/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2013, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.internal.util.xml;
import java.util.Deque;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;
/**
* Base class for {@link XMLEventReader}s that want to modify or remove events from the reader stream.
* If a {@link StartElement} event is removed the subclass's {@link #filterEvent(XMLEvent, boolean)} will
* not see any events until after the matching {@link EndElement} event.
*
* Note, copied from the uPortal project by permission of author. See
* https://github.com/Jasig/uPortal/blob/master/uportal-war/src/main/java/org/jasig/portal/xml/stream/FilteringXMLEventReader.java
*
* @author Eric Dalquist
*/
public abstract class FilteringXMLEventReader extends BaseXMLEventReader {
private final Deque<QName> prunedElements = new LinkedList<QName>();
private XMLEvent peekedEvent;
public FilteringXMLEventReader(XMLEventReader reader) {
super(reader);
}
@Override
protected final XMLEvent internalNextEvent() throws XMLStreamException {
return this.internalNext(false);
}
@Override
public boolean hasNext() {
try {
return peekedEvent != null || (super.hasNext() && this.peek() != null);
}
catch (XMLStreamException e) {
throw new RuntimeException(e.getMessage(), e);
}
catch (NoSuchElementException e) {
return false;
}
}
@Override
public final XMLEvent peek() throws XMLStreamException {
if (peekedEvent != null) {
return peekedEvent;
}
peekedEvent = internalNext(true);
return peekedEvent;
}
protected final XMLEvent internalNext(boolean peek) throws XMLStreamException {
XMLEvent event = null;
if (peekedEvent != null) {
event = peekedEvent;
peekedEvent = null;
return event;
}
do {
event = super.getParent().nextEvent();
//If there are pruned elements in the queue filtering events is still needed
if (!prunedElements.isEmpty()) {
//If another start element add it to the queue
if (event.isStartElement()) {
final StartElement startElement = event.asStartElement();
prunedElements.push(startElement.getName());
}
//If end element pop the newest name of the queue and double check that the start/end elements match up
else if (event.isEndElement()) {
final QName startElementName = prunedElements.pop();
final EndElement endElement = event.asEndElement();
final QName endElementName = endElement.getName();
if (!startElementName.equals(endElementName)) {
throw new IllegalArgumentException("Malformed XMLEvent stream. Expected end element for " + startElementName + " but found end element for " + endElementName);
}
}
event = null;
}
else {
final XMLEvent filteredEvent = this.filterEvent(event, peek);
//If the event is being removed and it is a start element all elements until the matching
//end element need to be removed as well
if (filteredEvent == null && event.isStartElement()) {
final StartElement startElement = event.asStartElement();
final QName name = startElement.getName();
prunedElements.push(name);
}
event = filteredEvent;
}
}
while (event == null);
return event;
}
/**
* @param event The current event
* @param peek If the event is from a {@link #peek()} call
* @return The event to return, if null is returned the event is dropped from the stream and the next event will be used.
*/
protected abstract XMLEvent filterEvent(XMLEvent event, boolean peek);
}