virtual nesting of list using XSLT - list

Question

I need nesting of list in the following manner, I have to create n-1 list wrappers, where n is the value of #virtual-nesting:
XML Doc:
<l virtual-nesting="3">
<li>
<lilabel/>
<p>
<text>Data used:</text>
</p>
</li>
</l>
Output Required:
<list>
<listitem>
<bodytext>
<list>
<listitem>
<label/>
<bodytext>
<p>
<text>Data used:</text>
</p>
</bodytext>
</listitem>
</list>
</bodytext>
</listitem>
</list>
XSLT Itried. As I am new to this:
<xsl:template match="l">
<xsl:choose>
<xsl:when test="#virtual-nesting">
<xsl:variable name="virtual"><xsl:value-of select="#virtual-nesting"/></xsl:variable>
<xsl:if test="$virtual>0">
<xsl:apply-templates select="generate-id(following-sibling::node()),#virtual-nesting-1"/>
</xsl:if>
<xsl:apply-templates select="li"/>
</xsl:when>
<xsl:otherwise>
<xsl:element name="list">
<xsl:apply-templates select="li"/> <!-- Template for list and lilabel is already created -->
</xsl:element>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
Kindly guide me through this.

Answer 1

Recursion is the key to creating nested structures in XSLT.
The following uses a recursive <xsl:template match="l"> with a $level parameter. This parameter defaults to #virtual-nesting - 1 and after that is decremented with every recursive step.
The template takes two different paths, depending on its value.
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:output method="xml" omit-xml-declaration="yes" encoding="UTF-8" indent="yes" />
<xsl:strip-space elements="*" />
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()" />
</xsl:copy>
</xsl:template>
<xsl:template match="l">
<xsl:param name="level" select="#virtual-nesting - 1" />
<list>
<listitem>
<xsl:if test="$level <= 1">
<xsl:apply-templates />
</xsl:if>
<xsl:if test="$level > 1">
<bodytext>
<xsl:apply-templates select=".">
<xsl:with-param name="level" select="$level - 1" />
</xsl:apply-templates>
</bodytext>
</xsl:if>
</listitem>
</list>
</xsl:template>
<xsl:template match="li">
<label>
<xsl:apply-templates select="lilabel/node()" />
</label>
<bodytext>
<xsl:apply-templates select="node()[not(self::lilabel)]" />
</bodytext>
</xsl:template>
</xsl:transform>
Result:
<list>
<listitem>
<bodytext>
<list>
<listitem>
<label/>
<bodytext>
<p>
<text>Data used:</text>
</p>
</bodytext>
</listitem>
</list>
</bodytext>
</listitem>
</list>