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//! ASN.1 `CHOICE` support.
use crate::{Decode, FixedTag, Tag, Tagged};
/// ASN.1 `CHOICE` denotes a union of one or more possible alternatives.
///
/// The types MUST have distinct tags.
///
/// This crate models choice as a trait, with a blanket impl for all types
/// which impl `Decode + FixedTag` (i.e. they are modeled as a `CHOICE`
/// with only one possible variant)
pub trait Choice<'a>: Decode<'a> + Tagged {
/// Is the provided [`Tag`] decodable as a variant of this `CHOICE`?
fn can_decode(tag: Tag) -> bool;
}
/// This blanket impl allows any [`Tagged`] type to function as a [`Choice`]
/// with a single alternative.
impl<'a, T> Choice<'a> for T
where
T: Decode<'a> + FixedTag,
{
fn can_decode(tag: Tag) -> bool {
T::TAG == tag
}
}
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