protogen, encoding/jsonpb, encoding/textpb: rename packages

Rename encoding/*pb to follow the convention of prefixing package names
with 'proto':

	google.golang.org/protobuf/encoding/protojson
	google.golang.org/protobuf/encoding/prototext

Move protogen under a compiler/ directory, just in case we ever do add
more compiler-related packages.

	google.golang.org/protobuf/compiler/protogen

Change-Id: I31010cb5cabcea8274fffcac468477b58b56e8eb
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/177178
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
diff --git a/encoding/protojson/decode.go b/encoding/protojson/decode.go
new file mode 100644
index 0000000..b6c056e
--- /dev/null
+++ b/encoding/protojson/decode.go
@@ -0,0 +1,726 @@
+// 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"
+	"math"
+	"strconv"
+	"strings"
+
+	"google.golang.org/protobuf/internal/encoding/json"
+	"google.golang.org/protobuf/internal/errors"
+	"google.golang.org/protobuf/internal/pragma"
+	"google.golang.org/protobuf/internal/set"
+	"google.golang.org/protobuf/proto"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+)
+
+// Unmarshal reads the given []byte into the given proto.Message.
+func Unmarshal(m proto.Message, b []byte) error {
+	return UnmarshalOptions{}.Unmarshal(m, b)
+}
+
+// UnmarshalOptions is a configurable JSON format parser.
+type UnmarshalOptions struct {
+	pragma.NoUnkeyedLiterals
+
+	// If AllowPartial is set, input for messages that will result in missing
+	// required fields will not return an error.
+	AllowPartial bool
+
+	// If DiscardUnknown is set, unknown fields are ignored.
+	DiscardUnknown bool
+
+	// Resolver is the registry used for type lookups when unmarshaling extensions
+	// and processing Any. If Resolver is not set, unmarshaling will default to
+	// using protoregistry.GlobalTypes.
+	Resolver *protoregistry.Types
+
+	decoder *json.Decoder
+}
+
+// Unmarshal reads the given []byte and populates the given proto.Message using
+// options in UnmarshalOptions object. It will clear the message first before
+// setting the fields. If it returns an error, the given message may be
+// partially set.
+func (o UnmarshalOptions) Unmarshal(m proto.Message, b []byte) error {
+	mr := m.ProtoReflect()
+	// TODO: Determine if we would like to have an option for merging or only
+	// have merging behavior.  We should at least be consistent with textproto
+	// marshaling.
+	resetMessage(mr)
+
+	if o.Resolver == nil {
+		o.Resolver = protoregistry.GlobalTypes
+	}
+	o.decoder = json.NewDecoder(b)
+
+	var nerr errors.NonFatal
+	if err := o.unmarshalMessage(mr, false); !nerr.Merge(err) {
+		return err
+	}
+
+	// Check for EOF.
+	val, err := o.decoder.Read()
+	if err != nil {
+		return err
+	}
+	if val.Type() != json.EOF {
+		return unexpectedJSONError{val}
+	}
+
+	if !o.AllowPartial {
+		nerr.Merge(proto.IsInitialized(m))
+	}
+	return nerr.E
+}
+
+// resetMessage clears all fields of given protoreflect.Message.
+func resetMessage(m pref.Message) {
+	knownFields := m.KnownFields()
+	knownFields.Range(func(num pref.FieldNumber, _ pref.Value) bool {
+		knownFields.Clear(num)
+		return true
+	})
+	unknownFields := m.UnknownFields()
+	unknownFields.Range(func(num pref.FieldNumber, _ pref.RawFields) bool {
+		unknownFields.Set(num, nil)
+		return true
+	})
+	extTypes := knownFields.ExtensionTypes()
+	extTypes.Range(func(xt pref.ExtensionType) bool {
+		extTypes.Remove(xt)
+		return true
+	})
+}
+
+// unexpectedJSONError is an error that contains the unexpected json.Value. This
+// is returned by methods to provide callers the read json.Value that it did not
+// expect.
