/*
* 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.atlas.iterator;
import java.util.Iterator ;
import java.util.NoSuchElementException ;
import java.util.concurrent.BlockingQueue ;
/** Iterator over a blocking queue until queue end seen */
public class IteratorBlockingQueue<T> implements Iterator<T>
{
private BlockingQueue<T> queue ;
private boolean finished = false ;
private T slot = null ;
private T endMarker ;
public IteratorBlockingQueue(BlockingQueue<T> queue, T endMarker) { this.queue = queue ; this.endMarker = endMarker ; }
@Override
public boolean hasNext()
{
if ( finished ) return false ;
if ( slot != null ) return true ;
try
{
slot = queue.take() ;
if ( slot == endMarker )
{
finished = true ;
slot = null ;
return false ;
}
return true ;
} catch (InterruptedException ex)
{
ex.printStackTrace();
}
return false ;
}
@Override
public T next()
{
if ( ! hasNext() )
throw new NoSuchElementException() ;
T item = slot ;
slot = null ;
return item ;
}
@Override
public void remove()
{ throw new UnsupportedOperationException() ; }
}