/*
* 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 java.util.NoSuchElementException ;
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.serializer.SerializationContext ;
/** Closeable empty query iterator */
public class QueryIterNullIterator extends QueryIter
{
public static QueryIterator create(ExecutionContext qCxt) { return new QueryIterNullIterator(qCxt) ; }
// Or QueryIterYieldN with N = 0 ;
// but sometimes it clearer just to w-r-i-t-e the code.
public QueryIterNullIterator(ExecutionContext qCxt) { super(qCxt) ; }
@Override
protected boolean hasNextBinding()
{ return false ; }
@Override
protected Binding moveToNextBinding()
{ throw new NoSuchElementException(Lib.className(this)) ; }
@Override
protected void closeIterator() {}
@Override
protected void requestCancel() { }
@Override
public void output(IndentedWriter out, SerializationContext sCxt)
{ out.println(Lib.className(this)) ; }
}