hr.fer.spocc.automaton.fsm.AbstractNondeterministicFiniteAutomaton.java Source code

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Here is the source code for hr.fer.spocc.automaton.fsm.AbstractNondeterministicFiniteAutomaton.java

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/*
 * AbstractNondeterministicFiniteAutomaton.java
 *
 * Copyright (C) 2010 Leo Osvald <leo.osvald@gmail.com>
 *
 * This file is part of SPoCC.
 *
 * SPoCC is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * SPoCC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with SPoCC. If not, see <http://www.gnu.org/licenses/>.
 */
package hr.fer.spocc.automaton.fsm;

import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang.Validate;

/**
 * Apstraktna implementacija sucelja {@link NondeterministicFiniteAutomaton}.
 * 
 * @author Leo Osvald
 *
 * @param <T>
 */
public abstract class AbstractNondeterministicFiniteAutomaton<T> extends AbstractFiniteStateMachine<T>
        implements NondeterministicFiniteAutomaton<T> {

    @Override
    public void addTransition(int fromId, int toId, T input) {
        State fromState = getState(fromId);
        Validate.notNull(fromState, "state fromId must be existent");
        State toState = getState(toId);
        Validate.notNull(toState, "state toId must be existent");

        addTransition(fromState, toState, input);
    }

    @Override
    public boolean process(T input) {
        if (getStartState() == null)
            throw new IllegalStateException("No start state defined");

        // za epsilon prijelaz ignoriramo
        if (input == null)
            return true;

        Set<State> nextStates = powerSet(getNextStates(input, powerSet(getCurrentStates())));
        setCurrentStates(nextStates);
        return !nextStates.isEmpty();
    }

    /**
     * Vraca skup stanja koji predstavlja neposrednu okolinu. 
     * Ova metoda ne uzima u obzir -okolinu; za to koristite metodu 
     * {@link #powerSet(Set)} nakon/prije ove.
     * 
     * @param input ulazni znak
     * @param states skup stanja iz kojih se razmatra prijelaz
     * @return skup stanja koji se dobije tocno jednim prijelazom iz
     * pocetnih stanja
     */
    protected Set<State> getNextStates(T input, Set<State> states) {
        Set<State> ret = new HashSet<State>();
        for (State state : states) {
            ret.addAll(getNextStates(input, state));
        }
        return ret;
    }

    protected abstract void setCurrentStates(Set<State> states);

}