org.apache.jackrabbit.webdav.xml.ElementIterator Maven / Gradle / Ivy
/*
* 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.jackrabbit.webdav.xml;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.xml.namespace.QName;
/**
* ElementIterator...
*/
public class ElementIterator implements Iterator {
private static Logger log = LoggerFactory.getLogger(ElementIterator.class);
private final Namespace namespace;
private final String localName;
private final QName qName;
private Element next;
/**
* Create a new instance of ElementIterator with the given
* parent element. Only child elements that match the given local name
* and namespace will be respected by {@link #hasNext()} and {@link #nextElement()}.
*
* @param parent
* @param localName local name the child elements must match
* @param namespace namespace the child elements must match
*/
public ElementIterator(Element parent, String localName, Namespace namespace) {
this.localName = localName;
this.namespace = namespace;
this.qName = null;
seek(parent);
}
/**
* Create a new instance of ElementIterator with the given
* parent element. Only child elements that match the given {@link QName}
* will be respected by {@link #hasNext()} and {@link #nextElement()}.
*
* @param parent
* @param qname name to match (exactly)
*/
public ElementIterator(Element parent, QName qname) {
this.localName = null;
this.namespace = null;
this.qName = qname;
seek(parent);
}
/**
* Create a new instance of ElementIterator with the given
* parent element. No filtering is applied to child elements that are
* iterated.
*
* @param parent
*/
public ElementIterator(Element parent) {
this(parent, null, null);
}
/**
* Not implemented
*
* @throws UnsupportedOperationException
*/
public void remove() {
throw new UnsupportedOperationException("Remove not implemented.");
}
/**
* Returns true if there is a next Element
*
* @return true if a next Element is available.
*/
public boolean hasNext() {
return next != null;
}
/**
* @see java.util.Iterator#next()
* @see #nextElement()
*/
public Element next() {
return nextElement();
}
/**
* Returns the next Element in the iterator.
*
* @return the next element
* @throws NoSuchElementException if there is no next element.
*/
public Element nextElement() {
if (next==null) {
throw new NoSuchElementException();
}
Element ret = next;
seek();
return ret;
}
/**
* Seeks for the first matching child element
*/
private void seek(Element parent) {
NodeList nodeList = parent.getChildNodes();
for (int i = 0; i < nodeList.getLength(); i++) {
Node n = nodeList.item(i);
if (matchesName(n)) {
next = (Element)n;
return;
}
}
}
/**
* Seeks for the next valid element (i.e. the next valid sibling)
*/
private void seek() {
Node n = next.getNextSibling();
while (n != null) {
if (matchesName(n)) {
next = (Element)n;
return;
} else {
n = n.getNextSibling();
}
}
// no next element found -> set to null in order to leave the loop.
next = null;
}
/**
* Matches the node name according to either {@link #qName} or the pair
* of {@link #localName) and {@link #namespace}.
*/
private boolean matchesName(Node n) {
if (!DomUtil.isElement(n)) {
return false;
} else if (qName != null) {
return DomUtil.matches(n, qName);
} else {
return DomUtil.matches(n, localName, namespace);
}
}
}