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Re: [xsl] Are these equivalent XPath expressions for determining that there are no duplicates in a list of items?

2012-11-01 10:22:27
Hi Roger,
   Sometimes, I use an XPath 2.0 expression like following to check if
a list of values do not contain duplicates,

count(Websites/Website/distinct-values()) = count(Websites/Website)

(this is not tested)

Btw, this doesn't answer your question :)

On Thu, Nov 1, 2012 at 6:31 PM, Costello, Roger L. 
<costello(_at_)mitre(_dot_)org> wrote:
Hi Folks,

Are there no duplicate websites in this list:

    <Websites>
        <Website id="Amazon"> http://www.amazon.com </Website>
        <Website id="Apple"> http://www.apple.com </Website>
        <Website id="Ebay"> http://www.ebay.com </Website>
        <Website id="Google"> http://www.google.com </Website>
        <Website id="Microsoft"> http://www.microsoft.com </Website>
        <Website id="VirginAtlantic"> http://www.virgin-atlantic.com 
</Website>
    </Websites>

Here is an XPath 2.0 expression to answer that question (thanks to Dimitre):

    empty(Websites/*[index-of(../*,.)[2]])

Here is an XPath 1.0 expression to answer that question:

    not(//Websites/*[. = preceding-sibling::*])

Are there any situations where those two XPath expressions differ in their 
answer?

/Roger




-- 
Regards,
Mukul Gandhi

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