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Re: Please make sure the grammar is directly machine consumable.

From: Richard Newman <r.newman@reading.ac.uk>
Date: Thu, 18 Aug 2005 13:26:54 -0700
Message-Id: <44E1FBDE-8D48-422A-9910-72DB8C5224E1@reading.ac.uk>
Cc: public-rdf-dawg-comments@w3.org, Yosi Scharf <syosi@mit.edu>
To: Tim Berners-Lee <timbl@w3.org>

As I recall from discussions with Andy Seaborne while I was  
implementing twinql[1], the grammar in the SPARQL docs are directly  
generated from a JavaCC grammar file. The source, therefore, is  
machine-consumable -- at least, if you're using JavaCC!

However, the output is not a particular friendly grammar to work with  
-- optional dots after productions, for example, tripped up my tool  
(so twinql makes them compulsory), and it took a bit of work to get  
it into a usable state (as I detailed in a previous email[2]).

-R

[1] <http://www.holygoat.co.uk/projects/twinql/>
[2] <http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/ 
2005Aug/0055.html>
On 18 Aug 2005, at 11:28, Tim Berners-Lee wrote:

>
> This is a followup from a discussion between Yosi Scharf,  
> implementer of SPARQL in cwm, currently on vacation,  and Eric  
> P'dH, co-editor of the spec, several weeks ago.
>
> Yosi has built his implementation of SPARQL from a file which is  
> almost the one generated from the TR, but with a slight tweak to  
> make the file grammar able to be parsed by a predictive parser [1]  
> a simple form of LL(1) recursive descent parser.  I understood that  
> the tweak was editorial in that the it didn't change the language,  
> just the way it was expressed as a context-free grammar.
>
> A situation in which code can be generated directly from the spec  
> is a very strong position to be in.  I am not aware of any time  
> this has previously happened for a W3C language, but I may be  
> wrong.  As it is demonstrably simple to make the step here I would  
> request it be done at last call stage before the call for  
> implementation at CR.
>
> [1] http://www.inf.ed.ac.uk/teaching/courses/cs2/LectureNotes/CS2Ah/ 
> LangProc/lp10.pdf
>
> Tim Berners-Lee
> MIT/CSAIL/DIG
>
>
>
Received on Thursday, 18 August 2005 20:27:06 GMT

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