Class: FSM

FSM FSM( string $initialState, &$payload, mixed $payload)

This method constructs a new Finite State Machine (FSM) object.

In addition to defining the machine's initial state, a "payload" may also be specified. The payload represents a variable that will be passed along to each of the action functions. If the FSM is being used for parsing, the payload is often a array that is used as a stack.

Parameters:

void addTransition( string $symbol, string $state, string $nextState, [string $action = null])

This method adds a new transition that associates:

(symbol, currentState) --> (nextState, action)

The action may be set to NULL, in which case the processing routine will ignore the action and just set the next state.

Parameters:

void addTransitionAny( string $state, string $nextState, [string $action = null])

This method adds a new transition that associates:

(currentState) --> (nextState, action)

The processing routine checks these associations if it cannot first find a match for (symbol, currentState).

Parameters:

void addTransitions( array $symbols, string $state, string $nextState, [string $action = null])

This method adds the same transition for multiple different symbols.

Parameters:

void addTransitionsArray( array $transitions)

This method adds an array of transitions. Each transition is itself defined as an array of values which will be passed to addTransition() as parameters.

Parameters:

mixed getTransition( string $symbol)

This method returns (nextState, action) given an input symbol and state. The FSM is not modified in any way. This method is rarely called directly (generally only for informational purposes).

If the transition cannot be found in either of the transitions lists, the default transition will be returned. Note that it is possible for the default transition to be set to NULL.

Parameters:

void process( string $symbol)

This method is the main processing routine. It causes the FSM to change states and execute actions.

The transition is determined by calling getTransition() with the provided symbol and the current state. If no valid transition is found, process() returns immediately.

The action callback may return the name of a new state. If one is returned, the current state will be updated to the new value.

If no action is defined for the transition, only the state will be changed.

Parameters:

void processList( array $symbols)

This method processes a list of symbols. Each symbol in the list is sent to process().

Parameters:

void reset( )

This method resets the FSM by setting the current state back to the initial state (set by the constructor).

void setDefaultTransition( string $nextState, string $action)

This method sets the default transition. This defines an action and next state that will be used if the processing routine cannot find a suitable match in either transition list. This is useful for catching errors caused by undefined states.

The default transition can be removed by setting $nextState to NULL.

Parameters: