Thanks, I was actually thinking this was in a table somewhere also, and I did find it. Table 22 says the minimum length for a binary signed integer is 2 bits, for unsigned 1. So definitely a parse error, and symmetrically, and unparse error if length is 0 for an int/unsignedint when unparsing. Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense | www.owlcyberdefense.com Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy <http://www.ogf.org/About/abt_policies.php> On Thu, Mar 19, 2020 at 7:28 PM Steve Hanson <smh@uk.ibm.com> wrote:
This is covered by section 9.3.2 (establishing representation) and section 9.5 (evaluation order).
Your integer is not nillable, so can't have nil rep. Assuming compliance with dfdl:emptyValueDelimiterPolicy it therefore has empty representation. Assuming this is a local element with minOccurs-=1 implicitly, and no default value, it is a parsing error. Section 9.5 says the assert will never be executed as it is lower down the evaluation order.
Regards
Steve Hanson
IBM Hybrid Integration, 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@uk.ibm.com* <smh@uk.ibm.com> tel:+44-1962-815848 mob:+44-7717-378890 Note: I work Tuesday to Friday
From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: DFDL-WG <dfdl-wg@ogf.org> Date: 19/03/2020 22:50 Subject: [EXTERNAL] [DFDL-WG] Clarification: zero-bit-long integer parses to value 0, or parse-error or? Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org> ------------------------------
Consider: <*xs**:element **name**="spare" **dfdl**:length**="{ $tns:WordPaddingBits }"*> <*xs**:simpleType* *dfdl**:lengthKind**="explicit"*> <*xs**:annotation*> <*xs**:appinfo **source**="**http://www.ogf.org/dfdl/* <http://www.ogf.org/dfdl/>*"*> <*dfdl**:assert **test**="{ . eq 0 }" */> </*xs**:appinfo*> </*xs**:annotation*> <*xs**:restriction **base**="xs:unsignedInt"*> <*xs**:enumeration **value**="0" */> </*xs**:restriction*> </*xs**:simpleType*> </xs:element>
Now, suppose the variable tns:WordPaddingBits has value 0. So this padding integer will be length 0 (this binary data with lengthUnits bits). Currently, Daffodil gives a runtime SDE on this. The assert test expression complains that "." has no value. I would claim this should either provide a value of 0 for this integer, or it should be a parse error because you must have at least 1 bit.
Thoughts? Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense | *www.owlcyberdefense.com* <http://www.owlcyberdefense.com> (Tresys is now part of Owl) Please note: Contributions to the DFDL Workgroup's email discussions are subject to the *OGF Intellectual Property Policy* <http://www.ogf.org/About/abt_policies.php>
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