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A headless browser intended for use in testing web-based applications.
/*
* Copyright (c) 2002-2022 Gargoyle Software Inc.
*
* Licensed 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
* https://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 com.gargoylesoftware.htmlunit.html;
import java.io.Serializable;
import java.lang.ref.WeakReference;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.List;
import org.w3c.dom.Node;
/**
* A generic DomNodeList implementation of {@link org.w3c.dom.NodeList}.
*
* @param The element type
*
* @author Daniel Gredler
* @author Tom Anderson
* @author Ronald Brill
*/
public abstract class AbstractDomNodeList extends AbstractList
implements DomNodeList, Serializable {
/** This node list's root node. */
private DomNode node_;
/** Element cache, used to avoid XPath expression evaluation as much as possible. */
private List cachedElements_;
/**
* Creates a new node list. The elements will be "calculated" using the specified XPath
* expression applied on the specified node.
* @param node the node to serve as root for the XPath expression
*/
public AbstractDomNodeList(final DomNode node) {
if (node != null) {
node_ = node;
final DomHtmlAttributeChangeListenerImpl listener = new DomHtmlAttributeChangeListenerImpl(this);
node_.addDomChangeListener(listener);
if (node_ instanceof HtmlElement) {
((HtmlElement) node_).addHtmlAttributeChangeListener(listener);
cachedElements_ = null;
}
}
}
/**
* Returns the DOM node.
* @return the DOM node
*/
protected DomNode getDomNode() {
return node_;
}
/**
* Returns the elements.
* @return the elements
*/
protected abstract List provideElements();
/**
* Returns the nodes in this node list, caching as necessary.
* @return the nodes in this node list
*/
private List getNodes() {
if (cachedElements_ == null) {
if (node_ == null) {
cachedElements_ = new ArrayList<>();
}
else {
cachedElements_ = provideElements();
}
}
return cachedElements_;
}
/**
* {@inheritDoc}
*/
@Override
public int size() {
return getLength();
}
/**
* {@inheritDoc}
*/
@Override
public int getLength() {
return getNodes().size();
}
/**
* {@inheritDoc}
*/
@Override
public Node item(final int index) {
return getNodes().get(index);
}
/**
* {@inheritDoc}
*/
@Override
public E get(final int index) {
return getNodes().get(index);
}
/**
* DOM change listener which clears the node cache when necessary.
*/
private static final class DomHtmlAttributeChangeListenerImpl
implements DomChangeListener, HtmlAttributeChangeListener {
private final transient WeakReference> nodeList_;
DomHtmlAttributeChangeListenerImpl(final AbstractDomNodeList nodeList) {
super();
nodeList_ = new WeakReference<>(nodeList);
}
/**
* {@inheritDoc}
*/
@Override
public void nodeAdded(final DomChangeEvent event) {
clearCache();
}
/**
* {@inheritDoc}
*/
@Override
public void nodeDeleted(final DomChangeEvent event) {
clearCache();
}
/**
* {@inheritDoc}
*/
@Override
public void attributeAdded(final HtmlAttributeChangeEvent event) {
clearCache();
}
/**
* {@inheritDoc}
*/
@Override
public void attributeRemoved(final HtmlAttributeChangeEvent event) {
clearCache();
}
/**
* {@inheritDoc}
*/
@Override
public void attributeReplaced(final HtmlAttributeChangeEvent event) {
clearCache();
}
private void clearCache() {
if (nodeList_ != null) {
final AbstractDomNodeList nodes = nodeList_.get();
if (nodes != null) {
nodes.cachedElements_ = null;
}
}
}
}
}