Add context_deserialize impl (#61)

* Add context_deserialize impl

* Use new `context_deserialize` version

Author: macladson

ssz/Cargo.toml

@@ -13,10 +13,9 @@ categories = ["cryptography::cryptocurrencies"]
 [lib]
 name = "ssz"
 
-[dev-dependencies]
-alloy-primitives = { version = "1.0", features = ["getrandom"] }
-ethereum_ssz_derive = { version = "0.9.0", path = "../ssz_derive" }
-serde_json = "1.0.0"
+[features]
+arbitrary = ["dep:arbitrary", "alloy-primitives/arbitrary"]
+context_deserialize = ["dep:context_deserialize"]
 
 [dependencies]
 alloy-primitives = "1.0"
@@ -27,6 +26,9 @@ serde = "1.0.0"
 serde_derive = "1.0.0"
 typenum = "1.12.0"
 arbitrary = { version = "1.0", features = ["derive"], optional = true }
+context_deserialize = { version = "0.2", optional = true }
 
-[features]
-arbitrary = ["dep:arbitrary", "alloy-primitives/arbitrary"]
+[dev-dependencies]
+alloy-primitives = { version = "1.0", features = ["getrandom"] }
+ethereum_ssz_derive = { version = "0.9.0", path = "../ssz_derive" }
+serde_json = "1.0.0"

ssz/src/context_deserialize.rs

@@ -0,0 +1,33 @@
+use crate::{Bitfield, Fixed, Variable};
+use context_deserialize::ContextDeserialize;
+use serde::{
+    de::{Deserializer, Error},
+    Deserialize,
+};
+use typenum::Unsigned;
+
+impl<'de, C, N> ContextDeserialize<'de, C> for Bitfield<Variable<N>>
+where
+    N: Unsigned + Clone,
+{
+    fn context_deserialize<D>(deserializer: D, _context: C) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Bitfield::<Variable<N>>::deserialize(deserializer)
+            .map_err(|e| D::Error::custom(format!("{:?}", e)))
+    }
+}
+
+impl<'de, C, N> ContextDeserialize<'de, C> for Bitfield<Fixed<N>>
+where
+    N: Unsigned + Clone,
+{
+    fn context_deserialize<D>(deserializer: D, _context: C) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Bitfield::<Fixed<N>>::deserialize(deserializer)
+            .map_err(|e| D::Error::custom(format!("{:?}", e)))
+    }
+}

ssz/src/lib.rs

@@ -40,6 +40,9 @@ mod encode;
 pub mod legacy;
 mod union_selector;
 
+#[cfg(feature = "context_deserialize")]
+mod context_deserialize;
+
 pub use bitfield::bitvector_dynamic::{BitVectorDynamic, Dynamic};
 #[doc(hidden)]
 pub use bitfield::{BitList, BitVector, Bitfield, Error as BitfieldError, Fixed, Variable};