declaration.java

drools 一个开放源码的规则引擎

package org.drools.rule;

/*
 * $Id: Declaration.java,v 1.1 2005/07/26 01:06:31 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 org.drools.spi.Extractor;
import org.drools.spi.ObjectType;

/**
 * A typed, named variable for <code>Test</code> evaluation.
 *
 * @see ObjectType
 * @see org.drools.spi.Condition
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * @author <a href="mailto:[e-mail]">Simon Harris </a>
 */
public class Declaration
    implements
    Serializable,
    Comparable
{
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------

    /** The identifier for the variable. */
    private final String identifier;

    /** The type of the variable. */
    private final ObjectType objectType;
    
    private final Extractor extractor;
    
    private final int column;
    
    /** The index within a rule. */
    private final int index;    
    


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

    /**
     * Construct.
     * @param identifier The name of the variable.
     * @param objectType The type of this variable declaration.
     * @param order The index within a rule.
     */
    public Declaration( int index,
                        String identifier,               
                        ObjectType objectType,
                        Extractor extractor,
                        int column )
    {
        this.identifier = identifier;
        this.objectType = objectType;   
        this.extractor = extractor;
        this.column = column;
        this.index = index;
    }

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

    /**
     * Retrieve the variable's identifier.
     *
     * @return The variable's identifier.
     */
    public String getIdentifier()
    {
        return this.identifier;
    }    
    
    
    /**
     * Retrieve the <code>ObjectType</code>.
     *
     * @return The object-type.
     */
    public ObjectType getObjectType()
    {
        return this.objectType;
    }         
    
    /**
     * Returns the index of the column
     * @return the column
     */
    public int getColumn()
    {
        return this.column;
    }
    
    /**
     * Returns the Extractor expression
     * @return
     */     
    public Extractor getExtractor()
    {
        return this.extractor;
    }    
   
    /**
     * Returns the index of the Decleration
     * @return
     */    
    public int getIndex()
    {
        return this.index;
    }
    
    public Object getValue(Object object)
    {
        return this.extractor.getValue( object );
    }    

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

    public int compareTo( Object object )
    {
        return this.index - ( ( Declaration ) object ).index;
    }

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

    public String toString()
    {
        return "[Declaration: " + this.identifier + "]";
    }

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

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

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

        Declaration other = ( Declaration ) object;

        return this.index == other.index
               && this.identifier.equals( other.identifier )
               && this.objectType.equals( other.objectType );
    }


}