parameternode.java

drools 一个开放源码的规则引擎

package org.drools.reteoo;

/*
 * $Id: ParameterNode.java,v 1.46 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.util.Collections;
import java.util.Set;

import org.drools.AssertionException;
import org.drools.FactHandle;
import org.drools.RetractionException;
import org.drools.rule.Declaration;

/**
 * Receives <code>Objects</code> from an <code>ObjectTypeNode</code>, and
 * creates a <code>ReteTuple</code>, passing the result to the following
 * node.
 *
 * <p>
 * The <code>ParameterNode</code> is the first node that works in terms of
 * <code>Tuples</code>. An instance of <code>ParameterNode</code> exists
 * for each <i>root fact object </i> parameter of each rule.
 * </p>
 *
 * @see ObjectTypeNode
 * @see TupleSink
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
class ParameterNode extends TupleSource
{
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** The object type node we attach to. */
    private final ObjectTypeNode    objectTypeNode;

    /** The parameter declaration. */
    private final Declaration       declaration;

    /** The parameter declaration as a set. */
    private final Set               declarations;

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

    /**
     * Construct.
     *
     * @param objectTypeNode The <code>ObjectTypeNode</code> input to this.
     * @param declaration The root fact object <code>Declaration</code>.
     */
    public ParameterNode( ObjectTypeNode objectTypeNode,
                          Declaration declaration )
    {
        this.objectTypeNode = objectTypeNode;
        this.declaration = declaration;
        this.declarations = Collections.singleton( declaration );
    }

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

    public void attach( )
    {
        this.objectTypeNode.addParameterNode( this );
    }

    /**
     * Assert a new fact object into this <code>RuleBase</code> and the
     * specified <code>WorkingMemory</code>.
     *
     * @param handle The fact handle.
     * @param object The object to assert.
     * @param workingMemory The working memory session.
     *
     * @throws AssertionException if an error occurs during assertion.
     */
    void assertObject( FactHandle handle,
                       Object object,
                       WorkingMemoryImpl workingMemory ) throws AssertionException
    {
        ReteTuple tuple = new ReteTuple( workingMemory, getDeclaration( ),
                                         handle );

        propagateAssertTuple( tuple,
                              workingMemory );
    }

    /**
     * Retract a fact object from this <code>RuleBase</code> and the specified
     * <code>WorkingMemory</code>.
     *
     * @param handle The handle to the fact to retract.
     * @param workingMemory The working memory session.
     *
     * @throws RetractionException if an error occurs during retraction.
     */
    void retractObject( FactHandle handle,
                        WorkingMemoryImpl workingMemory ) throws RetractionException
    {
        TupleKey key = new TupleKey( getDeclaration( ),
                                     handle );

        propagateRetractTuples( key,
                                workingMemory );
    }

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    // org.drools.reteoo.ParameterNode
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    /**
     * Retrieve the root fact object <code>Declaration</code>.
     *
     * @return The <code>Declaration</code>.
     */
    public Declaration getDeclaration()
    {
        return this.declaration;
    }

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

    /**
     * Retrieve the <code>Set</code> of <code>Declaration</code> s in the
     * propagated <code>Tuples</code>.
     *
     * @return The <code>Set</code> of <code>Declarations</code> in progated
     *         <code>Tuples</code>.
     */
    public Set getTupleDeclarations()
    {
        return declarations;
    }

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    public int hashCode()
    {
        return this.declaration.hashCode( );
    }

    public boolean equals( Object object )
    {
        if ( this == object )
        {
            return true;
        }

        if ( object == null || getClass( ) != object.getClass( ) )
        {
            return false;
        }

        return this.declaration.equals( ( ( ParameterNode ) object ).declaration );
    }
}