/**
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 Sep 28, 2010
*/
package com.bigdata.bop.ap.filter;
import java.util.Iterator;
import java.util.Map;
import com.bigdata.bop.BOp;
import com.bigdata.btree.AbstractBTree;
import com.bigdata.btree.BTree;
import com.bigdata.btree.IRangeQuery;
import com.bigdata.btree.ITuple;
import com.bigdata.btree.ITupleIterator;
import com.bigdata.btree.Tuple;
import com.bigdata.btree.filter.TupleFilter;
import com.bigdata.btree.filter.TupleFilter.TupleFilterator;
/**
* <p>
* Filter supporting {@link ITupleIterator}s.
* </p>
* <p>
* <strong>Warning: Unlike {@link BOpFilter}, this class correctly uses a second
* {@link Tuple} instance to perform filtering.<strong> This is necessary since
* the {@link Tuple} instance for the base {@link ITupleIterator}
* implementations for the {@link AbstractBTree} is reused by next() on each
* call and the {@link TupleFilter} uses one-step lookahead. Failure to use a
* second {@link Tuple} instance will result in <em>overwrite</em> of the
* current {@link Tuple} with data from the lookahead {@link Tuple}.
* </p>
* <p>
* Note: You must specify {@link IRangeQuery#KEYS} and/or
* {@link IRangeQuery#VALS} in order to filter on the keys and/or values
* associated with the visited tuples.
* </p>
* <p>
* Note: YOu must specify {@link IRangeQuery#CURSOR} to enabled
* {@link Iterator#remove()} for a <em>local</em> {@link BTree}
* </p>
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
abstract public class BOpTupleFilter<E> extends BOpFilterBase {
/**
*
*/
private static final long serialVersionUID = 1L;
// /**
// * Deserialization.
// */
// public BOpFilter() {
// super();
// }
/**
* Deep copy.
*
* @param op
*/
public BOpTupleFilter(BOpTupleFilter op) {
super(op);
}
/**
* Shallow copy.
*
* @param args
* @param annotations
*/
public BOpTupleFilter(BOp[] args, Map<String, Object> annotations) {
super(args, annotations);
}
@Override
final protected Iterator filterOnce(Iterator src, final Object context) {
return new TupleFilterator((ITupleIterator<E>) src, context,
new FilterImpl());
}
/**
* Return <code>true</code> iff the object should be accepted.
*
* @param obj
* The object.
*/
protected abstract boolean isValid(ITuple<E> obj);
private class FilterImpl extends TupleFilter<E> {
private static final long serialVersionUID = 1L;
@Override
protected boolean isValid(ITuple<E> tuple) {
return BOpTupleFilter.this.isValid(tuple);
}
}
}