[DFDL-WG] Clarification for nil processing and zero length

[Mike Beckerle]

My read of 13.16 says that for nilKind 'literalValue' and textual
representation, WSP* is already allowed for simple types.  So I think
nilValue="%WSP*;" should work and match empty string.

Delimiters have qualifiers on ES alone and WSP* alone e.g., for separator:
"However, the WSP* entity cannot appear on its own as one of the string
literals in the list when determining the length of a component by scanning
for delimiters, , and it is a schema definition error otherwise. delimiters"

(Note the fragment at the end of that sentence. That's a spec. bug)

But I see no such stipulation for nilValue.


Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
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On Fri, Mar 4, 2016 at 6:35 AM, Steve Hanson <smh at uk.ibm.com> wrote:

> The DFDL 1.0 spec current says:
>
> 9.3.2.1        *Simple element*
>
> If the result is length zero as described above, the representation is
> then established by checking, in order for:
>
> 1.        nil representation (if %ES; is a literal nil value).
>
> 2.        empty representation.
>
> 3.        normal representation (xs:string or xs:hexBinary only)
>
> 4.        absent representation (if none of the prior representations
> apply).
>
> But should bullet 1 be:
>
> 1. nil representation (if either %ES; or %WSP*; on its own is a literal
> nil value).
>
>
> I added a test to IBM DFDL and found that setting
> dfdl:nilKind="literalValue" & dfdl:nilValue="%WSP*;" did not match an
> element value of empty string. That surprised me, and I think the IBM DFDL
> code is strictly implementing bullet 1.  Using "%WSP*;" is useful for
> allowing zero or more white space to mean <nil>. I could use "%WSP+; %ES"
> to achieve the same goal but I'm not sure that was the intent here.
>
> Quick response appreciated.
>
> Regards
>
> Steve Hanson
> *IBM Integration Bus*
> <http://www-03.ibm.com/software/products/en/ibm-integration-bus>,
> Hursley, UK
> Architect, *IBM DFDL*
> <http://www.ibm.com/developerworks/library/se-dfdl/index.html>
> Co-Chair, *OGF DFDL Working Group* <http://www.ogf.org/dfdl/>
> *smh at uk.ibm.com* <smh at uk.ibm.com>
> tel:+44-1962-815848
> mob:+44-7717-378890
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