+// TODO: Consider moving this to internal/encoding/json for consistency with
+// errors that package returns.
+type unexpectedJSONError struct {
+	value json.Value
+}
+
+func (e unexpectedJSONError) Error() string {
+	return newError("unexpected value %s", e.value).Error()
+}
+
+// newError returns an error object. If one of the values passed in is of
+// json.Value type, it produces an error with position info.
+func newError(f string, x ...interface{}) error {
+	var hasValue bool
+	var line, column int
+	for i := 0; i < len(x); i++ {
+		if val, ok := x[i].(json.Value); ok {
+			line, column = val.Position()
+			hasValue = true
+			break
+		}
+	}
+	e := errors.New(f, x...)
+	if hasValue {
+		return errors.New("(line %d:%d): %v", line, column, e)
+	}
+	return e
+}
+
+// unmarshalMessage unmarshals a message into the given protoreflect.Message.
+func (o UnmarshalOptions) unmarshalMessage(m pref.Message, skipTypeURL bool) error {
+	var nerr errors.NonFatal
+
+	if isCustomType(m.Descriptor().FullName()) {
+		return o.unmarshalCustomType(m)
+	}
+
+	jval, err := o.decoder.Read()
+	if !nerr.Merge(err) {
+		return err
+	}
+	if jval.Type() != json.StartObject {
+		return unexpectedJSONError{jval}
+	}
+
+	if err := o.unmarshalFields(m, skipTypeURL); !nerr.Merge(err) {
+		return err
+	}
+
+	return nerr.E
+}
+
+// unmarshalFields unmarshals the fields into the given protoreflect.Message.
+func (o UnmarshalOptions) unmarshalFields(m pref.Message, skipTypeURL bool) error {
+	var nerr errors.NonFatal
+	var seenNums set.Ints
+	var seenOneofs set.Ints
+
+	messageDesc := m.Descriptor()
+	knownFields := m.KnownFields()
+	fieldDescs := messageDesc.Fields()
+	xtTypes := knownFields.ExtensionTypes()
+
+Loop:
+	for {
+		// Read field name.
+		jval, err := o.decoder.Read()
+		if !nerr.Merge(err) {
+			return err
+		}
+		switch jval.Type() {
+		default:
+			return unexpectedJSONError{jval}
+		case json.EndObject:
+			break Loop
+		case json.Name:
+			// Continue below.
+		}
+
+		name, err := jval.Name()
+		if !nerr.Merge(err) {
+			return err
+		}
+		// Unmarshaling a non-custom embedded message in Any will contain the
+		// JSON field "@type" which should be skipped because it is not a field
+		// of the embedded message, but simply an artifact of the Any format.
+		if skipTypeURL && name == "@type" {
+			o.decoder.Read()
+			continue
+		}
+
+		// Get the FieldDescriptor.
+		var fd pref.FieldDescriptor
+		if strings.HasPrefix(name, "[") && strings.HasSuffix(name, "]") {
+			// Only extension names are in [name] format.
+			xtName := pref.FullName(name[1 : len(name)-1])
+			xt := xtTypes.ByName(xtName)
+			if xt == nil {
+				xt, err = o.findExtension(xtName)
+				if err != nil && err != protoregistry.NotFound {
+					return errors.New("unable to resolve [%v]: %v", xtName, err)
+				}
+				if xt != nil {
+					xtTypes.Register(xt)
+				}
+			}
+			if xt != nil {
+				fd = xt.Descriptor()
+			}
+		} else {
+			// The name can either be the JSON name or the proto field name.
+			fd = fieldDescs.ByJSONName(name)
+			if fd == nil {
+				fd = fieldDescs.ByName(pref.Name(name))
+			}
+		}
+
+		if fd == nil {
+			// Field is unknown.
+			if o.DiscardUnknown {
+				if err := skipJSONValue(o.decoder); !nerr.Merge(err) {
+					return err
+				}
+				continue
+			}
+			return newError("%v contains unknown field %s", messageDesc.FullName(), jval)
+		}
+
+		// Do not allow duplicate fields.
