[DAFFODIL-2062] NadaParser not optimized out

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 2.4.0
• Component/s: Front End
• Assignee: Dave Thompson
• Reporter: Steve Lawrence
• Created: 01/Feb/19 13:13
• Updated: 20/May/21 12:35
• Resolved: 14/Feb/19 12:31

Description

Assume the following schema:

  <xs:element name="test">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="count" type="xs:int" dfdl:lengthKind="explicit" dfdl:length="1" />
        <xs:element name="record" dfdl:lengthKind="explicit" dfdl:length="2" maxOccurs="unbounded"
          dfdl:occursCountKind="expression" dfdl:occursCount="{ ../count }">
          <xs:complexType>
            <xs:sequence>
            <!--
              <xs:element name="value1" dfdl:lengthKind="explicit" dfdl:length="1" type="xs:string" />
              <xs:element name="value2" dfdl:lengthKind="explicit" dfdl:length="1" type="xs:string" />
            -->
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

This schema works if we uncomment the value1 and value2 elements. However, with them commented out, this schema should still work. The record element has an explciit length, so this should just skip over 2 bytes, count number of times. Instead, it results in the following exception:

org.apache.daffodil.exceptions.Abort: NadaParsers are all supposed to optimize out!
org.apache.daffodil.exceptions.Assert$.abort(Assert.scala:129)
org.apache.daffodil.processors.parsers.NadaParser.parse(Parser.scala:150)
org.apache.daffodil.processors.parsers.Parser.parse1(Parser.scala:76)
org.apache.daffodil.processors.parsers.Parser.parse1$(Parser.scala:70)
	at org.apache.daffodil.exceptions.Assert$.abort(Assert.scala:129)
	at org.apache.daffodil.processors.parsers.NadaParser.parse(Parser.scala:150)
	at org.apache.daffodil.processors.parsers.Parser.parse1(Parser.scala:76)

So the empty sequence results in a NadaParser, which should have been optimized out.