Further reduce boilerplate code by leveraging generics

tendermint/src/amino_types.rs

@@ -5,6 +5,7 @@
 
 pub mod block_id;
 pub mod ed25519;
+pub mod message;
 pub mod ping;
 pub mod proposal;
 pub mod remote_error;

tendermint/src/amino_types/message.rs

@@ -0,0 +1,39 @@
+/// A wrapper whose sole purpose is to extend the original
+/// prost::Message trait with a few helper functions in order to reduce boiler-plate code
+/// (and without modifying the prost-amino dependency).
+pub struct AminoMessage<M>(M); // Note: we have to introduce a new type in order to add methods like bytes_vec or impl Into<Vec<u8>>
+
+impl<M> AminoMessage<M>
+where
+    M: prost_amino::Message,
+{
+    /// Returns a wrapper for the given prost-amino message
+    pub fn new(m: M) -> AminoMessage<M> {
+        AminoMessage(m)
+    }
+    /// Directly amino encode a prost-amino message into a freshly created Vec<u8>.
+    /// This can be useful when passing those bytes directly to a hasher, or,
+    /// to reduce boiler plate code when working with the encoded bytes.
+    ///
+    /// Warning: Only use this method, if you are in control what will be encoded.
+    /// If there is an encoding error, this method will panic.
+    pub fn bytes_vec(m: M) -> Vec<u8> {
+        AminoMessage(m).into()
+    }
+}
+
+impl<M> Into<Vec<u8>> for AminoMessage<M>
+where
+    M: prost_amino::Message,
+{
+    /// Convert a wrapped prost-amino message directly into a byte vector which contains the amino
+    /// encoding.
+    ///
+    /// Warning: Only use this method, if you are in control what will be encoded. If there is an
+    /// encoding error, this method will panic.
+    fn into(self) -> Vec<u8> {
+        let mut res = Vec::with_capacity(self.0.encoded_len());
+        self.0.encode(&mut res).unwrap();
+        res
+    }
+}

tendermint/src/amino_types/vote.rs

@@ -245,6 +245,7 @@ impl ConsensusMessage for Vote {
 mod tests {
     use super::super::PartsSetHeader;
     use super::*;
+    use crate::amino_types::message::AminoMessage;
     use crate::amino_types::SignedMsgType;
     use chrono::{DateTime, Utc};
     use prost::Message;
@@ -333,8 +334,7 @@ mod tests {
             vt_precommit.vote_type = SignedMsgType::PreCommit.to_u32(); // precommit
             println!("{:?}", vt_precommit);
             let cv_precommit = CanonicalVote::new(vt_precommit, "");
-            got = vec![];
-            cv_precommit.encode(&mut got).unwrap();
+            let got = AminoMessage::bytes_vec(cv_precommit);
             let want = vec![
                 0x8,  // (field_number << 3) | wire_type
                 0x2,  // PrecommitType
@@ -355,10 +355,9 @@ mod tests {
             vt_prevote.round = 1;
             vt_prevote.vote_type = SignedMsgType::PreVote.to_u32();
 
-            got = vec![];
             let cv_prevote = CanonicalVote::new(vt_prevote, "");
 
-            cv_prevote.encode(&mut got).unwrap();
+            let got = AminoMessage::bytes_vec(cv_prevote);
 
             let want = vec![
                 0x8,  // (field_number << 3) | wire_type
@@ -379,9 +378,8 @@ mod tests {
             vt_no_type.height = 1;
             vt_no_type.round = 1;
 
-            got = vec![];
             let cv = CanonicalVote::new(vt_no_type, "");
-            cv.encode(&mut got).unwrap();
+            let got = AminoMessage::bytes_vec(cv);
 
             let want = vec![
                 0x11, // (field_number << 3) | wire_type
@@ -400,8 +398,7 @@ mod tests {
             no_vote_type2.round = 1;
 
             let with_chain_id = CanonicalVote::new(no_vote_type2, "test_chain_id");
-            got = vec![];
-            with_chain_id.encode(&mut got).unwrap();
+            got = AminoMessage::bytes_vec(with_chain_id);
             let want = vec![
                 0x11, // (field_number << 3) | wire_type
                 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,  // height