+		num := uint64(fd.Number())
+		if seenNums.Has(num) {
+			return newError("%v contains repeated field %s", messageDesc.FullName(), jval)
+		}
+		seenNums.Set(num)
+
+		// No need to set values for JSON null unless the field type is
+		// google.protobuf.Value or google.protobuf.NullValue.
+		if o.decoder.Peek() == json.Null && !isKnownValue(fd) && !isNullValue(fd) {
+			o.decoder.Read()
+			continue
+		}
+
+		switch {
+		case fd.IsList():
+			list := knownFields.Get(fd.Number()).List()
+			if err := o.unmarshalList(list, fd); !nerr.Merge(err) {
+				return errors.New("%v|%q: %v", fd.FullName(), name, err)
+			}
+		case fd.IsMap():
+			mmap := knownFields.Get(fd.Number()).Map()
+			if err := o.unmarshalMap(mmap, fd); !nerr.Merge(err) {
+				return errors.New("%v|%q: %v", fd.FullName(), name, err)
+			}
+		default:
+			// If field is a oneof, check if it has already been set.
+			if od := fd.ContainingOneof(); od != nil {
+				idx := uint64(od.Index())
+				if seenOneofs.Has(idx) {
+					return errors.New("%v: oneof is already set", od.FullName())
+				}
+				seenOneofs.Set(idx)
+			}
+
+			// Required or optional fields.
+			if err := o.unmarshalSingular(knownFields, fd); !nerr.Merge(err) {
+				return errors.New("%v|%q: %v", fd.FullName(), name, err)
+			}
+		}
+	}
+
+	return nerr.E
+}
+
+// findExtension returns protoreflect.ExtensionType from the resolver if found.
+func (o UnmarshalOptions) findExtension(xtName pref.FullName) (pref.ExtensionType, error) {
+	xt, err := o.Resolver.FindExtensionByName(xtName)
+	if err == nil {
+		return xt, nil
+	}
+
+	// Check if this is a MessageSet extension field.
+	xt, err = o.Resolver.FindExtensionByName(xtName + ".message_set_extension")
+	if err == nil && isMessageSetExtension(xt) {
+		return xt, nil
+	}
+	return nil, protoregistry.NotFound
+}
+
+func isKnownValue(fd pref.FieldDescriptor) bool {
+	md := fd.Message()
+	return md != nil && md.FullName() == "google.protobuf.Value"
+}
+
+func isNullValue(fd pref.FieldDescriptor) bool {
+	ed := fd.Enum()
+	return ed != nil && ed.FullName() == "google.protobuf.NullValue"
+}
+
+// unmarshalSingular unmarshals to the non-repeated field specified by the given
+// FieldDescriptor.
+func (o UnmarshalOptions) unmarshalSingular(knownFields pref.KnownFields, fd pref.FieldDescriptor) error {
+	var val pref.Value
+	var err error
+	num := fd.Number()
+
+	switch fd.Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		m := knownFields.NewMessage(num)
+		err = o.unmarshalMessage(m, false)
+		val = pref.ValueOf(m)
+	default:
+		val, err = o.unmarshalScalar(fd)
+	}
+
+	var nerr errors.NonFatal
+	if !nerr.Merge(err) {
+		return err
+	}
+	knownFields.Set(num, val)
+	return nerr.E
+}
+
+// unmarshalScalar unmarshals to a scalar/enum protoreflect.Value specified by
+// the given FieldDescriptor.
