tuplesource.java

drools 一个开放源码的规则引擎

package org.drools.reteoo;

/*
 * $Id: TupleSource.java,v 1.30 2005/02/02 00:23:22 mproctor 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 java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import org.drools.AssertionException;
import org.drools.RetractionException;

/**
 * A source of <code>ReteTuple</code> s for a <code>TupleSink</code>.
 *
 * <p>
 * Nodes that propagate <code>Tuples</code> extend this class.
 * </p>
 *
 * @see TupleSource
 * @see ReteTuple
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
abstract class TupleSource
    implements
    Serializable
{
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** The destination for <code>Tuples</code>. */
    private List tupleSinks = new ArrayList( 1 );

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

    /**
     * Construct.
     */
    TupleSource()
    {
        // intentionally left blank.
    }

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

    /**
     * Adds the <code>TupleSink</code> so that it may receive <code>Tuples</code>
     * propagated from this <code>TupleSource</code>.
     *
     * @param tupleSink The <code>TupleSink</code> to receive propagated <code>Tuples</code>.
     */
    protected void addTupleSink(TupleSink tupleSink)
    {
        if ( !this.tupleSinks.contains( tupleSink ) )
        {
            this.tupleSinks.add( tupleSink );
        }
    }

    /**
     * Propagate the assertion of a <code>Tuple</code> to this node's
     * <code>TupleSink</code>.
     *
     * @param tuple The <code>Tuple</code> to propagate.
     * @param workingMemory the working memory session.
     *
     * @throws AssertionException If an errors occurs while attempting assertion.
     */
    protected void propagateAssertTuple(ReteTuple tuple,
                                        WorkingMemoryImpl workingMemory) throws AssertionException
    {
        for ( int i = 0, size = this.tupleSinks.size( ); i < size; i++ )
        {
            ( ( TupleSink ) this.tupleSinks.get( i ) ).assertTuple( tuple,
                                                                    workingMemory );
        }
    }

    /**
     * Propagate the retration of a <code>Tuple</code> to this node's
     * <code>TupleSink</code>.
     *
     * @param key The tuple key.
     * @param workingMemory The working memory session.
     *
     * @throws RetractionException If an error occurs while attempting retraction
     *
     */
    protected void propagateRetractTuples(TupleKey key,
                                          WorkingMemoryImpl workingMemory) throws RetractionException
    {
        for ( int i = 0, size = this.tupleSinks.size( ); i < size; i++ )
        {
            ( ( TupleSink ) this.tupleSinks.get( i ) ).retractTuples( key,
                                                                      workingMemory );
        }
    }

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // org.drools.reteoo.TupleSource
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    /**
     * Retrieve the <code>TupleSinks</code> that receive propagated
     * <code>Tuples</code>.
     *
     * @return The <code>TupleSinks</code> that receive propagated
     *         <code>Tuples</code>.
     */
    public List getTupleSinks()
    {
        return this.tupleSinks;
    }

    /**
     * Retrieve the available tuple <code>Declaration</code>s.
     *
     * @return The available tuple declarations.
     */
    public abstract Set getTupleDeclarations();

    /**
     * Attaches this node into the network.
     */
    public abstract void attach( );
}