W3C home > Mailing lists > Public > public-rdf-dawg-comments@w3.org > June 2006

[OK?] Re: Ambiguity of NIL Token

From: Eric Prud'hommeaux <eric@w3.org>
Date: Thu, 1 Jun 2006 13:21:01 +0200
To: Chimezie Ogbuji <ogbujic@bio.ri.ccf.org>
Cc: public-rdf-dawg-comments@w3.org
Message-ID: <20060601112101.GB9291@unagi.w3.org>

On Fri, May 12, 2006 at 10:25:03AM -0400, Chimezie Ogbuji wrote:
> 
> This is regarding the following SPARQL Grammar rules and query (from the 
> DAWG test data/SyntaxFull/syntax-lists-05.rq):
> 
> [29] ArgList ::= ( NIL | '(' Expression (',' Expression )* ')' )
> [39] Collection := '(' GraphNode+ ')'
> [56] BrackettedExpression ::= '(' Expression ')'
> [85] NIL ::= '(' WS* ')'
> 
> SELECT * WHERE { ( ( ) ) }
> 
> It's not clear how to interpret the NIL token in the above query.  It's 
> not an empty collection or an empty bracketed expression since both of 
> these 'must' have content in between the parentheses.

I read this as a Collection of a NIL. Here's a LALR(1) trace of that query:

http://www.w3.org/2005/01/yacker/uploads/SPARQL?markup=html&lang=perl&text=SELECT+*+WHERE+%7B+%28+%28+%29+%29+%7D&action=validate+text


85 says that NIL may have 0 or more whitespace characters betweek the
parentheses, i.e. no content.


Does this answer your question? Please indicate whether you are
or are not satisfied. If you are, you can help our issue tracking
system by prefixing the subject of your response with [CLOSED]
(where this subject has [OK?]).


> Chimezie Ogbuji
> Lead Systems Analyst
> Thoracic and Cardiovascular Surgery
> Cleveland Clinic Foundation
> 9500 Euclid Avenue/ W26
> Cleveland, Ohio 44195
> Office: (216)444-8593
> ogbujic@ccf.org

--
-eric

home-office: +1.617.395.1213 (usually 900-2300 CET)
             +33.1.45.35.62.14
cell:        +81.90.6533.3882

(eric@w3.org)
Feel free to forward this message to any list for any purpose other than
email address distribution.
Received on Thursday, 1 June 2006 11:19:29 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:14:50 GMT