+func (o UnmarshalOptions) unmarshalScalar(fd pref.FieldDescriptor) (pref.Value, error) {
+	const b32 int = 32
+	const b64 int = 64
+
+	var nerr errors.NonFatal
+	jval, err := o.decoder.Read()
+	if !nerr.Merge(err) {
+		return pref.Value{}, err
+	}
+
+	kind := fd.Kind()
+	switch kind {
+	case pref.BoolKind:
+		return unmarshalBool(jval)
+
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
+		return unmarshalInt(jval, b32)
+
+	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		return unmarshalInt(jval, b64)
+
+	case pref.Uint32Kind, pref.Fixed32Kind:
+		return unmarshalUint(jval, b32)
+
+	case pref.Uint64Kind, pref.Fixed64Kind:
+		return unmarshalUint(jval, b64)
+
+	case pref.FloatKind:
+		return unmarshalFloat(jval, b32)
+
+	case pref.DoubleKind:
+		return unmarshalFloat(jval, b64)
+
+	case pref.StringKind:
+		pval, err := unmarshalString(jval)
+		if !nerr.Merge(err) {
+			return pval, err
+		}
+		return pval, nerr.E
+
+	case pref.BytesKind:
+		return unmarshalBytes(jval)
+
+	case pref.EnumKind:
+		return unmarshalEnum(jval, fd)
+	}
+
+	panic(fmt.Sprintf("invalid scalar kind %v", kind))
+}
+
+func unmarshalBool(jval json.Value) (pref.Value, error) {
+	if jval.Type() != json.Bool {
+		return pref.Value{}, unexpectedJSONError{jval}
+	}
+	b, err := jval.Bool()
+	return pref.ValueOf(b), err
+}
+
+func unmarshalInt(jval json.Value, bitSize int) (pref.Value, error) {
+	switch jval.Type() {
+	case json.Number:
+		return getInt(jval, bitSize)
+
+	case json.String:
+		// Decode number from string.
+		s := strings.TrimSpace(jval.String())
+		if len(s) != len(jval.String()) {
+			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
+		}
+		dec := json.NewDecoder([]byte(s))
+		var nerr errors.NonFatal
+		jval, err := dec.Read()
+		if !nerr.Merge(err) {
+			return pref.Value{}, err
+		}
+		return getInt(jval, bitSize)
+	}
+	return pref.Value{}, unexpectedJSONError{jval}
+}
+
+func getInt(jval json.Value, bitSize int) (pref.Value, error) {
+	n, err := jval.Int(bitSize)
+	if err != nil {
+		return pref.Value{}, err
+	}
+	if bitSize == 32 {
+		return pref.ValueOf(int32(n)), nil
+	}
+	return pref.ValueOf(n), nil
+}
+
+func unmarshalUint(jval json.Value, bitSize int) (pref.Value, error) {
+	switch jval.Type() {
+	case json.Number:
+		return getUint(jval, bitSize)
+
+	case json.String:
+		// Decode number from string.
+		s := strings.TrimSpace(jval.String())
+		if len(s) != len(jval.String()) {
+			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
+		}
+		dec := json.NewDecoder([]byte(s))
+		var nerr errors.NonFatal
+		jval, err := dec.Read()
+		if !nerr.Merge(err) {
+			return pref.Value{}, err
+		}
+		return getUint(jval, bitSize)
+	}
+	return pref.Value{}, unexpectedJSONError{jval}
+}
+
+func getUint(jval json.Value, bitSize int) (pref.Value, error) {
+	n, err := jval.Uint(bitSize)
+	if err != nil {
+		return pref.Value{}, err
+	}
+	if bitSize == 32 {
+		return pref.ValueOf(uint32(n)), nil
+	}
+	return pref.ValueOf(n), nil
+}
+
+func unmarshalFloat(jval json.Value, bitSize int) (pref.Value, error) {
+	switch jval.Type() {
+	case json.Number:
+		return getFloat(jval, bitSize)
+
+	case json.String:
+		s := jval.String()
+		switch s {
+		case "NaN":
+			if bitSize == 32 {
+				return pref.ValueOf(float32(math.NaN())), nil
+			}
+			return pref.ValueOf(math.NaN()), nil
+		case "Infinity":
+			if bitSize == 32 {
+				return pref.ValueOf(float32(math.Inf(+1))), nil
+			}
+			return pref.ValueOf(math.Inf(+1)), nil
+		case "-Infinity":
+			if bitSize == 32 {
+				return pref.ValueOf(float32(math.Inf(-1))), nil
+			}
+			return pref.ValueOf(math.Inf(-1)), nil
+		}
+		// Decode number from string.
