Re: [xsl] Re: Performance observation.

xsl:where-populated fluctuates as high as the try catch but at best there
is no performance penalty.


On Tue, Sep 8, 2020 at 6:19 AM Michael Kay mike-JkSD5nQpfvpWk0Htik3J/[email protected] <
xsl-list-service-VWJlPdIPk9umXcTjhJAOxCoMnp2j79Jp@public.gmane.org> wrote:

> I'm slightly suprised by the performance effect but it depends how often
> the pattern is matched, and what other patterns are present in the
> stylesheet. Certainly putting complex logic into patterns can be risky from
> a performance point of view.
>
> How about using xsl:where-populated rather than xsl:try?
>
> Michael Kay
> Saxonica
>
> On 8 Sep 2020, at 08:16, Ihe Onwuka <[email protected]> wrote:
>
> The goal is to create a namespace node if the value of xsi:type is a QName.
>
> The code here simulates the situation
>
> https://xsltfiddle.liberty-development.net/a9HjZj
>
> The problem is that this fails if the select evaluates to the empty string.
>
>  <xsl:template match="@xsi:type">
>          <xsl:namespace name="{substring-before(.,':')}"
> select="$schemas/thing/@targetNamespace"/>
>          <xsl:next-match/>
>    </xsl:template>
>
> Now in the real code the select is actually a key retrieval so looks more
> like this
>
>    <xsl:template match="@xsi:type">
>          <xsl:namespace name="{substring-before(.,':')}"
> select="key('myKey',.,$schemas)/@targetNamespace"/>
>          <xsl:next-match/>
>    </xsl:template>
>
> So in order to avoid failure I tried this
>
>      <xsl:template match="@xsi:type[
> key('myKey',.,$schemas)/@targetNamespace => normalize-space()]">
>          <xsl:namespace name="{substring-before(.,':')}"
> select="key('myKey',.,$schemas)/@targetNamespace"/>
>          <xsl:next-match/>
>    </xsl:template>
>
> now that works but quadrupled the execution time of the stylesheet.
>
> Doing it with try catch
>
>       <xsl:template match="@xsi:type">
>          <xsl:try>
>              <xsl:namespace name="{substring-before(.,':')}"
> select="key('myKey',.,$schemas)/@targetNamespace"/>
>              <xsl:catch/>
>          </xsl:try>
>          <xsl:next-match/>
>    </xsl:template>
>
> is a teenie bit quicker.
>
> Overall execution time is still tolerable so posting this as an
> observation.
>
> For the  XSL list
>
> Is there a way to code
>
>    <xsl:template match="@xsi:type[
> key('myKey',.,$schemas)/@targetNamespace => normalize-space()]">
>          <xsl:namespace name="{substring-before(.,':')}"
> select="key('myKey',.,$schemas)/@targetNamespace"/>
>          <xsl:next-match/>
>    </xsl:template>
>
> without repeating the code for the key access thats on the template rule
> predicate inside the template rule.
>
>
>
>
>
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