exprcondition.java

rule engine drools-2.0-beta-18

package org.drools.semantics.groovy;

/*
 * $Id: ExprCondition.java,v 1.11 2004/11/29 12:35:52 simon Exp $
 *
 * Copyright 2002 (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 registered trademark of The Werken Company.
 *
 * 5. Due credit should be given to The Werken Company.
 * (http://drools.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
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 *
 */

import org.drools.rule.Rule;
import org.drools.spi.Condition;
import org.drools.spi.ConditionException;
import org.drools.spi.Tuple;

/**
 * Groovy expression semantics <code>Condition</code>.
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * @author <a href="mailto:[e-mail]">James Strachan </a>
 */
public class ExprCondition extends Eval implements Condition
{
    // ------------------------------------------------------------
    //     Constructors
    // ------------------------------------------------------------

    /**
     * Construct.
     *
     * @param expr The expression.
     * @param rule The rule.
     */
    public ExprCondition(String expr,
                         Rule rule ) throws Exception
    {
        super( expr, rule );
    }

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

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    //     org.drools.spi.Condition
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    /**
     * Determine if the supplied <code>Tuple</code> is allowed by this
     * condition.
     *
     * @param tuple The <code>Tuple</code> to test.
     *
     * @return <code>true</code> if the <code>Tuple</code> passes this
     *         condition, else <code>false</code>.
     *
     * @throws ConditionException if an error occurs during filtering.
     */
    public boolean isAllowed(Tuple tuple) throws ConditionException
    {
        try
        {
            Object answer = evaluate( tuple );

            if ( !( answer instanceof Boolean ) )
            {
                throw new NonBooleanExprException( getText( ) );
            }

            return ( ( Boolean ) answer ).booleanValue( );
        }
        catch ( RuntimeException e )
        {
            throw new ConditionException( e,
                                          getRule( ),
                                          getText( ) );
        }
    }
}