/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
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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 Jun 24, 2008
*/
package com.bigdata.relation.rule.eval;
import com.bigdata.bop.IBindingSet;
import com.bigdata.relation.rule.IRule;
/**
* A solution bundles together any of (a) the materialized element corresponding
* to the bindings on the head of an {@link IRule}; (b) the {@link IBindingSet}
* used to generate that solution; and (c) the {@link IRule} from which those
* bindings were computed. All data are optional. Which data are included
* depends on a set of bit flags known to the {@link IJoinNexus} implementation
* and the behavior of its {@link IJoinNexus#newSolution(IRule, IBindingSet)}
* implementation.
* <p>
* Note: The {@link IBindingSet} is useful both for high-level query and to
* materialize the justifications for the entailments. The RDF DB uses this for
* to maintain a justifications index in support of truth maintenance.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
* @param <E>
* The generic type of elements materialized from the head of the
* rule.
*/
public interface ISolution<E> {
/**
* Return the element materialized from the head of the rule given a set of
* {@link IBindingSet bindings} for that rule (optional operation).
*
* @return The element -or- <code>null</code> if the element was not
* requested.
*/
public E get();
/**
* Return the {@link IRule} that generated this solution (optional
* operation).
*
* @return The {@link IRule} -or- <code>null</code> if the rule was not
* requested.
*/
public IRule<E> getRule();
/**
* Return the {@link IBindingSet} for this solution (optional operation).
*
* @return The {@link IBindingSet}.
*
* @return The {@link IBindingSet} -or- <code>null</code> if the binding
* set was not requested.
*/
public IBindingSet getBindingSet();
}