Use mattermost v5 module (#1192)

9 files changed, 2363 insertions, 0 deletions

diff --git a/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go b/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go
new file mode 100644
index 00000000..fdd9b13f
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go
@@ -0,0 +1,213 @@
+// Copyright 2018 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 defval marshals and unmarshals textual forms of default values.
+//
+// This package handles both the form historically used in Go struct field tags
+// and also the form used by google.protobuf.FieldDescriptorProto.default_value
+// since they differ in superficial ways.
+package defval
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+
+	ptext "google.golang.org/protobuf/internal/encoding/text"
+	errors "google.golang.org/protobuf/internal/errors"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// Format is the serialization format used to represent the default value.
+type Format int
+
+const (
+	_ Format = iota
+
+	// Descriptor uses the serialization format that protoc uses with the
+	// google.protobuf.FieldDescriptorProto.default_value field.
+	Descriptor
+
+	// GoTag uses the historical serialization format in Go struct field tags.
+	GoTag
+)
+
+// Unmarshal deserializes the default string s according to the given kind k.
+// When k is an enum, a list of enum value descriptors must be provided.
+func Unmarshal(s string, k pref.Kind, evs pref.EnumValueDescriptors, f Format) (pref.Value, pref.EnumValueDescriptor, error) {
+	switch k {
+	case pref.BoolKind:
+		if f == GoTag {
+			switch s {
+			case "1":
+				return pref.ValueOfBool(true), nil, nil
+			case "0":
+				return pref.ValueOfBool(false), nil, nil
+			}
+		} else {
+			switch s {
+			case "true":
+				return pref.ValueOfBool(true), nil, nil
+			case "false":
+				return pref.ValueOfBool(false), nil, nil
+			}
+		}
+	case pref.EnumKind:
+		if f == GoTag {
+			// Go tags use the numeric form of the enum value.
+			if n, err := strconv.ParseInt(s, 10, 32); err == nil {
+				if ev := evs.ByNumber(pref.EnumNumber(n)); ev != nil {
+					return pref.ValueOfEnum(ev.Number()), ev, nil
+				}
+			}
+		} else {
+			// Descriptor default_value use the enum identifier.
+			ev := evs.ByName(pref.Name(s))
+			if ev != nil {
+				return pref.ValueOfEnum(ev.Number()), ev, nil
+			}
+		}
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
+		if v, err := strconv.ParseInt(s, 10, 32); err == nil {
+			return pref.ValueOfInt32(int32(v)), nil, nil
+		}
+	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
+			return pref.ValueOfInt64(int64(v)), nil, nil
+		}
+	case pref.Uint32Kind, pref.Fixed32Kind:
+		if v, err := strconv.ParseUint(s, 10, 32); err == nil {
+			return pref.ValueOfUint32(uint32(v)), nil, nil
+		}
+	case pref.Uint64Kind, pref.Fixed64Kind:
+		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
+			return pref.ValueOfUint64(uint64(v)), nil, nil
+		}
+	case pref.FloatKind, pref.DoubleKind:
+		var v float64
+		var err error
+		switch s {
+		case "-inf":
+			v = math.Inf(-1)
+		case "inf":
+			v = math.Inf(+1)
+		case "nan":
+			v = math.NaN()
+		default:
+			v, err = strconv.ParseFloat(s, 64)
+		}
+		if err == nil {
+			if k == pref.FloatKind {
+				return pref.ValueOfFloat32(float32(v)), nil, nil
+			} else {
+				return pref.ValueOfFloat64(float64(v)), nil, nil
+			}
+		}
+	case pref.StringKind:
+		// String values are already unescaped and can be used as is.
+		return pref.ValueOfString(s), nil, nil
+	case pref.BytesKind:
+		if b, ok := unmarshalBytes(s); ok {
+			return pref.ValueOfBytes(b), nil, nil
+		}
+	}
+	return pref.Value{}, nil, errors.New("could not parse value for %v: %q", k, s)
+}
+
+// Marshal serializes v as the default string according to the given kind k.
+// When specifying the Descriptor format for an enum kind, the associated
+// enum value descriptor must be provided.
