Any discussion of more Perl-like regex capability in XPath 2.1?

[David Sewell]

So far as I can see in the working draft of "XPath and XQuery Functions
and Operators 1.1", the only real extension to regular expressions is
the addition of a "q" flag in matches to block metacharacter
interpretation:

http://www.w3.org/TR/xpath-functions-11/#flags

I'm just curious whether there has been discussion of adding any more
Perl-like expressivity to XPath regular expressions. For example, being
able to use the escape sequences \u, \l, etc. in replacement patterns
would allow concision that is currently not legal:

 let $s := "from George Washington, 17 May 1789"
 return replace($s, '^(.+),.*', '\u$1')   (: ILLEGAL :)

 ==> "From George Washington"

instead of the verbosity required currently to do the same thing:

  let $s := "from George Washington, 17 May 1789"
  return concat(
      upper-case(substring($s,1,1)),
      replace(substring($s,2), '^(.+),.*','$1')
      )

I understand this would impose more burden on implementers, but has
there been demand from the user community (including XSLT folk)?
(Count this email as "demand", of course.)

DS

-- 
David Sewell, Editorial and Technical Manager
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