I think I have it:
preceding::fig[.!="" and ancestor::grp = current()/ancestor::grp][1]
It's a bad mistake to use "=" to test whether two nodes are the same node (so
to speak). You're actually comparing the string values of the nodes, which is a
very expensive operation for nodes that have large subtrees, and if you're
unlucky it could give you a false positive. In 2.0, use the "is" operator. In
1.0, compare node identity using generate-id(), or count($X|$Y)=1.
The other problem with this expression is that if there isn't a preceding
figure within the subtree, it could take a long search to find out (back to the
start of the document).
It might be worth noting that preceding::x gives the same nodes as
ancestor-or-self::*/preceding-sibling::*/descendant-or-self::x. Using this
equivalence, you can stop the search earlier by qualifying the first step:
ancestor-or-self::*[ancestor::grp]/preceding-sibling::*/descendant-or-self::x
Michael Kay
Saxonica
-----Original Message-----
From: Rick Quatro rick(_at_)rickquatro(_dot_)com
[mailto:xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com]
Sent: Friday, February 27, 2015 3:44 PM
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] preceding with the same ancestor as self
Hi,
When I am at a <fig> with no text, I want to find the previous <fig> that
has text, but only within the same ancestor group.
I am using this:
preceding::fig[.!=""][1]
This works for all of the empty <fig> elements in the first <grp>, but in
the second <grp>, it incorrectly picks up the <fig> with the 4 value from
the previous <grp>. How can I restrict the preceding axis so a found node
will have the same ancestor as the context node? Thanks.
Rick
<?xml version="1.0" encoding="UTF-8"?>
<doc>
<grp>
<fig/>
<fig>1</fig>
<fig>2</fig>
<fig/>
<sub>
<fig>3</fig>
</sub>
<fig/>
<fig>4</fig>
</grp>
<grp>
<fig/>
<fig>1</fig>
<fig>2</fig>
<fig>3</fig>
<sub>
<fig/>
</sub>
<fig/>
</grp>
</doc>
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