+func Marshal(v pref.Value, ev pref.EnumValueDescriptor, k pref.Kind, f Format) (string, error) {
+	switch k {
+	case pref.BoolKind:
+		if f == GoTag {
+			if v.Bool() {
+				return "1", nil
+			} else {
+				return "0", nil
+			}
+		} else {
+			if v.Bool() {
+				return "true", nil
+			} else {
+				return "false", nil
+			}
+		}
+	case pref.EnumKind:
+		if f == GoTag {
+			return strconv.FormatInt(int64(v.Enum()), 10), nil
+		} else {
+			return string(ev.Name()), nil
+		}
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind, pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		return strconv.FormatInt(v.Int(), 10), nil
+	case pref.Uint32Kind, pref.Fixed32Kind, pref.Uint64Kind, pref.Fixed64Kind:
+		return strconv.FormatUint(v.Uint(), 10), nil
+	case pref.FloatKind, pref.DoubleKind:
+		f := v.Float()
+		switch {
+		case math.IsInf(f, -1):
+			return "-inf", nil
+		case math.IsInf(f, +1):
+			return "inf", nil
+		case math.IsNaN(f):
+			return "nan", nil
+		default:
+			if k == pref.FloatKind {
+				return strconv.FormatFloat(f, 'g', -1, 32), nil
+			} else {
+				return strconv.FormatFloat(f, 'g', -1, 64), nil
+			}
+		}
+	case pref.StringKind:
+		// String values are serialized as is without any escaping.
+		return v.String(), nil
+	case pref.BytesKind:
+		if s, ok := marshalBytes(v.Bytes()); ok {
+			return s, nil
+		}
+	}
+	return "", errors.New("could not format value for %v: %v", k, v)
+}
+
+// unmarshalBytes deserializes bytes by applying C unescaping.
+func unmarshalBytes(s string) ([]byte, bool) {
+	// Bytes values use the same escaping as the text format,
+	// however they lack the surrounding double quotes.
+	v, err := ptext.UnmarshalString(`"` + s + `"`)
+	if err != nil {
+		return nil, false
+	}
+	return []byte(v), true
+}
+
+// marshalBytes serializes bytes by using C escaping.
+// To match the exact output of protoc, this is identical to the
+// CEscape function in strutil.cc of the protoc source code.
+func marshalBytes(b []byte) (string, bool) {
+	var s []byte
+	for _, c := range b {
+		switch c {
+		case '\n':
+			s = append(s, `\n`...)
+		case '\r':
+			s = append(s, `\r`...)
+		case '\t':
+			s = append(s, `\t`...)
+		case '"':
+			s = append(s, `\"`...)
+		case '\'':
+			s = append(s, `\'`...)
+		case '\\':
+			s = append(s, `\\`...)
+		default:
+			if printableASCII := c >= 0x20 && c <= 0x7e; printableASCII {
+				s = append(s, c)
+			} else {
+				s = append(s, fmt.Sprintf(`\%03o`, c)...)
+			}
+		}
+	}
+	return string(s), true
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/messageset/messageset.go b/vendor/google.golang.org/protobuf/internal/encoding/messageset/messageset.go
new file mode 100644
index 00000000..b1eeea50
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/messageset/messageset.go
@@ -0,0 +1,258 @@
+// 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 messageset encodes and decodes the obsolete MessageSet wire format.
+package messageset
+
+import (
+	"math"
+
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/internal/errors"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	preg "google.golang.org/protobuf/reflect/protoregistry"
+)
+
+// The MessageSet wire format is equivalent to a message defiend as follows,
+// where each Item defines an extension field with a field number of 'type_id'
+// and content of 'message'. MessageSet extensions must be non-repeated message
+// fields.
+//
+//	message MessageSet {
+//		repeated group Item = 1 {
+//			required int32 type_id = 2;
+//			required string message = 3;
+//		}
+//	}
+const (
+	FieldItem    = protowire.Number(1)
+	FieldTypeID  = protowire.Number(2)
+	FieldMessage = protowire.Number(3)
+)
+
+// ExtensionName is the field name for extensions of MessageSet.
+//
+// A valid MessageSet extension must be of the form:
+//	message MyMessage {
+//		extend proto2.bridge.MessageSet {
+//			optional MyMessage message_set_extension = 1234;
+//		}
+//		...
+//	}
+const ExtensionName = "message_set_extension"
+
+// IsMessageSet returns whether the message uses the MessageSet wire format.
+func IsMessageSet(md pref.MessageDescriptor) bool {
+	xmd, ok := md.(interface{ IsMessageSet() bool })
+	return ok && xmd.IsMessageSet()
+}
+
+// IsMessageSetExtension reports this field extends a MessageSet.
+func IsMessageSetExtension(fd pref.FieldDescriptor) bool {
+	if fd.Name() != ExtensionName {
+		return false
+	}
+	if fd.FullName().Parent() != fd.Message().FullName() {
+		return false
+	}
+	return IsMessageSet(fd.ContainingMessage())
+}
+
+// FindMessageSetExtension locates a MessageSet extension field by name.
+// In text and JSON formats, the extension name used is the message itself.
+// The extension field name is derived by appending ExtensionName.
