rationals

Interface StateMachine

All Known Implementing Classes:

Automaton

public interface StateMachine

An interface for abstract state machines.

A state machine - or labelled transition system - is defined by a tuple (Q,S,q0,d) where:

• Q is a set of states ;
• S is a finite set of labels ;
• q0 is the initial state of the machine ;
• d is a transition relation in Q x S x Q.

This definition is slightly modified for this interface as the initials is defined as a set instead of a single state. null may be used to denote silent transitions, that is unobservable internal behavior of the machine, which can lead to non determinism.

The rationals.Automaton is the main implementation for this interface.

Version:

$Id: StateMachine.java 10 2007-05-30 17:25:00Z oqube $

Author:

nono

Method Summary

Modifier and Type	Method and Description
Set<Object>	alphabet() Returns the alphabet - S - of this state machine.
Set<Transition>	delta(Set<State> s) Returns all transitions from a given set of states.
Set<Transition>	delta(State state) Return all transitions from a State.
Set<Transition>	delta(State state, Object label) Returns the set of all transitions of this machine starting from a given state and labelled with a given label.
Set<Transition>	deltaMinusOne(State st) Returns the set of states that can access the given states' set st.
StateFactory	getStateFactory() Retrieves the state factory associated to this SM.
Set<State>	initials() Returns the set of initial states for this machine.
Set<State>	step(Set<State> s, Object o) Return the set of states accessible in one transition from given set of states s and letter o.
Set<State>	steps(Set<State> s, List<?> word) Return the set of states this SM will be in after reading the word from start states s.

Method Detail

alphabet

Set<Object> alphabet()

Returns the alphabet - S - of this state machine.

Returns:

a Set of Object.

getStateFactory

StateFactory getStateFactory()

Retrieves the state factory associated to this SM.

Returns:

a StateFactory instance

delta

Set<Transition> delta(State state,
                      Object label)

Returns the set of all transitions of this machine starting from a given state and labelled with a given label.

Parameters:

state - a state of this SM.

label - a label used in this SM.

Returns:

the set of all transitions of this automaton starting from state state and labelled by label. Objects which are contained in this set are instances of class Transition.

See Also:

Transition

delta

Set<Transition> delta(State state)

Return all transitions from a State.

Parameters:

state - start state

Returns:

a new Set of transitions (maybe empty)

delta

Set<Transition> delta(Set<State> s)

Returns all transitions from a given set of states.

Parameters:

s - a Set of State objects

Returns:

a Set of Transition objects

steps

Set<State> steps(Set<State> s,
                 List<?> word)

Return the set of states this SM will be in after reading the word from start states s.

Parameters:

s - the set of starting states

word - the word to read.

Returns:

the set of reached states. Maybe empty or null.

step

Set<State> step(Set<State> s,
                Object o)

Return the set of states accessible in one transition from given set of states s and letter o.

Parameters:

s - the starting states

o - the letter

Returns:

a set of reachable states. Maybe empty or null.

initials

Set<State> initials()

Returns the set of initial states for this machine.

Returns:

a Set of State objects.

deltaMinusOne

Set<Transition> deltaMinusOne(State st)

Returns the set of states that can access the given states' set st. This is the inverse relation of d

Parameters:

st - end states

Returns:

a set of states that can reach st. May be empty or null.