Re: [xsl] An XPath expression which checks that no two websites have the same username

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2012-11-05 10:44 +0000, Costello, Roger L. wrote:
> I need a good XPath expression which checks that no two websites 
> have the same username.
>
> Here is a map between websites and usernames:
>
>     <map>
>         <singletonMap from="Amazon"             to="BasketballKing" />
>         <singletonMap from="Apple"              to="RandomGamer" />
>         <singletonMap from="Ebay"               to="CornFoo" />
>         <singletonMap from="Google"             to="LatenightRevolution" />
>         <singletonMap from="Microsoft"          to="OldTrue" />
>         <singletonMap from="VirginAtlantic"     to="TheSinger" />
>     </map>
>
> In that example no two websites have the same username.
>
> I created an XPath expression which does the job, but I suspect 
> there is a simpler expression. Here is my attempt:
>
> empty(for $i in map/*/@to return map/*[@to eq $i][2])
>
> Would you provide a simpler (more efficient, more elegant) version please?

Did you try:

  count(map/*/@to) = count(distinct-values(map/*/@to))

I hope this helps.

. . . . . . . . Ken

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