Thanks for the reply! Some further comments though...
On Fri, May 03, 2002 at 11:43:19AM -0400, Joseph Kesselman/CAM/Lotus wrote:
>
> You're talking about stuff that's at the Xalan implementatin level, not at
> the XPathAPI level...
Well, yes! The problem I having with using the XPathAPI class is that I would
like to use SAX and that all methods in the XPathAPI-class require
org.w3c.dom.Node objects. And that seems to imply that I have to use a
DOMBuilder, right?
On top of that, quoting the JavaDoc for the XPathAPI "A faster way is to
precompile the XPaths using the low-level API, and then just use the XPaths
over and over" - is begging people like me to try to do just that! :-)
> > c. How do I associate a DTM document with an XPathContext?
>
> That gets done when you invoke XPathAPI. The DTM is created in the context
> of a specific DTM Manager, and the XPathContext, when instantiated, obtains
> a DTM Manager to use for this purpose.
See above!
> > e. What is the value of the root node / when executing an xpath query
> with a
> > given xpath-context? (Can it be assumed to be 0 for example?)
>
> Do you mean XSLT value, or DTM Node Handle? Generally, as noted above, you
> shouldn't be attempting to work with the DTM APIs directly unless you have
> very special needs; they're part of Xalan's internals, not part of the
> intended public API.
The special needs is that I would like to use SAX and not DOM for the
XML-documents.
It is a DTM Node Handle. Currently I am using
execute( mXPathContext, mNode, mPrefixResolver );
on an XPath instance and mNode is obtained from
mNode = mXPathContext.getDTMHandleFromNode( document );
And it works fine. (I figured this out using part of the code from the
XPathAPI class, I think...) My main problem, still, is how to substitute this
for something that doesn't use a org.w3c.dom.Node-object and secondary to
precompile XPaths. I figure I can use the getDTM( Source source...) method in
XPathContext but that returns a DTM instead of a node handle - thereby making
me think about what node handle to use.
/Christoffer
(BTW - seem like I forgot to include the code I was referring to, so I have
attached it to this mail instead.)
>
>
>
--
Christoffer Soop <[EMAIL PROTECTED]>
+46 (0)730 74 68 15 / +46 (0)8 651 24 36
package com.score.data;
import com.score.logging.Logger;
import org.apache.xpath.XPath;
import org.apache.xpath.XPathContext;
import org.apache.xpath.objects.XObject;
import org.apache.xml.utils.PrefixResolver;
import org.apache.xml.utils.PrefixResolverDefault;
import org.w3c.dom.Document;
import javax.xml.transform.TransformerException;
public class XPathDocument {
// -- fields -------------------------------------------------------------------
public static final Logger log =
Logger.Factory.getInstance( XPathDocument.class );
private int mNode;
private XPathContext mXPathContext;
private PrefixResolver mPrefixResolver;
// -- constructors -------------------------------------------------------------
public XPathDocument( Document document ) {
// save relevant document information
mPrefixResolver =
new PrefixResolverDefault( document.getDocumentElement() );
mXPathContext = new XPathContext();
mNode = mXPathContext.getDTMHandleFromNode( document );
}
// -- methods ------------------------------------------------------------------
public XObject evaluate( String xpathString )
throws TransformerException {
XPath xpath = new XPath( xpathString, null, mPrefixResolver, XPath.SELECT );
return xpath.execute( mXPathContext, mNode, mPrefixResolver );
}
}
