Re: Closest ancestor with one of set of names

Hi Paul,

> I have a node stored in a variable, and a list of element names.
> The stored node is not the context node 
>
> I need to find the node that meets these criteria:
> 1) name is in the list 
> 2) is an ancestor of the stored node.
> 3) is the closest (most direct)  ancestor of the stored node, from 
> all ancestor nodes whose names (element names) are in the list, 

You can find all ancestor elements of the node $NODE with:

  $NODE/ancestor::*

When you use a variable reference at the beginning of a path then the
node(s) in that variable form the starting point for the path.

Assuming that the element names are given as the values of nodes in a
node set, held in the $NAMES variable, then you can find those
ancestor elements that have a name from that list with:

  $NODE/ancestor::*[local-name() = $NAMES]

This works because if you compare a string (the local name) to a node
set, then the comparison is true if of the nodes have a value equal to
the string.

And you can find the closest one by looking at the first of those (the
ancestor:: axis is a reverse axis, so the first is the nearest
ancestor):

  $NODE/ancestor::*[local-name() = $NAMES][1]

If the element names (e.g. FRONT and OPEN) are known to you, such that
they can be hardcoded in the stylesheet, then you could use something
like:

  $NODE/ancestor::*[self::FRONT or self::OPEN][1]

This deals better with namespace issues than testing the local-name()
would.

If the element names are in a string (e.g. 'FRONT,OPEN') then you can
use contains() instead:

  $NODE/ancestor::*[contains(concat(',', $NAMES, ','),
                             concat(',', local-name(), ','))][1]

I hope that helps,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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