/**
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 Apr 10, 2012
*/
package com.bigdata.bop.rdf.join;
import java.util.NoSuchElementException;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.IVariable;
import com.bigdata.rdf.lexicon.LexiconRelation;
import cutthecrap.utils.striterators.ICloseableIterator;
/**
* Iterator pattern for chunked materialization.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*
* @see ChunkedMaterializationOp
*/
public class ChunkedMaterializationIterator implements
ICloseableIterator<IBindingSet[]> {
private final IVariable<?>[] required;
private final LexiconRelation lex;
private final boolean materializeInlineIVs;
private final ICloseableIterator<IBindingSet[]> src;
private boolean open = false;
/**
*
* @param vars
* The variables to be materialized (required; must not be an
* empty array).
* @param lex
* The {@link LexiconRelation}.
* @param materializeInlineIVs
* When <code>true</code>, inline IVs will also be materialized.
* @param src
* The source iterator.
*/
public ChunkedMaterializationIterator(//
final IVariable<?>[] vars,//
final LexiconRelation lex,//
final boolean materializeInlineIVs,//
final ICloseableIterator<IBindingSet[]> src) {
if (vars == null)
throw new IllegalArgumentException();
if (vars != null && vars.length == 0)
throw new IllegalArgumentException();
if (lex == null)
throw new IllegalArgumentException();
if (src == null)
throw new IllegalArgumentException();
this.required = vars;
this.lex = lex;
this.materializeInlineIVs = materializeInlineIVs;
this.src = src;
}
@Override
public void close() {
if (open) {
open = false;
src.close();
}
}
@Override
public boolean hasNext() {
if (open && !src.hasNext()) {
close();
return false;
}
return open;
}
@Override
public IBindingSet[] next() {
if (!hasNext())
throw new NoSuchElementException();
final IBindingSet[] chunkIn = src.next();
final IBindingSet[] chunkOut =
ChunkedMaterializationOp.resolveChunk(
required, lex, chunkIn, materializeInlineIVs);
return chunkOut;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}