com.bigdata.bop.joinGraph.IEvaluationPlan Maven / Gradle / Ivy

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/*

Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016.  All rights reserved.

Contact:
     SYSTAP, LLC DBA Blazegraph
     2501 Calvert ST NW #106
     Washington, DC 20008
     [email protected]

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/
/*
 * Created on Jun 26, 2008
 */

package com.bigdata.bop.joinGraph;

import com.bigdata.relation.rule.IRule;

/**
 * Interface for evaluation orders.
 * 
 * @author Bryan Thompson
 * @version $Id$
 */
public interface IEvaluationPlan {

    /**
     * Return the evaluation order.
     * 
     * @return The evaluation order. This is an array of indices into the
     *         predicates in the tail of the rule. Each tail predicate must be
     *         used exactly once. The elements in this array are the order in
     *         which each tail predicate will be evaluated. The index into the
     *         array is the index of the tail predicate whose evaluation order
     *         you want. So [2,0,1] says that the predicates will
     *         be evaluated in the order tail[2], then tail[0], then tail[1].
     */
    public int[] getOrder();

    /**
     * true iff the {@link IRule} was proven to be empty based on
     * range counts or other data.
     */
    public boolean isEmpty();

    /**
     * The range count for the predicate.
     * 
     * @param tailIndex
     *            The index of the predicate in the tail of the rule.
     *            
     * @return The range count for that predicate.
     * 
     * @see IRangeCountFactory
     */
    public long rangeCount(int tailIndex);
    
}