W3C home > Mailing lists > Public > public-qt-comments@w3.org > August 2009

[Bug 7257] New: LL parsing issues with outer for

From: <bugzilla@wiggum.w3.org>
Date: Mon, 10 Aug 2009 21:57:29 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-7257-523@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=7257

           Summary: LL parsing issues with outer for
           Product: XPath / XQuery / XSLT
           Version: Working drafts
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XQueryX 1.1
        AssignedTo: jim.melton@acm.org
        ReportedBy: nikolay.ognyanov@gmail.com
         QAContact: public-qt-comments@w3.org


Please consider the following 2 expressions:

for $a in outer for $b in c return d
for $a in outer for $b in c return d return e

Both are syntactically correct. In the first 'outer' is relative path and in
the second it is part of "outer for" clause. To distinguish between the 2 a
parser needs to look across c which is generally ExprSingle and hence -
recursive. This is of course a problem for LL parsers.

Feasibility of LL parsing is not necessarily a requirement for XQuery 1.1
grammar but it is certainly a nice feature, so I wonder whether you would you
consider the possibility of changing the syntax. Two options that I would
suggest are:

ForClause ::=  ("for" | "outer"    ) "$" VarName TypeDeclaration?
PositionalVar? 
                "in" ExprSingle ("," "$" VarName TypeDeclaration?
PositionalVar? 

ForClause ::=  ("for" | "outer-for") "$" VarName TypeDeclaration?
PositionalVar? 
                "in" ExprSingle ("," "$" VarName TypeDeclaration?
PositionalVar? 

Thank you
Regards
Nikolay


-- 
Configure bugmail: http://www.w3.org/Bugs/Public/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
Received on Monday, 10 August 2009 21:57:40 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 15:45:40 UTC