+func FindMessageSetExtension(r preg.ExtensionTypeResolver, s pref.FullName) (pref.ExtensionType, error) {
+	name := s.Append(ExtensionName)
+	xt, err := r.FindExtensionByName(name)
+	if err != nil {
+		if err == preg.NotFound {
+			return nil, err
+		}
+		return nil, errors.Wrap(err, "%q", name)
+	}
+	if !IsMessageSetExtension(xt.TypeDescriptor()) {
+		return nil, preg.NotFound
+	}
+	return xt, nil
+}
+
+// SizeField returns the size of a MessageSet item field containing an extension
+// with the given field number, not counting the contents of the message subfield.
+func SizeField(num protowire.Number) int {
+	return 2*protowire.SizeTag(FieldItem) + protowire.SizeTag(FieldTypeID) + protowire.SizeVarint(uint64(num))
+}
+
+// Unmarshal parses a MessageSet.
+//
+// It calls fn with the type ID and value of each item in the MessageSet.
+// Unknown fields are discarded.
+//
+// If wantLen is true, the item values include the varint length prefix.
+// This is ugly, but simplifies the fast-path decoder in internal/impl.
+func Unmarshal(b []byte, wantLen bool, fn func(typeID protowire.Number, value []byte) error) error {
+	for len(b) > 0 {
+		num, wtyp, n := protowire.ConsumeTag(b)
+		if n < 0 {
+			return protowire.ParseError(n)
+		}
+		b = b[n:]
+		if num != FieldItem || wtyp != protowire.StartGroupType {
+			n := protowire.ConsumeFieldValue(num, wtyp, b)
+			if n < 0 {
+				return protowire.ParseError(n)
+			}
+			b = b[n:]
+			continue
+		}
+		typeID, value, n, err := ConsumeFieldValue(b, wantLen)
+		if err != nil {
+			return err
+		}
+		b = b[n:]
+		if typeID == 0 {
+			continue
+		}
+		if err := fn(typeID, value); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// ConsumeFieldValue parses b as a MessageSet item field value until and including
+// the trailing end group marker. It assumes the start group tag has already been parsed.
+// It returns the contents of the type_id and message subfields and the total
+// item length.
+//
+// If wantLen is true, the returned message value includes the length prefix.
+func ConsumeFieldValue(b []byte, wantLen bool) (typeid protowire.Number, message []byte, n int, err error) {
+	ilen := len(b)
+	for {
+		num, wtyp, n := protowire.ConsumeTag(b)
+		if n < 0 {
+			return 0, nil, 0, protowire.ParseError(n)
+		}
+		b = b[n:]
+		switch {
+		case num == FieldItem && wtyp == protowire.EndGroupType:
+			if wantLen && len(message) == 0 {
+				// The message field was missing, which should never happen.
+				// Be prepared for this case anyway.
+				message = protowire.AppendVarint(message, 0)
+			}
+			return typeid, message, ilen - len(b), nil
+		case num == FieldTypeID && wtyp == protowire.VarintType:
+			v, n := protowire.ConsumeVarint(b)
+			if n < 0 {
+				return 0, nil, 0, protowire.ParseError(n)
+			}
+			b = b[n:]
+			if v < 1 || v > math.MaxInt32 {
+				return 0, nil, 0, errors.New("invalid type_id in message set")
+			}
+			typeid = protowire.Number(v)
+		case num == FieldMessage && wtyp == protowire.BytesType:
+			m, n := protowire.ConsumeBytes(b)
+			if n < 0 {
+				return 0, nil, 0, protowire.ParseError(n)
+			}
+			if message == nil {
+				if wantLen {
+					message = b[:n:n]
+				} else {
+					message = m[:len(m):len(m)]
+				}
+			} else {
+				// This case should never happen in practice, but handle it for
+				// correctness: The MessageSet item contains multiple message
+				// fields, which need to be merged.
+				//
+				// In the case where we're returning the length, this becomes
+				// quite inefficient since we need to strip the length off
+				// the existing data and reconstruct it with the combined length.
+				if wantLen {
+					_, nn := protowire.ConsumeVarint(message)
+					m0 := message[nn:]
+					message = nil
+					message = protowire.AppendVarint(message, uint64(len(m0)+len(m)))
+					message = append(message, m0...)
+					message = append(message, m...)
+				} else {
+					message = append(message, m...)
+				}
+			}
+			b = b[n:]
+		default:
+			// We have no place to put it, so we just ignore unknown fields.
+			n := protowire.ConsumeFieldValue(num, wtyp, b)
+			if n < 0 {
+				return 0, nil, 0, protowire.ParseError(n)
+			}
+			b = b[n:]
+		}
+	}
+}
+
+// AppendFieldStart appends the start of a MessageSet item field containing
+// an extension with the given number. The caller must add the message
+// subfield (including the tag).
+func AppendFieldStart(b []byte, num protowire.Number) []byte {
+	b = protowire.AppendTag(b, FieldItem, protowire.StartGroupType)
+	b = protowire.AppendTag(b, FieldTypeID, protowire.VarintType)
+	b = protowire.AppendVarint(b, uint64(num))
+	return b
+}
+
+// AppendFieldEnd appends the trailing end group marker for a MessageSet item field.
