defaultagenda.java

jboss规则引擎

package org.drools.common;

/*
 * 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.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.drools.Agenda;
import org.drools.WorkingMemory;
import org.drools.spi.Activation;
import org.drools.spi.ActivationGroup;
import org.drools.spi.AgendaFilter;
import org.drools.spi.AgendaGroup;
import org.drools.spi.ConsequenceException;
import org.drools.spi.KnowledgeHelper;
import org.drools.util.LinkedListNode;
import org.drools.util.Queueable;

/**
 * Rule-firing Agenda.
 * 
 * <p>
 * Since many rules may be matched by a single assertObject(...) all scheduled
 * actions are placed into the <code>Agenda</code>.
 * </p>
 * 
 * <p>
 * While processing a scheduled action, it may modify or retract objects in
 * other scheduled actions, which must then be removed from the agenda.
 * Non-invalidated actions are left on the agenda, and are executed in turn.
 * </p>
 * 
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * @author <a href="mailto:[e-mail]">Simon Harris </a>
 */
public class DefaultAgenda
    implements
    Serializable, 
    InternalAgenda {
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /**
     * 
     */
    private static final long          serialVersionUID = -9112292414291983688L;

    /** Working memory of this Agenda. */
    private final WorkingMemory        workingMemory;

    private org.drools.util.LinkedList scheduledActivations;

    /** Items time-delayed. */

    private final Map                  agendaGroups;

    private final Map                  activationGroups;

    private final LinkedList           focusStack;

    private AgendaGroupImpl            currentModule;

    private AgendaGroup                main;

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

    /**
     * Construct.
     * 
     * @param workingMemory
     *            The <code>WorkingMemory</code> of this agenda.
     * @param conflictResolver
     *            The conflict resolver.
     */
    public DefaultAgenda(final WorkingMemory workingMemory) {
        this.workingMemory = workingMemory;
        this.agendaGroups = new HashMap();
        this.activationGroups = new HashMap();
        this.focusStack = new LinkedList();

        // MAIN should always be the first AgendaGroup and can never be removed
        this.main = new AgendaGroupImpl( AgendaGroup.MAIN );

        this.agendaGroups.put( AgendaGroup.MAIN,
                               this.main );

        this.focusStack.add( this.main );

    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getWorkingMemory()
     */
    public WorkingMemory getWorkingMemory() {
        return this.workingMemory;
    }

    /**
     * Schedule an agenda item for delayed firing.
     * 
     * @param item
     *            The item to schedule.
     */
    public void scheduleItem(final ScheduledAgendaItem item) {
        Scheduler.getInstance().scheduleAgendaItem( item );

        if ( this.scheduledActivations == null ) {
            this.scheduledActivations = new org.drools.util.LinkedList();
        }

        this.scheduledActivations.add( item );
    }

    public void removeScheduleItem(final ScheduledAgendaItem item) {
        this.scheduledActivations.remove( item );
        item.cancel();
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getScheduledItems()
     */
    public org.drools.util.LinkedList getScheduledItems() {
        return this.scheduledActivations;
    }

    public void addAgendaGroup(final AgendaGroup agendaGroup) {
        this.agendaGroups.put( agendaGroup.getName(),
                               agendaGroup );
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#setFocus(org.drools.spi.AgendaGroup)
     */
    public boolean setFocus(final AgendaGroup agendaGroup) {
        // Set the focus to the agendaGroup if it doesn't already have the focus
        if ( this.focusStack.getLast() != agendaGroup ) {
            this.focusStack.add( agendaGroup );
            return true;
        }
        return false;
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#setFocus(java.lang.String)
     */
    public void setFocus(final String name) {
        AgendaGroup agendaGroup = (AgendaGroup) this.agendaGroups.get( name );

        // Agenda may not have been created yet, if not create it.
        if ( agendaGroup == null ) {
            agendaGroup = new AgendaGroupImpl( name );
            ( ( DefaultAgenda ) this.workingMemory.getAgenda() ).addAgendaGroup( agendaGroup );
        }
        setFocus( agendaGroup );
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getFocus()
     */
    public AgendaGroup getFocus() {
        return (AgendaGroup) this.focusStack.getLast();
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getNextFocus()
     */
    public AgendaGroup getNextFocus() {
        AgendaGroupImpl agendaGroup = null;
        // Iterate untill we find a populate AgendaModule or we reach the MAIN, default, AgendaGroup
        while ( true ) {
            agendaGroup = (AgendaGroupImpl) this.focusStack.getLast();

            final boolean empty = agendaGroup.isEmpty();

            // No populated queus found so pop the focusStack and repeat            
            if ( empty && (this.focusStack.size() > 1) ) {
                this.focusStack.removeLast();
            } else {
                agendaGroup = (empty) ? null : agendaGroup;
                break;
            }
        }

        return agendaGroup;
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#setCurrentAgendaGroup(org.drools.spi.AgendaGroup)
     */
    public void setCurrentAgendaGroup(final AgendaGroup agendaGroup) {
        this.currentModule = (AgendaGroupImpl) agendaGroup;
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getCurrentAgendaGroup()
     */
    public AgendaGroup getCurrentAgendaGroup() {
        return this.currentModule;
    }

    /* (non-Javadoc)
     * @see org.drools.common.AgendaI#getAgendaGroup(java.lang.String)