xslt wrap multiple sibling-nodes from one specific node up to next occurance of specific node

Question

I read some answers here on moving nodes down/wrapping elements, but can´t figure out the solution to my problem. Here it is: I want to turn a flat document hierarchy in a "deep" hierarchy with xslt (2.0). The problem is to limit the search for siblings to a certain sibling, in my case: Search all siblings from h1 up to next h1 node.

xml-code

<root>
   <h1>A heading</h1>
   <para>Some text.</para>
   <h2>More text</h2>         
   <table>Content</table>
   <pic>a picture</pic>
   <h1>Another heading.</h1>
   <para>Some text again.</para>
   <para>More text.</para>
   ...
</root>

Real document is much longer, there are up to five levels of headings, there is no fixed order of elements, and in real life I need to move not only the h1-sections, but also the h2-sections and so on. I´ve tried several attempts with copy-of- and similar expressions, but I´ma newbie in xslt. So how to wrap all h1-elements and its siblings up to the next h1-element with a chapter-element and h2-elements in the same way with section-elements?

Desired output is

<root>
   <chapter>
      <h1>A heading</h1>
      <para>Some text.</para>
      <section>
         <h2>More text</h2>         
         <table>Content</table>
         <pic>a picture</pic>
      </section>
   </chapter>
   <chapter>
      <h1>Another heading.</h1>
      <para>Some text again.</para>
      <para>More text.</para>
   </chapter>
   ...
</root>

Answer 1

The method you can use is two embedded for-each-group commands:

• One for all elements in root , for groups starting with h1 .
• And the second for the content of the current group (from the first loop), for groups starting with h2 .

One important feature of for-each-group coupled with group-starting-with is that when the source content does not start with the tag specified in group-starting-with , then the "starting part" (without the specified starting tag) is the first group.

To distinguish between this "initial" group (starting actually with h1 ) and groups starting with h2 , I used xsl:choose .

So the whole script can look like below:

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:transform version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" encoding="UTF-8" indent="yes" />

  <xsl:template match="root">
    <xsl:copy>
      <xsl:for-each-group select="*" group-starting-with="h1">
        <chapter>
          <xsl:for-each-group select="current-group()" group-starting-with="h2">
            <xsl:choose>
              <xsl:when test="name()='h1'">
                <xsl:copy-of select="current-group()"/>
              </xsl:when>
              <xsl:otherwise>
                <section>
                  <xsl:copy-of select="current-group()"/>
                </section>
              </xsl:otherwise>
            </xsl:choose>
          </xsl:for-each-group>
        </chapter>
      </xsl:for-each-group>
    </xsl:copy>
  </xsl:template>
</xsl:transform>

For a working example see http://xsltransform.net/pNvs5w8