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PS grammar question

From: Hassan Ait-Kaci <hak@ilog.com>
Date: Sat, 20 Sep 2008 17:32:51 -0700
Message-ID: <9FC9C6B2EA71ED4B826F55AC7C8B9AAB01F33695@mvmbx01.ilog.biz>
To: "harold boley" <Harold.Boley@nrc-cnrc.gc.ca>
Cc: "RIF WG" <public-rif-wg@w3.org>
Hi Harold,

I am in the process of implementing a tokenizer for the RIF and I am
having headaches sorting out the various kinds of tokens a RIF-BLD PS
lexer should have for a quick prototype. I have a specific question:

In http://www.w3.org/TR/rif-bld/#EBNF_for_the_Rule_Language, you specified:

IRIMETA        ::= '(*' IRICONST? (Frame | 'And' '(' Frame* ')')? '*)'
Frame          ::= TERM '[' (TERM '->' TERM)* ']'
TERM           ::= IRIMETA? (Const | Var | Expr | 'External' '(' Expr ')')
Const          ::= '"' UNICODESTRING '"^^' SYMSPACE | CONSTSHORT
SYMSPACE       ::= ANGLEBRACKIRI | CURIE

where CONSTSHORT, ANGLEBRACKIRI, and CURIE are defined in:

http://www.w3.org/TR/2008/WD-rif-dtb-20080730/#sec-shortcuts-constants

by:

  ANGLEBRACKIRI ::= IRI_REF
  CURIE         ::= PNAME_LN | PNAME_NS
  CONSTSHORT    ::= ANGLEBRACKIRI         // shortcut for "..."^^rif:iri
                  | CURIE                 // shortcut for "..."^^rif:iri
                  | '"' UNICODESTRING '"' // shortcut for "..."^^xs:string
                  | NumericLiteral        // shortcut for "..."^^xs:integer,xs:decimal,xs:double
                  | '_' LocalName         // shortcut for "..."^^rif:local


However, when one looks at the example you give with meta-annotation:

> Example 4 (A RIF-BLD document containing an annotated group).

the meta-annoation PS you give for that example is:

> (* "http://sample.org"^^rif:iri pd[dc:publisher -> http://www.w3.org/
>                                    dc:date -> "2008-04-04"^^xs:date] *)

Can you please explain to me how http://www.w3.org/ can be derived as a
TERM according to the EBNF rules cited above?

Thanks.

-hak

PS/ BTW, the PS grammar's tokenizing is now complexified due to using PS
    to declare Prefix and Base pragmas not using double-quoted strings
    around the IRI's. The alternative would be to parse IRI's - which is
    beyond such a prototype's goal. In the canonical PS, all such IRI's
    are double-quoted strings which greatly simplifies the tokenizing.
    It'd be as simple and as easy to do so for the Prefix and Base pragmas.
--
Hassan At-Kaci  *  ILOG, Inc. - Product Division R&D
http://koala.ilog.fr/wiki/bin/view/Main/HassanAitKaci
Received on Sunday, 21 September 2008 00:35:30 GMT

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