+func AppendFieldEnd(b []byte) []byte {
+	return protowire.AppendTag(b, FieldItem, protowire.EndGroupType)
+}
+
+// SizeUnknown returns the size of an unknown fields section in MessageSet format.
+//
+// See AppendUnknown.
+func SizeUnknown(unknown []byte) (size int) {
+	for len(unknown) > 0 {
+		num, typ, n := protowire.ConsumeTag(unknown)
+		if n < 0 || typ != protowire.BytesType {
+			return 0
+		}
+		unknown = unknown[n:]
+		_, n = protowire.ConsumeBytes(unknown)
+		if n < 0 {
+			return 0
+		}
+		unknown = unknown[n:]
+		size += SizeField(num) + protowire.SizeTag(FieldMessage) + n
+	}
+	return size
+}
+
+// AppendUnknown appends unknown fields to b in MessageSet format.
+//
+// For historic reasons, unresolved items in a MessageSet are stored in a
+// message's unknown fields section in non-MessageSet format. That is, an
+// unknown item with typeID T and value V appears in the unknown fields as
+// a field with number T and value V.
+//
+// This function converts the unknown fields back into MessageSet form.
+func AppendUnknown(b, unknown []byte) ([]byte, error) {
+	for len(unknown) > 0 {
+		num, typ, n := protowire.ConsumeTag(unknown)
+		if n < 0 || typ != protowire.BytesType {
+			return nil, errors.New("invalid data in message set unknown fields")
+		}
+		unknown = unknown[n:]
+		_, n = protowire.ConsumeBytes(unknown)
+		if n < 0 {
+			return nil, errors.New("invalid data in message set unknown fields")
+		}
+		b = AppendFieldStart(b, num)
+		b = protowire.AppendTag(b, FieldMessage, protowire.BytesType)
+		b = append(b, unknown[:n]...)
+		b = AppendFieldEnd(b)
+		unknown = unknown[n:]
+	}
+	return b, nil
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/tag/tag.go b/vendor/google.golang.org/protobuf/internal/encoding/tag/tag.go
new file mode 100644
index 00000000..16c02d7b
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/tag/tag.go
@@ -0,0 +1,207 @@
+// Copyright 2018 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 tag marshals and unmarshals the legacy struct tags as generated
+// by historical versions of protoc-gen-go.
+package tag
+
+import (
+	"reflect"
+	"strconv"
+	"strings"
+
+	defval "google.golang.org/protobuf/internal/encoding/defval"
+	fdesc "google.golang.org/protobuf/internal/filedesc"
+	"google.golang.org/protobuf/internal/strs"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+)
+
+var byteType = reflect.TypeOf(byte(0))
+
+// Unmarshal decodes the tag into a prototype.Field.
+//
+// The goType is needed to determine the original protoreflect.Kind since the
+// tag does not record sufficient information to determine that.
+// The type is the underlying field type (e.g., a repeated field may be
+// represented by []T, but the Go type passed in is just T).
+// A list of enum value descriptors must be provided for enum fields.
+// This does not populate the Enum or Message (except for weak message).
+//
+// This function is a best effort attempt; parsing errors are ignored.
+func Unmarshal(tag string, goType reflect.Type, evs pref.EnumValueDescriptors) pref.FieldDescriptor {
+	f := new(fdesc.Field)
+	f.L0.ParentFile = fdesc.SurrogateProto2
+	for len(tag) > 0 {
+		i := strings.IndexByte(tag, ',')
+		if i < 0 {
+			i = len(tag)
+		}
+		switch s := tag[:i]; {
+		case strings.HasPrefix(s, "name="):
+			f.L0.FullName = pref.FullName(s[len("name="):])
+		case strings.Trim(s, "0123456789") == "":
+			n, _ := strconv.ParseUint(s, 10, 32)
+			f.L1.Number = pref.FieldNumber(n)
+		case s == "opt":
+			f.L1.Cardinality = pref.Optional
+		case s == "req":
+			f.L1.Cardinality = pref.Required
+		case s == "rep":
+			f.L1.Cardinality = pref.Repeated
+		case s == "varint":
+			switch goType.Kind() {
+			case reflect.Bool:
+				f.L1.Kind = pref.BoolKind
+			case reflect.Int32:
+				f.L1.Kind = pref.Int32Kind
+			case reflect.Int64:
+				f.L1.Kind = pref.Int64Kind
+			case reflect.Uint32:
+				f.L1.Kind = pref.Uint32Kind
