Re: [xsl] Detecting presence of attributes

Hi Peter,

> <thesis faculty="arts" department="history" options="foo bar blort">
>
> where foo.sty, bar.sty, and blort.sty are among the allowed options
> (ie declared entities in the DTD) for translation to LaTeX's
> \usepackage{foo,bar,blort}. Just a safety check to make sure a
> student doesn't go haywire.

Well, inspired by Dimitre's insight about id(), here's a solution that
doesn't involve recursive templates, as long as you don't mind
repeating in the stylesheet the list of allowed options:

<?xml version="1.0"?>
<!DOCTYPE xsl:stylesheet [
<!ATTLIST thesis:opt id ID #REQUIRED>
]>
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:thesis="http://www.silmaril.ie/thesis"
                exclude-result-prefixes="thesis">

<thesis:opts>
  <thesis:opt id="foo" />
  <thesis:opt id="bar" />
</thesis:opts>

<xsl:template match="thesis">
   <xsl:text>Options: </xsl:text>
   <xsl:variable name="options" select="@options" />
   <!-- change the context to the stylesheet document -->
   <xsl:for-each select="document('')/*">
      <!-- get the id attributes of any options identified by ID -->
      <xsl:for-each select="id($options)/@id">
         <xsl:value-of select="." />
         <xsl:if test="position() != last()">, </xsl:if>
      </xsl:for-each>
   </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

It has the advantage that you can deal with bad values (e.g. if
'blort' wasn't actually allowed) within the stylesheet - if that's an
advantage.

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/



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