/*
* 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 com.hp.hpl.jena.sparql.engine.main.iterator;
import java.util.List ;
import org.apache.jena.atlas.io.IndentedWriter ;
import com.hp.hpl.jena.sparql.algebra.Op ;
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.QueryIterConcat ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterRepeatApply ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterSingleton ;
import com.hp.hpl.jena.sparql.engine.main.QC ;
import com.hp.hpl.jena.sparql.serializer.SerializationContext ;
import com.hp.hpl.jena.sparql.util.Utils ;
/** Execute each sub stage against the input.
* Streamed SPARQL Union. */
public class QueryIterUnion extends QueryIterRepeatApply
{
protected List<Op> subOps ;
public QueryIterUnion(QueryIterator input,
List<Op> subOps,
ExecutionContext context)
{
super(input, context) ;
this.subOps = subOps ;
}
@Override
protected QueryIterator nextStage(Binding binding)
{
QueryIterConcat unionQIter = new QueryIterConcat(getExecContext()) ;
for (Op subOp : subOps)
{
subOp = QC.substitute(subOp, binding) ;
QueryIterator parent = QueryIterSingleton.create(binding, getExecContext()) ;
QueryIterator qIter = QC.execute(subOp, parent, getExecContext()) ;
unionQIter.add(qIter) ;
}
return unionQIter ;
}
@Override
public void output(IndentedWriter out, SerializationContext sCxt)
{
out.println(Utils.className(this)) ;
out.incIndent() ;
for (Op op : subOps)
op.output(out, sCxt) ;
out.decIndent() ;
out.ensureStartOfLine() ;
}
}