/*
 * Copyright (C) 1999-2004 <a href="mailto:mandarax@jbdietrich.com">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.mandarax.kernel;


import java.util.Iterator;
import java.util.Vector;

import org.mandarax.util.logging.*;

/**
 * Abstract super class providing some common functionality
 * for classes implementing <code>org.mandarax.kernel.Clause</code>.
 * @author <A HREF="mailto:mandarax@jbdietrich.com">Jens Dietrich</A>
 * @version 3.3.1 <9 August 2004>
 * @since 1.0
 */
public abstract class AbstractClause extends AbstractPropertiesSupport implements Clause, LogCategories {

    protected transient Vector clauseSetChangeListener = new Vector ();
    protected ClauseSet container = this;

    /**
     * Constructor.
     */
    public AbstractClause() {
        super ();
    }

    /**
     * Add a clause set listener.
     * @param l the listener
     */
    public void addClauseSetChangeListener(ClauseSetChangeListener l) {
        clauseSetChangeListener.add (l);
    }

    /**
     * Get a clause iterator.
     * @return a clause iterator
     */
    public org.mandarax.util.ClauseIterator clauses() {
        return new org.mandarax.util.SingleClauseIterator (this);
    }

    /**
     * Get a clause iterator.
     * @param query the query clause
     * @param additionalParameter an optional additional parameter
     * @return a clause iterator
     */
    public org.mandarax.util.ClauseIterator clauses(Clause query,Object additionalParameter) {
        return clauses ();
    }

    /**
     * Fire a clause set change event.
     * @param e the change event
     */
    protected void fireClauseSetChangeEvent(ClauseSetChangeEvent e) {
        ClauseSetChangeListener l;
        for(Iterator it =  clauseSetChangeListener.iterator (); it.hasNext (); ) {
            l = (ClauseSetChangeListener) it.next ();
            l.clauseSetChanged (e);
        }
    }

    /**
     * Get the clause set containing the clause. This method is in particular useful for analyzing derivations,
     * since derivations show only the clauses used, not the clause set generating this clauses (e.g., AutoFacts). On the other
     * hand, knowledge bases contain often clause sets. So it could be hard to find the clause sets in the knowledge base
     * that caused a certain result. For sme clauses such as facts, the container is just the fact itself.
     * @return a clause set
     */
    public ClauseSet getContainer() {
        return container;
    }

    /**
     * Remove a clause set listener.
     * @param l the listener
     */
    public void removeClauseSetChangeListener(ClauseSetChangeListener l) {
        clauseSetChangeListener.remove (l);
    }

    /**
     * Set a container.
     * @param aContainerthe new container
     */
    public void setContainer(ClauseSet aContainer) {
        container = aContainer;
    }
}
