From 52bd867fd918513e7cab9d57cf4fdf9c78396a03 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Wed, 30 May 2018 17:50:17 -0400
Subject: [PATCH] merkle: use amino for byteslice encoding

---
 merkle/simple_map.go      | 15 +++++++--------
 merkle/simple_map_test.go |  4 +---
 merkle/types.go           | 19 ++++---------------
 3 files changed, 12 insertions(+), 26 deletions(-)

diff --git a/merkle/simple_map.go b/merkle/simple_map.go
index b073ecdd6..cde5924f4 100644
--- a/merkle/simple_map.go
+++ b/merkle/simple_map.go
@@ -1,8 +1,8 @@
 package merkle
 
 import (
-	cmn "github.com/tendermint/tmlibs/common"
 	"github.com/tendermint/go-crypto/tmhash"
+	cmn "github.com/tendermint/tmlibs/common"
 )
 
 // Merkle tree from a map.
@@ -65,21 +65,20 @@ func (sm *simpleMap) KVPairs() cmn.KVPairs {
 //----------------------------------------
 
 // A local extension to KVPair that can be hashed.
-// XXX: key and value do not need to already be hashed -
-// the kvpair ("abc", "def") would not give the same result
-// as ("ab", "cdef") as we're using length-prefixing.
+// Key and value are length prefixed and concatenated,
+// then hashed.
 type kvPair cmn.KVPair
 
 func (kv kvPair) Hash() []byte {
 	hasher := tmhash.New()
 	err := encodeByteSlice(hasher, kv.Key)
 	if err != nil {
-			panic(err)
-		}
+		panic(err)
+	}
 	err = encodeByteSlice(hasher, kv.Value)
 	if err != nil {
-			panic(err)
-		}
+		panic(err)
+	}
 	return hasher.Sum(nil)
 }
 
diff --git a/merkle/simple_map_test.go b/merkle/simple_map_test.go
index 9d0c25a2a..a89289a8f 100644
--- a/merkle/simple_map_test.go
+++ b/merkle/simple_map_test.go
@@ -11,9 +11,7 @@ import (
 type strHasher string
 
 func (str strHasher) Hash() []byte {
-	h := tmhash.New()
-	h.Write([]byte(str))
-	return h.Sum(nil)
+	return tmhash.Sum([]byte(str))
 }
 
 func TestSimpleMap(t *testing.T) {
diff --git a/merkle/types.go b/merkle/types.go
index ddc420659..2fcb3f39d 100644
--- a/merkle/types.go
+++ b/merkle/types.go
@@ -1,8 +1,9 @@
 package merkle
 
 import (
-	"encoding/binary"
 	"io"
+
+	amino "github.com/tendermint/go-amino"
 )
 
 // Tree is a Merkle tree interface.
@@ -30,20 +31,8 @@ type Hasher interface {
 }
 
 //-----------------------------------------------------------------------
-// NOTE: these are duplicated from go-amino so we dont need go-amino as a dep
 
+// Uvarint length prefixed byteslice
 func encodeByteSlice(w io.Writer, bz []byte) (err error) {
-	err = encodeUvarint(w, uint64(len(bz)))
-	if err != nil {
-		return
-	}
-	_, err = w.Write(bz)
-	return
-}
-
-func encodeUvarint(w io.Writer, i uint64) (err error) {
-	var buf [10]byte
-	n := binary.PutUvarint(buf[:], i)
-	_, err = w.Write(buf[0:n])
-	return
+	return amino.EncodeByteSlice(w, bz)
 }