jsonpb: New package.

This is the official JSON support for protocol buffers,
matching the standard format for proto3.
diff --git a/jsonpb/jsonpb.go b/jsonpb/jsonpb.go
new file mode 100644
index 0000000..f3e53d4
--- /dev/null
+++ b/jsonpb/jsonpb.go
@@ -0,0 +1,429 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2015 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/*
+Package jsonpb provides marshalling/unmarshalling functionality between
+protocol buffer and JSON objects.
+
+Compared to encoding/json, this library:
+ - encodes int64, uint64 as strings
+ - optionally encodes enums as strings
+*/
+package jsonpb
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/golang/protobuf/proto"
+)
+
+var (
+	byteArrayType = reflect.TypeOf([]byte{})
+)
+
+// Marshaller is a configurable object for converting between
+// protocol buffer objects and a JSON representation for them
+type Marshaller struct {
+	// Use string values for enums (as opposed to integer values)
+	EnumsAsString bool
+
+	// A string to indent each level by. The presence of this field will
+	// also cause a space to appear between the field separator and
+	// value, and for newlines to be appear between fields and array
+	// elements.
+	Indent string
+}
+
+// Marshal marshals a protocol buffer into JSON.
+func (m *Marshaller) Marshal(out io.Writer, pb proto.Message) error {
+	writer := &errWriter{writer: out}
+	return m.marshalObject(writer, pb, "")
+}
+
+// MarshalToString converts a protocol buffer object to JSON string.
+func (m *Marshaller) MarshalToString(pb proto.Message) (string, error) {
+	var buf bytes.Buffer
+	if err := m.Marshal(&buf, pb); err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}
+
+// marshalObject writes a struct to the Writer.
+func (m *Marshaller) marshalObject(out *errWriter, v proto.Message, indent string) error {
+	out.write("{")
+	if m.Indent != "" {
+		out.write("\n")
+	}
+
+	s := reflect.ValueOf(v).Elem()
+	writeBeforeField := ""
+	for i := 0; i < s.NumField(); i++ {
+		value := s.Field(i)
+		valueField := s.Type().Field(i)
+		fieldName, omitFieldIfNil := parseFieldOptions(valueField)
+
+		// Fields which should not be serialized will specify a json tag with '-'
+		// TODO: proto3 objects should have default values omitted.
+		if fieldName == "-" {
+			continue
+		} else if omitFieldIfNil {
+			// IsNil will panic on most value kinds.
+			skip := false
+			switch value.Kind() {
+			case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+				skip = value.IsNil()
+			}
+			if skip {
+				continue
+			}
+		}
+
+		out.write(writeBeforeField)
+		if m.Indent != "" {
+			out.write(indent)
+			out.write(m.Indent)
+		}
+		out.write(`"`)
+		out.write(fieldName)
+		out.write(`":`)
+		if m.Indent != "" {
+			out.write(" ")
+		}
+
+		if err := m.marshalValue(out, value, valueField, indent); err != nil {
+			return err
+		}
+
+		if m.Indent != "" {
+			writeBeforeField = ",\n"
+		} else {
+			writeBeforeField = ","
+		}
+	}
+
+	if m.Indent != "" {
+		out.write("\n")
+		out.write(indent)
+	}
+	out.write("}")
+	return out.err
+}
+
+// marshalValue writes the value to the Writer.
+func (m *Marshaller) marshalValue(out *errWriter, v reflect.Value,
+	structField reflect.StructField, indent string) error {
+
+	var err error
+	v = reflect.Indirect(v)
+
+	// Handle repeated elements.
+	if v.Type() != byteArrayType && v.Kind() == reflect.Slice {
+		out.write("[")
+		comma := ""
+		for i := 0; i < v.Len(); i++ {
+			sliceVal := v.Index(i)
+			out.write(comma)
+			if m.Indent != "" {
+				out.write("\n")
+				out.write(indent)
+				out.write(m.Indent)
+				out.write(m.Indent)
+			}
+			m.marshalValue(out, sliceVal, structField, indent+m.Indent)
+			comma = ","
+		}
+		if m.Indent != "" {
+			out.write("\n")
+			out.write(indent)
+			out.write(m.Indent)
+		}
+		out.write("]")
+		return out.err
+	}
+
+	// Handle enumerations.
