RE: [xsl] Source Reducer

["Andrew Welch" <ajwelch@xxxxxxxxxxxxxxx>]

> I have a source xml which is 19MB +  I'm running the
> following "source reducer" template against it using the
> MSXML4 parser, however it is slow (has been running well over
> 2 min. now).  Any suggestions on how to optimize this source
> reducer template?  Also, how does the ancestor match below
> work, what does it do exactly?
>
> <xsl:strip-space elements="*"/>
>
>  <xsl:template match="node()|@*">
>    <xsl:copy>
>      <xsl:apply-templates select="node()|@*"/>
>    </xsl:copy>
>  </xsl:template>
>
>  <xsl:template match="/*/*[position() > 20]"/>
>
>  <xsl:template match="*[ancestor::*[3]]"/>

The final no-op template will match any element with 3 ancestors - it
means the result tree will be no more than 3 deep.

To improve performance you need to replace the use of the ancestor axis
with something else... but the only thing that instantly springs to mind
is to use modes eg:

 <xsl:template match="node()|@*">
   <xsl:copy>
     <xsl:apply-templates select="node()|@*" mode="second"/>
   </xsl:copy>
 </xsl:template>

 <xsl:template match="node()|@*" mode="second">
   <xsl:copy>
     <xsl:apply-templates select="node()|@*" mode="stop"/>
   </xsl:copy>
 </xsl:template>

 <xsl:template match="node()" mode="stop"/>

I'm sure there is a better way...