Sectioning different heading levels

Question

The goal is to group elements starting with different heading levels into sections nested according to those levels.

Problem is similar to XSLT: moving a grouping ht

Answer 1

I would simply let the function group by the current level and stop at the maximum level (which is 6 in HTML):

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

<xsl:function name="mf:group" as="node()*">
  <xsl:param name="nodes" as="node()*"/>
  <xsl:param name="level" as="xs:integer"/>
  <xsl:for-each-group select="$nodes" group-starting-with="*[starts-with(local-name(), concat('h', $level))]">
    <xsl:choose>
      <xsl:when test="self::*[starts-with(local-name(), concat('h', $level))]">
        <section level="{$level}">
          <xsl:apply-templates select="."/>
          <xsl:sequence select="mf:group(current-group() except ., $level + 1)"/>
        </section>
      </xsl:when>
      <xsl:when test="$level lt 6">
        <xsl:sequence select="mf:group(current-group(), $level + 1)"/>
      </xsl:when>
      <xsl:otherwise>
        <xsl:apply-templates select="current-group()"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:for-each-group>
</xsl:function>

<xsl:template match="@* | node()">
  <xsl:copy>
    <xsl:apply-templates select="@* , node()"/>
  </xsl:copy>
</xsl:template>

<xsl:template match="body">
  <xsl:copy>
    <xsl:sequence select="mf:group(node(), 1)"/>
  </xsl:copy>
</xsl:template>

</xsl:stylesheet>

Obviously the level to search for could be provided as a parameter instead of hardcoding it in the stylesheet:

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

<xsl:param name="max-level" as="xs:integer" select="6"/>

<xsl:param name="name-prefix" as="xs:string" select="'h'"/>

<xsl:output method="html" indent="yes"/>

<xsl:function name="mf:group" as="node()*">
  <xsl:param name="nodes" as="node()*"/>
  <xsl:param name="level" as="xs:integer"/>
  <xsl:for-each-group select="$nodes" group-starting-with="*[starts-with(local-name(), concat($name-prefix, $level))]">
    <xsl:choose>
      <xsl:when test="self::*[starts-with(local-name(), concat($name-prefix, $level))]">
        <section level="{$level}">
          <xsl:apply-templates select="."/>
          <xsl:sequence select="mf:group(current-group() except ., $level + 1)"/>
        </section>
      </xsl:when>
      <xsl:when test="$level lt $max-level">
        <xsl:sequence select="mf:group(current-group(), $level + 1)"/>
      </xsl:when>
      <xsl:otherwise>
        <xsl:apply-templates select="current-group()"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:for-each-group>
</xsl:function>

<xsl:template match="@* | node()">
  <xsl:copy>
    <xsl:apply-templates select="@* , node()"/>
  </xsl:copy>
</xsl:template>

<xsl:template match="body">
  <xsl:copy>
    <xsl:sequence select="mf:group(*, 1)"/>
  </xsl:copy>
</xsl:template>

</xsl:stylesheet>