+	protoInfo := structField.Tag.Get("protobuf")
+	if m.EnumsAsString && strings.Contains(protoInfo, ",enum=") {
+		// Unknown enum values will are stringified by the proto library as their
+		// value. Such values should _not_ be quoted or they will be intrepreted
+		// as an enum string instead of their value.
+		enumStr := v.Interface().(fmt.Stringer).String()
+		var valStr string
+		if v.Kind() == reflect.Ptr {
+			valStr = strconv.Itoa(int(v.Elem().Int()))
+		} else {
+			valStr = strconv.Itoa(int(v.Int()))
+		}
+		isKnownEnum := enumStr != valStr
+		if isKnownEnum {
+			out.write(`"`)
+		}
+		out.write(enumStr)
+		if isKnownEnum {
+			out.write(`"`)
+		}
+		return out.err
+	}
+
+	// Handle nested messages.
+	if v.Kind() == reflect.Struct {
+		return m.marshalObject(out, v.Addr().Interface().(proto.Message), indent+m.Indent)
+	}
+
+	// Handle maps.
+	// NOTE: Since Go randomizes map iteration, we sort keys for stable output.
+	if v.Kind() == reflect.Map {
+		out.write(`{`)
+		keys := v.MapKeys()
+		sort.Sort(mapKeys(keys))
+		for i, k := range keys {
+			if i > 0 {
+				out.write(`,`)
+			}
+			if m.Indent != "" {
+				out.write("\n")
+				out.write(indent)
+				out.write(m.Indent)
+				out.write(m.Indent)
+			}
+
+			b, err := json.Marshal(k.Interface())
+			if err != nil {
+				return err
+			}
+			s := string(b)
+
+			// If the JSON is not a string value, encode it again to make it one.
+			if !strings.HasPrefix(s, `"`) {
+				b, err := json.Marshal(s)
+				if err != nil {
+					return err
+				}
+				s = string(b)
+			}
+
+			out.write(s)
+			out.write(`:`)
+			if m.Indent != "" {
+				out.write(` `)
+			}
+
+			if err := m.marshalValue(out, v.MapIndex(k), structField, indent+m.Indent); err != nil {
+				return err
+			}
+		}
+		if m.Indent != "" {
+			out.write("\n")
+			out.write(indent)
+			out.write(m.Indent)
+		}
+		out.write(`}`)
+		return out.err
+	}
+
+	// Default handling defers to the encoding/json library.
+	b, err := json.Marshal(v.Interface())
+	if err != nil {
+		return err
+	}
+	needToQuote := string(b[0]) != `"` && (v.Kind() == reflect.Int64 || v.Kind() == reflect.Uint64)
+	if needToQuote {
+		out.write(`"`)
+	}
+	out.write(string(b))
+	if needToQuote {
+		out.write(`"`)
+	}
+	return out.err
+}
+
+// Unmarshal unmarshals a JSON object stream into a protocol
+// buffer. This function is lenient and will decode any options
+// permutations of the related Marshaller.
+func Unmarshal(r io.Reader, pb proto.Message) error {
+	inputValue := json.RawMessage{}
+	if err := json.NewDecoder(r).Decode(&inputValue); err != nil {
+		return err
+	}
+	return unmarshalValue(reflect.ValueOf(pb).Elem(), inputValue)
+}
+
+// UnmarshalString will populate the fields of a protocol buffer based
+// on a JSON string. This function is lenient and will decode any options
+// permutations of the related Marshaller.
+func UnmarshalString(str string, pb proto.Message) error {
+	return Unmarshal(bytes.NewReader([]byte(str)), pb)
+}
+
+// unmarshalValue converts/copies a value into the target.
+func unmarshalValue(target reflect.Value, inputValue json.RawMessage) error {
+	targetType := target.Type()
+
+	// Allocate memory for pointer fields.
+	if targetType.Kind() == reflect.Ptr {
+		target.Set(reflect.New(targetType.Elem()))
+		return unmarshalValue(target.Elem(), inputValue)
+	}
+
+	// Handle nested messages.
