/*
* Copyright (c) 2002-2010 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
* 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 com.gargoylesoftware.htmlunit.html.xpath;
import java.util.ArrayList;
import java.util.List;
import javax.xml.transform.TransformerException;
import org.apache.xml.utils.PrefixResolver;
import org.apache.xpath.XPathContext;
import org.apache.xpath.objects.XBoolean;
import org.apache.xpath.objects.XNodeSet;
import org.apache.xpath.objects.XNumber;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XString;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.gargoylesoftware.htmlunit.html.DomNode;
/**
* Collection of XPath utility methods.
*
* @version $Revision: 5301 $
* @author Ahmed Ashour
*/
public final class XPathUtils {
private static ThreadLocal<Boolean> PROCESS_XPATH_ = new ThreadLocal<Boolean>() {
@Override
protected synchronized Boolean initialValue() {
return false;
}
};
/**
* Private to avoid instantiation.
*/
private XPathUtils() {
// Empty.
}
/**
* Evaluates an XPath expression from the specified node, returning the resultant nodes.
*
* @param node the node to start searching from
* @param xpathExpr the XPath expression
* @return the list of objects found
*/
public static List<Object> getByXPath(final DomNode node, final String xpathExpr) {
if (xpathExpr == null) {
throw new NullPointerException("Null is not a valid XPath expression");
}
PROCESS_XPATH_.set(true);
final List<Object> list = new ArrayList<Object>();
try {
final XObject result = evaluateXPath(node, xpathExpr);
if (result instanceof XNodeSet) {
final NodeList nodelist = ((XNodeSet) result).nodelist();
for (int i = 0; i < nodelist.getLength(); i++) {
list.add(nodelist.item(i));
}
}
else if (result instanceof XNumber) {
list.add(result.num());
}
else if (result instanceof XBoolean) {
list.add(result.bool());
}
else if (result instanceof XString) {
list.add(result.str());
}
else {
throw new RuntimeException("Unproccessed " + result.getClass().getName());
}
}
catch (final Exception e) {
throw new RuntimeException("Could not retrieve XPath >" + xpathExpr + "< on " + node, e);
}
finally {
PROCESS_XPATH_.set(false);
}
return list;
}
/**
* Returns whether the thread is currently evaluating XPath expression or no.
* @return whether the thread is currently evaluating XPath expression or no
*/
public static boolean isProcessingXPath() {
return PROCESS_XPATH_.get();
}
/**
* Evaluates an XPath expression to an XObject.
* @param contextNode the node to start searching from
* @param str a valid XPath string
* @return an XObject, which can be used to obtain a string, number, nodelist, etc (should never be <tt>null</tt>)
* @throws TransformerException if a syntax or other error occurs
*/
private static XObject evaluateXPath(final DomNode contextNode, final String str) throws TransformerException {
final XPathContext xpathSupport = new XPathContext();
final Node xpathExpressionContext;
if (contextNode.getNodeType() == Node.DOCUMENT_NODE) {
xpathExpressionContext = ((Document) contextNode).getDocumentElement();
}
else {
xpathExpressionContext = contextNode;
}
final PrefixResolver prefixResolver = new HtmlUnitPrefixResolver(xpathExpressionContext);
final boolean caseSensitive = contextNode.getPage().hasCaseSensitiveTagNames();
final XPathAdapter xpath = new XPathAdapter(str, null, prefixResolver, null, caseSensitive);
final int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);
return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
}
}