objectsource.java

jboss规则引擎

package org.drools.reteoo;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.Serializable;
import java.util.Iterator;
import java.util.List;

import org.drools.common.DefaultFactHandle;
import org.drools.spi.PropagationContext;

/**
 * A source of <code>FactHandle</code>s for an <code>ObjectSink</code>.
 * 
 * <p>
 * Nodes that propagate <code>FactHandleImpl</code> extend this class.
 * </p>
 * 
 * @see ObjectSource
 * @see DefaultFactHandle
 * 
 * @author <a href="mailto:[e-mail]">Mark Proctor</a>
 * @author <a href="mailto:[e-mail]">Bob McWhirter</a>
 */
abstract class ObjectSource extends BaseNode
    implements
    Serializable {
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** The destination for <code>FactHandleImpl</code>. */
    protected ObjectSinkList objectSinks;

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

    /**
     * Single parameter constructor that specifies the unique id of the node.
     * 
     * @param id
     */
    ObjectSource(final int id) {
        this( id,
              null );
    }

    /**
     * Single parameter constructor that specifies the unique id of the node.
     * 
     * @param id
     */
    ObjectSource(final int id,
                 final ObjectSinkList objectSinks) {
        super( id );
        this.objectSinks = (objectSinks != null) ? objectSinks : ObjectSinkListFactory.newDefaultObjectSinkList();
    }

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

    /**
     * Adds the <code>ObjectSink</code> so that it may receive
     * <code>FactHandleImpl</code> propagated from this
     * <code>ObjectSource</code>.
     * 
     * @param objectSink
     *            The <code>ObjectSink</code> to receive propagated
     *            <code>FactHandleImpl</code>.
     */
    protected void addObjectSink(final ObjectSink objectSink) {
        if ( !this.objectSinks.contains( objectSink ) ) {
            this.objectSinks.add( objectSink );
        }
    }

    /**
     * Removes the <code>ObjectSink</code>
     * 
     * @param objectSink
     *            The <code>ObjectSink</code> to remove
     */
    protected void removeObjectSink(final ObjectSink objectSink) {
        this.objectSinks.remove( objectSink );
    }

    /**
     * Propagate the assertion of a <code>FactHandleImpl/code> to this node's
     * <code>ObjectSink</code>s.
     * 
     * @param handle
     *           the FactHandleImpl to be asserted
     * @param context
     *             The <code>PropagationContext</code> of the <code>WorkingMemory<code> action            
     * @param workingMemory
     *            the <code>WorkingMemory</code> session.
     */
    protected void propagateAssertObject(final DefaultFactHandle handle,
                                         final PropagationContext context,
                                         final ReteooWorkingMemory workingMemory) {
        for ( final Iterator i = this.objectSinks.iterator( workingMemory,
                                                            handle ); i.hasNext(); ) {
            ((ObjectSink) i.next()).assertObject( handle,
                                                  context,
                                                  workingMemory );
        }
    }

    /**
     * Propagate the retration of a <code>FactHandleImpl/code> to this node's
     * <code>ObjectSink</code>.
     * 
     * @param handle
     *           the FactHandleImpl to be retractred
     * @param context
     *             The <code>PropagationContext</code> of the <code>WorkingMemory<code> action            
     * @param workingMemory
     *            the <code>WorkingMemory</code> session.
     *
     */
    protected void propagateRetractObject(final DefaultFactHandle handle,
                                          final PropagationContext context,
                                          final ReteooWorkingMemory workingMemory) {
        for ( final Iterator i = this.objectSinks.iterator(); i.hasNext(); ) {
            ((ObjectSink) i.next()).retractObject( handle,
                                                   context,
                                                   workingMemory );
        }
    }

    protected void propagateModifyObject(final DefaultFactHandle handle,
                                         final PropagationContext context,
                                         final ReteooWorkingMemory workingMemory) {
        for ( final Iterator i = this.objectSinks.iterator(); i.hasNext(); ) {
            ((ObjectSink) i.next()).modifyObject( handle,
                                                  context,
                                                  workingMemory );
        }
    }

    /**
     * Retrieve the <code>ObectsSinks</code> that receive propagated
     * <code>FactHandleImpl</code>s.
     * 
     * @return The <code>ObjectsSinks</code> that receive propagated
     *         <code>FactHandles</code>.
     */
    public ObjectSinkList getObjectSinks() {
        return this.objectSinks;
    }

    /**
     * Returns the object sinks as an unmodifiable list
     * @return
     */
    public List getObjectSinksAsList() {
        return this.objectSinks.getObjectsAsList();
    }

}