/*
* 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.sparql.engine.iterator;
import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.atlas.lib.Lib ;
import org.apache.jena.sparql.engine.ExecutionContext ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.procedure.Procedure ;
import org.apache.jena.sparql.serializer.SerializationContext ;
/** QueryIterator for a procedure. Delays first touch until first call because
* first touch may cause work to be done.
*
* Assumes .build already called. */
public class QueryIterProcedure extends QueryIter1
{
private Procedure proc ;
private boolean initialized = false ;
private QueryIterator procIter = null ;
public QueryIterProcedure(QueryIterator input, Procedure proc, ExecutionContext execCxt)
{
super(input, execCxt) ;
this.proc = proc ;
}
private void init()
{
if ( ! initialized )
{
procIter = proc.proc(getInput(), getExecContext()) ;
initialized = true ;
}
}
@Override
protected void closeSubIterator()
{
init() ; // Ensure initialized even if immediately closed.
procIter.close();
}
@Override
protected void requestSubCancel()
{
if (procIter != null)
procIter.cancel();
}
@Override
protected boolean hasNextBinding()
{
init() ;
return procIter.hasNext() ;
}
@Override
protected Binding moveToNextBinding()
{
init( ) ;
return procIter.nextBinding() ;
}
@Override
protected void details(IndentedWriter out, SerializationContext sCxt)
{
out.print(Lib.className(this)) ;
out.print(" ") ;
proc.output(out, sCxt) ;
}
}