defaultconflictresolver.java

rule engine drools-2.0-beta-18

package org.drools.conflict;

/*
 * $Id: DefaultConflictResolver.java,v 1.11 2004/11/19 02:12:42 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
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import org.drools.spi.Activation;
import org.drools.spi.ConflictResolver;
import org.drools.spi.Tuple;

/**
 * Strategy for resolving conflicts amongst multiple rules.
 * 
 * <p>
 * Since a fact or set of facts may activate multiple rules, a
 * <code>ConflictResolutionStrategy</code> is used to provide priority
 * ordering of conflicting rules.
 * </p>
 * 
 * @see Activation
 * @see Tuple
 * @see org.drools.rule.Rule
 * 
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * @author <a href="mailto:[e-mail]">Simon Harris </a>
 */
public class DefaultConflictResolver extends CompositeConflictResolver
{
    // ----------------------------------------------------------------------
    // Class members
    // ----------------------------------------------------------------------

    private static final ConflictResolver[] CONFLICT_RESOLVERS = new ConflictResolver[]{SalienceConflictResolver.getInstance( ), RecencyConflictResolver.getInstance( ), ComplexityConflictResolver.getInstance( ),
                                                                                        LoadOrderConflictResolver.getInstance( )};

    /** Singleton instance. */
    private static final DefaultConflictResolver INSTANCE = new DefaultConflictResolver( );

    // ----------------------------------------------------------------------
    // Class methods
    // ----------------------------------------------------------------------

    /**
     * Retrieve the singleton instance.
     * 
     * @return The singleton instance.
     */
    public static ConflictResolver getInstance()
    {
        return INSTANCE;
    }

    /**
     * Setup a default ConflictResolver configuration
     */
    public DefaultConflictResolver()
    {
        super( CONFLICT_RESOLVERS );
    }
}