Re: [xsl] group by tags

[Dave Pawson <davep@xxxxxxxxxxxxx>]

Michael Kay wrote:
> A bit tricky, this one!
>
> I think I would tackle it by first flattening the structure into something
> like this:
>
> <Book rdf:ID="boo2">
>    <address rdf:dataytpe="aaa" path="">Almogavers 56</address>
>    <month rdf:dataytpe="bbb" path="event/Inbook">July</month>
>    <year rdf:dataytpe="ccc" path="event/Inbook">2006</year>
>    <year rdf:dataytpe="ddd" path="proceedings/Proceedings">2008</year>
>    <month rdf:dataytpe="ddd" path="proceedings/Proceedings">May</month>
>
> etc.
>
> That part can be done by
>
> <xsl:for-each select="//*[not(*)]">
>   <xsl:copy>
>     <xsl:copy-of select="@*"/>
>     <xsl:attribute name="path" select="string-join(ancestor::*/name(),
> '/')"/>
>   </xsl:copy>
> </xsl:for-each>
>
> Then you can construct the output with
>
> <xsl:for-each-group select="*" group-by="@path">
>   <xsl:sequence select="f:nest(tokenize(@path, '/'), current-group())"/>
> </xsl:for-each>
>
> using the recursive function
>
> <xsl:function name="f:nest" as="element()*">
>   <xsl:param name="path" as="xs:string*"/>
>   <xsl:param name="content" as="element()*"/>
>   <xsl:choose>
>     <xsl:when test="exists($path)">
>       <xsl:element name="{$path[1]}">
>          <xsl:sequence select="f:nest(remove($path, 1), $content)"/>
>       </xsl:element>
>     </xsl:when>
>     <xsl:otherwise>
>        <xsl:sequence select="$content"/>
>     </xsl:otherwise>
>   </xsl:choose>
> </xsl:function>
>
> Not tested. Needs refinement if namespaces are involved. 


 <xsl:variable name='flattened'>
      <xsl:for-each select="//*[not(*)]">
        <xsl:copy>
          <xsl:copy-of select="@*"/>
          <xsl:attribute name="path" 
select="string-join(ancestor::*[not(position() = last())]/name(),
                                             '/')"/>
        </xsl:copy>
      </xsl:for-each>
    </xsl:variable>

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>

  <xsl:for-each-group select="$flattened/*" group-by="@path">
      <xsl:sequence select="f:nest(tokenize(@path, '/'), 
current-group())"/>
    </xsl:for-each-group>
  </rdf:RDF>

Neat Michael.

regards


regards

--
Dave Pawson
XSLT XSL-FO FAQ.
http://www.dpawson.co.uk