org.mindswap.pellet.jena.graph.query.BooleanQueryHandler Maven / Gradle / Ivy

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// Copyright (c) 2006 - 2008, Clark & Parsia, LLC. 
// This source code is available under the terms of the Affero General Public License v3.
//
// Please see LICENSE.txt for full license terms, including the availability of proprietary exceptions.
// Questions, comments, or requests for clarification: [email protected]

package org.mindswap.pellet.jena.graph.query;

import org.mindswap.pellet.KnowledgeBase;
import org.mindswap.pellet.jena.graph.loader.GraphLoader;

import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;
import com.hp.hpl.jena.util.iterator.NullIterator;
import com.hp.hpl.jena.util.iterator.SingletonIterator;

abstract class BooleanQueryHandler extends TripleQueryHandler {
	@Override
	public ExtendedIterator find(KnowledgeBase kb, GraphLoader loader, Node subj, Node pred, Node obj) {
		return contains( kb, loader, subj, pred, obj )
			? new SingletonIterator( Triple.create( subj, pred, obj ) )
			: NullIterator.instance();
	}			
}