+	if targetType.Kind() == reflect.Struct {
+		var jsonFields map[string]json.RawMessage
+		if err := json.Unmarshal(inputValue, &jsonFields); err != nil {
+			return err
+		}
+
+		for i := 0; i < target.NumField(); i++ {
+			fieldName, _ := parseFieldOptions(target.Type().Field(i))
+
+			// Fields which should not be serialized will specify a json tag with '-'
+			if fieldName == "-" {
+				continue
+			}
+
+			if valueForField, ok := jsonFields[fieldName]; ok {
+				if err := unmarshalValue(target.Field(i), valueForField); err != nil {
+					return err
+				}
+			}
+		}
+		return nil
+	}
+
+	// Handle arrays (which aren't encoded bytes)
+	if targetType != byteArrayType && targetType.Kind() == reflect.Slice {
+		var slc []json.RawMessage
+		if err := json.Unmarshal(inputValue, &slc); err != nil {
+			return err
+		}
+		len := len(slc)
+		target.Set(reflect.MakeSlice(targetType, len, len))
+		for i := 0; i < len; i++ {
+			if err := unmarshalValue(target.Index(i), slc[i]); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	// Handle maps (whose keys are always strings)
+	if targetType.Kind() == reflect.Map {
+		var mp map[string]json.RawMessage
+		if err := json.Unmarshal(inputValue, &mp); err != nil {
+			return err
+		}
+		target.Set(reflect.MakeMap(targetType))
+		for ks, raw := range mp {
+			// Unmarshal map key. The core json library already decoded the key into a
+			// string, so we handle that specially. Other types were quoted post-serialization.
+			var k reflect.Value
+			if targetType.Key().Kind() == reflect.String {
+				k = reflect.ValueOf(ks)
+			} else {
+				k = reflect.New(targetType.Key()).Elem()
+				if err := unmarshalValue(k, json.RawMessage(ks)); err != nil {
+					return err
+				}
+			}
+
+			// Unmarshal map value.
+			v := reflect.New(targetType.Elem()).Elem()
+			if err := unmarshalValue(v, raw); err != nil {
+				return err
+			}
+			target.SetMapIndex(k, v)
+		}
+		return nil
+	}
+
+	// 64-bit integers can be encoded as strings. In this case we drop
+	// the quotes and proceed as normal.
+	isNum := targetType.Kind() == reflect.Int64 || targetType.Kind() == reflect.Uint64
+	if isNum && strings.HasPrefix(string(inputValue), `"`) {
+		inputValue = inputValue[1 : len(inputValue)-1]
+	}
+
+	// Use the encoding/json for parsing other value types.
+	return json.Unmarshal(inputValue, target.Addr().Interface())
+}
+
+// hasUnmarshalJSON is a interface implemented by protocol buffer enums.
+type hasUnmarshalJSON interface {
+	UnmarshalJSON(data []byte) error
+}
+
+// parseFieldOptions returns the field name and if it should be omited.
+func parseFieldOptions(f reflect.StructField) (string, bool) {
+	name := f.Name
+	omitEmpty := false
+	tag := f.Tag.Get("json")
+	tagParts := strings.Split(tag, ",")
+	for i := range tagParts {
+		if tagParts[i] == "omitempty" || tagParts[i] == "" {
+			omitEmpty = true
+		} else {
+			name = tagParts[i]
+		}
+	}
+	return name, omitEmpty
+}
+
+// Writer wrapper inspired by https://blog.golang.org/errors-are-values
+type errWriter struct {
+	writer io.Writer
+	err    error
+}
+
+func (w *errWriter) write(str string) {
+	if w.err != nil {
+		return
+	}
+	_, w.err = w.writer.Write([]byte(str))
+}
+
+// Map fields may have key types of non-float scalars, strings and enums.
+// The easiest way to sort them in some deterministic order is to use fmt.
+// If this turns out to be inefficient we can always consider other options,
+// such as doing a Schwartzian transform.
