INTEGER as C-like enums ( or enums with discriminators)

[naveedpash]

I have the following ASN.1

Result ::= INTEGER {
  acceptance (0),
  user-rejection (1),
  provider-rejection (2)
}

One way to represent this in rust would be

#[derive(Debug, AsnType, Encode, Decode)]
#[rasn(automatic_tags)]
struct StructContainingResult {
  result: rasn::types::Integer
}

However I would then have to write code to check if result actually contains a 0 or 1 or 2 and return an error if it had anything else. Also my code will be less self-explanatory. Is the following a valid way to declare the same asn.1 using rasn:

#[derive(Debug, AsnType, Encode, Decode)]
#[repr(u8)]
enum Result {
  Acceptance=0,
  UserRejection=1,
  ProviderRejection=2
}

(I know the ideal answer is "try and test" but I actually don't know how to calculate the encoding by hand)

[XAMPPRocky]

Thank you for your question. Yeah this falls under #6 as providing constraints for integers, which isn't supported directly at the moment.

For this specific instance though, you should be able to model pretty well in rasn by using enumerated and setting #[rasn(tag(universal, 2)], which would encode it as an integer but also check if it matches any of the variants. It's a bit hacky, but if you don't want to write the validation it should work.

[naveedpash]

Alright for how I'll use enumerated along with the integer universal tag because the document I'm implementing has a lot of this kind of scenario

Wish I was literate enough to help you with constraints....