/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2004-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
*/
package org.geotools.feature;
import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.geotools.data.FeatureReader;
import org.opengis.feature.Feature;
import org.opengis.feature.type.FeatureType;
/**
* An iterator that wraps around a FeatureReader.
* <p>
* The Iterator's hasNext() will return false if the wrapped feature reader's hasNext method throws
* an exception. If next() throws an exception a NoSuchElementException will be thrown.
* </p>
* <p>
* {@link #close()} shall be called before disposing the iterator. Before propagating an exception
* from {@link #next()} or eating an exception from the underlying feature reader at
* {@link #hasNext()}, this iterator will auto-close.
* </p>
*
* @author jeichar
* @author Jody Garnett
* @author Gabriel Roldan
*
*
* @source $URL$
*/
public class FeatureReaderIterator<F extends Feature> implements Iterator<F>, Closeable {
FeatureReader<? extends FeatureType, F> reader;
public FeatureReaderIterator(FeatureReader<? extends FeatureType, F> reader) {
this.reader = reader;
}
public boolean hasNext() {
try {
if (reader == null)
return false;
if (reader.hasNext()) {
return true;
} else {
// auto close because we don't trust
// client code to call closed :-)
close();
return false;
}
} catch (Exception e) {
close();
return false; // failure sounds like lack of next to me
}
}
public F next() {
if (reader == null) {
throw new NoSuchElementException("Iterator has been closed");
}
try {
return reader.next();
} catch (IOException io) {
close();
NoSuchElementException problem = new NoSuchElementException(
"Could not obtain the next feature:" + io);
problem.initCause(io);
throw problem;
} catch (org.opengis.feature.IllegalAttributeException create) {
close();
NoSuchElementException problem = new NoSuchElementException(
"Could not create the next feature:" + create);
problem.initCause(create);
throw problem;
}
}
/** If this is a problem, a different iterator can be made based on FeatureWriter */
public void remove() {
throw new UnsupportedOperationException("Modification of contents is not supported");
}
/**
* Close the reader please.
*/
public void close() {
if (reader != null) {
try {
reader.close();
} catch (Exception e) {
// sorry but iterators die quitely in the night
}
reader = null;
}
}
}