+		if len(s) != len(strings.TrimSpace(s)) {
+			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
+		}
+		dec := json.NewDecoder([]byte(s))
+		var nerr errors.NonFatal
+		jval, err := dec.Read()
+		if !nerr.Merge(err) {
+			return pref.Value{}, err
+		}
+		return getFloat(jval, bitSize)
+	}
+	return pref.Value{}, unexpectedJSONError{jval}
+}
+
+func getFloat(jval json.Value, bitSize int) (pref.Value, error) {
+	n, err := jval.Float(bitSize)
+	if err != nil {
+		return pref.Value{}, err
+	}
+	if bitSize == 32 {
+		return pref.ValueOf(float32(n)), nil
+	}
+	return pref.ValueOf(n), nil
+}
+
+func unmarshalString(jval json.Value) (pref.Value, error) {
+	if jval.Type() != json.String {
+		return pref.Value{}, unexpectedJSONError{jval}
+	}
+	return pref.ValueOf(jval.String()), nil
+}
+
+func unmarshalBytes(jval json.Value) (pref.Value, error) {
+	if jval.Type() != json.String {
+		return pref.Value{}, unexpectedJSONError{jval}
+	}
+
+	s := jval.String()
+	enc := base64.StdEncoding
+	if strings.ContainsAny(s, "-_") {
+		enc = base64.URLEncoding
+	}
+	if len(s)%4 != 0 {
+		enc = enc.WithPadding(base64.NoPadding)
+	}
+	b, err := enc.DecodeString(s)
+	if err != nil {
+		return pref.Value{}, err
+	}
+	return pref.ValueOf(b), nil
+}
+
+func unmarshalEnum(jval json.Value, fd pref.FieldDescriptor) (pref.Value, error) {
+	switch jval.Type() {
+	case json.String:
+		// Lookup EnumNumber based on name.
+		s := jval.String()
+		if enumVal := fd.Enum().Values().ByName(pref.Name(s)); enumVal != nil {
+			return pref.ValueOf(enumVal.Number()), nil
+		}
+		return pref.Value{}, newError("invalid enum value %q", jval)
+
+	case json.Number:
+		n, err := jval.Int(32)
+		if err != nil {
+			return pref.Value{}, err
+		}
+		return pref.ValueOf(pref.EnumNumber(n)), nil
+
+	case json.Null:
+		// This is only valid for google.protobuf.NullValue.
+		if isNullValue(fd) {
+			return pref.ValueOf(pref.EnumNumber(0)), nil
+		}
+	}
+
+	return pref.Value{}, unexpectedJSONError{jval}
+}
+
+func (o UnmarshalOptions) unmarshalList(list pref.List, fd pref.FieldDescriptor) error {
+	var nerr errors.NonFatal
+	jval, err := o.decoder.Read()
+	if !nerr.Merge(err) {
+		return err
+	}
+	if jval.Type() != json.StartArray {
+		return unexpectedJSONError{jval}
+	}
+
+	switch fd.Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		for {
+			m := list.NewMessage()
+			err := o.unmarshalMessage(m, false)
+			if !nerr.Merge(err) {
+				if e, ok := err.(unexpectedJSONError); ok {
+					if e.value.Type() == json.EndArray {
+						// Done with list.
+						return nerr.E
+					}
+				}
+				return err
+			}
+			list.Append(pref.ValueOf(m))
+		}
+	default:
+		for {
+			val, err := o.unmarshalScalar(fd)
+			if !nerr.Merge(err) {
+				if e, ok := err.(unexpectedJSONError); ok {
+					if e.value.Type() == json.EndArray {
+						// Done with list.
