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[Bug 6131] [XPath 2.1] Requirement: context-free paths

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Date: Thu, 09 Jul 2009 11:27:29 +0000
To: public-qt-comments@w3.org
Message-Id: <E1MOrmj-0008Qd-Vs@wiggum.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=6131





--- Comment #15 from Michael Kay <mike@saxonica.com>  2009-07-09 11:27:29 ---
>XQuery SX doesn't have an expression that starts with "{" any more.

That's good. In that case the only problem I can see "by eye" is

[134] CompElemConstructor  ::= "element" (QName | ("{" Expr "}")) "{"
ContentExpr? "}"

and the equivalent for attributes, where one would have to insist that the
QName is a QName in the current sense, and not an EQName. An EQName could be
used in the form

element { {uri}local } { "value" }

or, if we choose to allow it

<{uri}local>value</{uri}local>

If we go for Clark names, the other question is what do about namespace names
containing "{" or "}". The simplest is just to say they aren't allowed when
using this format. That's not a big restriction because the namespace spec
strongly encourages that namespace names should be valid IRIs (though it
doesn't make it an error if they aren't).

However, I do feel this syntax is a bit more fragile in that it overloads use
of existing symbols. Using a new character such as back-tick would give less
risk of future problems extending the grammar, and less danger of poor error
messages for incorrect queries.


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Received on Thursday, 9 July 2009 11:27:38 UTC

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