Implement Zcash(De)serialize traits specifically for MerkleTree<Transaction>

This is a general placeholder for now.

zebra-chain/src/block.rs

@@ -28,6 +28,18 @@ impl From<BlockHeader> for BlockHash {
 /// hashed transactions in a block.
 pub struct MerkleRootHash([u8; 32]);
 
+impl<Transaction> ZcashSerialize for MerkleTree<Transaction> {
+    fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), SerializationError> {
+        unimplemented!();
+    }
+}
+
+impl<Transaction> ZcashDeserialize for MerkleTree<Transaction> {
+    fn zcash_deserialize<R: io::Read>(reader: R) -> Result<Self, SerializationError> {
+        unimplemented!();
+    }
+}
+
 impl From<MerkleTree<Transaction>> for MerkleRootHash {
     fn from(merkle_tree: MerkleTree<Transaction>) -> Self {
         let mut hash_writer = Sha256dWriter::default();

zebra-chain/src/merkle_tree.rs

@@ -2,9 +2,8 @@
 //! node values.
 
 use std::io;
-use std::io::prelude::*;
 
-use sha2::{Digest, Sha256};
+use sha2::Sha256;
 
 use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize};
 
@@ -20,15 +19,3 @@ impl<T> MerkleTree<T> {
         unimplemented!();
     }
 }
-
-impl<T> ZcashSerialize for MerkleTree<T> {
-    fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), SerializationError> {
-        unimplemented!();
-    }
-}
-
-impl<T> ZcashDeserialize for MerkleTree<T> {
-    fn zcash_deserialize<R: io::Read>(reader: R) -> Result<Self, SerializationError> {
-        unimplemented!();
-    }
-}