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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"
"sort"
"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/flags"
"google.golang.org/protobuf/internal/pragma"
"google.golang.org/protobuf/proto"
pref "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) {
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
}
// marshalMessage marshals the given protoreflect.Message.
func (e encoder) marshalMessage(m pref.Message) error {
if isCustomType(m.Descriptor().FullName()) {
return e.marshalCustomType(m)
}
e.StartObject()
defer e.EndObject()
if err := e.marshalFields(m); err != nil {
return err
}
return nil
}
// marshalFields marshals the fields in the given protoreflect.Message.
func (e encoder) marshalFields(m pref.Message) error {
messageDesc := m.Descriptor()
if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
return errors.New("no support for proto1 MessageSets")
}
// Marshal out known fields.
fieldDescs := messageDesc.Fields()
for i := 0; i < fieldDescs.Len(); {
fd := fieldDescs.Get(i)
if od := fd.ContainingOneof(); od != nil {
fd = m.WhichOneof(od)
i += od.Fields().Len()
if fd == nil {
continue // unpopulated oneofs are not affected by EmitUnpopulated
}
} else {
i++
}
val := m.Get(fd)
if !m.Has(fd) {
if !e.opts.EmitUnpopulated {
continue
}
isProto2Scalar := fd.Syntax() == pref.Proto2 && fd.Default().IsValid()
isSingularMessage := fd.Cardinality() != pref.Repeated && fd.Message() != nil
if isProto2Scalar || isSingularMessage {
// Use invalid value to emit null.
val = pref.Value{}
}
}
name := fd.JSONName()
if e.opts.UseProtoNames {
name = string(fd.Name())
// Use type name for group field name.
if fd.Kind() == pref.GroupKind {
name = string(fd.Message().Name())
}
}
if err := e.WriteName(name); err != nil {
return err
}
if err := e.marshalValue(val, fd); err != nil {
return err
}
}
// Marshal out extensions.
if err := e.marshalExtensions(m); err != nil {
return err
}
return nil
}
// marshalValue marshals the given protoreflect.Value.
func (e encoder) marshalValue(val pref.Value, fd pref.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 pref.Value, fd pref.FieldDescriptor) error {
if !val.IsValid() {
e.WriteNull()
return nil
}
switch kind := fd.Kind(); kind {
case pref.BoolKind:
e.WriteBool(val.Bool())
case pref.StringKind:
if e.WriteString(val.String()) != nil {
return errors.InvalidUTF8(string(fd.FullName()))
}
case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
e.WriteInt(val.Int())
case pref.Uint32Kind, pref.Fixed32Kind:
e.WriteUint(val.Uint())
case pref.Int64Kind, pref.Sint64Kind, pref.Uint64Kind,
pref.Sfixed64Kind, pref.Fixed64Kind:
// 64-bit integers are written out as JSON string.
e.WriteString(val.String())
case pref.FloatKind:
// Encoder.WriteFloat handles the special numbers NaN and infinites.
e.WriteFloat(val.Float(), 32)
case pref.DoubleKind:
// Encoder.WriteFloat handles the special numbers NaN and infinites.
e.WriteFloat(val.Float(), 64)
case pref.BytesKind:
e.WriteString(base64.StdEncoding.EncodeToString(val.Bytes()))
case pref.EnumKind:
if fd.Enum().FullName() == "google.protobuf.NullValue" {
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 pref.MessageKind, pref.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 pref.List, fd pref.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
}
type mapEntry struct {
key pref.MapKey
value pref.Value
}
// marshalMap marshals given protoreflect.Map.
func (e encoder) marshalMap(mmap pref.Map, fd pref.FieldDescriptor) error {
e.StartObject()
defer e.EndObject()
// Get a sorted list based on keyType first.
entries := make([]mapEntry, 0, mmap.Len())
mmap.Range(func(key pref.MapKey, val pref.Value) bool {
entries = append(entries, mapEntry{key: key, value: val})
return true
})
sortMap(fd.MapKey().Kind(), entries)
// Write out sorted list.
for _, entry := range entries {
if err := e.WriteName(entry.key.String()); err != nil {
return err
}
if err := e.marshalSingular(entry.value, fd.MapValue()); err != nil {
return err
}
}
return nil
}
// sortMap orders list based on value of key field for deterministic ordering.
func sortMap(keyKind pref.Kind, values []mapEntry) {
sort.Slice(values, func(i, j int) bool {
switch keyKind {
case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind,
pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
return values[i].key.Int() < values[j].key.Int()
case pref.Uint32Kind, pref.Fixed32Kind,
pref.Uint64Kind, pref.Fixed64Kind:
return values[i].key.Uint() < values[j].key.Uint()
}
return values[i].key.String() < values[j].key.String()
})
}
// marshalExtensions marshals extension fields.
func (e encoder) marshalExtensions(m pref.Message) error {
type entry struct {
key string
value pref.Value
desc pref.FieldDescriptor
}
// Get a sorted list based on field key first.
var entries []entry
m.Range(func(fd pref.FieldDescriptor, v pref.Value) bool {
if !fd.IsExtension() {
return true
}
// For MessageSet extensions, the name used is the parent message.
name := fd.FullName()
if messageset.IsMessageSetExtension(fd) {
name = name.Parent()
}
// Use [name] format for JSON field name.
entries = append(entries, entry{
key: string(name),
value: v,
desc: fd,
})
return true
})
// Sort extensions lexicographically.
sort.Slice(entries, func(i, j int) bool {
return entries[i].key < entries[j].key
})
// Write out sorted list.
for _, entry := range entries {
// JSON field name is the proto field name enclosed in [], similar to
// textproto. This is consistent with Go v1 lib. C++ lib v3.7.0 does not
// marshal out extension fields.
if err := e.WriteName("[" + entry.key + "]"); err != nil {
return err
}
if err := e.marshalValue(entry.value, entry.desc); err != nil {
return err
}
}
return nil
}