src/org/apache/xml/security/transforms/implementations/FuncHereContext.java

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package org.apache.xml.security.transforms.implementations;



import org.apache.xml.dtm.DTMManager;
import org.apache.xml.security.utils.I18n;
import org.apache.xpath.CachedXPathAPI;
import org.apache.xpath.XPathContext;
import org.w3c.dom.Node;


/**
 * {@link FuncHereContext} extends {@link XPathContext} for supplying context
 * for the <CODE>here()</CODE> function. The here() function needs to know
 * <I>where</I> in an XML instance the XPath text string appeared. This can be
 * in {@link Text}, {@link Attr}ibutes and {@ProcessingInstrinction} nodes. The
 * correct node must be supplied to the constructor of {@link FuncHereContext}.
 * The supplied Node MUST contain the XPath which is to be executed.
 *
 * <PRE>
 * From: Scott_Boag\@lotus.com
 * To: Christian Geuer-Pollmann <maillist\@nue.et-inf.uni-siegen.de>
 * CC: xalan-dev@xml.apache.org
 * Subject: Re: Cleanup of XPathContext & definition of XSLTContext
 * Date: Tue, 21 Aug 2001 18:36:24 -0400
 *
 * > My point is to say to get this baby to run, the XPath must have a
 * > possibility to retrieve the information where itself occured in a
 * > document.
 *
 * It sounds to me like you have to derive an XMLSigContext from the
 * XPathContext?
 *
 * > and supplied the Node which contains the xpath string as "owner". Question:
 * > Is this the correct use of the owner object? It works, but I don't know
 * > whether this is correct from the xalan-philosophy...
 *
 * Philosophically it's fine.  The owner is the TransformerImpl if XPath is
 * running under XSLT.  If it is not running under XSLT, it can be whatever
 * you want.
 *
 * -scott
 * </PRE>
 *
 * @author $Author$
 * @see org.apache.xml.security.transforms.implementations.FuncHere
 * @see org.apache.xml.security.utils.XPathFuncHereAPI;
 * @see <A HREF="http://www.w3.org/Signature/Drafts/xmldsig-core/Overview.html#function-here">XML Signature - The here() function</A>
 */
public class FuncHereContext extends XPathContext {

   /**
    * This constuctor is disabled because if we use the here() function we
    * <I>always</I> need to know in which node the XPath occured.
    */
   private FuncHereContext() {}

   /**
    * Constructor FuncHereContext
    *
    * @param owner
    */
   public FuncHereContext(Node owner) {
      super((Object) owner);
   }

   /**
    * Constructor FuncHereContext
    *
    * @param owner
    * @param xpathContext
    */
   public FuncHereContext(Node owner, XPathContext xpathContext) {

      super((Object) owner);

      try {
         super.m_dtmManager = xpathContext.getDTMManager();
      } catch (IllegalAccessError iae) {
         throw new IllegalAccessError(I18n.translate("endorsed.jdk1.4.0")
                                      + " Original message was \""
                                      + iae.getMessage() + "\"");
      }
   }

   /**
    * Constructor FuncHereContext
    *
    * @param owner
    * @param previouslyUsed
    */
   public FuncHereContext(Node owner, CachedXPathAPI previouslyUsed) {

      super((Object) owner);

      try {
         super.m_dtmManager = previouslyUsed.getXPathContext().getDTMManager();
      } catch (IllegalAccessError iae) {
         throw new IllegalAccessError(I18n.translate("endorsed.jdk1.4.0")
                                      + " Original message was \""
                                      + iae.getMessage() + "\"");
      }
   }

   /**
    * Constructor FuncHereContext
    *
    * @param owner
    * @param dtmManager
    */
   public FuncHereContext(Node owner, DTMManager dtmManager) {

      super((Object) owner);

      try {
         super.m_dtmManager = dtmManager;
      } catch (IllegalAccessError iae) {
         throw new IllegalAccessError(I18n.translate("endorsed.jdk1.4.0")
                                      + " Original message was \""
                                      + iae.getMessage() + "\"");
      }
   }
}