/**
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 Aug 14, 2012
*/
package com.bigdata.rdf.sparql.ast.cache;
import info.aduna.iteration.CloseableIteration;
import java.util.Set;
import org.apache.log4j.Logger;
import org.openrdf.query.Binding;
import org.openrdf.query.BindingSet;
import org.openrdf.query.QueryEvaluationException;
import com.bigdata.bop.IVariable;
import com.bigdata.rdf.model.BigdataValue;
/**
* Collects and reports the distinct bindings observed on some set of variables.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
public class DescribeBindingsCollector implements
CloseableIteration<BindingSet, QueryEvaluationException> {
private static final transient Logger log = Logger
.getLogger(DescribeBindingsCollector.class);
private final IVariable<?>[] originalVars;
private final Set<BigdataValue> describedResources;
private final CloseableIteration<BindingSet, QueryEvaluationException> src;
private boolean open = true;
/**
*
* @param originalVars
* The set of variables whose distinct bound values will be
* reported.
* @param describedResources
* The set of distinct bound values for those variables (a high
* concurrency, thread-safe set).
* @param src
* The source iterator.
*/
public DescribeBindingsCollector(final Set<IVariable<?>> originalVars,
final Set<BigdataValue> describedResources,
final CloseableIteration<BindingSet, QueryEvaluationException> src) {
if (originalVars == null)
throw new IllegalArgumentException();
if (originalVars.isEmpty())
throw new IllegalArgumentException();
if (describedResources == null)
throw new IllegalArgumentException();
if (src == null)
throw new IllegalArgumentException();
this.originalVars = originalVars.toArray(new IVariable[originalVars
.size()]);
this.describedResources = describedResources;
this.src = src;
}
@Override
public void close() throws QueryEvaluationException {
open = false;
}
@Override
public boolean hasNext() throws QueryEvaluationException {
if (!src.hasNext()) {
close();
return false;
}
return true;
}
@Override
public BindingSet next() throws QueryEvaluationException {
if (!open)
throw new QueryEvaluationException("Closed");
final BindingSet bs = src.next();
for (IVariable<?> var : originalVars) {
final Binding binding = bs.getBinding(var.getName());
if (binding == null)
continue;
final BigdataValue boundValue = (BigdataValue) binding.getValue();
if (boundValue != null) {
if(describedResources.add(boundValue)) {
if(log.isInfoEnabled()) {
log.info("Will describe: var=" + var + ",boundValue="
+ boundValue);
}
}
}
}
return bs;
}
@Override
public void remove() throws QueryEvaluationException {
throw new UnsupportedOperationException();
}
}