[DFDL-WG] clarification: on suppressed ZL string/hexBinary - do we keep variable assignments?

[Steve Hanson]

Whether to add a zero-length string or hexBinary to the infoset for an 
optional element depends on the setting of emptyValueDelimiterPolicy. A 
setting of 'none' stops it from being added.

Regardless, it does not give a processing error, so is therefore 
known-to-exist, and therefore does not cause backtracking, so preserving 
discriminators and variables.

Regards
 
Steve Hanson
IBM Hybrid Integration, Hursley, UK
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
smh at uk.ibm.com
tel:+44-1962-815848
mob:+44-7717-378890
Note: I work Tuesday to Friday 



From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     dfdl-wg at ogf.org
Date:   24/07/2018 15:15
Subject:        [DFDL-WG] clarification: on suppressed ZL string/hexBinary 
- do we keep variable assignments?
Sent by:        "dfdl-wg" <dfdl-wg-bounces at ogf.org>




In some situations we parse and get a successful zero-length parse for a 
string or hexBinary.

But because the occurrence is optional, we do NOT add an element to the 
infoset.

In that case, what happens to side-effects that occurred during the 
successful parse. There are two possible kinds of side-effects. Variables 
can be set, and a discriminator can be set to true.

It seems to me that if a discriminator is set, then that *must* be 
preserved, and in that case it would seem the variable settings should be 
retained as well.

Comments?

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
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