tendermint/src/block/header.rs

@@ -1,7 +1,7 @@
 //! Block headers
 use crate::merkle::simple_hash_from_byte_slices;
 use crate::{account, amino_types, block, chain, lite, Hash, Time};
-use prost::Message;
+use amino_types::{message::AminoMessage, BlockId, ConsensusVersion, TimeMsg};
 use {
     crate::serializers,
     serde::{Deserialize, Serialize},
@@ -89,32 +89,21 @@ impl lite::Header for Header {
     }
 
     fn hash(&self) -> Hash {
-        let mut version_enc = vec![];
-        // TODO: if there is an encoding problem this will
+        // Note that if there is an encoding problem this will
         // panic (as the golang code would):
         // https://github.com/tendermint/tendermint/blob/134fe2896275bb926b49743c1e25493f6b24cc31/types/block.go#L393
         // https://github.com/tendermint/tendermint/blob/134fe2896275bb926b49743c1e25493f6b24cc31/types/encoding_helper.go#L9:6
-        // Instead, handle errors gracefully here.
-        amino_types::ConsensusVersion::from(&self.version)
-            .encode(&mut version_enc)
-            .unwrap();
-        let mut time_enc = vec![];
-        amino_types::TimeMsg::from(self.time)
-            .encode(&mut time_enc)
-            .unwrap();
-        let mut last_block_id_enc = vec![];
-        amino_types::BlockId::from(&self.last_block_id)
-            .encode(&mut last_block_id_enc)
-            .unwrap();
-
-        let mut byteslices: Vec<Vec<u8>> = vec![];
-        byteslices.push(version_enc);
+
+        let mut byteslices: Vec<Vec<u8>> = Vec::with_capacity(16);
+        byteslices.push(AminoMessage::bytes_vec(ConsensusVersion::from(
+            &self.version,
+        )));
         byteslices.push(bytes_enc(self.chain_id.as_bytes()));
         byteslices.push(encode_varint(self.height.value()));
-        byteslices.push(time_enc);
+        byteslices.push(AminoMessage::bytes_vec(TimeMsg::from(self.time)));
         byteslices.push(encode_varint(self.num_txs));
         byteslices.push(encode_varint(self.total_txs));
-        byteslices.push(last_block_id_enc);
+        byteslices.push(AminoMessage::bytes_vec(BlockId::from(&self.last_block_id)));
         byteslices.push(encode_hash(self.last_commit_hash));
         byteslices.push(encode_hash(self.data_hash));
         byteslices.push(encode_hash(self.validators_hash));

tendermint/src/validator.rs

@@ -1,8 +1,8 @@
 //! Tendermint validators
 
+use crate::amino_types::message::AminoMessage;
 use crate::validator::signatory::{Signature, Verifier};
 use crate::{account, lite, merkle, vote, Hash, PublicKey};
-use prost::Message;
 use serde::{de::Error as _, Deserialize, Deserializer, Serialize, Serializer};
 use signatory;
 use signatory::ed25519;
@@ -147,9 +147,7 @@ impl From<&Info> for InfoHashable {
 // pubkey and voting power, so it includes the pubkey's amino prefix.
 impl Info {
     fn hash_bytes(&self) -> Vec<u8> {
-        let mut bytes: Vec<u8> = Vec::new();
-        InfoHashable::from(self).encode(&mut bytes).unwrap();
-        bytes
+        AminoMessage::bytes_vec(InfoHashable::from(self))
     }
 }
 

tendermint/src/vote.rs

@@ -3,8 +3,8 @@
 mod power;
 
 pub use self::power::Power;
+use crate::amino_types::message::AminoMessage;
 use crate::amino_types::vote::CanonicalVote;
-use crate::prost::Message;
 use crate::{account, block, lite, Signature, Time};
 use {
     crate::serializers,
@@ -99,9 +99,7 @@ impl lite::Vote for SignedVote {
     }
 
     fn sign_bytes(&self) -> Vec<u8> {
-        let mut sign_bytes = vec![];
-        self.vote.encode(&mut sign_bytes).unwrap();
-        sign_bytes
+        AminoMessage::bytes_vec(self.vote.to_owned())
     }
     fn signature(&self) -> &[u8] {
         match &self.signature {