+			case reflect.Uint64:
+				f.L1.Kind = pref.Uint64Kind
+			}
+		case s == "zigzag32":
+			if goType.Kind() == reflect.Int32 {
+				f.L1.Kind = pref.Sint32Kind
+			}
+		case s == "zigzag64":
+			if goType.Kind() == reflect.Int64 {
+				f.L1.Kind = pref.Sint64Kind
+			}
+		case s == "fixed32":
+			switch goType.Kind() {
+			case reflect.Int32:
+				f.L1.Kind = pref.Sfixed32Kind
+			case reflect.Uint32:
+				f.L1.Kind = pref.Fixed32Kind
+			case reflect.Float32:
+				f.L1.Kind = pref.FloatKind
+			}
+		case s == "fixed64":
+			switch goType.Kind() {
+			case reflect.Int64:
+				f.L1.Kind = pref.Sfixed64Kind
+			case reflect.Uint64:
+				f.L1.Kind = pref.Fixed64Kind
+			case reflect.Float64:
+				f.L1.Kind = pref.DoubleKind
+			}
+		case s == "bytes":
+			switch {
+			case goType.Kind() == reflect.String:
+				f.L1.Kind = pref.StringKind
+			case goType.Kind() == reflect.Slice && goType.Elem() == byteType:
+				f.L1.Kind = pref.BytesKind
+			default:
+				f.L1.Kind = pref.MessageKind
+			}
+		case s == "group":
+			f.L1.Kind = pref.GroupKind
+		case strings.HasPrefix(s, "enum="):
+			f.L1.Kind = pref.EnumKind
+		case strings.HasPrefix(s, "json="):
+			jsonName := s[len("json="):]
+			if jsonName != strs.JSONCamelCase(string(f.L0.FullName.Name())) {
+				f.L1.JSONName.Init(jsonName)
+			}
+		case s == "packed":
+			f.L1.HasPacked = true
+			f.L1.IsPacked = true
+		case strings.HasPrefix(s, "weak="):
+			f.L1.IsWeak = true
+			f.L1.Message = fdesc.PlaceholderMessage(pref.FullName(s[len("weak="):]))
+		case strings.HasPrefix(s, "def="):
+			// The default tag is special in that everything afterwards is the
+			// default regardless of the presence of commas.
+			s, i = tag[len("def="):], len(tag)
+			v, ev, _ := defval.Unmarshal(s, f.L1.Kind, evs, defval.GoTag)
+			f.L1.Default = fdesc.DefaultValue(v, ev)
+		case s == "proto3":
+			f.L0.ParentFile = fdesc.SurrogateProto3
+		}
+		tag = strings.TrimPrefix(tag[i:], ",")
+	}
+
+	// The generator uses the group message name instead of the field name.
+	// We obtain the real field name by lowercasing the group name.
+	if f.L1.Kind == pref.GroupKind {
+		f.L0.FullName = pref.FullName(strings.ToLower(string(f.L0.FullName)))
+	}
+	return f
+}
+
+// Marshal encodes the protoreflect.FieldDescriptor as a tag.
+//
+// The enumName must be provided if the kind is an enum.
+// Historically, the formulation of the enum "name" was the proto package
+// dot-concatenated with the generated Go identifier for the enum type.
+// Depending on the context on how Marshal is called, there are different ways
+// through which that information is determined. As such it is the caller's
+// responsibility to provide a function to obtain that information.
+func Marshal(fd pref.FieldDescriptor, enumName string) string {
+	var tag []string
+	switch fd.Kind() {
+	case pref.BoolKind, pref.EnumKind, pref.Int32Kind, pref.Uint32Kind, pref.Int64Kind, pref.Uint64Kind:
+		tag = append(tag, "varint")
+	case pref.Sint32Kind:
+		tag = append(tag, "zigzag32")
+	case pref.Sint64Kind:
+		tag = append(tag, "zigzag64")
+	case pref.Sfixed32Kind, pref.Fixed32Kind, pref.FloatKind:
+		tag = append(tag, "fixed32")
+	case pref.Sfixed64Kind, pref.Fixed64Kind, pref.DoubleKind:
+		tag = append(tag, "fixed64")
+	case pref.StringKind, pref.BytesKind, pref.MessageKind:
+		tag = append(tag, "bytes")
+	case pref.GroupKind:
+		tag = append(tag, "group")
+	}
+	tag = append(tag, strconv.Itoa(int(fd.Number())))
+	switch fd.Cardinality() {
+	case pref.Optional:
+		tag = append(tag, "opt")
+	case pref.Required:
+		tag = append(tag, "req")
+	case pref.Repeated:
+		tag = append(tag, "rep")
+	}
+	if fd.IsPacked() {
+		tag = append(tag, "packed")
+	}
+	name := string(fd.Name())
+	if fd.Kind() == pref.GroupKind {
+		// The name of the FieldDescriptor for a group field is
+		// lowercased. To find the original capitalization, we
+		// look in the field's MessageType.
