Re: [xsl] Selecting only the first node that matches.

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2002-11-04 17:50 -0800, Shawn O. McKenzie wrote:
> If possible, I need to be able to select only the first instance of a match.

Not sure what you mean here by "of a match", so I've made some assumptions 
below.

>  Consider the following:
>
> <ancestor name="1">
>    <propertyref name="foo"/>
>    <ancestor name="2">
>        <propertyref name="bar"/>
>        <ancestor name="3">
>            <propertyref name="foo"/>
>            <ancestor name="4">
>                 <propertyref name="fnord"/>

Are we to assume your current node is somewhere inside here, beneath 
ancestor "4" when you are doing your looking?

>              </ancestor>
>         </ancestor>
>    </ancestor>
> </ancestor>
>
> I would like to be able to match on the first ancestor element that has a 
> propertyref/@name of foo, but not the second one. These nested "ancestor" 
> elements vary in depth and can have any number of propertyref attributes.

By "first" do you mean "first in document order" or "closest up the ancestry"?

If the latter, and your current node is a descendant of the deepest 
ancestor, then you can use:

  select="ancestor::*[propertyref/@name='foo'][1]"

Perhaps your "foo" is in a variable, so you would use:

  select="ancestor::*[propertyref/@name=$look][1]"

This selects from all ancestors of any name whose child element propertyref 
has a name attribute equal to the variable $look, the first one in reverse 
document order ... which would be the closes such ancestor.

> I plan to solve this with recursion,

You may be jumping to a conclusion of needing recursion, when you may not 
if your needs are as simple as I've interpreted them to be.  I've assumed 
that your processing is happening inside the nested ancestors and you are 
looking "up" the ancestry.

I hope this helps.

............. Ken


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