Re: [xsl] effecient inline multi-conditional testing

[Jeni Tennison <jeni@xxxxxxxxxxxxxxxx>]

Hi Jeff,

> here's the task:
>   -create a template to cast an overloaded boolean value

I'd probably use separate variables for boolean true and boolean
false, perhaps based on the $cast parameter, and then return the
appropriate one of those, so something like:

<xsl:template name="cast:boolean">
  <xsl:param name="b-value" />
  <xsl:param name="cast" select="'true-false'" />
  <xsl:variable name="true" select="substring-before($cast, '-')" />
  <xsl:variable name="false" select="substring-after($cast, '-')" />
  <xsl:choose>
    <xsl:when test="$b-value = 'true' or $b-value = 't' or
                    $b-value = 'yes' or $b-value = 'y' or
                    $b-value = 1">
      <xsl:value-of select="$true" />
    </xsl:when>
    <xsl:when test="$b-value = 'false' or $b-value = 'f' or
                    $b-value = 'no' or $b-value = 'n' or
                    $b-value = 0">
      <xsl:value-of select="$false" />
    </xsl:when>
    <xsl:otherwise>
      <xsl:message terminate="yes">
        ERROR: Invalid boolean value '<xsl:value-of select="$b-value" />'
      </xsl:message>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

Another option is to store all the possible 'true' and 'false' values
in an XML structure that you can then test against. For example:

<values type="boolean-true">
  <value>true</value>
  <value>t</value>
  <value>yes</value>
  <value>y</value>
  <value>1</value>
</values>
<values type="boolean-false">
  <value>false</value>
  <value>f</value>
  <value>no</value>
  <value>n</value>
  <value>0</value>
</values>

You could then store the relevant value elements in $boolean-trues and
$boolean-falses variables using your preferred method (document('') or
node-set() function, or use XSLT 1.1), and test against them:

<xsl:template name="cast:boolean">
  <xsl:param name="b-value" />
  <xsl:param name="cast" select="'true-false'" />
  <xsl:variable name="true" select="substring-before($cast, '-')" />
  <xsl:variable name="false" select="substring-after($cast, '-')" />
  <xsl:choose>
    <xsl:when test="$b-value = $boolean-trues">
      <xsl:value-of select="$true" />
    </xsl:when>
    <xsl:when test="$b-value = $boolean-falses">
      <xsl:value-of select="$false" />
    </xsl:when>
    <xsl:otherwise>
      <xsl:message terminate="yes">
        ERROR: Invalid boolean value '<xsl:value-of select="$b-value" />'
      </xsl:message>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

Or something similar.

Cheers,

Jeni

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


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