Dear list,

while developing I want to use functors for a guard. The state machine compiles well until I added a

function call to the FSM which has a template parameter. Then I always got the following error message

while compiling it with gcc 4.4.1.

SubtractionControllerNew.cpp: In member function ‘bool<unnamed>::player_::isCDLoaded::operator()(const EVT&, FSM&, SourceState&, TargetState&)’:

SubtractionControllerNew.cpp:175: error: expected primary-expression before ‘>’ token

SubtractionControllerNew.cpp:175: error: expected primary-expression before ‘)’ token

Does anybody know why this happens and how to circumvent it?

Kind regards,

Sven

---- Example from flags.

I have modified the CDLoaded example to present the bug with the following lines:

struct isCDLoaded

{

template <class EVT,class FSM,class SourceState,class TargetState>

bool operator()(EVT const& ,FSM& fsm,SourceState& ,TargetState& )

{

//return fsm.is_contained(); // this works well

return fsm.is_flag_active<CDLoaded>(); // Line 175

}

};

Row < Stopped , open_close , Open , none , isCDLoaded >,

// 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:

// 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>

#include <boost/msm/front/functor_row.hpp>

#include <boost/msm/front/euml/common.hpp>

namespace msm = boost::msm;

namespace mpl = boost::mpl;

using namespace msm::front;

namespace // Concrete FSM implementation

{

// events

struct play {};

struct end_pause {};

struct stop {};

struct pause {};

struct open_close {};

struct NextSong {};

struct PreviousSong {};

// Flags. Allow information about a property of the current state

struct PlayingPaused{};

struct CDLoaded {};

struct FirstSongPlaying {};

// A "complicated" event type that carries some data.

struct cd_detected

{

cd_detected(std::string name)

: name(name)

{}

std::string name;

};

// front-end: define the FSM structure

struct player_ : public msm::front::state_machine_def<player_>

{

// 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<>

{

typedef mpl::vector1<CDLoaded> flag_list;

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;}

};

struct Stopped : public msm::front::state<>

{

// when stopped, the CD is loaded

typedef mpl::vector1<CDLoaded> flag_list;

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;}

};

// the player state machine contains a state which is himself a state machine

// as you see, no need to declare it anywhere so Playing can be developed separately

// by another team in another module. For simplicity I just declare it inside 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)

typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;

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<>

{

typedef mpl::vector1<FirstSongPlaying> flag_list;

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<>

{

typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list;

};

// 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

struct isCDLoaded

{

template <class EVT,class FSM,class SourceState,class TargetState>

bool operator()(EVT const& ,FSM& fsm,SourceState& ,TargetState& )

{

//return fsm.is_contained();

return fsm.is_flag_active<CDLoaded>();

}

};

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 >,

Row < Stopped , open_close , Open , none , isCDLoaded >,

a_row < Stopped , stop , Stopped , &p::stopped_again >,

// +---------+-------------+---------+---------------------+----------------------+

a_row < Open , open_close , Empty , &p::close_drawer >,

// +---------+-------------+---------+---------------------+----------------------+

a_row < Empty , open_close , Open , &p::open_drawer >,

a_row < Empty , cd_detected , Stopped , &p::store_cd_info >,

// +---------+-------------+---------+---------------------+----------------------+

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()

{

player p;

// needed to start the highest-level SM. This will call on_entry and mark the start of the SM

p.start();

// tests some flags

std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet)

// 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(cd_detected("louie, louie"));

p.process_event(play());

// at this point, Play is active

std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true

std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true

// make transition happen inside it. Player has no idea about this event but it's ok.

p.process_event(NextSong());pstate(p); //2nd song active

p.process_event(NextSong());pstate(p);//3rd song active

p.process_event(PreviousSong());pstate(p);//2nd song active

std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false

std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true

p.process_event(pause()); pstate(p);

std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true

// go back to Playing

// as you see, it starts back from the original state

p.process_event(end_pause()); pstate(p);

p.process_event(pause()); pstate(p);

p.process_event(stop()); pstate(p);

std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false

std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true

// event leading to the same state

p.process_event(stop()); pstate(p);

}

int main()

{

test();

return 0;

}