XPath parsing or Extending MSXML

Hello

I have come to the point where I have to add some functionality to MSXML4 (in javascript) and it's capabilities to do XPath queries. The MSXML4 parser can only return nodesets or single nodes when you give it some XPath expression. I need the possibility to use the sum, count (and other functions) to get integer, string and boolean values as well. The only solution I have come up with is to parse the XPath expression and build some object tree that I execute against the MSXML parser.  So my question is: Is there any state diagram (I want to base the parser on it) publicly available for XPath or is the only solution to build this diagram to go through the spec?

If anyone has another solution (ie not evaluate with a state machine based parser) I will be more than happy to hear of it...

/Marcus

ps. I have thought of using XSLT to do this but I don't want to invoke the processor for every little calculation ds.

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list