Altova Mailing List Archives


Re: [XSL] Obtaining an attribute from self or ancestor

From: "Dimitre Novatchev" <dnovatchev@-----.--->
To: NULL
Date: 10/25/2008 1:51:00 PM
"Richard Tobin" <richard@c...> wrote in message 
news:gdsk17$2hbq$1@p......
> In article <490139f9$0$17067$6e1ede2f@r...>,
> Dimitre Novatchev <dnovatchev@c...> wrote:
>
>>Actually, this can be achieved with a single XPath one-liner (even without
>>XSLT being involved).
>>
>>Use:
>>
>>   //node[@id = $id]/ancestor-or-self::*[@attr][1]/@attr
>
> Or, if you find it clearer not to repeat @attr:
>
>   (//node[@id = $id]/ancestor-or-self::*/@attr)[last()]
>

This may be "clearer" but risks to be less efficient.

Using [1] in a reverse axis is a strong optimization hint and a clever XPath 
engine will not traverse the whole way up -- it wil just stop on the first 
self-or-ancestor element found that has an "attr" attribute.

Cheers,
Dimitre Novatchev

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