1 files changed, 26 insertions, 0 deletions
diff --git a/vendor/der/src/asn1/choice.rs b/vendor/der/src/asn1/choice.rs
new file mode 100644
index 0000000..40c7720
--- /dev/null
+++ b/vendor/der/src/asn1/choice.rs
@@ -0,0 +1,26 @@
+//! 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
+    }
+}