feat: Introduce shared codec lib (#71)

closes #65

pallas-codec/src/lib.rs

@@ -0,0 +1,30 @@
+use minicbor::encode::Write;
+
+/// Shared re-export of minicbor lib across all Pallas
+pub use minicbor;
+
+/// Round-trip friendly common helper structs
+pub mod utils;
+
+pub trait Fragment: Sized {
+    fn read_cbor(buffer: &[u8]) -> Result<Self, minicbor::decode::Error>;
+    fn write_cbor<W: Write>(&self, write: W) -> Result<(), minicbor::encode::Error<W::Error>>;
+}
+
+#[macro_export]
+macro_rules! impl_fragment {
+    ($Struct:ty) => {
+        impl $crate::Fragment for $Struct {
+            fn read_cbor(buffer: &[u8]) -> Result<Self, decode::Error> {
+                $crate::minicbor::decode(buffer)
+            }
+
+            fn write_cbor<W: encode::Write>(
+                &self,
+                write: W,
+            ) -> Result<(), encode::Error<W::Error>> {
+                $crate::minicbor::encode(self, write)
+            }
+        }
+    };
+}