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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package protojson
import (
"encoding/base64"
"fmt"
"google.golang.org/protobuf/internal/encoding/json"
"google.golang.org/protobuf/internal/encoding/messageset"
"google.golang.org/protobuf/internal/errors"
"google.golang.org/protobuf/internal/filedesc"
"google.golang.org/protobuf/internal/flags"
"google.golang.org/protobuf/internal/genid"
"google.golang.org/protobuf/internal/order"
"google.golang.org/protobuf/internal/pragma"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/reflect/protoregistry"
)
const defaultIndent = " "
// Format formats the message as a multiline string.
// This function is only intended for human consumption and ignores errors.
// Do not depend on the output being stable. It may change over time across
// different versions of the program.
func Format(m proto.Message) string {
return MarshalOptions{Multiline: true}.Format(m)
}
// Marshal writes the given proto.Message in JSON format using default options.
// Do not depend on the output being stable. It may change over time across
// different versions of the program.
func Marshal(m proto.Message) ([]byte, error) {
return MarshalOptions{}.Marshal(m)
}
// MarshalOptions is a configurable JSON format marshaler.
type MarshalOptions struct {
pragma.NoUnkeyedLiterals
// Multiline specifies whether the marshaler should format the output in
// indented-form with every textual element on a new line.
// If Indent is an empty string, then an arbitrary indent is chosen.
Multiline bool
// Indent specifies the set of indentation characters to use in a multiline
// formatted output such that every entry is preceded by Indent and
// terminated by a newline. If non-empty, then Multiline is treated as true.
// Indent can only be composed of space or tab characters.
Indent string
// AllowPartial allows messages that have missing required fields to marshal
// without returning an error. If AllowPartial is false (the default),
// Marshal will return error if there are any missing required fields.
AllowPartial bool
// UseProtoNames uses proto field name instead of lowerCamelCase name in JSON
// field names.
UseProtoNames bool
// UseEnumNumbers emits enum values as numbers.
UseEnumNumbers bool
// EmitUnpopulated specifies whether to emit unpopulated fields. It does not
// emit unpopulated oneof fields or unpopulated extension fields.
// The JSON value emitted for unpopulated fields are as follows:
// ╔═══════╤════════════════════════════╗
// ║ JSON │ Protobuf field ║
// ╠═══════╪════════════════════════════╣
// ║ false │ proto3 boolean fields ║
// ║ 0 │ proto3 numeric fields ║
// ║ "" │ proto3 string/bytes fields ║
// ║ null │ proto2 scalar fields ║
// ║ null │ message fields ║
// ║ [] │ list fields ║
// ║ {} │ map fields ║
// ╚═══════╧════════════════════════════╝
EmitUnpopulated bool
// Resolver is used for looking up types when expanding google.protobuf.Any
// messages. If nil, this defaults to using protoregistry.GlobalTypes.
Resolver interface {
protoregistry.ExtensionTypeResolver
protoregistry.MessageTypeResolver
}
}
// Format formats the message as a string.
// This method is only intended for human consumption and ignores errors.
// Do not depend on the output being stable. It may change over time across
// different versions of the program.
func (o MarshalOptions) Format(m proto.Message) string {
if m == nil || !m.ProtoReflect().IsValid() {
return "<nil>" // invalid syntax, but okay since this is for debugging
}
o.AllowPartial = true
b, _ := o.Marshal(m)
return string(b)
}
// Marshal marshals the given proto.Message in the JSON format using options in
// MarshalOptions. Do not depend on the output being stable. It may change over
// time across different versions of the program.
func (o MarshalOptions) Marshal(m proto.Message) ([]byte, error) {
return o.marshal(m)
}
// marshal is a centralized function that all marshal operations go through.
// For profiling purposes, avoid changing the name of this function or
// introducing other code paths for marshal that do not go through this.
func (o MarshalOptions) marshal(m proto.Message) ([]byte, error) {
if o.Multiline && o.Indent == "" {
o.Indent = defaultIndent
}
if o.Resolver == nil {
o.Resolver = protoregistry.GlobalTypes
}
internalEnc, err := json.NewEncoder(o.Indent)
if err != nil {
return nil, err
}
// Treat nil message interface as an empty message,
// in which case the output in an empty JSON object.
if m == nil {
return []byte("{}"), nil
}
enc := encoder{internalEnc, o}
if err := enc.marshalMessage(m.ProtoReflect(), ""); err != nil {
return nil, err
}
if o.AllowPartial {
return enc.Bytes(), nil
}
return enc.Bytes(), proto.CheckInitialized(m)
}
type encoder struct {
*json.Encoder
opts MarshalOptions
}
// typeFieldDesc is a synthetic field descriptor used for the "@type" field.
var typeFieldDesc = func() protoreflect.FieldDescriptor {
var fd filedesc.Field
fd.L0.FullName = "@type"
fd.L0.Index = -1
fd.L1.Cardinality = protoreflect.Optional
fd.L1.Kind = protoreflect.StringKind
return &fd
}()
// typeURLFieldRanger wraps a protoreflect.Message and modifies its Range method
// to additionally iterate over a synthetic field for the type URL.
type typeURLFieldRanger struct {
order.FieldRanger
typeURL string
}
func (m typeURLFieldRanger) Range(f func(protoreflect.FieldDescriptor, protoreflect.Value) bool) {
if !f(typeFieldDesc, protoreflect.ValueOfString(m.typeURL)) {
return
}
m.FieldRanger.Range(f)
}
// unpopulatedFieldRanger wraps a protoreflect.Message and modifies its Range
// method to additionally iterate over unpopulated fields.
