RE: [xsl] the fastest way to test if variable is empty

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Dusan,

Joining in again....

At 11:21 AM 12/8/2004, Mike wrote:
> >
> > Can anybody tell me the fastest way, how to test, if variable
> > contains some
> > text or number?
> >
> > For now, i am using test "string-length($variable)=0", but
> > seems not to be the fastest.
>
> What makes you think it isn't the fastest?
>
> Speed of different operations will vary between processors, but I would be
> very surprised if this operation is the cause of your performance
> difficulties.
>
> I would recommend writing it as $variable='' since a non-optimizing
> processor will otherwise count all the characters in the string, which can
> take a while if the string is long and a variable-length character
> representation is used (e.g. UTF-8 or UTF-16).
>
> > Somebody tells me to use test "$variable", but with my
> > XalanC, it seems to be true everytime.
>
> That makes me suspect you have declared the variable as
>
> <xsl:variable name="x">
>   ...
> </xsl:variable>
>
> which means that (contrary to what you said) its value isn't a string or a
> number, but a result-tree-fragment, which is likely to be much less
> efficient.

I left out the possibility of $variable being an RTF; but problems with 
testing RTFs are similar to those testing node-sets, and the string() and 
normalize-space() tests work on them too.

But I should also add that the normalize-space() approach will *not* be 
fast, since it requires processing the string to collapse white space, 
which is not unlike counting the characters....

So listen to Mike (I know you do :-).

Cheers,
Wendell


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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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