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XPathFuncHereAPI.javaAPI DocJava SE 6 API12317Tue Jun 10 00:23:04 BST 2008com.sun.org.apache.xml.internal.security.utils

XPathFuncHereAPI

public class XPathFuncHereAPI extends Object
This class does the same as {@link com.sun.org.apache.xpath.internal.XPathAPI} except that the XPath strings are not supplied as Strings but as {@link Text}, {@link Attr}ibute or {ProcessingInstruction} nodes which contain the XPath string. This enables us to use the here() function.
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.
author
$Author: raul $
see
XPath Specification

Fields Summary
Constructors Summary
Methods Summary
public static com.sun.org.apache.xpath.internal.objects.XObjecteval(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode)
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
xpathnode
return
An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
see
com.sun.org.apache.xpath.internal.objects.XObject
see
com.sun.org.apache.xpath.internal.objects.XNull
see
com.sun.org.apache.xpath.internal.objects.XBoolean
see
com.sun.org.apache.xpath.internal.objects.XNumber
see
com.sun.org.apache.xpath.internal.objects.XString
see
com.sun.org.apache.xpath.internal.objects.XRTreeFrag
throws
TransformerException

      return eval(contextNode, xpathnode, contextNode);
public static com.sun.org.apache.xpath.internal.objects.XObjecteval(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode, org.w3c.dom.Node namespaceNode)
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
xpathnode
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
com.sun.org.apache.xpath.internal.objects.XObject
see
com.sun.org.apache.xpath.internal.objects.XNull
see
com.sun.org.apache.xpath.internal.objects.XBoolean
see
com.sun.org.apache.xpath.internal.objects.XNumber
see
com.sun.org.apache.xpath.internal.objects.XString
see
com.sun.org.apache.xpath.internal.objects.XRTreeFrag
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.)
      FuncHereContext xpathSupport = new FuncHereContext(xpathnode);

      // 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);
      String str = getStrFromNode(xpathnode);

      // 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);
      int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);

      return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
public static com.sun.org.apache.xpath.internal.objects.XObjecteval(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode, com.sun.org.apache.xml.internal.utils.PrefixResolver 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
xpathnode
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
com.sun.org.apache.xpath.internal.objects.XObject
see
com.sun.org.apache.xpath.internal.objects.XNull
see
com.sun.org.apache.xpath.internal.objects.XBoolean
see
com.sun.org.apache.xpath.internal.objects.XNumber
see
com.sun.org.apache.xpath.internal.objects.XString
see
com.sun.org.apache.xpath.internal.objects.XRTreeFrag
throws
TransformerException


      String str = getStrFromNode(xpathnode);

      // 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
      FuncHereContext xpathSupport = new FuncHereContext(xpathnode);
      int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);

      return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
private static java.lang.StringgetStrFromNode(org.w3c.dom.Node xpathnode)
Method getStrFromNode

param
xpathnode
return
the string from the node


      if (xpathnode.getNodeType() == Node.TEXT_NODE) {
         return ((Text) xpathnode).getData();
      } else if (xpathnode.getNodeType() == Node.ATTRIBUTE_NODE) {
         return ((Attr) xpathnode).getNodeValue();
      } else if (xpathnode.getNodeType() == Node.PROCESSING_INSTRUCTION_NODE) {
         return ((ProcessingInstruction) xpathnode).getNodeValue();
      }

      return "";
public static org.w3c.dom.traversal.NodeIteratorselectNodeIterator(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode)
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
xpathnode
return
A NodeIterator, should never be null.
throws
TransformerException

      return selectNodeIterator(contextNode, xpathnode, contextNode);
public static org.w3c.dom.traversal.NodeIteratorselectNodeIterator(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode, org.w3c.dom.Node namespaceNode)
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
xpathnode
param
namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
return
A NodeIterator, should never be null.
throws
TransformerException


      // Execute the XPath, and have it return the result
      XObject list = eval(contextNode, xpathnode, namespaceNode);

      // Have the XObject return its result as a NodeSetDTM.
      return list.nodeset();
public static org.w3c.dom.NodeListselectNodeList(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode)
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
xpathnode
return
A NodeIterator, should never be null.
throws
TransformerException

      return selectNodeList(contextNode, xpathnode, contextNode);
public static org.w3c.dom.NodeListselectNodeList(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode, org.w3c.dom.Node namespaceNode)
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
xpathnode
param
namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
return
A NodeIterator, should never be null.
throws
TransformerException


      // Execute the XPath, and have it return the result
      XObject list = eval(contextNode, xpathnode, namespaceNode);

      // Return a NodeList.
      return list.nodelist();
public static org.w3c.dom.NodeselectSingleNode(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode)
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
xpathnode A Node containing a valid XPath string.
return
The first node found that matches the XPath, or null.
throws
TransformerException

      return selectSingleNode(contextNode, xpathnode, contextNode);
public static org.w3c.dom.NodeselectSingleNode(org.w3c.dom.Node contextNode, org.w3c.dom.Node xpathnode, org.w3c.dom.Node namespaceNode)
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
xpathnode
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


      // Have the XObject return its result as a NodeSetDTM.
      NodeIterator nl = selectNodeIterator(contextNode, xpathnode,
                                           namespaceNode);

      // Return the first node, or null
      return nl.nextNode();