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Re: [xsl] What does //distinct-values(...) mean?

2020-04-08 08:12:45
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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