Re: RE: FW: Path Reversal

For easy extraction of all the "steps" in an XPath expression with
unknown in advance number of "steps" one can re-use an existing
template -- the Functional Tokenizer:

http://aspn.activestate.com/ASPN/Mail/Message/xsl-list/914654

Cheers,
Dimitre Novatchev.


Jarno.Elovirta@xxxxxxxxx  wrote:

Hip hei,

> Suppose I have the following piece of XML:
> 
> <node name="funstuff">
>   <node name="jokes">
>     <node name="veryfunnyjoke"/>
>   </node>
> </node>
> 
> I have a path (as a string) which is composed of the @names of the
> nodes. It looks like /funstuff/jokes/veryfunnyjoke. How can I write a
> template (or an EXSLT function) that returns the node the 
> path points to
> (e.g. veryfunnyjoke)?

With XSLT 1.0 you can't return the node, but you can write a
named/moded template which is called for the node you want to return.
David McNally already posted a solution, but here's another one with
separate templates to evaluate the step and process the return value -
basically they're the same solution, really.

<?xml version="1.0" encoding="ISO-8859-1"?> 
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

<xsl:template match="/">
	<xsl:text>
/funstuff/jokes2/veryfunnyjoke  = </xsl:text>
  <xsl:call-template name="parser">
    <xsl:with-param name="path"
select="'/funstuff/jokes2/veryfunnyjoke'" />
  </xsl:call-template>
  <xsl:text>
/funstuff/jokes/veryfunnyjoke2  = </xsl:text>
  <xsl:call-template name="parser">
    <xsl:with-param name="path"
select="'/funstuff/jokes/veryfunnyjoke2'" />
  </xsl:call-template>
</xsl:template>

<xsl:template name="parser">
  <xsl:param name="path" />

  <xsl:choose>
    <xsl:when test="contains($path, '/')">
      <xsl:choose>
        <xsl:when test="starts-with($path, '/')">
          <xsl:for-each select="/">
            <xsl:call-template name="step">
              <xsl:with-param name="test"
select="substring-before(substring-after($path, '/'), '/')" />
              <xsl:with-param name="path"
select="substring-after(substring-after($path, '/'), '/')" />
            </xsl:call-template>            
          </xsl:for-each>
        </xsl:when>
        <xsl:otherwise>
          <xsl:call-template name="step">
            <xsl:with-param name="test" select="substring-before($path,
'/')" />
            <xsl:with-param name="path" select="substring-after($path,
'/')" />
          </xsl:call-template>
        </xsl:otherwise>
      </xsl:choose>
    </xsl:when>
    <xsl:when test="$path != ''">
      <xsl:call-template name="step">
        <xsl:with-param name="test" select="$path" />
        <xsl:with-param name="path" select="''" />
      </xsl:call-template>
    </xsl:when>
    <xsl:otherwise>
      <xsl:call-template name="return" />        
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

<!-- here always forward $path to parser -->
<xsl:template name="step" >
  <xsl:param name="test" />
  <xsl:param name="path" />

  <xsl:for-each select="node[@name = $test]">
    <xsl:call-template name="parser">
      <xsl:with-param name="path" select="$path" />
    </xsl:call-template>
  </xsl:for-each>
</xsl:template>

<xsl:template name="return">
  <xsl:value-of select="." />
</xsl:template>

</xsl:stylesheet>

Hope this helps in writing the stylesheet you need,

Santtu




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