Re: [xsl] lookup table keyed by position

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Kevin,

At 03:02 PM 2/23/2005, you wrote:
> I tried to build a lookup table that would convert 2-digit month numbers
> to their 3-letter abbreviation like this:
>
> <xsl:variable name="months">
>   <abbrev>Jan</abbrev>
>   <abbrev>Feb</abbrev>
>   <abbrev>Mar</abbrev>
>   <abbrev>Apr</abbrev>
>   <abbrev>May</abbrev>
>   <abbrev>Jun</abbrev>
>   <abbrev>Jul</abbrev>
>   <abbrev>Aug</abbrev>
>   <abbrev>Sep</abbrev>
>   <abbrev>Oct</abbrev>
>   <abbrev>Nov</abbrev>
>   <abbrev>Dec</abbrev>
> </xsl:variable>
>
> And given a variable in YYYY-MM-DD format, I can get the abbreviation
> with this expression:
>
> $months/abbrev[number(substring($yyyy-mm-dd, 6, 2))]
>
> Then I tried to index the table like this:
>
> <xsl:key name="months-by-position" match="abbrev" use="position()"/>
>
> And look up the abbreviation with this expression:
>
> key('months-by-position', number(substring($yyyy-mm-dd, 6, 2)), $months)
>
> But my output indicates that for all of the '02' through '12' numbers,
> the key function returns an empty sequence, and for '01' it returns a
> sequence of all the abbrev elements (which are serialized with a space
> between them).
>
> It seems that the context node when position is evaluated is the months
> element, not the individual abbbrev elements.  Can this be made to work
> as I want?

No, it's the abbrev -- but each of them is getting assigned position() = 1.

This is because of the way position() works, which is different from what 
you're expecting. It is specified to return not a number representing the 
position of a node among its siblings, but one representing the position of 
a node in a given processing context (the "current node list"). Since there 
is none such when you declare a key, position() is pretty well useless 
here: each node is taken to be the first in its current node list, so 
they're all '1'.

You might have better luck with:

<xsl:key name="months-by-position" match="abbrev" 
use="count(preceding-sibling::*) + 1"/>

which actually assigns the index number you want.

Cheers,
Wendell


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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
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Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
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