Lexing RIF PS

Hi Axel,

Still in the process of deciphering the intricacies of what
constitutes a RIF BLD/DTB lexical unit, I have a question for you
regarding how you describe the RIF symbol spaces, and specifically
the use of the Base directive to expand on relative IRI's.

In http://www.w3.org/TR/2008/WD-rif-dtb-20080730/#Relative_IRIs,
you describe how the Base directive (at most one per RIF document)
can be used to declare a base IRI for resolving relative IRI's
in RIF. You wrote:

> 2.1.3 Relative IRIs
> 
> Relative IRIs in RIF documents are resolved with respect to the base
> IRI. Relative IRIs are combined with base IRIs as per Uniform
> Resource Identifier (URI): Generic Syntax [RFC-3986] using only the
> basic algorithm in Section 5.2.

You go on giving the following examples :

> For instance, the constant <./xyz> or "./xyz"^^rif:iri are both
> valid abbreviations for the constant "http://www.example.org/xyz"^^rif:iri
> in a RIF document in presentation syntax that has the single base
> directive Base( http://www.example.org ) in its preamble.

Basically, the above entails that the internal structure of IRI's
must be parsed out of all RIF PS string constants and identifiers
that happen to be legal IRI's.  At least this is what I understand
from the avove and reference you cite [RFC 3986, Berners-Lee, et al.,
January 2005, Standards Track, Page 25, (URI Generic Syntax)], which
states:

> 4.1.  URI Reference
> 
>    URI-reference is used to denote the most common usage of a resource
>    identifier.
> 
>       URI-reference = URI / relative-ref
> 
>    A URI-reference is either a URI or a relative reference.  If the
>    URI-reference's prefix does not match the syntax of a scheme followed
>    by its colon separator, then the URI-reference is a relative
>    reference.
> 
>    A URI-reference is typically parsed first into the five URI
>    components, in order to determine what components are present and
>    whether the reference is relative.

This, unfortunately again, requires that any lexical analyzer for the
RIF PS include complete IRI parser - which I am not willing to invest
any effort in at this nor any near future time.

-hak
--
Hassan Aït-Kaci  *  ILOG, Inc. - Product Division R&D
http://koala.ilog.fr/wiki/bin/view/Main/HassanAitKaci