Re: [xsl] grouping + global variable (?) (was re: regexs, grouping (?) and XSLT2?)

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Bruce,

At 04:56 PM 8/12/2004, you wrote:
> OK. I understand this conceptually, but I never understood how to create 
> -- and to access -- this "intermediate version".

There are several approaches to doing this kind of pipelining:

1. Poor man's version: run two stylesheets in succession: the second runs 
on the result of the first. Good for prototyping and debugging and even 
works in a production environment. Downside: very old-fashioned; slow; 
requires cleanup.

2. Extended XSLT 1.0: create your first result by applying templates to 
your source and binding the results to a variable, which you then use a 
processor extension to turn into a node set for further processing. You'll 
probably need modes (if only to keep yourself sane), so:

<xsl:variable name="intermediate-result">
  <xsl:apply-templates select="/" mode="pass1"/>
</xsl:variable>

<xsl:template match="/">
  <xsl:apply-templates select="exslt:node-set($intermediate-result)" 
mode="pass2"/>
</xsl:template>

<xsl:template match="/" mode="pass1">
  <xsl:apply-templates select="pass1"/>
</xsl:template>

where exslt:node-set is an extension function that creates a node-set from 
a result-tree-fragment (see exslt.org or consult your processor's 
documentation).

3. XSLT 2.0 -- same as 2, except no extension function is needed: it'll 
happen transparently.

4. External pipeline support: many environments, and some processors, allow 
you to chain stylesheets directly, thereby eliminating the need to write 
out the intermediate result as a file (as option 1 does). This is the 
in-between solution. For example, Saxon has a saxon:next-in-chain attribute 
you can use on xsl:output.

Jeni was less than specific because there are so many ways to do this, 
which you should use depends on your own case, and she has a baby to feed. 
(Waa!)

Cheers,
Wendell



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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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