/*
* 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;
import java.util.Iterator ;
import java.util.List ;
import java.util.NoSuchElementException ;
import org.apache.jena.atlas.lib.Closeable ;
import com.hp.hpl.jena.query.QuerySolution ;
import com.hp.hpl.jena.query.ResultSet ;
import com.hp.hpl.jena.rdf.model.Model ;
import com.hp.hpl.jena.sparql.core.ResultBinding ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
/** The main ResultSet implementation for returning results from queries.
* This version is "use once" - you can not reset the result set because
* the results of the query are not remembered so as not to consume potentially
* large amounts of memory. */
public class ResultSetStream implements ResultSet
{
// Could use QueryIteratorWrapper
private Iterator<Binding> queryExecutionIter ;
private List<String> resultVars ;
private QuerySolution currentQuerySolution ;
private int rowNumber ;
private Model model ;
public ResultSetStream(List<String> resultVars, Model m, Iterator<Binding> iter)
{
queryExecutionIter = iter ;
this.resultVars = resultVars ;
currentQuerySolution = null ;
rowNumber = 0 ;
model = m ;
}
/**
* @throws UnsupportedOperationException Always thrown.
*/
@Override
public void remove() throws java.lang.UnsupportedOperationException
{
throw new UnsupportedOperationException(this.getClass().getName()+".remove") ;
}
/**
* Is there another possibility?
*/
@Override
public boolean hasNext()
{
if ( queryExecutionIter == null )
return false ;
boolean r = queryExecutionIter.hasNext() ;
if ( !r )
close() ;
return r;
}
@Override
public Binding nextBinding()
{
if (queryExecutionIter == null) throw new NoSuchElementException(this.getClass() + ".next") ;
try {
Binding binding = queryExecutionIter.next() ;
if (binding != null) rowNumber++ ;
return binding ;
} catch (NoSuchElementException ex) {
close() ;
throw ex ;
}
}
private void close()
{
// ARQ QueryIterators are org.apache.jena.atlas.lib.Closable.
if ( queryExecutionIter instanceof Closeable )
((Closeable)queryExecutionIter).close() ;
}
/** Moves onto the next result possibility.
* The returned object is actual the binding for this
* result.
*/
@Override
public QuerySolution nextSolution()
{
if ( queryExecutionIter == null )
// ||
// ( queryExecution != null && ! queryExecution.isActive() ) )
throw new NoSuchElementException(this.getClass()+".next") ;
Binding binding = nextBinding() ;
currentQuerySolution = new ResultBinding(model, binding) ;
return currentQuerySolution ;
}
/** Moves onto the next result possibility.*/
@Override
public QuerySolution next() { return nextSolution() ; }
/** Return the "row number" - a count of the number of possibilities returned so far.
* Remains valid (as the total number of possibilities) after the iterator ends.
*/
@Override
public int getRowNumber()
{
return rowNumber ;
}
/** Get the variable names for the projection
*/
@Override
public List<String> getResultVars() { return resultVars ; }
public Model getModel() { return model ; }
@Override
public Model getResourceModel() { return model ; }
}