/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xalan" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 1999, Lotus
* Development Corporation., http://www.lotus.com. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
import org.xml.sax.SAXException;
import org.w3c.dom.Node;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.apache.xalan.xpath.XPathSupport;
import org.apache.xalan.xpath.XPath;
import org.apache.xalan.xpath.XPathProcessorImpl;
import org.apache.xalan.xpath.xml.XMLParserLiaisonDefault;
import org.apache.xalan.xpath.xml.PrefixResolverDefault;
import org.apache.xalan.xpath.XObject;
/**
* The methods in this class are convenience methods into the
* low-level XPath API. We would like to eventually move these
* methods into the XPath core, but would like to do some peer
* review first to make sure we have it right.
* Please note that these methods execute pure XPaths. They do not
* implement those parts of XPath extended by XSLT, such as the
* document() function). If you want to install XSLT functions, you
* have to use the low-level API.
* These functions tend to be a little slow, since a number of objects must be
* created for each evaluation. A faster way is to precompile the
* XPaths using the low-level API, and then just use the XPaths
* over and over.
* @see http://www.w3.org/TR/xpath
*/
public class XPathAPI
{
/**
* Use an XPath string to select a single node. XPath namespace
* prefixes are resolved from the context node, which may not
* be what you want (see the next method).
*
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @return The first node found that matches the XPath, or null.
*/
public static Node selectSingleNode(Node contextNode, String str)
throws SAXException
{
return selectSingleNode(contextNode, str, contextNode);
}
/**
* Use an XPath string to select a single node.
* XPath namespace prefixes are resolved from the namespaceNode.
*
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
* @return The first node found that matches the XPath, or null.
*/
public static Node selectSingleNode(Node contextNode, String str, Node namespaceNode)
throws SAXException
{
// Have the XObject return its result as a NodeSet.
NodeList nl = selectNodeList(contextNode, str, namespaceNode);
// Return the first node, or null
return (nl.getLength() > 0) ? nl.item(0) : null;
}
/**
* Use an XPath string to select a nodelist.
* XPath namespace prefixes are resolved from the contextNode.
*
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @return A nodelist, should never be null.
*/
public static NodeList selectNodeList(Node contextNode, String str)
throws SAXException
{
return selectNodeList(contextNode, str, contextNode);
}
/**
* Use an XPath string to select a nodelist.
* XPath namespace prefixes are resolved from the namespaceNode.
*
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
* @return A nodelist, should never be null.
*/
public static NodeList selectNodeList(Node contextNode, String str, Node namespaceNode)
throws SAXException
{
// Execute the XPath, and have it return the result
XObject list = eval(contextNode, str, namespaceNode);
// Have the XObject return its result as a NodeSet.
return list.nodeset();
}
/**
* Evaluate XPath string to an XObject. Using this method,
* XPath namespace prefixes will be resolved from the namespaceNode.
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
* @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
* @see org.apache.xalan.xpath.XObject
* @see org.apache.xalan.xpath.XNull
* @see org.apache.xalan.xpath.XBoolean
* @see org.apache.xalan.xpath.XNumber
* @see org.apache.xalan.xpath.XString
* @see org.apache.xalan.xpath.XRTreeFrag
*/
public static XObject eval(Node contextNode, String str)
throws SAXException
{
return eval(contextNode, str, contextNode);
}
/**
* Evaluate XPath string to an XObject.
* XPath namespace prefixes are resolved from the namespaceNode.
* The implementation of this is a little slow, since it creates
* a number of objects each time it is called. This could be optimized
* to keep the same objects around, but then thread-safety issues would arise.
*
* @param contextNode The node to start searching from.
* @param str A valid XPath string.
* @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
* @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
* @see org.apache.xalan.xpath.XObject
* @see org.apache.xalan.xpath.XNull
* @see org.apache.xalan.xpath.XBoolean
* @see org.apache.xalan.xpath.XNumber
* @see org.apache.xalan.xpath.XString
* @see org.apache.xalan.xpath.XRTreeFrag
*/
public static XObject eval(Node contextNode, String str, Node namespaceNode)
throws SAXException
{
// Since we don't have a XML Parser involved here, install some default support
// for things like namespaces, etc.
// (Changed from: XPathSupportDefault xpathSupport = new XPathSupportDefault();
// because XPathSupportDefault is weak in a number of areas... perhaps
// XPathSupportDefault should be done away with.)
XPathSupport xpathSupport = new XMLParserLiaisonDefault();
// Create an object to resolve namespace prefixes.
// XPath namespaces are resolved from the input context node's document element
// if it is a root node, or else the current context node (for lack of a better
// resolution space, given the simplicity of this sample code).
PrefixResolverDefault prefixResolver = new PrefixResolverDefault((contextNode.getNodeType() == Node.DOCUMENT_NODE)
? ((Document)contextNode).getDocumentElement() :
contextNode);
// Create the XPath object.
XPath xpath = new XPath();
// Create a XPath parser.
XPathProcessorImpl parser = new XPathProcessorImpl(xpathSupport);
parser.initXPath(xpath, str, prefixResolver);
// Execute the XPath, and have it return the result
return xpath.execute(xpathSupport, contextNode, prefixResolver);
}
}