Martin didn't say that it operated on a sequence of strings.
He explained that the "//" operator expands to address a bunch of
nodes, and then the distinct-values() function is evaluated from each
of those nodes.
XPath is evaluated from left to right and the "//" is evaluated
before the distinct-values() function is evaluated.
I hope this helps.
. . . . . . Ken
At 2020-04-08 13:13 +0000, Costello, Roger L. costello(_at_)mitre(_dot_)org
wrote:
Hi Martin,
But, but, but, ...
I thought that // operates on nodes. The distinct-values function
doesn't return nodes, does it? I thought it returns a sequence of
strings. If so, then how can // operate on a sequence of strings?
/Roger
-----Original Message-----
From: Martin Honnen martin(_dot_)honnen(_at_)gmx(_dot_)de
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>
Sent: Wednesday, April 8, 2020 8:25 AM
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [EXT] Re: [xsl] What does //distinct-values(...) mean?
Am 08.04.2020 um 14:19 schrieb Costello, Roger L. costello(_at_)mitre(_dot_)org:
> Hi Folks,
> I executed this XPath query in Oxygen:
> //distinct-values(//Row[matches(Advertiser, 'TS3', 'i')]/Subscribers)
> The two slashes at the beginning were an accident. At the bottom
of the screen Oxygen shows the matches. All of a sudden it showed
111,000 matches, then a moment later 438,000 matches, and then
finally 525,946 matches.
> "Yikes!" I thought, "What is going on? There is supposed to be
around 17 matches. How can there be half a million matches?"
> Then I saw the two slashes at the start.
> "Hmm, what is the meaning of two slashes preceding the
distinct-values function?" I thought.
> So, I ask you: what is the meaning of two slashes preceding the
distinct-values function? Why does its evaluation result in so many matches?
// is short for /descendant-or-self::node()/ so
//distinct-values(//Row[matches(Advertiser, 'TS3', 'i')]/Subscribers)
is
/descendant-or-self::node()/distinct-values(//Row[matches(Advertiser,
'TS3', 'i')]/Subscribers)
meaning it returns
distinct-values(//Row[matches(Advertiser, 'TS3', 'i')]/Subscribers)
as many times as the document has any nodes selectable by
/descendant-or-self::node().
--
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