Re: [xsl] check for whitespace value between nodes

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Hi,

At 04:07 PM 8/19/2010, Liam wrote:
> On Thu, 2010-08-19 at 12:58 -0500, a kusa wrote:
> > Hi
> >
> > Is there any way in XSLT to check if the value between two nodes is a
> > whitespace?
> >
> > I tried normalize-space(product/text()) !=' ' but that is not working.
> > I want tocheck if the actual value between <product> </product> is a
> > white space.
>
> Whitespace is a tricky thing to get right. It's impossible to give you a
> good answer without knowing more about what you are trying to do and
> why, and the context, and without seeing your XSLT.

Problems relating to "whitespace" are more often underspecified than 
not. XML has a definition of "white space" (any space, carriage 
return, line feed or tab character or run of such characters), but 
whether your definition in your problem aligns exactly with XML's is 
a different question. And even if it does, there are often other questions.

For example, in the problem statement here, what does "a white space" 
mean? By one reasonable reading it matches "^\s$", while another has 
it match "^\s+$" as Liam suggests. (Other readings allow strings that 
match neither.) Does a run of whitespace characters count as "a white space"?

Dimitre's XPath 1.0 solution, "product/text() and 
not(normalize-space(product/text())", works with the second of these 
definitions, since a run of whitespace is collapsed by 
normalize-space() into an empty string (and then coerced to Boolean 
false). That is, the test is refactored to (a) the text node exists 
(the 'product' element is not empty), but (b) it has no value other 
than whitespace characters.

For the first definition, one might want

  translate(product/text(),'&#xA;&#x9;',' ')=' '

(in XPath 1.0). This turns any LF or TAB into a space, then sees if 
the resulting string is a single space. (Ordinarily one doesn't have 
to worry about CR since it has already been normalized by a parser. 
But even this isn't always so.)

Cheers,
Wendell



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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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