I expect you know that the Saxon implementation of distinct-values()
does exactly what you want, but this doesn't help you much because it's
not interoperable.
Perhaps
for $i in 1 to count($in)
return
(if ($i = index-of($in, $in[$i])[1]) then $in[$i] else ())
It's O(n^2), of course, or worse if $in[$i] takes linear time, as it
does in some implementations.
Michael Kay
Saxonica
On 09/10/2012 01:32, Birnbaum, David J wrote:
Dear XSLT list,
Is there an easy way in XPath (not using XSLT instructions) to select only the
first occurrence of a specific value in a sequence of atomic values, so as to
return the sequence in the original order, but with re-occurrences of each
value after the first appearance of that value removed? For example, given an
input sequence:
('Matthew','Mark','Luke','Matthew','John')
I want to produce
('Matthew','Mark','Luke','John')
I can't rely on using distinct-values() because that isn't guaranteed to keep
specifically the *first* occurrence of a value.
In an XSLT context I can construct a temporary tree, poke each value into an
element, all on the same level in the hierarchy, and then test for:
*[not(preceding-sibling::* = .)]
but I don't know how to write an XPath predicate that will filter the sequence
of *atomic values* the way I want. Is this just a blind spot? Can anyone advise?
Thanks,
David
djbpitt(_at_)gmail(_dot_)com
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