Re: [xsl] most efficient flat file listing to hierarchical

this is an elegant template, really shows the power and sweetspot hit by
XSLT 2.0 (anyone doing this in XSLT 1.0, barring FXSL, this becomes a
bit of a nightmare)....any alternate approaches which makes things more
efficient (i dont think its possible to optimise the MKay recursive
approach).

Why bar FXSL -- are we masochistic? :oO)

Here's my take on this problem. Trying to adhere to the KISS
principle, I'm using a two-step approach naturally expressed as
functional composition.

Notice that not only is this a litlle easier to understand, but that
the main "powerhorse" (the function f:makeTree() ) is just 17 lines of
code:

<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:f="http://fxsl.sf.net/"
exclude-result-prefixes="f xs">

<xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:template match="/*">
   <xsl:sequence select="f:makeTree(f:tokenizePaths(/*/*), 1)"/>
 </xsl:template>

 <xsl:function name="f:tokenizePaths">
   <xsl:param name="pfilePaths" as="element()+"/>
   <xsl:for-each select="$pfilePaths">
      <item>
         <xsl:for-each select="tokenize(.,'/')">
            <q><xsl:value-of select="."/></q>
         </xsl:for-each>
      </item>
   </xsl:for-each>
 </xsl:function>

 <xsl:function name="f:makeTree" as="element()*">
   <xsl:param name="pItems" as="element()*"/>
   <xsl:param name="pqLevel" as="xs:integer"/>

<xsl:for-each-group select="$pItems" group-by="q[$pqLevel]">
<xsl:choose>
<xsl:when test="count(current-group()) = 1">
<file name="{q[$pqLevel]}"/>
</xsl:when>
<xsl:otherwise>
<dir name="{q[$pqLevel]}">
<xsl:sequence select="f:makeTree(current-group(), $pqLevel+1)"/>
</dir>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</xsl:function>
</xsl:stylesheet>