Re: [xsl] Chewy key problem

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

To add to this,

At 04:22 PM 3/1/2005, David wrote:
> Still I'll avoid answering that (because explaining the 2 pass version
> is easier:-)first do an identity template
>
> <xsl:template match="*">
> <xsl:copy>
> <xsl:copy-of select="@*"/>
> <xsl:apply-templates/>
> </xsl:copy>
> </xsl:template>
>
> Then add a template to work out your sorting key which is, I think
>
> <xsl:template match"b">
> <xsl:copy-of select="@*"/>
> <xsl:variable name="x">
> <xsl:copy-of select=".//desc"/>
> </xsl:variable>
> <b sort="$x">
> <xsl:apply-templates/>
> </b>
> </xsl:template>
>
> that's all you need the first transform, now you have an intermediate
> file that's like your original except every b has a sort attribute.
> Now you can just sort/group on that as usual as described in
> www.jenitennison.com/xslt/grouping.
> You are in a better situation now as your grouping key is just a singke
> Xpath @sort.
>
> If you are doing this from java you should be able to avoid the costs of
> writing out the intermediate document as a file and parsing it back
> again and just pass it as an in memory object from the first transform
> to the next. The details of that depend on the API you are using (and
> anyway there are others who can tell you a lot more about java.

I'll fill in a bit by adding that two passes can be accomplished in a 
single run of a stylesheet, if you use either XSLT version 2.0, or a very 
popular extension function in XSLT 1.0, usually called node-set().

The node-set() extension is popular enough almost to be official, and for 
an extension, it's very portable: see http://www.exslt.org. The idea here 
is that you would bind the results of the first pass to a variable, use the 
extension function to convert it from a result tree (which, in XSLT 1.0, 
you cannot process further as such, merely copy it or process it as a 
string), and then process the node set you get back as input to your second 
pass. Putting two transforms together like this into a single stylesheet, 
it's probably wise to use modes to disciminate the passes and keep yourself 
from going nuts.

I hope that helps,
Wendell


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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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