condition.java

rule engine drools-2.0-beta-18

package org.drools.spi;

/*
 * $Id: Condition.java,v 1.12 2004/11/19 02:14:48 mproctor Exp $
 *
 * Copyright 2001-2003 (C) The Werken Company. All Rights Reserved.
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 * ("Software"), with or without modification, are permitted provided that the
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 *
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import org.drools.rule.Declaration;

/**
 * A <code>Condition</code> that filters facts.
 * 
 * @see Tuple
 * 
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
public interface Condition
    extends
    SemanticComponent
{
    /**
     * Retrieve the array of <code>Declaration</code> s required by this
     * condition to perform its duties.
     * 
     * @return The array of <code>Declarations</code> expected on incoming
     *         <code>Tuples</code>.
     */
    Declaration[] getRequiredTupleMembers();

    /**
     * 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.
     */
    boolean isAllowed(Tuple tuple) throws ConditionException;
}