+type mapKeys []reflect.Value
+
+func (s mapKeys) Len() int      { return len(s) }
+func (s mapKeys) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s mapKeys) Less(i, j int) bool {
+	return fmt.Sprint(s[i].Interface()) < fmt.Sprint(s[j].Interface())
+}
diff --git a/jsonpb/jsonpb_test.go b/jsonpb/jsonpb_test.go
new file mode 100644
index 0000000..fe8cd3f
--- /dev/null
+++ b/jsonpb/jsonpb_test.go
@@ -0,0 +1,367 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2015 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package jsonpb
+
+import (
+	"testing"
+
+	pb "github.com/golang/protobuf/jsonpb/jsonpb_test_proto"
+	"github.com/golang/protobuf/proto"
+)
+
+var (
+	marshaller = Marshaller{}
+
+	marshallerAllOptions = Marshaller{
+		EnumsAsString: true,
+		Indent:        "  ",
+	}
+
+	simpleObject = &pb.Simple{
+		OInt32:  proto.Int32(-32),
+		OInt64:  proto.Int64(-6400000000),
+		OUint32: proto.Uint32(32),
+		OUint64: proto.Uint64(6400000000),
+		OSint32: proto.Int32(-13),
+		OSint64: proto.Int64(-2600000000),
+		OFloat:  proto.Float32(3.14),
+		ODouble: proto.Float64(6.02214179e23),
+		OBool:   proto.Bool(true),
+		OString: proto.String("hello \"there\""),
+		OBytes:  []byte("beep boop"),
+	}
+
+	simpleObjectJSON = `{` +
+		`"o_bool":true,` +
+		`"o_int32":-32,` +
+		`"o_int64":"-6400000000",` +
+		`"o_uint32":32,` +
+		`"o_uint64":"6400000000",` +
+		`"o_sint32":-13,` +
+		`"o_sint64":"-2600000000",` +
+		`"o_float":3.14,` +
+		`"o_double":6.02214179e+23,` +
+		`"o_string":"hello \"there\"",` +
+		`"o_bytes":"YmVlcCBib29w"` +
+		`}`
+
+	simpleObjectPrettyJSON = `{
+  "o_bool": true,
+  "o_int32": -32,
+  "o_int64": "-6400000000",
+  "o_uint32": 32,
+  "o_uint64": "6400000000",
+  "o_sint32": -13,
+  "o_sint64": "-2600000000",
+  "o_float": 3.14,
+  "o_double": 6.02214179e+23,
+  "o_string": "hello \"there\"",
+  "o_bytes": "YmVlcCBib29w"
+}`
+
+	repeatsObject = &pb.Repeats{
+		RBool:   []bool{true, false, true},
+		RInt32:  []int32{-3, -4, -5},
+		RInt64:  []int64{-123456789, -987654321},
+		RUint32: []uint32{1, 2, 3},
+		RUint64: []uint64{6789012345, 3456789012},
+		RSint32: []int32{-1, -2, -3},
+		RSint64: []int64{-6789012345, -3456789012},
+		RFloat:  []float32{3.14, 6.28},
+		RDouble: []float64{299792458, 6.62606957e-34},
+		RString: []string{"happy", "days"},
+		RBytes:  [][]byte{[]byte("skittles"), []byte("m&m's")},
+	}
+
+	repeatsObjectJSON = `{` +
+		`"r_bool":[true,false,true],` +
+		`"r_int32":[-3,-4,-5],` +
+		`"r_int64":["-123456789","-987654321"],` +
+		`"r_uint32":[1,2,3],` +
+		`"r_uint64":["6789012345","3456789012"],` +
+		`"r_sint32":[-1,-2,-3],` +
+		`"r_sint64":["-6789012345","-3456789012"],` +
+		`"r_float":[3.14,6.28],` +
+		`"r_double":[2.99792458e+08,6.62606957e-34],` +
+		`"r_string":["happy","days"],` +
+		`"r_bytes":["c2tpdHRsZXM=","bSZtJ3M="]` +
+		`}`
+
+	repeatsObjectPrettyJSON = `{
+  "r_bool": [
+    true,
+    false,
+    true
+  ],
+  "r_int32": [
+    -3,
+    -4,
+    -5
+  ],
+  "r_int64": [
+    "-123456789",
+    "-987654321"
+  ],
+  "r_uint32": [
+    1,
+    2,
+    3
+  ],
+  "r_uint64": [
+    "6789012345",
+    "3456789012"
