[DAFFODIL-2657] prefixedLengthType which itself has lengthKind 'implict' fails with None.get

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.1
• Fix Version/s: 3.3.0
• Component/s: Middle "End"
• Assignee: Mike Beckerle
• Reporter: Mike Beckerle
• Created: 14/Feb/22 18:30
• Updated: 28/Feb/22 19:01
• Resolved: 28/Feb/22 15:00

Description

When an element has prefixed lengthKind, prefixIncludesPrefixLength='yes' the prefixLengthKind itself is derived from xs:unsignedInt and has implicit lengthKind (hence, length 4 bytes) and representation is 'binary'. 

This should work to subtract 4 bytes from the value of the prefix to get the value of the length of the content. 

However, I get this backtrace:

java.util.NoSuchElementException: None.get    at scala.None$.get(Option.scala:529)
    at scala.None$.get(Option.scala:527)
    at org.apache.daffodil.grammar.ElementBaseGrammarMixin.prefixedLengthAdjustmentInUnits(ElementBaseGrammarMixin.scala:201)
    at org.apache.daffodil.grammar.ElementBaseGrammarMixin.prefixedLengthAdjustmentInUnits$(ElementBaseGrammarMixin.scala:193)
    at org.apache.daffodil.dsom.AbstractElementRef.prefixedLengthAdjustmentInUnits$lzycompute(ElementRef.scala:38)
    at org.apache.daffodil.dsom.AbstractElementRef.prefixedLengthAdjustmentInUnits(ElementRef.scala:38)
    at org.apache.daffodil.grammar.primitives.SpecifiedLengthPrefixed.pladj$lzycompute(SpecifiedLength.scala:156)
    at org.apache.daffodil.grammar.primitives.SpecifiedLengthPrefixed.pladj(SpecifiedLength.scala:156) 

It seems to be because Daffodil is assuming there will be a lengthEv for the length of the prefix, but if the prefixLengthType itself uses lengthKind 'implicit' there will not be a lengthEv (currently).