[DAFFODIL-2193] dfdl:lengthKind="prefixed" with dfdl:lengthUnits="characters" gives wrong parse result

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.4.0
• Component/s: Back End, Front End
• Assignee: Unassigned
• Reporter: Steve Lawrence
• Created: 28/Aug/19 11:27
• Updated: 23/Jan/23 19:32

Description

3ABC

That data can be described with the following schema:

Unable to find source-code formatter for language: xsd. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

<xs:element name="D"type="xs:string"
    dfdl:lengthUnits="characters"
    dfdl:lengthKind="prefixed"
    dfdl:prefixLengthType="D-type"
    dfdl:prefixIncludesPrefixLength="no"/>

<xs:simpleType name="D-type"
    dfdl:lengthKind="explicit"
    dfdl:length="1"> 
  <xs:restrictionbase="xs:integer"/>
</xs:simpleType>

DAFFODIL-114 added support for lengthKind="characters", but upon testing it looks like it created an Assert.invariant if the lengthKind="characters" for a prefixed length element. On 2.4.0, that invariant doesn't happen, but the lenght is calculated incorrectly. In 2.4.0, it only parses a single character, even though the prefix length is 3.

Also see related DAFFODIL-2029, which is to add support for unparsing lengthKind="characters" prefixed length elements.

If we don't support this yet, we might just want to make it a notYetImplemented error.