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Re: Bug? SPARQL query comma-joined object variables

From: Tim Berners-Lee <timbl@w3.org>
Date: Tue, 3 Oct 2006 08:46:54 -0400
Message-Id: <B38FC33E-771F-4E40-8524-B0E05EE98761@w3.org>
Cc: public-cwm-bugs@w3.org, Yosi Scharf <syosi@mit.edu>
To: Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>

Yoshio,

Looks like a bug in the SPARQL compiler.
Yosi, do you have any time to look at that?

Tim


On Oct 3, 2006, at 7:11, Yoshio Fukushige wrote:

>
> Hi,
>
> With the data triples in file <gomi.n3>
> --
> @prefix : <#> .
> :s :p :o1, :o2.
> --
>
> and a SPARQL query
> --
> PREFIX  : <gomi.n3#>
>
> SELECT ?x ?y
> WHERE{
>  :s :p ?x, ?y.
> }
> --
>
> cwm (1.1.0rc2) breaks (on cygwin).
>

Did you mean "cwm works"?  Or is there a separate bug in that test?


> But with
> --
> PREFIX  : <gomi.n3#>
>
> SELECT ?x ?y
> WHERE{
>  :s :p ?x.
>  :s :p ?y.
> }
> --
> or
> --
> PREFIX  : <gomi.n3#>
>
> SELECT ?x ?y
> WHERE{
>  :s :p ?x; :p ?y.
> }
> --
>
> it's OK and spit
> (A)
> --
>      @prefix : <http://www.w3.org/2000/10/swap/sparqlCwm#> .
>      @prefix gomi: <#> .
>     {
>         gomi:o1     :bound "x",
>                     "y" .
>
>         }     a :Result .
>     {
>         gomi:o1     :bound "x" .
>         gomi:o2     :bound "y" .
>
>         }     a :Result .
>     {
>         gomi:o1     :bound "y" .
>         gomi:o2     :bound "x" .
>
>         }     a :Result .
>     {
>         gomi:o2     :bound "x",
>                     "y" .
>
>         }     a :Result .
> --
>
> I'm afraid it's a bug.
>
> Here's what I got as the error message
>
> --
> #Processed by Id: cwm.py,v 1.177 2005/08/28 22:53:56 syosi Exp
>         #    using base file:/cygdrive/c/home/MEI/NEDO2006/local- 
> test/member/fuku/sparql-test/gomi.n3
> loaded from file  0.196000099182
>         ['_O_QCOMMA_E____QObjectList_E__C', ('http://www.w3.org/ 
> 2000/10/swap/grammar/sparql#GT_COMMA', u','), ('andExtra',  
> ('objectList', [('Var', y)]), [])]
> Traceback (most recent call last):
>   File "/usr/local/cwm-1.1.0rc2/cwm", line 715, in ?
>     doCommand()
>   File "/usr/local/cwm-1.1.0rc2/cwm", line 534, in doCommand
>     filterContext = _store.load(_uri, why=r, referer="",  
> contentType="x-application/sparql")
>   File "/usr/local/cwm-1.1.0rc2/swap/llyn.py", line 1329, in load
>     F = webAccess.load(store, uri, openFormula, asIfFrom,  
> contentType, flags, referer, why)
>   File "/usr/local/cwm-1.1.0rc2/swap/webAccess.py", line 166, in load
>     F = p.parse(sparql_parser.start).close()
>   File "/usr/local/cwm-1.1.0rc2/swap/sparql/sparql_parser.py", line  
> 100, in parse
>     self.onFinish()
>   File "/usr/local/cwm-1.1.0rc2/swap/sparql/sparql_parser.py", line  
> 112, in onFinish
>     prod = self.sink.prod(self.productions.pop())
>   File "/usr/local/cwm-1.1.0rc2/swap/sparql2cwm.py", line 388, in prod
>     return getattr(self, 'on_' + abbr(production[0]))(production)
>   File "/usr/local/cwm-1.1.0rc2/swap/sparql2cwm.py", line 1409, in  
> on__O_QCOMMA_E____QObjectList_E__C
>     raise RuntimeError(`p`)
> RuntimeError: ['_O_QCOMMA_E____QObjectList_E__C', ('http:// 
> www.w3.org/2000/10/swap/grammar/sparql#GT_COMMA', u','),  
> ('andExtra', ('objectList', [('Var', y)]), [
> ])]
> --
>
> And I'm not completely sure if it's OK
> to have only one variable bound in the result (A) above.
> (and always with "x" bound but not "y")
>
> In contrast SPARQLer [1] returns a result
> where the two variables got always bound,
> although there are cases where the two variables are bound to a  
> single resource (:o1 or :o2).
>
> [1] http://sparql.org/sparql.html
>
> Best,
> Yoshio
>
> -- 
> Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>
> Network Development Center,
> Matsushita Electric Industrial Co., Ltd.
>
>
Received on Tuesday, 3 October 2006 12:47:38 UTC

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