+		name = string(fd.Message().Name())
+	}
+	tag = append(tag, "name="+name)
+	if jsonName := fd.JSONName(); jsonName != "" && jsonName != name && !fd.IsExtension() {
+		// NOTE: The jsonName != name condition is suspect, but it preserve
+		// the exact same semantics from the previous generator.
+		tag = append(tag, "json="+jsonName)
+	}
+	if fd.IsWeak() {
+		tag = append(tag, "weak="+string(fd.Message().FullName()))
+	}
+	// The previous implementation does not tag extension fields as proto3,
+	// even when the field is defined in a proto3 file. Match that behavior
+	// for consistency.
+	if fd.Syntax() == pref.Proto3 && !fd.IsExtension() {
+		tag = append(tag, "proto3")
+	}
+	if fd.Kind() == pref.EnumKind && enumName != "" {
+		tag = append(tag, "enum="+enumName)
+	}
+	if fd.ContainingOneof() != nil {
+		tag = append(tag, "oneof")
+	}
+	// This must appear last in the tag, since commas in strings aren't escaped.
+	if fd.HasDefault() {
+		def, _ := defval.Marshal(fd.Default(), fd.DefaultEnumValue(), fd.Kind(), defval.GoTag)
+		tag = append(tag, "def="+def)
+	}
+	return strings.Join(tag, ",")
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/decode.go b/vendor/google.golang.org/protobuf/internal/encoding/text/decode.go
new file mode 100644
index 00000000..eb10ea10
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/decode.go
@@ -0,0 +1,665 @@
+// Copyright 2018 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 text
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"regexp"
+	"strconv"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/internal/errors"
+)
+
+// Decoder is a token-based textproto decoder.
+type Decoder struct {
+	// lastCall is last method called, either readCall or peekCall.
+	// Initial value is readCall.
+	lastCall call
+
+	// lastToken contains the last read token.
+	lastToken Token
+
+	// lastErr contains the last read error.
+	lastErr error
+
+	// openStack is a stack containing the byte characters for MessageOpen and
+	// ListOpen kinds. The top of stack represents the message or the list that
+	// the current token is nested in. An empty stack means the current token is
+	// at the top level message. The characters '{' and '<' both represent the
+	// MessageOpen kind.
+	openStack []byte
+
+	// orig is used in reporting line and column.
+	orig []byte
+	// in contains the unconsumed input.
+	in []byte
+}
+
+// NewDecoder returns a Decoder to read the given []byte.
+func NewDecoder(b []byte) *Decoder {
+	return &Decoder{orig: b, in: b}
+}
+
+// ErrUnexpectedEOF means that EOF was encountered in the middle of the input.
+var ErrUnexpectedEOF = errors.New("%v", io.ErrUnexpectedEOF)
+
+// call specifies which Decoder method was invoked.
+type call uint8
+
+const (
+	readCall call = iota
+	peekCall
+)
+
+// Peek looks ahead and returns the next token and error without advancing a read.
+func (d *Decoder) Peek() (Token, error) {
+	defer func() { d.lastCall = peekCall }()
+	if d.lastCall == readCall {
+		d.lastToken, d.lastErr = d.Read()
+	}
+	return d.lastToken, d.lastErr
+}
+
+// Read returns the next token.
+// It will return an error if there is no valid token.
+func (d *Decoder) Read() (Token, error) {
+	defer func() { d.lastCall = readCall }()
+	if d.lastCall == peekCall {
+		return d.lastToken, d.lastErr
+	}
+
+	tok, err := d.parseNext(d.lastToken.kind)
+	if err != nil {
+		return Token{}, err
+	}
+
+	switch tok.kind {
+	case comma, semicolon:
+		tok, err = d.parseNext(tok.kind)
+		if err != nil {
+			return Token{}, err
+		}
+	}
+	d.lastToken = tok
+	return tok, nil
+}
+
+const (
+	mismatchedFmt = "mismatched close character %q"
+	unexpectedFmt = "unexpected character %q"
+)
+
+// parseNext parses the next Token based on given last kind.
+func (d *Decoder) parseNext(lastKind Kind) (Token, error) {
+	// Trim leading spaces.
+	d.consume(0)
+	isEOF := false
+	if len(d.in) == 0 {
+		isEOF = true
+	}
+
+	switch lastKind {
+	case EOF:
+		return d.consumeToken(EOF, 0, 0), nil
+
+	case bof:
+		// Start of top level message. Next token can be EOF or Name.
+		if isEOF {
+			return d.consumeToken(EOF, 0, 0), nil
+		}
+		return d.parseFieldName()
+
+	case Name:
+		// Next token can be MessageOpen, ListOpen or Scalar.