+  ],
+  "r_sint32": [
+    -1,
+    -2,
+    -3
+  ],
+  "r_sint64": [
+    "-6789012345",
+    "-3456789012"
+  ],
+  "r_float": [
+    3.14,
+    6.28
+  ],
+  "r_double": [
+    2.99792458e+08,
+    6.62606957e-34
+  ],
+  "r_string": [
+    "happy",
+    "days"
+  ],
+  "r_bytes": [
+    "c2tpdHRsZXM=",
+    "bSZtJ3M="
+  ]
+}`
+
+	innerSimple   = &pb.Simple{OInt32: proto.Int32(-32)}
+	innerSimple2  = &pb.Simple{OInt64: proto.Int64(25)}
+	innerRepeats  = &pb.Repeats{RString: []string{"roses", "red"}}
+	innerRepeats2 = &pb.Repeats{RString: []string{"violets", "blue"}}
+	complexObject = &pb.Widget{
+		Color:    pb.Widget_GREEN.Enum(),
+		RColor:   []pb.Widget_Color{pb.Widget_RED, pb.Widget_GREEN, pb.Widget_BLUE},
+		Simple:   innerSimple,
+		RSimple:  []*pb.Simple{innerSimple, innerSimple2},
+		Repeats:  innerRepeats,
+		RRepeats: []*pb.Repeats{innerRepeats, innerRepeats2},
+	}
+
+	complexObjectJSON = `{"color":1,` +
+		`"r_color":[0,1,2],` +
+		`"simple":{"o_int32":-32},` +
+		`"r_simple":[{"o_int32":-32},{"o_int64":"25"}],` +
+		`"repeats":{"r_string":["roses","red"]},` +
+		`"r_repeats":[{"r_string":["roses","red"]},{"r_string":["violets","blue"]}]` +
+		`}`
+
+	complexObjectPrettyJSON = `{
+  "color": "GREEN",
+  "r_color": [
+    "RED",
+    "GREEN",
+    "BLUE"
+  ],
+  "simple": {
+    "o_int32": -32
+  },
+  "r_simple": [
+    {
+      "o_int32": -32
+    },
+    {
+      "o_int64": "25"
+    }
+  ],
+  "repeats": {
+    "r_string": [
+      "roses",
+      "red"
+    ]
+  },
+  "r_repeats": [
+    {
+      "r_string": [
+        "roses",
+        "red"
+      ]
+    },
+    {
+      "r_string": [
+        "violets",
+        "blue"
+      ]
+    }
+  ]
+}`
+
+	colorPrettyJSON = `{
+ "color": 2
+}`
+
+	colorListPrettyJSON = `{
+  "color": 1000,
+  "r_color": [
+    "RED"
+  ]
+}`
+
+	nummyPrettyJSON = `{
+  "nummy": {
+    "1": 2,
+    "3": 4
+  }
+}`
+
+	objjyPrettyJSON = `{
+  "objjy": {
+    "1": {
+      "dub": 1
+    }
+  }
+}`
+)
+
+var marshallingTests = []struct {
+	desc       string
+	marshaller Marshaller
+	pb         proto.Message
+	json       string
+}{
+	{"simple flat object", marshaller, simpleObject, simpleObjectJSON},
+	{"simple pretty object", marshallerAllOptions, simpleObject, simpleObjectPrettyJSON},
+	{"repeated fields flat object", marshaller, repeatsObject, repeatsObjectJSON},
+	{"repeated fields pretty object", marshallerAllOptions, repeatsObject, repeatsObjectPrettyJSON},
+	{"nested message/enum flat object", marshaller, complexObject, complexObjectJSON},
+	{"nested message/enum pretty object", marshallerAllOptions, complexObject, complexObjectPrettyJSON},
+	{"enum-string flat object", Marshaller{EnumsAsString: true},
+		&pb.Widget{Color: pb.Widget_BLUE.Enum()}, `{"color":"BLUE"}`},
+	{"enum-value pretty object", Marshaller{Indent: " "},
+		&pb.Widget{Color: pb.Widget_BLUE.Enum()}, colorPrettyJSON},
+	{"unknown enum value object", marshallerAllOptions,
+		&pb.Widget{Color: pb.Widget_Color(1000).Enum(), RColor: []pb.Widget_Color{pb.Widget_RED}}, colorListPrettyJSON},
+	{"proto3 object with empty value", marshaller, &pb.Simple3{}, `{"dub":0}`},
