/*
* 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 org.apache.jena.atlas.AtlasException ;
import org.apache.jena.atlas.io.IO ;
import org.apache.jena.atlas.lib.Closeable ;
/**
* This iterator will automatically close a {@link org.apache.jena.atlas.lib.Closeable} or {@link java.io.Closeable}
* resource when the iterator is exhausted. Alternatively, the resource will be closed when {@link #close()} is
* called. An {@link AtlasException} will be thrown if access is attempted after {@link #close()} has been called.
*/
public class IteratorResourceClosing<T> implements Iterator<T>, Closeable
{
private final Iterator<T> iter ;
private final Object resource ;
private boolean finished;
public IteratorResourceClosing(Iterator<T> iter, Closeable resource)
{
this.iter = iter;
this.resource = resource;
this.finished = false;
}
public IteratorResourceClosing(Iterator<T> iter, java.io.Closeable resource)
{
this.iter = iter;
this.resource = resource ;
this.finished = false;
}
private void checkFinished()
{
if (finished) throw new AtlasException("IteratorResourceClosing is closed, no further operations can be performed on it.") ;
}
@Override
public boolean hasNext()
{
if (finished)
return false;
boolean toReturn = iter.hasNext();
// Clean up if we are done
if (!toReturn)
{
close();
}
return toReturn ;
}
@Override
public T next()
{
checkFinished();
return iter.next() ;
}
@Override
public void remove()
{
checkFinished();
iter.remove() ;
}
@Override
public void close()
{
if (!finished)
{
Iter.close(iter) ;
if (null != resource)
{
if (resource instanceof Closeable)
{
((Closeable)resource).close() ;
}
else
{
IO.close((java.io.Closeable)resource) ;
}
}
finished = true;
}
}
}