A state is the simplest kind of state in a machine: it has no child states. More...

#include <chsm.h>

Inheritance diagram for CHSM::state:

Public Types
typedef void(machine::*	action )(state const &s, event const &trigger)
	An action is a function (machine member function) that is optionally called upon enter/exit of a state. More...

typedef int	id
	The identification number of a state. More...

Public Member Functions
bool	active () const
	Returns whether this state is active. More...

virtual void	deep_clear ()
	Clears the history for all child clusters of a cluster, recursively. More...

char const *	name () const
	Return the name of the state. More...

parent *	parent_of () const
	Return the parent cluster or set. More...

	state (CHSM_STATE_ARGS)
	Construct a state. More...

	~state ()
	Destroy a state. More...

Protected Member Functions
virtual bool	enter (event const &trigger, state *from_child=0)
	Enter a state. More...

virtual bool	exit (event const &trigger, state *to=0)
	Exit a state. More...

Detailed Description

A state is the simplest kind of state in a machine: it has no child states.

A state can either be active (in the state) or inactive (not in the state); a state may have a parent, and enter/exit actions.

The state class can be extended either to add additional data members and member functions, or to alter its behavior upon being entered or exited.

Author: Paul J. Lucas

Member Typedef Documentation

typedef void(machine::* CHSM::state::action)(state const &s, event const &trigger)

An action is a function (machine member function) that is optionally called upon enter/exit of a state.

Parameters

s	The state that is being entered or exited.
trigger	The event that triggered the transition.

typedef int CHSM::state::id

The identification number of a state.

Constructor & Destructor Documentation

CHSM::state::state ( CHSM_STATE_ARGS )

Construct a state.

When deriving a class from state, the macros CHSM_STATE_ARGS and CHSM_STATE_INIT can be used to avoid having to deal with the many constructor arguments, e.g.:

class place : public CHSM::state {
public:
    place( CHSM_STATE_ARGS ) : CHSM::state( CHSM_STATE_INIT ) {
        // ...
    }
    // ...
};

CHSM::state::~state ( )

Destroy a state.

Member Function Documentation

bool CHSM::state::active ( ) const

inline

Returns whether this state is active.

Returns: Returns true only if the state is active.

Referenced by CHSM::machine::active(), CHSM::machine::dump_state(), enter(), exit(), and CHSM::cluster::exit().

void CHSM::state::deep_clear ( )

virtual

Clears the history for all child clusters of a cluster, recursively.

Plain states have neither children nor a history. Placing this function here is a wart on the design; by having it here, however, run-time type-identification can be avoided.

Reimplemented in CHSM::cluster, and CHSM::parent.

bool CHSM::state::enter	(	event const &	trigger,
		state *	from_child = `0`
	)

protectedvirtual

Enter a state.

If this state's parent state (if any) isn't active, enter it first. The event $enter(state) is broadcast and the state's enter-action block is executed, if any.

When overriding in a derived class, the form must be:

bool enter( CHSM::event const &amp;trigger, CHSM::state *from_child ) {
    if ( !CHSM::state::enter( trigger, from_child ) )
        return false;
    // ... new functionality here ...
    return true;
}

Parameters

trigger	The event that triggered the transition.
from_child	Not used here.

Returns: Returns true only if the state was actually entered, i.e., it wasn't already active.

Reimplemented in CHSM::set, and CHSM::cluster.

References active(), CHSM::machine::D_enex, CHSM::machine::debug(), enter(), name(), and parent_of().

Referenced by enter(), and CHSM::cluster::enter().

bool CHSM::state::exit	(	event const &	trigger,
		state *	to = `0`
	)

protectedvirtual

Exit a state.

If the "to" state doesn't have this state's parent state (if any) as an ancestor, exit this state's parent state first. The event $exit(state) is broadcast and the state's exit-action block is executed, if any.

When overriding in a derived class, the form must be:

boolean exit( CHSM::event const &amp;trigger, CHSM::state *to ) {
    if ( !CHSM::state::exit( trigger, to ) )
        return false;
    // ... new functionality here ...
    return true;
}