terminalnode.java

rule engine drools-2.0-beta-18

package org.drools.reteoo;

/*
 * $Id: TerminalNode.java,v 1.36 2004/11/22 02:38:38 simon Exp $
 *
 * Copyright 2001-2003 (C) The Werken Company. All Rights Reserved.
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. The name "drools" must not be used to endorse or promote products derived
 * from this Software without prior written permission of The Werken Company.
 * For written permission, please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "drools" nor may
 * "drools" appear in their names without prior written permission of The Werken
 * Company. "drools" is a trademark of The Werken Company.
 *
 * 5. Due credit should be given to The Werken Company. (http://werken.com/)
 *
 * THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE WERKEN COMPANY OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

import org.drools.AssertionException;
import org.drools.FactHandle;
import org.drools.rule.Rule;

/**
 * Leaf Rete-OO node responsible for enacting <code>Action</code> s on a
 * matched <code>Rule</code>.
 *
 * @see org.drools.rule.Rule
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
final class TerminalNode
    implements
    TupleSink
{
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** The rule to invoke upon match. */
    private final Rule rule;

    // ------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------

    /**
     * Construct.
     *
     * @param inputSource
     *            The parent tuple source.
     * @param rule
     *            The rule.
     */
    TerminalNode(TupleSource inputSource,
                 Rule rule)
    {
        this.rule = rule;

        inputSource.setTupleSink( this );
    }

    // ------------------------------------------------------------
    // Instance methods
    // ------------------------------------------------------------

    /**
     * Retrieve the <code>Action</code> associated with this node.
     *
     * @return The <code>Action</code> associated with this node.
     */
    public Rule getRule()
    {
        return this.rule;
    }

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // org.drools.impl.TupleSink
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    /**
     * Assert a new <code>Tuple</code>.
     *
     * @param tuple
     *            The <code>Tuple</code> being asserted.
     * @param workingMemory
     *            The working memory seesion.
     *
     * @throws AssertionException
     *             If an error occurs while asserting.
     */
    public void assertTuple(ReteTuple tuple,
                            WorkingMemoryImpl workingMemory) throws AssertionException
    {
        workingMemory.getAgenda( ).addToAgenda( tuple,
                                                this.rule );
    }

    /**
     * Retract tuples.
     *
     * @param key
     *            The tuple key.
     * @param workingMemory
     *            The working memory seesion.
     */
    public void retractTuples(TupleKey key,
                              WorkingMemoryImpl workingMemory)
    {
        workingMemory.getAgenda( ).removeFromAgenda( key,
                                                     this.rule );
    }

    /**
     * Modify tuples.
     *
     * @param trigger
     *            The root fact object handle.
     * @param newTuples
     *            Modification replacement tuples.
     * @param workingMemory
     *            The working memory session.
     */
    public void modifyTuples(FactHandle trigger,
                             TupleSet newTuples,
                             WorkingMemoryImpl workingMemory)
    {
        workingMemory.getAgenda( ).modifyAgenda( trigger,
                                                 newTuples,
                                                 this.rule );
    }

    public String toString()
    {
        return "[TerminalNode: rule=" + rule.getName( ) + "]";
    }
}