//! 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,

{

}