type unpopulatedFieldRanger struct{ protoreflect.Message }
func (m unpopulatedFieldRanger) Range(f func(protoreflect.FieldDescriptor, protoreflect.Value) bool) {
fds := m.Descriptor().Fields()
for i := 0; i < fds.Len(); i++ {
fd := fds.Get(i)
if m.Has(fd) || fd.ContainingOneof() != nil {
continue // ignore populated fields and fields within a oneofs
}
v := m.Get(fd)
isProto2Scalar := fd.Syntax() == protoreflect.Proto2 && fd.Default().IsValid()
isSingularMessage := fd.Cardinality() != protoreflect.Repeated && fd.Message() != nil
if isProto2Scalar || isSingularMessage {
v = protoreflect.Value{} // use invalid value to emit null
}
if !f(fd, v) {
return
}
}
m.Message.Range(f)
}
// marshalMessage marshals the fields in the given protoreflect.Message.
// If the typeURL is non-empty, then a synthetic "@type" field is injected
// containing the URL as the value.
func (e encoder) marshalMessage(m protoreflect.Message, typeURL string) error {
if !flags.ProtoLegacy && messageset.IsMessageSet(m.Descriptor()) {
return errors.New("no support for proto1 MessageSets")
}
if marshal := wellKnownTypeMarshaler(m.Descriptor().FullName()); marshal != nil {
return marshal(e, m)
}
e.StartObject()
defer e.EndObject()
var fields order.FieldRanger = m
if e.opts.EmitUnpopulated {
fields = unpopulatedFieldRanger{m}
}
if typeURL != "" {
fields = typeURLFieldRanger{fields, typeURL}
}
var err error
order.RangeFields(fields, order.IndexNameFieldOrder, func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
name := fd.JSONName()
if e.opts.UseProtoNames {
name = fd.TextName()
}
if err = e.WriteName(name); err != nil {
return false
}
if err = e.marshalValue(v, fd); err != nil {
return false
}
return true
})
return err
}
// marshalValue marshals the given protoreflect.Value.
func (e encoder) marshalValue(val protoreflect.Value, fd protoreflect.FieldDescriptor) error {
switch {
case fd.IsList():
return e.marshalList(val.List(), fd)
case fd.IsMap():
return e.marshalMap(val.Map(), fd)
default:
return e.marshalSingular(val, fd)
}
}
// marshalSingular marshals the given non-repeated field value. This includes
// all scalar types, enums, messages, and groups.
func (e encoder) marshalSingular(val protoreflect.Value, fd protoreflect.FieldDescriptor) error {
if !val.IsValid() {
e.WriteNull()
return nil
}
switch kind := fd.Kind(); kind {
case protoreflect.BoolKind:
e.WriteBool(val.Bool())
case protoreflect.StringKind:
if e.WriteString(val.String()) != nil {
return errors.InvalidUTF8(string(fd.FullName()))
}
case protoreflect.Int32Kind, protoreflect.Sint32Kind, protoreflect.Sfixed32Kind:
e.WriteInt(val.Int())
case protoreflect.Uint32Kind, protoreflect.Fixed32Kind:
e.WriteUint(val.Uint())
case protoreflect.Int64Kind, protoreflect.Sint64Kind, protoreflect.Uint64Kind,
protoreflect.Sfixed64Kind, protoreflect.Fixed64Kind:
// 64-bit integers are written out as JSON string.
e.WriteString(val.String())
case protoreflect.FloatKind:
// Encoder.WriteFloat handles the special numbers NaN and infinites.
e.WriteFloat(val.Float(), 32)
case protoreflect.DoubleKind:
// Encoder.WriteFloat handles the special numbers NaN and infinites.
e.WriteFloat(val.Float(), 64)
case protoreflect.BytesKind:
e.WriteString(base64.StdEncoding.EncodeToString(val.Bytes()))
case protoreflect.EnumKind:
if fd.Enum().FullName() == genid.NullValue_enum_fullname {
e.WriteNull()
} else {
desc := fd.Enum().Values().ByNumber(val.Enum())
if e.opts.UseEnumNumbers || desc == nil {
e.WriteInt(int64(val.Enum()))
} else {
e.WriteString(string(desc.Name()))
}
}
case protoreflect.MessageKind, protoreflect.GroupKind:
if err := e.marshalMessage(val.Message(), ""); err != nil {
return err
}
default:
panic(fmt.Sprintf("%v has unknown kind: %v", fd.FullName(), kind))
}
return nil
}
// marshalList marshals the given protoreflect.List.
func (e encoder) marshalList(list protoreflect.List, fd protoreflect.FieldDescriptor) error {
e.StartArray()
defer e.EndArray()
for i := 0; i < list.Len(); i++ {
item := list.Get(i)
if err := e.marshalSingular(item, fd); err != nil {
return err
}
}
return nil
}
// marshalMap marshals given protoreflect.Map.
func (e encoder) marshalMap(mmap protoreflect.Map, fd protoreflect.FieldDescriptor) error {
e.StartObject()
defer e.EndObject()
var err error
order.RangeEntries(mmap, order.GenericKeyOrder, func(k protoreflect.MapKey, v protoreflect.Value) bool {
if err = e.WriteName(k.String()); err != nil {
return false
}
if err = e.marshalSingular(v, fd.MapValue()); err != nil {
return false
}
return true
})
return err
}