1 files changed, 76 insertions, 0 deletions
diff --git a/vendor/der/src/decode.rs b/vendor/der/src/decode.rs
new file mode 100644
index 000000000..1c63b322a
--- /dev/null
+++ b/vendor/der/src/decode.rs
@@ -0,0 +1,76 @@
+//! Trait definition for [`Decode`].
+
+use crate::{FixedTag, Header, Reader, Result, SliceReader};
+
+#[cfg(feature = "pem")]
+use crate::{pem::PemLabel, PemReader};
+
+#[cfg(doc)]
+use crate::{Length, Tag};
+
+/// Decoding trait.
+///
+/// This trait provides the core abstraction upon which all decoding operations
+/// are based.
+pub trait Decode<'a>: Sized {
+    /// Attempt to decode this message using the provided decoder.
+    fn decode<R: Reader<'a>>(decoder: &mut R) -> Result<Self>;
+
+    /// Parse `Self` from the provided DER-encoded byte slice.
+    fn from_der(bytes: &'a [u8]) -> Result<Self> {
+        let mut reader = SliceReader::new(bytes)?;
+        let result = Self::decode(&mut reader)?;
+        reader.finish(result)
+    }
+}
+
+impl<'a, T> Decode<'a> for T
+where
+    T: DecodeValue<'a> + FixedTag,
+{
+    fn decode<R: Reader<'a>>(reader: &mut R) -> Result<T> {
+        let header = Header::decode(reader)?;
+        header.tag.assert_eq(T::TAG)?;
+        T::decode_value(reader, header)
+    }
+}
+
+/// Marker trait for data structures that can be decoded from DER without
+/// borrowing any data from the decoder.
+///
+/// This is primarily useful for trait bounds on functions which require that
+/// no data is borrowed from the decoder, for example a PEM decoder which needs
+/// to first decode data from Base64.
+///
+/// This trait is inspired by the [`DeserializeOwned` trait from `serde`](https://docs.rs/serde/latest/serde/de/trait.DeserializeOwned.html).
+pub trait DecodeOwned: for<'a> Decode<'a> {}
+
+impl<T> DecodeOwned for T where T: for<'a> Decode<'a> {}
+
+/// PEM decoding trait.
+///
+/// This trait is automatically impl'd for any type which impls both
+/// [`DecodeOwned`] and [`PemLabel`].
+#[cfg(feature = "pem")]
+#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
+pub trait DecodePem: DecodeOwned + PemLabel {
+    /// Try to decode this type from PEM.
+    fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self>;
+}
+
+#[cfg(feature = "pem")]
+#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
+impl<T: DecodeOwned + PemLabel> DecodePem for T {
+    fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self> {
+        let mut reader = PemReader::new(pem.as_ref())?;
+        Self::validate_pem_label(reader.type_label())?;
+        T::decode(&mut reader)
+    }
+}
+
+/// Decode the value part of a Tag-Length-Value encoded field, sans the [`Tag`]
+/// and [`Length`].
+pub trait DecodeValue<'a>: Sized {
+    /// Attempt to decode this message using the provided [`Reader`].
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self>;
+}