/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
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 Sep 3, 2008
*/
package com.bigdata.relation.rule;
import java.io.Serializable;
import com.bigdata.bop.IPredicate;
import com.bigdata.relation.accesspath.IAccessPath;
/**
* An interface for expander patterns for an {@link IPredicate} when it appears
* in the right-hand position of a JOIN.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public interface IAccessPathExpander<E> extends Serializable {
/**
* Return the {@link IAccessPath} that will be used to evaluate the
* {@link IPredicate}.
*
* @param accessPath
* The {@link IAccessPath} that will be used by default.
*
* @return The {@link IAccessPath} that will be used. You can return the
* given <i>accessPath</i> or you can layer additional semantics
* onto or otherwise override the given {@link IAccessPath}.
*/
IAccessPath<E> getAccessPath(IAccessPath<E> accessPath);
/**
* Add the backchainer on top of the expander.
*
* @return true if the backchainer should run
*
* @deprecated Never <code>true</code>. The backchainer is only run for
* normal predicates in triples mode at this time. If it is to
* be layer, it should be layered as an annotation. See
* https://sourceforge.net/apps/trac/bigdata/ticket/231.
*/
boolean backchain();
/**
* If true, the predicate for this expander will be given priority in the
* join order.
*
* @return true if the predicate should be run first
*/
boolean runFirst();
}