Sdk2 kvpair (#102)

* Canonical KVPair in common
* Simplify common/Bytes to just hex encode

common/bytes.go

@@ -0,0 +1,53 @@
+package common
+
+import (
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// The main purpose of Bytes is to enable HEX-encoding for json/encoding.
+type Bytes []byte
+
+// Marshal needed for protobuf compatibility
+func (b Bytes) Marshal() ([]byte, error) {
+	return b, nil
+}
+
+// Unmarshal needed for protobuf compatibility
+func (b *Bytes) Unmarshal(data []byte) error {
+	*b = data
+	return nil
+}
+
+// This is the point of Bytes.
+func (b Bytes) MarshalJSON() ([]byte, error) {
+	s := strings.ToUpper(hex.EncodeToString(b))
+	jb := make([]byte, len(s)+2)
+	jb[0] = '"'
+	copy(jb[1:], []byte(s))
+	jb[1] = '"'
+	return jb, nil
+}
+
+// This is the point of Bytes.
+func (b *Bytes) UnmarshalJSON(data []byte) error {
+	if len(data) < 2 || data[0] != '"' || data[len(data)-1] != '"' {
+		return fmt.Errorf("Invalid hex string: %s", data)
+	}
+	bytes, err := hex.DecodeString(string(data[1 : len(data)-1]))
+	if err != nil {
+		return err
+	}
+	*b = bytes
+	return nil
+}
+
+// Allow it to fulfill various interfaces in light-client, etc...
+func (b Bytes) Bytes() []byte {
+	return b
+}
+
+func (b Bytes) String() string {
+	return strings.ToUpper(hex.EncodeToString(b))
+}

common/bytes_test.go

@@ -0,0 +1,68 @@
+package common
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// This is a trivial test for protobuf compatibility.
+func TestMarshal(t *testing.T) {
+	assert := assert.New(t)
+
+	b := []byte("hello world")
+	dataB := Bytes(b)
+	b2, err := dataB.Marshal()
+	assert.Nil(err)
+	assert.Equal(b, b2)
+
+	var dataB2 Bytes
+	err = (&dataB2).Unmarshal(b)
+	assert.Nil(err)
+	assert.Equal(dataB, dataB2)
+}
+
+// Test that the hex encoding works.
+func TestJSONMarshal(t *testing.T) {
+	assert := assert.New(t)
+
+	type TestStruct struct {
+		B1 []byte
+		B2 Bytes
+	}
+
+	cases := []struct {
+		input    []byte
+		expected string
+	}{
+		{[]byte(``), `{"B1":"","B2":""}`},
+		{[]byte(``), `{"B1":"","B2":""}`},
+		{[]byte(``), `{"B1":"","B2":""}`},
+	}
+
+	for i, tc := range cases {
+		t.Run(fmt.Sprintf("Case %d", i), func(t *testing.T) {
+			ts := TestStruct{B1: tc.input, B2: tc.input}
+
+			// Test that it marshals correctly to JSON.
+			jsonBytes, err := json.Marshal(ts)
+			if err != nil {
+				t.Fatal(err)
+			}
+			assert.Equal(string(jsonBytes), tc.expected)
+
+			// TODO do fuzz testing to ensure that unmarshal fails
+
+			// Test that unmarshaling works correctly.
+			ts2 := TestStruct{}
+			err = json.Unmarshal(jsonBytes, &ts2)
+			if err != nil {
+				t.Fatal(err)
+			}
+			assert.Equal(ts2.B1, tc.input)
+			assert.Equal(ts2.B2, Bytes(tc.input))
+		})
+	}
+}

common/kvpair.go

@@ -0,0 +1,30 @@
+package common
+
+import (
+	"bytes"
+	"sort"
+)
+
+type KVPair struct {
+	Key   Bytes
+	Value Bytes
+}
+
+type KVPairs []KVPair
+
+// Sorting
+func (kvs KVPairs) Len() int { return len(kvs) }
+func (kvs KVPairs) Less(i, j int) bool {
+	switch bytes.Compare(kvs[i].Key, kvs[j].Key) {
+	case -1:
+		return true
+	case 0:
+		return bytes.Compare(kvs[i].Value, kvs[j].Value) < 0
+	case 1:
+		return false
+	default:
+		panic("invalid comparison result")
+	}
+}
+func (kvs KVPairs) Swap(i, j int) { kvs[i], kvs[j] = kvs[j], kvs[i] }
+func (kvs KVPairs) Sort()         { sort.Sort(kvs) }