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Re: SPARQL: QuotedIRIref too lax [OK?]

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Wed, 05 Oct 2005 17:22:20 +0200
To: andy.seaborne@hp.com
Cc: public-rdf-dawg-comments@w3.org
Message-ID: <tar7k1ds9fp6t81l93io6egnb0c0pqeul5@hive.bjoern.hoehrmann.de>

* Seaborne, Andy wrote:
>The SPARQL grammar section [1] says that the syntax produces IRIs (A.1)
>Text matched by the  Q_IRI_REF production and QName  (after prefix expansion) 
>production must be conform to the generic syntax of IRI references in section 
>2.2 of RFC 3987 "ABNF for IRI References and IRIs" [RFC3987]. For example, the 
>  Q_IRI_REF <abc#def> may occur in a SPARQL query string, but the  Q_IRI_REF 
><abc##def> must not.

This prohibes use of \u... escapes as the escape sequence would be part
of the matched text which must conform to the IRI syntax which excludes
the \ character, so this contradicts A.5. It should probably say that
the unescaped text must match.

>and in addition the grammar itself has:
>Q_IRI_REF ::= '<' ([^<>]-[#00-#20])* '>' /* An IRI reference : RFC 3987 */
>(rather than duplicate the whole of the ABNF in RFC 3986 and 3987).

This should also exclude other disallowed characters like { and } and it
might make sense to note that this "IRI reference" comment refers to the
value space rather than the lexical space.

I would prefer to "duplicate" the IRI Reference grammar (either in the
document or some normative reference) with some flexible means to allow
for the additional escape syntax as that would encourage early error
detection (parser would likely be derived from the grammar and the IRIs
be passed to some generic IRI handling API e.g. in case of FROM <...>
which are likely more tolerant, so keeping this out of the grammar is
likely to cause some implementations to fail to detect errors), but I
understand that this might be too much work for the DAWG at this point.
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Received on Wednesday, 5 October 2005 15:21:43 UTC

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