Re: [xsl] are all strings in a sequence valid potential QNames

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

At 2010-02-04 09:04 +0000, Andrew Welch wrote:
> > Just to check that by "valid potential QName" you mean a string that is in
> > the lexical space of xs:QName and will therefore constitute a valid QName
> > provided the prefix is in scope?
> >
> > ($x castable as xs:QName) will not work because (a) it also tests whether
> > the prefix is in scope, and (b) to avoid the issues of it therefore being
> > context-sensitive, the W3C spec says this is only allowed if the argument
> > ($x) is a string literal.
> >
> > So you do need to use the regex approach.
>
> Could you do a  fn:prefix-from-QName($x) = fn:in-scope-prefixes(.)
> check before doing the castable as check?

Nope:

  http://www.w3.org/TR/2007/REC-xpath20-20070123/#id-castable
  "[if] the input argument of the expression is of type xs:string but it is
   not a literal string, the result of the castable expression is false."

I hope this helps.

. . . . . . . . . . . . Ken


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