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package runtime
import (
"bytes"
"encoding/json"
"fmt"
"io"
"reflect"
"github.com/golang/protobuf/jsonpb"
"github.com/golang/protobuf/proto"
)
// JSONPb is a Marshaler which marshals/unmarshals into/from JSON
// with the "github.com/golang/protobuf/jsonpb".
// It supports fully functionality of protobuf unlike JSONBuiltin.
type JSONPb jsonpb.Marshaler
// ContentType always returns "application/json".
func (*JSONPb) ContentType() string {
return "application/json"
}
// Marshal marshals "v" into JSON
// Currently it can marshal only proto.Message.
// TODO(yugui) Support fields of primitive types in a message.
func (j *JSONPb) Marshal(v interface{}) ([]byte, error) {
if _, ok := v.(proto.Message); !ok {
return j.marshalNonProtoField(v)
}
var buf bytes.Buffer
if err := j.marshalTo(&buf, v); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (j *JSONPb) marshalTo(w io.Writer, v interface{}) error {
p, ok := v.(proto.Message)
if !ok {
buf, err := j.marshalNonProtoField(v)
if err != nil {
return err
}
_, err = w.Write(buf)
return err
}
return (*jsonpb.Marshaler)(j).Marshal(w, p)
}
// marshalNonProto marshals a non-message field of a protobuf message.
// This function does not correctly marshals arbitary data structure into JSON,
// but it is only capable of marshaling non-message field values of protobuf,
// i.e. primitive types, enums; pointers to primitives or enums; maps from
// integer/string types to primitives/enums/pointers to messages.
func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
rv := reflect.ValueOf(v)
for rv.Kind() == reflect.Ptr {
if rv.IsNil() {
return []byte("null"), nil
}
rv = rv.Elem()
}
if rv.Kind() == reflect.Map {
m := make(map[string]*json.RawMessage)
for _, k := range rv.MapKeys() {
buf, err := j.Marshal(rv.MapIndex(k).Interface())
if err != nil {
return nil, err
}
m[fmt.Sprintf("%v", k.Interface())] = (*json.RawMessage)(&buf)
}
if j.Indent != "" {
return json.MarshalIndent(m, "", j.Indent)
}
return json.Marshal(m)
}
if enum, ok := rv.Interface().(protoEnum); ok && !j.EnumsAsInts {
return json.Marshal(enum.String())
}
return json.Marshal(rv.Interface())
}
// Unmarshal unmarshals JSON "data" into "v"
// Currently it can marshal only proto.Message.
// TODO(yugui) Support fields of primitive types in a message.
func (j *JSONPb) Unmarshal(data []byte, v interface{}) error {
return unmarshalJSONPb(data, v)
}
// NewDecoder returns a Decoder which reads JSON stream from "r".
func (j *JSONPb) NewDecoder(r io.Reader) Decoder {
d := json.NewDecoder(r)
return DecoderFunc(func(v interface{}) error { return decodeJSONPb(d, v) })
}
// NewEncoder returns an Encoder which writes JSON stream into "w".
func (j *JSONPb) NewEncoder(w io.Writer) Encoder {
return EncoderFunc(func(v interface{}) error { return j.marshalTo(w, v) })
}
func unmarshalJSONPb(data []byte, v interface{}) error {
d := json.NewDecoder(bytes.NewReader(data))
return decodeJSONPb(d, v)
}
func decodeJSONPb(d *json.Decoder, v interface{}) error {
p, ok := v.(proto.Message)
if !ok {
return decodeNonProtoField(d, v)
}
unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: true}
return unmarshaler.UnmarshalNext(d, p)
}
func decodeNonProtoField(d *json.Decoder, v interface{}) error {
rv := reflect.ValueOf(v)
if rv.Kind() != reflect.Ptr {
return fmt.Errorf("%T is not a pointer", v)
}
for rv.Kind() == reflect.Ptr {
if rv.IsNil() {
rv.Set(reflect.New(rv.Type().Elem()))
}
if rv.Type().ConvertibleTo(typeProtoMessage) {
unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: true}
return unmarshaler.UnmarshalNext(d, rv.Interface().(proto.Message))
}
rv = rv.Elem()
}
if rv.Kind() == reflect.Map {
if rv.IsNil() {
rv.Set(reflect.MakeMap(rv.Type()))
}
conv, ok := convFromType[rv.Type().Key().Kind()]
if !ok {
return fmt.Errorf("unsupported type of map field key: %v", rv.Type().Key())
}
m := make(map[string]*json.RawMessage)
if err := d.Decode(&m); err != nil {
return err
}
for k, v := range m {
result := conv.Call([]reflect.Value{reflect.ValueOf(k)})
if err := result[1].Interface(); err != nil {
return err.(error)
}
bk := result[0]
bv := reflect.New(rv.Type().Elem())
if err := unmarshalJSONPb([]byte(*v), bv.Interface()); err != nil {
return err
}
rv.SetMapIndex(bk, bv.Elem())
}
return nil
}
if _, ok := rv.Interface().(protoEnum); ok {
var repr interface{}
if err := d.Decode(&repr); err != nil {
return err
}
switch repr.(type) {
case string:
// TODO(yugui) Should use proto.StructProperties?
return fmt.Errorf("unmarshaling of symbolic enum %q not supported: %T", repr, rv.Interface())
case float64:
rv.Set(reflect.ValueOf(int32(repr.(float64))).Convert(rv.Type()))
return nil
default:
return fmt.Errorf("cannot assign %#v into Go type %T", repr, rv.Interface())
}
}
return d.Decode(v)
}
type protoEnum interface {
fmt.Stringer
EnumDescriptor() ([]byte, []int)
}
var typeProtoMessage = reflect.TypeOf((*proto.Message)(nil)).Elem()
|
