XSL. Evaluate expression

Question

Sorry for my English.

XSL 1.0. How can I to calculate expression from element or attribute value?

For example XML:

<position>
  <localizedName>ref-help</localizedName>
  <reference>concat('../help/', $lang, '/index.html')</reference>
</position>

I try use expression from 'reference' attribute:

<xsl:for-each select="/content/positions/position">
        <li>
          <!--Save expression to variable...-->
          <xsl:variable name="path" select="reference"/>
          <!--Evaluate variable and set it value to 'href'-->
          <a target="frDocument" href="{$path}">
            <xsl:variable name="x" select="localizedName"/>
            <xsl:value-of select="$resources/lang:resources/lang:record[@id=$x]"/>
          </a>
        </li>
      </xsl:for-each>

But I get string:

file:///C:/sendbox/author/application/support/concat('../help/',%20%24lang,%20'/index.html')

How can I evaluate it?

Regards

Answer 1

If your XSLT processor implements the EXSLT extensions, you can reference a function that dynamically evaluates strings as XPath expressions:

<xsl:stylesheet 
  version="1.0"
  xmlns="http://www.w3.org/1999/XSL/Transform"
  xmlns:dyn="http://exslt.org/dynamic"
  extension-element-prefixes="dyn"
>
  <xsl:template match="content">
    <xsl:apply-templates select="positions/position" />
  </xsl:template>

  <xsl:template match="position">
    <li>
      <a target="frDocument" href="{dyn:evaluate(reference)}">
        <xsl:value-of select="
          $resources/lang:resources/lang:record[@id=current()/localizedName]
        "/>
      </a>
    </li>
  </xsl:template>
</xsl:stylesheet>

Note:

• there is no need to save things in a variable before using them
• there is a current() function you might have missed
• use <xsl:apply-templates> and <xsl:template> in favor of <xsl:for-each>