263 lines
6.9 KiB
Go
263 lines
6.9 KiB
Go
package runtime
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"io"
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"reflect"
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"github.com/golang/protobuf/jsonpb"
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"github.com/golang/protobuf/proto"
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)
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// JSONPb is a Marshaler which marshals/unmarshals into/from JSON
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// with the "github.com/golang/protobuf/jsonpb".
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// It supports fully functionality of protobuf unlike JSONBuiltin.
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//
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// The NewDecoder method returns a DecoderWrapper, so the underlying
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// *json.Decoder methods can be used.
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type JSONPb jsonpb.Marshaler
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// ContentType always returns "application/json".
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func (*JSONPb) ContentType() string {
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return "application/json"
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}
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// Marshal marshals "v" into JSON.
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func (j *JSONPb) Marshal(v interface{}) ([]byte, error) {
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if _, ok := v.(proto.Message); !ok {
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return j.marshalNonProtoField(v)
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}
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var buf bytes.Buffer
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if err := j.marshalTo(&buf, v); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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func (j *JSONPb) marshalTo(w io.Writer, v interface{}) error {
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p, ok := v.(proto.Message)
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if !ok {
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buf, err := j.marshalNonProtoField(v)
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if err != nil {
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return err
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}
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_, err = w.Write(buf)
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return err
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}
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return (*jsonpb.Marshaler)(j).Marshal(w, p)
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}
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var (
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// protoMessageType is stored to prevent constant lookup of the same type at runtime.
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protoMessageType = reflect.TypeOf((*proto.Message)(nil)).Elem()
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)
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// marshalNonProto marshals a non-message field of a protobuf message.
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// This function does not correctly marshals arbitrary data structure into JSON,
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// but it is only capable of marshaling non-message field values of protobuf,
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// i.e. primitive types, enums; pointers to primitives or enums; maps from
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// integer/string types to primitives/enums/pointers to messages.
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func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
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if v == nil {
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return []byte("null"), nil
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}
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rv := reflect.ValueOf(v)
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for rv.Kind() == reflect.Ptr {
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if rv.IsNil() {
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return []byte("null"), nil
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}
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rv = rv.Elem()
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}
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if rv.Kind() == reflect.Slice {
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if rv.IsNil() {
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if j.EmitDefaults {
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return []byte("[]"), nil
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}
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return []byte("null"), nil
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}
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if rv.Type().Elem().Implements(protoMessageType) {
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var buf bytes.Buffer
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err := buf.WriteByte('[')
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if err != nil {
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return nil, err
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}
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for i := 0; i < rv.Len(); i++ {
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if i != 0 {
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err = buf.WriteByte(',')
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if err != nil {
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return nil, err
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}
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}
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if err = (*jsonpb.Marshaler)(j).Marshal(&buf, rv.Index(i).Interface().(proto.Message)); err != nil {
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return nil, err
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}
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}
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err = buf.WriteByte(']')
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if err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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}
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if rv.Kind() == reflect.Map {
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m := make(map[string]*json.RawMessage)
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for _, k := range rv.MapKeys() {
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buf, err := j.Marshal(rv.MapIndex(k).Interface())
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if err != nil {
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return nil, err
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}
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m[fmt.Sprintf("%v", k.Interface())] = (*json.RawMessage)(&buf)
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}
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if j.Indent != "" {
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return json.MarshalIndent(m, "", j.Indent)
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}
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return json.Marshal(m)
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}
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if enum, ok := rv.Interface().(protoEnum); ok && !j.EnumsAsInts {
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return json.Marshal(enum.String())
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}
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return json.Marshal(rv.Interface())
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}
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// Unmarshal unmarshals JSON "data" into "v"
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func (j *JSONPb) Unmarshal(data []byte, v interface{}) error {
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return unmarshalJSONPb(data, v)
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}
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// NewDecoder returns a Decoder which reads JSON stream from "r".
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func (j *JSONPb) NewDecoder(r io.Reader) Decoder {
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d := json.NewDecoder(r)
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return DecoderWrapper{Decoder: d}
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}
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// DecoderWrapper is a wrapper around a *json.Decoder that adds
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// support for protos to the Decode method.