+	{"map<int64, int32>", marshaller, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}, `{"nummy":{"1":2,"3":4}}`},
+	{"map<int64, int32>", marshallerAllOptions, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}, nummyPrettyJSON},
+	{"map<string, string>", marshaller,
+		&pb.Mappy{Strry: map[string]string{`"one"`: "two", "three": "four"}},
+		`{"strry":{"\"one\"":"two","three":"four"}}`},
+	{"map<int32, Object>", marshaller,
+		&pb.Mappy{Objjy: map[int32]*pb.Simple3{1: &pb.Simple3{Dub: 1}}}, `{"objjy":{"1":{"dub":1}}}`},
+	{"map<int32, Object>", marshallerAllOptions,
+		&pb.Mappy{Objjy: map[int32]*pb.Simple3{1: &pb.Simple3{Dub: 1}}}, objjyPrettyJSON},
+	{"map<int64, string>", marshaller, &pb.Mappy{Buggy: map[int64]string{1234: "yup"}},
+		`{"buggy":{"1234":"yup"}}`},
+	{"map<bool, bool>", marshaller, &pb.Mappy{Booly: map[bool]bool{false: true}}, `{"booly":{"false":true}}`},
+	{"proto2 map<int64, string>", marshaller, &pb.Maps{MInt64Str: map[int64]string{213: "cat"}},
+		`{"m_int64_str":{"213":"cat"}}`},
+	{"proto2 map<bool, Object>", marshaller,
+		&pb.Maps{MBoolSimple: map[bool]*pb.Simple{true: &pb.Simple{OInt32: proto.Int32(1)}}},
+		`{"m_bool_simple":{"true":{"o_int32":1}}}`},
+}
+
+func TestMarshalling(t *testing.T) {
+	for _, tt := range marshallingTests {
+		json, err := tt.marshaller.MarshalToString(tt.pb)
+		if err != nil {
+			t.Errorf("%s: marshalling error: %v", tt.desc, err)
+		} else if tt.json != json {
+			t.Errorf("%s: got [%v] want [%v]", tt.desc, json, tt.json)
+		}
+	}
+}
+
+var unmarshallingTests = []struct {
+	desc string
+	json string
+	pb   proto.Message
+}{
+	{"simple flat object", simpleObjectJSON, simpleObject},
+	{"simple pretty object", simpleObjectPrettyJSON, simpleObject},
+	{"repeated fields flat object", repeatsObjectJSON, repeatsObject},
+	{"repeated fields pretty object", repeatsObjectPrettyJSON, repeatsObject},
+	{"nested message/enum flat object", complexObjectJSON, complexObject},
+	{"nested message/enum pretty object", complexObjectPrettyJSON, complexObject},
+	{"enum-string object", `{"color":"BLUE"}`, &pb.Widget{Color: pb.Widget_BLUE.Enum()}},
+	{"enum-value object", "{\n \"color\": 2\n}", &pb.Widget{Color: pb.Widget_BLUE.Enum()}},
+	{"unknown enum value object",
+		"{\n  \"color\": 1000,\n  \"r_color\": [\n    \"RED\"\n  ]\n}",
+		&pb.Widget{Color: pb.Widget_Color(1000).Enum(), RColor: []pb.Widget_Color{pb.Widget_RED}}},
+	{"unquoted int64 object", `{"o_int64":-314}`, &pb.Simple{OInt64: proto.Int64(-314)}},
+	{"unquoted uint64 object", `{"o_uint64":123}`, &pb.Simple{OUint64: proto.Uint64(123)}},
+	{"map<int64, int32>", `{"nummy":{"1":2,"3":4}}`, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}},
+	{"map<string, string>", `{"strry":{"\"one\"":"two","three":"four"}}`, &pb.Mappy{Strry: map[string]string{`"one"`: "two", "three": "four"}}},
+	{"map<int32, Object>", `{"objjy":{"1":{"dub":1}}}`, &pb.Mappy{Objjy: map[int32]*pb.Simple3{1: &pb.Simple3{Dub: 1}}}},
+}
+
+func TestUnmarshalling(t *testing.T) {
+	for _, tt := range unmarshallingTests {
+		// Make a new instance of the type of our expected object.
