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Re: question about Trig spec

From: Andy Seaborne <andy@apache.org>
Date: Wed, 18 Sep 2013 14:07:10 +0100
Message-ID: <5239A57E.8070700@apache.org>
To: Sandro Hawke <sandro@w3.org>
CC: public-rdf-wg@w3.org
>>> On 16/09/13 13:39, Sandro Hawke wrote:
>>>> - is it a bug that the grammar says (blankNodePropertyList |
>>>> collection)
>>>> can preceed { } but not if GRAPH is used?  How about getting rid of
>>>> triples2 and instead change labelOrSubject to include alternatives
>>>> blankNodePropertyList and collection?    I don't have a working
>>>> grammar-driven-parser right now, so maybe I'm doing that wrong in my
>>>> head.
>>>
>>> It was intentional as being the conservative choice.
>>>
>>> We did discuss
>>>
>>> GRAPH [:p 123 ; :q "" ] { ... }
>>> [:p 123 ; :q "" ] { ... }
>>>
>>> but c.f.
>>>
>>> [:p 123 ; :q "" ] :predicate :object .
>>>
>>> the discussion did not result in an agreement.  Restricting the graph
>>> name to a single term form, not a triple generating one, is the
>>> conservative choice at this point in time.
>>>
>>
>> I don't have any opinion about whether we should allow
>>
>> GRAPH [:p 123 ; :q "" ] { ... }
>> and
>> [:p 123 ; :q "" ] { ... }
>>
>> but as I read the grammar it seems to be saying we allow the second of
>> those two, but not the first.  And that doesn't seem good.
>>
>> I agree the conservative route is to forbid this construction, but if
>> so, I'd think we should forbid it in both forms.
>
> What derivation of rules allows
>
> [:p 123 ; :q "" ] { ... }
>
> ?
>
> A non [] blankNodePropertyList matches only:
>
> [4g]    triples2    ::=
>      (blankNodePropertyList | collection) predicateObjectList? '.'
>
>
> which must end in a '.'
>
> so
>
> [:p 123 ; :q "" ] .
> { ... }
>
> is OK (bare Turtle, then a {} default graph part - ugly but hard to
> avoid) but
>
> [:p 123 ; :q "" ] { ... }
>
> is not.
>
> Could provide a concrete example and the parse rules you are reading?

Ping Sandro.

(I have checked with a javacc parser and can not see how it can be 
accepted by the grammar)

	Andy

>
>      Andy
>
>>
>>        -- Sandro
>>
>>> It would apply if the word GRAPH were not used via triplesOrGraph
>>> (caveat: I do not have my reference parser on this machine)
>>>
>>>     Andy
>>>
>>>>
>>>> Thanks.
>>>>
>>>>         -- Sandro
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>
Received on Wednesday, 18 September 2013 13:14:50 UTC

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