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type DecoderWrapper struct {
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*json.Decoder
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}
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// Decode wraps the embedded decoder's Decode method to support
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// protos using a jsonpb.Unmarshaler.
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func (d DecoderWrapper) Decode(v interface{}) error {
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return decodeJSONPb(d.Decoder, v)
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}
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// NewEncoder returns an Encoder which writes JSON stream into "w".
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func (j *JSONPb) NewEncoder(w io.Writer) Encoder {
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return EncoderFunc(func(v interface{}) error {
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if err := j.marshalTo(w, v); err != nil {
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return err
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}
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// mimic json.Encoder by adding a newline (makes output
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// easier to read when it contains multiple encoded items)
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_, err := w.Write(j.Delimiter())
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return err
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})
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}
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func unmarshalJSONPb(data []byte, v interface{}) error {
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d := json.NewDecoder(bytes.NewReader(data))
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return decodeJSONPb(d, v)
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}
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func decodeJSONPb(d *json.Decoder, v interface{}) error {
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p, ok := v.(proto.Message)
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if !ok {
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return decodeNonProtoField(d, v)
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}
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unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields}
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return unmarshaler.UnmarshalNext(d, p)
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}
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func decodeNonProtoField(d *json.Decoder, v interface{}) error {
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rv := reflect.ValueOf(v)
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if rv.Kind() != reflect.Ptr {
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return fmt.Errorf("%T is not a pointer", v)
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}
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for rv.Kind() == reflect.Ptr {
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if rv.IsNil() {
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rv.Set(reflect.New(rv.Type().Elem()))
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}
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if rv.Type().ConvertibleTo(typeProtoMessage) {
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unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields}
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return unmarshaler.UnmarshalNext(d, rv.Interface().(proto.Message))
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}
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rv = rv.Elem()
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}
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if rv.Kind() == reflect.Map {
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if rv.IsNil() {
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rv.Set(reflect.MakeMap(rv.Type()))
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}
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conv, ok := convFromType[rv.Type().Key().Kind()]
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if !ok {
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return fmt.Errorf("unsupported type of map field key: %v", rv.Type().Key())
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}
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m := make(map[string]*json.RawMessage)
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if err := d.Decode(&m); err != nil {
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return err
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}
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for k, v := range m {
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result := conv.Call([]reflect.Value{reflect.ValueOf(k)})
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if err := result[1].Interface(); err != nil {
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return err.(error)
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}
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bk := result[0]
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bv := reflect.New(rv.Type().Elem())
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if err := unmarshalJSONPb([]byte(*v), bv.Interface()); err != nil {
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return err
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}
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rv.SetMapIndex(bk, bv.Elem())
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}
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return nil
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}
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if _, ok := rv.Interface().(protoEnum); ok {
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var repr interface{}
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if err := d.Decode(&repr); err != nil {
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return err
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}
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switch repr.(type) {
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case string:
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// TODO(yugui) Should use proto.StructProperties?
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return fmt.Errorf("unmarshaling of symbolic enum %q not supported: %T", repr, rv.Interface())
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case float64:
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rv.Set(reflect.ValueOf(int32(repr.(float64))).Convert(rv.Type()))
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return nil
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default:
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return fmt.Errorf("cannot assign %#v into Go type %T", repr, rv.Interface())
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}
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}
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return d.Decode(v)
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}
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type protoEnum interface {
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fmt.Stringer
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EnumDescriptor() ([]byte, []int)
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}
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var typeProtoMessage = reflect.TypeOf((*proto.Message)(nil)).Elem()
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// Delimiter for newline encoded JSON streams.
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func (j *JSONPb) Delimiter() []byte {
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return []byte("\n")
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}
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// allowUnknownFields helps not to return an error when the destination
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// is a struct and the input contains object keys which do not match any
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// non-ignored, exported fields in the destination.
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var allowUnknownFields = true
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// DisallowUnknownFields enables option in decoder (unmarshaller) to
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// return an error when it finds an unknown field. This function must be
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// called before using the JSON marshaller.
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func DisallowUnknownFields() {
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allowUnknownFields = false
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}
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