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Java client API for Franz AllegroGraph

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/******************************************************************************
** Copyright (c) 2008-2016 Franz Inc.
** All rights reserved. This program and the accompanying materials
** are made available under the terms of the Eclipse Public License v1.0
** which accompanies this distribution, and is available at
** http://www.eclipse.org/legal/epl-v10.html
******************************************************************************/

package com.franz.agraph.jena;

import org.openrdf.model.Statement;
import org.openrdf.query.GraphQueryResult;
import org.openrdf.query.QueryEvaluationException;

import com.franz.util.Closeable;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.util.iterator.NiceIterator;

/**
 * 
 * A utility class for iterating over Jena Triples.
 *
 */
public class AGTripleIteratorGQ extends NiceIterator
implements Closeable {
	
	private final AGGraph graph;
	private final GraphQueryResult result;
	private Statement current = null;

	AGTripleIteratorGQ(AGGraph graph, GraphQueryResult result) {
		this.graph = graph;
		this.result = result;
	}

	@Override
	public void close() {
		try {
			result.close();
		} catch (QueryEvaluationException e) {
			throw new RuntimeException(e);		
		}
	}

	@Override
	public boolean hasNext() {
		try {
			return result.hasNext();
		} catch (QueryEvaluationException e) {
			throw new RuntimeException(e);		
		}
	}

	@Override
	public Triple next() {
		Triple tr;
		try {
			current = result.next();
			tr = AGNodeFactory.asTriple(current);
		} catch (QueryEvaluationException e) {
			throw new RuntimeException(e);		
		}
		return tr;
	}

	@Override
	public void remove() {
		if (current != null) {
			Triple tr = AGNodeFactory.asTriple(current);
			graph.delete(tr);
			// TODO the following only removes triples from the underlying
			// collection (in memory), rather than from the store.   
			//result.remove();
			current = null;
		}
	}
}