xpath expression validity?

Hi,
 I have tried to use the modified version "gatherSchema" XSLT that runs
through the xsd files, collecting list of includes (no  imports) and then
provide some output from the collected node-sets.
Using XMLSpy v5, I can execute the following stylesheet.

The problem I am facing is although the XSLT debugger allows me to watch
the XPath expression $includes/xsd:schema/xsd:include/@schemaLocation, if
the resulting nodeset count is 0 or empty, the XSLT processor throws error
"invalid XPath expression" (2nd time around).

Unless I can use this XPath the recursion cannot be terminated.

Please explain, what went wrong in my stylesheet?

The stylesheet valid for any xsd schemas with includes is as follows:
==================
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="
http://www.w3.org/1999/XSL/Transform" xmlns:fo="
http://www.w3.org/1999/XSL/Format" xmlns:xsd="
http://www.w3.org/2001/XMLSchema">
  <xsl:output method="xml" omit-xml-declaration="no" indent="yes"/>
  <xsl:template match="/">
    <xsl:variable name="includes" select="/"/>
    <xsl:call-template name="gatherSchema">
      <!-- ... and any *new* includes in the $include parameter -->
      <xsl:with-param name="includes" select="."/>
    </xsl:call-template>
  </xsl:template>
  <xsl:template name="gatherSchema">
    <xsl:param name="schemas"/>
    <xsl:param name="includes"/>
    <xsl:choose>
      <xsl:when test="count($schemas) &lt; count($schemas | $includes)">
        <!-- when $includes includes something new, recurse ... -->
        <xsl:call-template name="gatherSchema">
           <!-- ... with current $includes added to the $schemas
parameter... -->
           <xsl:with-param name="schemas" select="$schemas | $includes"/>
           <!-- ... and any *new* includes in the $include parameter -->
==>          <xsl:with-param name="includes" select="document
($includes/xsd:schema/xsd:include/@schemaLocation)"/>
        </xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <!-- do something with the "$schemas" nodeset containing the root
nodes of all included schemas -->
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>
</xsl:stylesheet>
==================
Bibhakar Saran
_________________________
B2B Technical Architect
TXU IT Architecture & Planning
Level 15 452 Flinders St, Melbourne
Phone : (+61 3) 9229 6151
Mobile: 0411 203036
Email: bibhaker.saran@xxxxxxxxxx



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