func()

in jsonpb/encode.go [130:303]
152 lines of code
41 McCabe index (conditional complexity)

func (w *jsonWriter) marshalMessage(m protoreflect.Message, indent, typeURL string) error {
	if jsm, ok := proto.MessageV1(m.Interface()).(JSONPBMarshaler); ok {
		b, err := jsm.MarshalJSONPB(w.Marshaler)
		if err != nil {
			return err
		}
		if typeURL != "" {
			// we are marshaling this object to an Any type
			var js map[string]*json.RawMessage
			if err = json.Unmarshal(b, &js); err != nil {
				return fmt.Errorf("type %T produced invalid JSON: %v", m.Interface(), err)
			}
			turl, err := json.Marshal(typeURL)
			if err != nil {
				return fmt.Errorf("failed to marshal type URL %q to JSON: %v", typeURL, err)
			}
			js["@type"] = (*json.RawMessage)(&turl)
			if b, err = json.Marshal(js); err != nil {
				return err
			}
		}
		w.write(string(b))
		return nil
	}

	md := m.Descriptor()
	fds := md.Fields()

	// Handle well-known types.
	const secondInNanos = int64(time.Second / time.Nanosecond)
	switch wellKnownType(md.FullName()) {
	case "Any":
		return w.marshalAny(m, indent)
	case "BoolValue", "BytesValue", "StringValue",
		"Int32Value", "UInt32Value", "FloatValue",
		"Int64Value", "UInt64Value", "DoubleValue":
		fd := fds.ByNumber(1)
		return w.marshalValue(fd, m.Get(fd), indent)
	case "Duration":
		const maxSecondsInDuration = 315576000000
		// "Generated output always contains 0, 3, 6, or 9 fractional digits,
		//  depending on required precision."
		s := m.Get(fds.ByNumber(1)).Int()
		ns := m.Get(fds.ByNumber(2)).Int()
		if s < -maxSecondsInDuration || s > maxSecondsInDuration {
			return fmt.Errorf("seconds out of range %v", s)
		}
		if ns <= -secondInNanos || ns >= secondInNanos {
			return fmt.Errorf("ns out of range (%v, %v)", -secondInNanos, secondInNanos)
		}
		if (s > 0 && ns < 0) || (s < 0 && ns > 0) {
			return errors.New("signs of seconds and nanos do not match")
		}
		var sign string
		if s < 0 || ns < 0 {
			sign, s, ns = "-", -1*s, -1*ns
		}
		x := fmt.Sprintf("%s%d.%09d", sign, s, ns)
		x = strings.TrimSuffix(x, "000")
		x = strings.TrimSuffix(x, "000")
		x = strings.TrimSuffix(x, ".000")
		w.write(fmt.Sprintf(`"%vs"`, x))
		return nil
	case "Timestamp":
		// "RFC 3339, where generated output will always be Z-normalized
		//  and uses 0, 3, 6 or 9 fractional digits."
		s := m.Get(fds.ByNumber(1)).Int()
		ns := m.Get(fds.ByNumber(2)).Int()
		if ns < 0 || ns >= secondInNanos {
			return fmt.Errorf("ns out of range [0, %v)", secondInNanos)
		}
		t := time.Unix(s, ns).UTC()
		// time.RFC3339Nano isn't exactly right (we need to get 3/6/9 fractional digits).
		x := t.Format("2006-01-02T15:04:05.000000000")
		x = strings.TrimSuffix(x, "000")
		x = strings.TrimSuffix(x, "000")
		x = strings.TrimSuffix(x, ".000")
		w.write(fmt.Sprintf(`"%vZ"`, x))
		return nil
	case "Value":
		// JSON value; which is a null, number, string, bool, object, or array.
		od := md.Oneofs().Get(0)
		fd := m.WhichOneof(od)
		if fd == nil {
			return errors.New("nil Value")
		}
		return w.marshalValue(fd, m.Get(fd), indent)
	case "Struct", "ListValue":
		// JSON object or array.
		fd := fds.ByNumber(1)
		return w.marshalValue(fd, m.Get(fd), indent)
	}

	w.write("{")
	if w.Indent != "" {
		w.write("\n")
	}

	firstField := true
	if typeURL != "" {
		if err := w.marshalTypeURL(indent, typeURL); err != nil {
			return err
		}
		firstField = false
	}

	for i := 0; i < fds.Len(); {
		fd := fds.Get(i)
		if od := fd.ContainingOneof(); od != nil {
			fd = m.WhichOneof(od)
			i += od.Fields().Len()
			if fd == nil {
				continue
			}
		} else {
			i++
		}

		v := m.Get(fd)

		if !m.Has(fd) {
			if !w.EmitDefaults || fd.ContainingOneof() != nil {
				continue
			}
			if fd.Cardinality() != protoreflect.Repeated && (fd.Message() != nil || fd.Syntax() == protoreflect.Proto2) {
				v = protoreflect.Value{} // use "null" for singular messages or proto2 scalars
			}
		}

		if !firstField {
			w.writeComma()
		}
		if err := w.marshalField(fd, v, indent); err != nil {
			return err
		}
		firstField = false
	}

	// Handle proto2 extensions.
	if md.ExtensionRanges().Len() > 0 {
		// Collect a sorted list of all extension descriptor and values.
		type ext struct {
			desc protoreflect.FieldDescriptor
			val  protoreflect.Value
		}
		var exts []ext
		m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
			if fd.IsExtension() {
				exts = append(exts, ext{fd, v})
			}
			return true
		})
		sort.Slice(exts, func(i, j int) bool {
			return exts[i].desc.Number() < exts[j].desc.Number()
		})

		for _, ext := range exts {
			if !firstField {
				w.writeComma()
			}
			if err := w.marshalField(ext.desc, ext.val, indent); err != nil {
				return err
			}
			firstField = false
		}
	}

	if w.Indent != "" {
		w.write("\n")
		w.write(indent)
	}
	w.write("}")
	return nil
}