+		if isEOF {
+			return Token{}, ErrUnexpectedEOF
+		}
+		switch ch := d.in[0]; ch {
+		case '{', '<':
+			d.pushOpenStack(ch)
+			return d.consumeToken(MessageOpen, 1, 0), nil
+		case '[':
+			d.pushOpenStack(ch)
+			return d.consumeToken(ListOpen, 1, 0), nil
+		default:
+			return d.parseScalar()
+		}
+
+	case Scalar:
+		openKind, closeCh := d.currentOpenKind()
+		switch openKind {
+		case bof:
+			// Top level message.
+			// 	Next token can be EOF, comma, semicolon or Name.
+			if isEOF {
+				return d.consumeToken(EOF, 0, 0), nil
+			}
+			switch d.in[0] {
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		case MessageOpen:
+			// Next token can be MessageClose, comma, semicolon or Name.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case closeCh:
+				d.popOpenStack()
+				return d.consumeToken(MessageClose, 1, 0), nil
+			case otherCloseChar[closeCh]:
+				return Token{}, d.newSyntaxError(mismatchedFmt, ch)
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		case ListOpen:
+			// Next token can be ListClose or comma.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case ']':
+				d.popOpenStack()
+				return d.consumeToken(ListClose, 1, 0), nil
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			default:
+				return Token{}, d.newSyntaxError(unexpectedFmt, ch)
+			}
+		}
+
+	case MessageOpen:
+		// Next token can be MessageClose or Name.
+		if isEOF {
+			return Token{}, ErrUnexpectedEOF
+		}
+		_, closeCh := d.currentOpenKind()
+		switch ch := d.in[0]; ch {
+		case closeCh:
+			d.popOpenStack()
+			return d.consumeToken(MessageClose, 1, 0), nil
+		case otherCloseChar[closeCh]:
+			return Token{}, d.newSyntaxError(mismatchedFmt, ch)
+		default:
+			return d.parseFieldName()
+		}
+
+	case MessageClose:
+		openKind, closeCh := d.currentOpenKind()
+		switch openKind {
+		case bof:
+			// Top level message.
+			// Next token can be EOF, comma, semicolon or Name.
+			if isEOF {
+				return d.consumeToken(EOF, 0, 0), nil
+			}
+			switch ch := d.in[0]; ch {
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		case MessageOpen:
+			// Next token can be MessageClose, comma, semicolon or Name.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case closeCh:
+				d.popOpenStack()
+				return d.consumeToken(MessageClose, 1, 0), nil
+			case otherCloseChar[closeCh]:
+				return Token{}, d.newSyntaxError(mismatchedFmt, ch)
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		case ListOpen:
+			// Next token can be ListClose or comma
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case closeCh:
+				d.popOpenStack()
+				return d.consumeToken(ListClose, 1, 0), nil
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			default:
+				return Token{}, d.newSyntaxError(unexpectedFmt, ch)
+			}
+		}
+
+	case ListOpen:
+		// Next token can be ListClose, MessageStart or Scalar.
+		if isEOF {
+			return Token{}, ErrUnexpectedEOF
+		}
+		switch ch := d.in[0]; ch {
+		case ']':
+			d.popOpenStack()
+			return d.consumeToken(ListClose, 1, 0), nil
+		case '{', '<':
+			d.pushOpenStack(ch)
+			return d.consumeToken(MessageOpen, 1, 0), nil
+		default:
+			return d.parseScalar()
+		}
+
+	case ListClose:
+		openKind, closeCh := d.currentOpenKind()
+		switch openKind {
+		case bof:
+			// Top level message.
+			// Next token can be EOF, comma, semicolon or Name.
+			if isEOF {
+				return d.consumeToken(EOF, 0, 0), nil
+			}
+			switch ch := d.in[0]; ch {
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		case MessageOpen:
+			// Next token can be MessageClose, comma, semicolon or Name.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case closeCh:
+				d.popOpenStack()
+				return d.consumeToken(MessageClose, 1, 0), nil
+			case otherCloseChar[closeCh]:
+				return Token{}, d.newSyntaxError(mismatchedFmt, ch)
+			case ',':
+				return d.consumeToken(comma, 1, 0), nil
+			case ';':
+				return d.consumeToken(semicolon, 1, 0), nil
+			default:
+				return d.parseFieldName()
+			}
+
+		default:
+			// It is not possible to have this case. Let it panic below.
+		}
+
+	case comma, semicolon:
+		openKind, closeCh := d.currentOpenKind()
+		switch openKind {
+		case bof:
+			// Top level message. Next token can be EOF or Name.
