builder.java

drools 一个开放源码的规则引擎

package org.drools.reteoo;

/*
 * $Id: Builder.java,v 1.72 2005/02/02 00:23:21 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.
 *
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import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.drools.RuleBase;
import org.drools.RuleIntegrationException;
import org.drools.RuleSetIntegrationException;
import org.drools.conflict.DefaultConflictResolver;
import org.drools.rule.Declaration;
import org.drools.rule.Rule;
import org.drools.rule.RuleSet;
import org.drools.spi.Condition;
import org.drools.spi.ConflictResolver;
import org.drools.spi.RuleBaseContext;

/**
 * Builds the Rete-OO network for a <code>RuleSet</code>.
 * 
 * @see org.drools.rule.RuleSet
 * 
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * 
 * TODO Make joinForCondition actually be intelligent enough to build optimal
 * joins. Currently using forgy's original description of 2-input nodes, which I
 * feel (but don't know for sure, is sub-optimal.
 */
public class Builder
{
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** Rete network to build against. */
    private Rete              rete;

    /** Rule-sets added. */
    private List              ruleSets;

    /** Nodes that have been attached. */
    private Map               attachedNodes;

    private Map               applicationData;

    private FactHandleFactory factHandleFactory;

    private ConflictResolver  conflictResolver;

    private RuleBaseContext   ruleBaseContext;

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

    /**
     * Construct a <code>Builder</code> against an existing <code>Rete</code>
     * network.
     */
    public Builder()
    {
        reset( );
        this.ruleBaseContext = new RuleBaseContext( );
    }

    /**
     * Construct a <code>Builder</code> against an existing <code>Rete</code>
     * network.
     */
    public Builder(RuleBaseContext ruleBaseContext)
    {
        reset( );
        this.ruleBaseContext = ruleBaseContext;
    }

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

    /**
     * Build the <code>RuleBase</code>.
     * 
     * @return The rule-base.
     */
    public RuleBase buildRuleBase()
    {
        RuleBase ruleBase = new RuleBaseImpl( this.rete,
                                              this.conflictResolver,
                                              this.factHandleFactory,
                                              this.ruleSets,
                                              this.applicationData,
                                              this.ruleBaseContext );

        reset( );

        return ruleBase;
    }

    /**
     * Set the <code>FactHandleFactory</code>.
     * 
     * @param factHandleFactory
     *            The fact handle factory.
     */
    public void setFactHandleFactory(FactHandleFactory factHandleFactory)
    {
        this.factHandleFactory = factHandleFactory;
    }

    /**
     * Set the <code>ConflictResolver</code>.
     * 
     * @param conflictResolver
     *            The conflict resolver.
     */
    public void setConflictResolver(ConflictResolver conflictResolver)
    {
        this.conflictResolver = conflictResolver;
    }

    /**
     * Add a <code>RuleSet</code> to the network.
     * 
     * @param ruleSet
     *            The rule-set to add.
     * 
     * @throws RuleIntegrationException
     *             if an error prevents complete construction of the network for
     *             the <code>Rule</code>.
     */
    public void addRuleSet(RuleSet ruleSet) throws RuleIntegrationException,
                                           RuleSetIntegrationException
    {
        this.ruleSets.add( ruleSet );

        Map newApplicationData = ruleSet.getApplicationData( );
        Iterator it = newApplicationData.keySet( ).iterator( );
        String identifier;
        Class type;
        while ( it.hasNext( ) )
        {
            identifier = (String) it.next( );
            type = (Class) newApplicationData.get( identifier );
            if ( this.applicationData.containsKey( identifier ) && !this.applicationData.get( identifier ).equals( type ) )
            {
                throw new RuleSetIntegrationException( ruleSet );
            }

        }
        this.applicationData.putAll( newApplicationData );

        Rule[] rules = ruleSet.getRules( );

        for ( int i = 0; i < rules.length; ++i )
        {
            addRule( rules[i] );
        }
    }

    /**
     * Add a <code>Rule</code> to the network.
     * 
     * @param rule
     *            The rule to add.
     * 
     * @throws RuleIntegrationException
     *             if an error prevents complete construction of the network for
     *             the <code>Rule</code>.
     */
    protected void addRule(Rule rule) throws RuleIntegrationException
    {
        List conds = new LinkedList( rule.getConditions( ) );
        List leafNodes = createParameterNodes( rule );

        boolean performedJoin;
        boolean joinedForCondition;

        while ( true )
        {
            joinedForCondition = false;

            if ( !conds.isEmpty( ) )
            {
                attachConditions( rule,
                                  conds,
                                  leafNodes );
            }

            performedJoin = createJoinNodes( leafNodes );

            if ( !performedJoin && !conds.isEmpty( ) )
            {
                joinedForCondition = joinForCondition( conds,
                                                       leafNodes );
            }

            if ( joinedForCondition )
            {
                continue;
            }

            if ( leafNodes.size( ) > 1 )
            {
                if ( !performedJoin )
                {
                    joinArbitrary( leafNodes );
                }
            }
            else
            {
                break;
            }
        }

        if ( leafNodes.size( ) != 1 )
        {
            throw new RuleIntegrationException( rule );
        }

        TupleSource lastNode = (TupleSource) leafNodes.iterator( ).next( );

        TerminalNode terminal = new TerminalNode( lastNode,
                                                  rule );
    }

    /**
     * Create the <code>ParameterNode</code> s for the <code>Rule</code>,
     * and link into the network.
     * 
     * @param rule
     *            The rule.
     * 
     * @return A <code>Set</code> of <code>ParameterNodes</code> created and
     *         linked into the network.
     */
    List createParameterNodes(Rule rule)
    {
        List leafNodes = new LinkedList( );
        Iterator declIter = rule.getParameterDeclarations( ).iterator( );

        Declaration eachDecl;
        while ( declIter.hasNext( ) )
        {
            eachDecl = (Declaration) declIter.next( );

            attachNode( new ParameterNode( this.rete.getOrCreateObjectTypeNode( eachDecl.getObjectType( ) ),
                                           eachDecl ),
                        leafNodes );
        }

        return leafNodes;
    }

    /**
     * Attaches a node into the network. If a node already exists that could
     * substitute, it is used instead.
     * 
     * @param candidate