Add binary package for base64 encoding (#137)

binary/binary.go

@@ -0,0 +1,45 @@
+// Copyright (c) 2018 Palantir Technologies. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package binary
+
+import (
+	"encoding/base64"
+)
+
+var b64 = base64.StdEncoding
+
+// Binary wraps binary data and provides encoding helpers using base64.StdEncoding.
+// Use this type for binary fields serialized/deserialized as base64 text.
+// Type is specified as string rather than []byte so that it can be used as a map key.
+// Use Bytes() to access the raw bytes.
+// Values of this type are only valid when the backing string is Base64-encoded using standard encoding.
+type Binary string
+
+func New(data []byte) Binary {
+	return Binary(b64.EncodeToString(data))
+}
+
+func (b Binary) Bytes() ([]byte, error) {
+	return b64.DecodeString(string(b))
+}
+
+func (b Binary) MarshalText() (text []byte, err error) {
+	// Verify that data is base64-encoded
+	if _, err := b.Bytes(); err != nil {
+		return nil, err
+	}
+
+	return []byte(b), nil
+}
+
+func (b *Binary) UnmarshalText(data []byte) error {
+	// Verify that data is base64-encoded
+	if _, err := Binary(data).Bytes(); err != nil {
+		return err
+	}
+
+	*b = Binary(data)
+	return nil
+}

binary/binary_test.go

@@ -0,0 +1,57 @@
+// Copyright (c) 2018 Palantir Technologies. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package binary_test
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/palantir/pkg/binary"
+)
+
+func TestBinary_Marshal(t *testing.T) {
+	for _, test := range []struct {
+		Name   string
+		Input  []byte
+		Output []byte
+	}{
+		{
+			Name:   "hello world",
+			Input:  []byte(`hello world`),
+			Output: []byte(`"aGVsbG8gd29ybGQ="`),
+		},
+	} {
+		t.Run(test.Name, func(t *testing.T) {
+			out, err := json.Marshal(binary.New(test.Input))
+			assert.NoError(t, err)
+			assert.Equal(t, string(test.Output), string(out))
+		})
+	}
+}
+
+func TestBinary_Unmarshal(t *testing.T) {
+	for _, test := range []struct {
+		Name   string
+		Input  []byte
+		Output []byte
+	}{
+		{
+			Name:   "hello world",
+			Input:  []byte(`"aGVsbG8gd29ybGQ="`),
+			Output: []byte(`hello world`),
+		},
+	} {
+		t.Run(test.Name, func(t *testing.T) {
+			var bin binary.Binary
+			err := json.Unmarshal(test.Input, &bin)
+			assert.NoError(t, err)
+			bytes, err := bin.Bytes()
+			assert.NoError(t, err)
+			assert.Equal(t, string(test.Output), string(bytes))
+		})
+	}
+}