/*
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 Jun 21, 2008
*/
package com.bigdata.striterator;
import java.util.NoSuchElementException;
/**
* An extension of {@link IChunkedIterator} interface that knows about natural
* traversal orders and how to re-order the elements that are being visited to
* support JOINs where the natural order for the access paths is different for
* the left- and right-hand side of the JOIN.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*
* @param <R>
* The generic type for the [R]elation elements.
*/
public interface IChunkedOrderedIterator<R> extends IChunkedIterator<R> {
/**
* The natural order in which elements are being visited.
*
* @return The natural order in which the elements are being visited -or-
* <code>null</code> if not known.
*/
public IKeyOrder<R> getKeyOrder();
/**
* Return the next "chunk" of elements. The elements will be in the
* specified order. If {@link #getKeyOrder()} would return non-<code>null</code>
* and the request order corresponds to the value that would be returned by
* {@link #getKeyOrder()} then the elements in the next chunk are NOT
* sorted. Otherwise the elements in the next chunk are sorted before they
* are returned. The size of the chunk is up to the implementation.
*
* @param keyOrder
* The natural order for the elements in the chunk.
*
* @return The next chunk of elements in the specified order.
*
* @throws NoSuchElementException
* if the iterator is exhausted.
* @throws IllegalArgumentException
* if the <i>keyOrder</i> is <code>null</code>.
*/
public R[] nextChunk(IKeyOrder<R> keyOrder);
}