/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
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* 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
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* 2. Redistributions in binary form must reproduce the above copyright
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* 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.
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* 4. The names "Xalan" and "Apache Software Foundation" must
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* ====================================================================
*
* 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/>.
*/
package org.apache.xpath;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Node;
import org.w3c.dom.Document;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.NodeList;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPath;
import org.apache.xpath.compiler.XPathParser;
import org.apache.xpath.XPathContext;
import org.apache.xml.utils.PrefixResolverDefault;
import org.apache.xml.utils.PrefixResolver;
import org.apache.xpath.objects.XObject;
/**
* The methods in this class are convenience methods into the
* low-level XPath 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 <a href="http://www.w3.org/TR/xpath">XPath Specification</a>
*/
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.
*
* @throws TransformerException
*/
public static Node selectSingleNode(Node contextNode, String str)
throws TransformerException
{
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.
*
* @throws TransformerException
*/
public static Node selectSingleNode(
Node contextNode, String str, Node namespaceNode)
throws TransformerException
{
// Have the XObject return its result as a NodeSet.
NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode);
// Return the first node, or null
return nl.nextNode();
}
/**
* 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 NodeIterator, should never be null.
*
* @throws TransformerException
*/
public static NodeIterator selectNodeIterator(Node contextNode, String str)
throws TransformerException
{
return selectNodeIterator(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 NodeIterator, should never be null.
*
* @throws TransformerException
*/
public static NodeIterator selectNodeIterator(
Node contextNode, String str, Node namespaceNode)
throws TransformerException
{
// 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();
}
/**
* 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 NodeIterator, should never be null.
*
* @throws TransformerException
*/
public static NodeList selectNodeList(Node contextNode, String str)
throws TransformerException
{
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 NodeIterator, should never be null.
*
* @throws TransformerException
*/
public static NodeList selectNodeList(
Node contextNode, String str, Node namespaceNode)
throws TransformerException
{
// Execute the XPath, and have it return the result
XObject list = eval(contextNode, str, namespaceNode);
// Patch attributed to nboyd@atg.com (Norris Boyd)
NodeSet nodeset = list.mutableNodeset();
// setShouldCacheNodes(true) be called before the first nextNode() is
// called, in order that nodes can be added as they are fetched.
nodeset.setShouldCacheNodes(true);
// Return a NodeList.
return (NodeList) 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.xpath.objects.XObject
* @see org.apache.xpath.objects.XNull
* @see org.apache.xpath.objects.XBoolean
* @see org.apache.xpath.objects.XNumber
* @see org.apache.xpath.objects.XString
* @see org.apache.xpath.objects.XRTreeFrag
*
* @throws TransformerException
*/
public static XObject eval(Node contextNode, String str) throws TransformerException
{
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.xpath.objects.XObject
* @see org.apache.xpath.objects.XNull
* @see org.apache.xpath.objects.XBoolean
* @see org.apache.xpath.objects.XNumber
* @see org.apache.xpath.objects.XString
* @see org.apache.xpath.objects.XRTreeFrag
*
* @throws TransformerException
*/
public static XObject eval(Node contextNode, String str, Node namespaceNode)
throws TransformerException
{
// Since we don't have a XML Parser involved here, install some default support
// for things like namespaces, etc.
// (Changed from: XPathContext xpathSupport = new XPathContext();
// because XPathContext is weak in a number of areas... perhaps
// XPathContext should be done away with.)
XPathContext xpathSupport = new XPathContext();
// 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(
(namespaceNode.getNodeType() == Node.DOCUMENT_NODE)
? ((Document) namespaceNode).getDocumentElement() : namespaceNode);
// Create the XPath object.
XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
// Execute the XPath, and have it return the result
return xpath.execute(xpathSupport, contextNode, prefixResolver);
}
/**
* 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.
* @param prefixResolver Will be called if the parser encounters namespace
* prefixes, to resolve the prefixes to URLs.
* @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
* @see org.apache.xpath.objects.XObject
* @see org.apache.xpath.objects.XNull
* @see org.apache.xpath.objects.XBoolean
* @see org.apache.xpath.objects.XNumber
* @see org.apache.xpath.objects.XString
* @see org.apache.xpath.objects.XRTreeFrag
*
* @throws TransformerException
*/
public static XObject eval(
Node contextNode, String str, PrefixResolver prefixResolver)
throws TransformerException
{
// Since we don't have a XML Parser involved here, install some default support
// for things like namespaces, etc.
// (Changed from: XPathContext xpathSupport = new XPathContext();
// because XPathContext is weak in a number of areas... perhaps
// XPathContext should be done away with.)
// Create the XPath object.
XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
// Execute the XPath, and have it return the result
return xpath.execute(new XPathContext(), contextNode, prefixResolver);
}
}