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If the first byte encountered is a 3 then the reader will fail with an error since the snippet only handles 1 or 2 in the first byte. If a 3 is a valid possibility there are three possible solutions:
Solution 1
Add an additional Attribute Node to the Choice Node with a discriminator of 3, as below:
| Code Block | ||
|---|---|---|
| ||
<Choice>
<Sequence name="option1">
<Attr name="type1" discriminator="1" type="String"/>
<Attr name="numberValue" bytes="2" type="Integer"/>
</Sequence>
<Sequence name="option2">
<Attr name="type2" discriminator="2" type="String"/>
<Attr name="stringValue" bytes="8" type="String"/>
</Sequence>
<Attr name="type3" discriminator="3" type="String/>
</Choice>
<Attr name="final" bytes="2" type="Integer"/> |
Solution 2
Add an Attribute Node to the Choice Node to pick up any value that is not 1 or 2, as below:
| Code Block | ||
|---|---|---|
| ||
<Choice>
<Sequence name="option1">
<Attr name="type1" discriminator="1" type="String"/>
<Attr name="numberValue" bytes="2" type="Integer"/>
</Sequence>
<Sequence name="option2">
<Attr name="type2" discriminator="2" type="String"/>
<Attr name="stringValue" bytes="8" type="String"/>
</Sequence>
<Attr name="type3" bytes="1" type="String/>
</Choice>
<Attr name="final" bytes="2" type="Integer"/> |
Solution 3
Note that in the snippet above, if no discriminator is set on the Attribute Node type3 then the number of bytes or bits must be set. You cannot have more than one generic option like this in a Choice Node, since this will make the grammar ambiguous.
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