empty state" << std::endl;
p2.set_states(msm::back::states_ << player_::Empty(5));
std::cout << "Empty's data should be 5. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
std::cout << "Set new Empty and Open states" << std::endl;
p2.set_states(msm::back::states_ << player_::Empty(7) << player_::Open(2));
std::cout << "Empty's data should be 7. Is: " << p2.get_state<player_::Empty&>().data_ << std::endl;
std::cout << "Open's data should be 2. Is: " << p2.get_state<player_::Open&>().data_ << std::endl;
// example 3
// create a player with a copy of an Empty state, a copy of a Playing submachine
// (which is itself created by a copy of Song1)
// an argument by reference and an int
// (last 2 go to the constructor front-end)
player p(msm::back::states_ << player_::Empty(1)
<< player_::Playing(msm::back::states_ << player_::Playing_::Song1(8)),
boost::ref(ctx),5);
std::cout << "Song1's data should be 8. Is: "
<< p.get_state<player_::Playing&>().get_state<player_::Playing_::Song1&>().data_ << std::endl;
}
}
int main()
{
test();
return 0;
}