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XQuery was originally based on XDuce's tree grammar system but has since
evolved. XDuce was a poor basis for an XML type system considering that
it didn't handle attributes or namespaces[0] nor does it's successor
Xtatic based on the presentation I saw at Microsoft Research a few
months ago.
I suggest reading the recent crop of XQuery related specs released about
two weeks to bring yourself up to speed. The formal semantics is
slightly behind but given conversations I had with our standards reps a
few minutes ago plus my impressions from talking to other working group
members a few weeks ago, it will lean more towards named typing than
tree grammars (which are complex to implement and also raise concerns
about scalability).
XQuery is NOT based on regular tree grammars.
[0] http://xduce.sourceforge.net/papers.html
--
PITHY WORDS OF WISDOM
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This posting is provided "AS IS" with no warranties, and confers no
rights.
>
>
> -----Original Message-----
> From: Murali Mani [mailto:mani@CS.UCLA.EDU]
> Sent: Friday, August 30, 2002 12:58 PM
> To: Dare Obasanjo
> Cc: Maciejewski, Thomas; xml-dev@lists.xml.org
>
>
> On Fri, 30 Aug 2002, Dare Obasanjo wrote:
>
> > Two points
> > 1.) XQuery's type system used to be based on regular tree grammars
> > but this is no longer the case working group since they adopted W3C
> > XML Schema as the basis of its type system. Now XQuery's
> data model is
> > primarily based on named typing where the named types are W3C XML
> > Schema types.
>
> Their processing is based fully on regular tree grammars, the
> restrictions such as 1-unambiguity and single type tree
> grammar has no relationship to XQuery what so ever, to the
> best of my knowledge.
>
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