+						return nerr.E
+					}
+				}
+				return err
+			}
+			list.Append(val)
+		}
+	}
+	return nerr.E
+}
+
+func (o UnmarshalOptions) unmarshalMap(mmap pref.Map, fd pref.FieldDescriptor) error {
+	var nerr errors.NonFatal
+	jval, err := o.decoder.Read()
+	if !nerr.Merge(err) {
+		return err
+	}
+	if jval.Type() != json.StartObject {
+		return unexpectedJSONError{jval}
+	}
+
+	// Determine ahead whether map entry is a scalar type or a message type in
+	// order to call the appropriate unmarshalMapValue func inside the for loop
+	// below.
+	var unmarshalMapValue func() (pref.Value, error)
+	switch fd.MapValue().Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		unmarshalMapValue = func() (pref.Value, error) {
+			var nerr errors.NonFatal
+			m := mmap.NewMessage()
+			if err := o.unmarshalMessage(m, false); !nerr.Merge(err) {
+				return pref.Value{}, err
+			}
+			return pref.ValueOf(m), nerr.E
+		}
+	default:
+		unmarshalMapValue = func() (pref.Value, error) {
+			return o.unmarshalScalar(fd.MapValue())
+		}
+	}
+
+Loop:
+	for {
+		// Read field name.
+		jval, err := o.decoder.Read()
+		if !nerr.Merge(err) {
+			return err
+		}
+		switch jval.Type() {
+		default:
+			return unexpectedJSONError{jval}
+		case json.EndObject:
+			break Loop
+		case json.Name:
+			// Continue.
+		}
+
+		name, err := jval.Name()
+		if !nerr.Merge(err) {
+			return err
+		}
+
+		// Unmarshal field name.
+		pkey, err := unmarshalMapKey(name, fd.MapKey())
+		if !nerr.Merge(err) {
+			return err
+		}
+
+		// Check for duplicate field name.
+		if mmap.Has(pkey) {
+			return newError("duplicate map key %q", jval)
+		}
+
+		// Read and unmarshal field value.
+		pval, err := unmarshalMapValue()
+		if !nerr.Merge(err) {
+			return err
+		}
+
+		mmap.Set(pkey, pval)
+	}
+
+	return nerr.E
+}
+
+// unmarshalMapKey converts given string into a protoreflect.MapKey. A map key type is any
+// integral or string type.
+func unmarshalMapKey(name string, fd pref.FieldDescriptor) (pref.MapKey, error) {
+	const b32 = 32
+	const b64 = 64
+	const base10 = 10
+
+	kind := fd.Kind()
+	switch kind {
+	case pref.StringKind:
+		return pref.ValueOf(name).MapKey(), nil
+
+	case pref.BoolKind:
+		switch name {
+		case "true":
+			return pref.ValueOf(true).MapKey(), nil
+		case "false":
+			return pref.ValueOf(false).MapKey(), nil
+		}
+		return pref.MapKey{}, errors.New("invalid value for boolean key %q", name)
+
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
+		n, err := strconv.ParseInt(name, base10, b32)
+		if err != nil {
+			return pref.MapKey{}, err
+		}
+		return pref.ValueOf(int32(n)).MapKey(), nil
+
+	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		n, err := strconv.ParseInt(name, base10, b64)
+		if err != nil {
+			return pref.MapKey{}, err
+		}
+		return pref.ValueOf(int64(n)).MapKey(), nil
+
+	case pref.Uint32Kind, pref.Fixed32Kind:
+		n, err := strconv.ParseUint(name, base10, b32)
+		if err != nil {
+			return pref.MapKey{}, err
+		}
+		return pref.ValueOf(uint32(n)).MapKey(), nil
+
+	case pref.Uint64Kind, pref.Fixed64Kind:
+		n, err := strconv.ParseUint(name, base10, b64)
+		if err != nil {
+			return pref.MapKey{}, err
+		}
+		return pref.ValueOf(uint64(n)).MapKey(), nil
+	}
+
+	panic(fmt.Sprintf("%s: invalid kind %s for map key", fd.FullName(), kind))
+}