+		p := proto.Clone(tt.pb)
+		p.Reset()
+
+		err := UnmarshalString(tt.json, p)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		// For easier diffs, compare text strings of the protos.
+		exp := proto.MarshalTextString(tt.pb)
+		act := proto.MarshalTextString(p)
+		if string(exp) != string(act) {
+			t.Errorf("%s: got [%s] want [%s]", tt.desc, act, exp)
+		}
+	}
+}
+
+var unmarshallingShouldError = []struct {
+	desc string
+	in   string
+}{
+	{"a value", "666"},
+	{"gibberish", "{adskja123;l23=-="},
+}
+
+func TestUnmarshallingBadInput(t *testing.T) {
+	for _, tt := range unmarshallingShouldError {
+		obj := &pb.Simple{}
+		err := UnmarshalString(tt.in, obj)
+		if err == nil {
+			t.Errorf("an error was expected when parsing %q instead of an object", tt.desc)
+		}
+	}
+}
diff --git a/jsonpb/jsonpb_test_proto/Makefile b/jsonpb/jsonpb_test_proto/Makefile
new file mode 100644
index 0000000..e53e6a6
--- /dev/null
+++ b/jsonpb/jsonpb_test_proto/Makefile
@@ -0,0 +1,33 @@
+# Go support for Protocol Buffers - Google's data interchange format
+#
+# Copyright 2015 The Go Authors.  All rights reserved.
+# https://github.com/golang/protobuf
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+regenerate:
+	protoc --go_out=. *.proto
diff --git a/jsonpb/jsonpb_test_proto/more_test_objects.proto b/jsonpb/jsonpb_test_proto/more_test_objects.proto
new file mode 100644
index 0000000..6535791
--- /dev/null
+++ b/jsonpb/jsonpb_test_proto/more_test_objects.proto
@@ -0,0 +1,46 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2015 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto3";
+
+package jsonpb;
+
+message Simple3 {
+  double dub = 1;
+}
+
+message Mappy {
+  map<int64, int32> nummy = 1;
+  map<string, string> strry = 2;
+  map<int32, Simple3> objjy = 3;
+  map<int64, string> buggy = 4;
+  map<bool, bool> booly = 5;
+}
diff --git a/jsonpb/jsonpb_test_proto/test_objects.proto b/jsonpb/jsonpb_test_proto/test_objects.proto
new file mode 100644
index 0000000..e48a3e8
--- /dev/null
+++ b/jsonpb/jsonpb_test_proto/test_objects.proto
@@ -0,0 +1,86 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2015 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package jsonpb;
+
+// Test message for holding primitive types.
+message Simple {
+  optional bool o_bool = 1;
+  optional int32 o_int32 = 2;
+  optional int64 o_int64 = 3;
+  optional uint32 o_uint32 = 4;
+  optional uint64 o_uint64 = 5;
+  optional sint32 o_sint32 = 6;
+  optional sint64 o_sint64 = 7;
+  optional float o_float = 8;
+  optional double o_double = 9;
+  optional string o_string = 10;
+  optional bytes o_bytes = 11;
+}
+
+// Test message for holding repeated primitives.
+message Repeats {
+  repeated bool r_bool = 1;
+  repeated int32 r_int32 = 2;
+  repeated int64 r_int64 = 3;
+  repeated uint32 r_uint32 = 4;
+  repeated uint64 r_uint64 = 5;
+  repeated sint32 r_sint32 = 6;
+  repeated sint64 r_sint64 = 7;
+  repeated float r_float = 8;
+  repeated double r_double = 9;
+  repeated string r_string = 10;
+  repeated bytes r_bytes = 11;
+}
+
+// Test message for holding enums and nested messages.
+message Widget {
+  enum Color {
+    RED = 0;
+    GREEN = 1;
+    BLUE = 2;
+  };
+  optional Color color = 1;
+  repeated Color r_color = 2;
+
+  optional Simple simple = 10;
+  repeated Simple r_simple = 11;
+
+  optional Repeats repeats = 20;
+  repeated Repeats r_repeats = 21;
+}
+
+message Maps {
+  map<int64, string> m_int64_str = 1;
+  map<bool, Simple> m_bool_simple = 2;
+}