/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.propertytable.graph;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import org.apache.jena.atlas.io.IndentedWriter;
import com.hp.hpl.jena.graph.Graph;
import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.sparql.core.BasicPattern;
import com.hp.hpl.jena.sparql.engine.ExecutionContext;
import com.hp.hpl.jena.sparql.engine.QueryIterator;
import com.hp.hpl.jena.sparql.engine.binding.Binding;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIter1;
import com.hp.hpl.jena.sparql.serializer.SerializationContext;
import com.hp.hpl.jena.sparql.util.FmtUtils;
import com.hp.hpl.jena.sparql.util.Utils;
/**
* Split the incoming BasicPattern by subjects, (i.e. it becomes multiple sub BasicPatterns grouped by the same subjects.
*
*/
public class QueryIterPropertyTable extends QueryIter1 {
private BasicPattern pattern;
private Graph graph;
private QueryIterator output;
public static QueryIterator create(QueryIterator input,
BasicPattern pattern, ExecutionContext execContext) {
return new QueryIterPropertyTable(input, pattern, execContext);
}
private QueryIterPropertyTable(QueryIterator input, BasicPattern pattern,
ExecutionContext execContext) {
super(input, execContext);
this.pattern = pattern;
graph = execContext.getActiveGraph();
// Create a chain of triple iterators.
QueryIterator chain = getInput();
Collection<BasicPattern> patterns = sort(pattern);
for (BasicPattern p : patterns)
chain = new QueryIterPropertyTableRow(chain, p, execContext);
output = chain;
}
private Collection<BasicPattern> sort(BasicPattern pattern) {
HashMap<Node, BasicPattern> map = new HashMap<Node, BasicPattern>();
for (Triple triple : pattern.getList()) {
Node subject = triple.getSubject();
if (!map.containsKey(subject)) {
List<Triple> triples = new ArrayList<Triple>();
BasicPattern p = BasicPattern.wrap(triples);
map.put(subject, p);
p.add(triple);
} else {
map.get(subject).add(triple);
}
}
return map.values();
}
@Override
protected boolean hasNextBinding() {
return output.hasNext();
}
@Override
protected Binding moveToNextBinding() {
return output.nextBinding();
}
@Override
protected void closeSubIterator() {
if (output != null)
output.close();
output = null;
}
@Override
protected void requestSubCancel() {
if (output != null)
output.cancel();
}
@Override
protected void details(IndentedWriter out, SerializationContext sCxt) {
out.print(Utils.className(this));
out.println();
out.incIndent();
FmtUtils.formatPattern(out, pattern, sCxt);
out.decIndent();
}
}