+			if isEOF {
+				return d.consumeToken(EOF, 0, 0), nil
+			}
+			return d.parseFieldName()
+
+		case MessageOpen:
+			// Next token can be MessageClose or Name.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case closeCh:
+				d.popOpenStack()
+				return d.consumeToken(MessageClose, 1, 0), nil
+			case otherCloseChar[closeCh]:
+				return Token{}, d.newSyntaxError(mismatchedFmt, ch)
+			default:
+				return d.parseFieldName()
+			}
+
+		case ListOpen:
+			if lastKind == semicolon {
+				// It is not be possible to have this case as logic here
+				// should not have produced a semicolon Token when inside a
+				// list. Let it panic below.
+				break
+			}
+			// Next token can be MessageOpen or Scalar.
+			if isEOF {
+				return Token{}, ErrUnexpectedEOF
+			}
+			switch ch := d.in[0]; ch {
+			case '{', '<':
+				d.pushOpenStack(ch)
+				return d.consumeToken(MessageOpen, 1, 0), nil
+			default:
+				return d.parseScalar()
+			}
+		}
+	}
+
+	line, column := d.Position(len(d.orig) - len(d.in))
+	panic(fmt.Sprintf("Decoder.parseNext: bug at handling line %d:%d with lastKind=%v", line, column, lastKind))
+}
+
+var otherCloseChar = map[byte]byte{
+	'}': '>',
+	'>': '}',
+}
+
+// currentOpenKind indicates whether current position is inside a message, list
+// or top-level message by returning MessageOpen, ListOpen or bof respectively.
+// If the returned kind is either a MessageOpen or ListOpen, it also returns the
+// corresponding closing character.
+func (d *Decoder) currentOpenKind() (Kind, byte) {
+	if len(d.openStack) == 0 {
+		return bof, 0
+	}
+	openCh := d.openStack[len(d.openStack)-1]
+	switch openCh {
+	case '{':
+		return MessageOpen, '}'
+	case '<':
+		return MessageOpen, '>'
+	case '[':
+		return ListOpen, ']'
+	}
+	panic(fmt.Sprintf("Decoder: openStack contains invalid byte %s", string(openCh)))
+}
+
+func (d *Decoder) pushOpenStack(ch byte) {
+	d.openStack = append(d.openStack, ch)
+}
+
+func (d *Decoder) popOpenStack() {
+	d.openStack = d.openStack[:len(d.openStack)-1]
+}
+
+// parseFieldName parses field name and separator.
+func (d *Decoder) parseFieldName() (tok Token, err error) {
+	defer func() {
+		if err == nil && d.tryConsumeChar(':') {
+			tok.attrs |= hasSeparator
+		}
+	}()
+
+	// Extension or Any type URL.
+	if d.in[0] == '[' {
+		return d.parseTypeName()
+	}
+
+	// Identifier.
+	if size := parseIdent(d.in, false); size > 0 {
+		return d.consumeToken(Name, size, uint8(IdentName)), nil
+	}
+
+	// Field number. Identify if input is a valid number that is not negative
+	// and is decimal integer within 32-bit range.
+	if num := parseNumber(d.in); num.size > 0 {
+		if !num.neg && num.kind == numDec {
+			if _, err := strconv.ParseInt(string(d.in[:num.size]), 10, 32); err == nil {
+				return d.consumeToken(Name, num.size, uint8(FieldNumber)), nil
+			}
+		}
+		return Token{}, d.newSyntaxError("invalid field number: %s", d.in[:num.size])
+	}
+
+	return Token{}, d.newSyntaxError("invalid field name: %s", errRegexp.Find(d.in))
+}
+
+// parseTypeName parses Any type URL or extension field name. The name is
+// enclosed in [ and ] characters. The C++ parser does not handle many legal URL
+// strings. This implementation is more liberal and allows for the pattern
+// ^[-_a-zA-Z0-9]+([./][-_a-zA-Z0-9]+)*`). Whitespaces and comments are allowed
+// in between [ ], '.', '/' and the sub names.
+func (d *Decoder) parseTypeName() (Token, error) {
+	startPos := len(d.orig) - len(d.in)
+	// Use alias s to advance first in order to use d.in for error handling.
+	// Caller already checks for [ as first character.
+	s := consume(d.in[1:], 0)
+	if len(s) == 0 {
+		return Token{}, ErrUnexpectedEOF
+	}
+
+	var name []byte
+	for len(s) > 0 && isTypeNameChar(s[0]) {
+		name = append(name, s[0])
+		s = s[1:]
+	}
+	s = consume(s, 0)
+
+	var closed bool
+	for len(s) > 0 && !closed {
+		switch {
+		case s[0] == ']':
+			s = s[1:]
+			closed = true
+
+		case s[0] == '/', s[0] == '.':
+			if len(name) > 0 && (name[len(name)-1] == '/' || name[len(name)-1] == '.') {
+				return Token{}, d.newSyntaxError("invalid type URL/extension field name: %s",
+					d.orig[startPos:len(d.orig)-len(s)+1])
+			}
+			name = append(name, s[0])
+			s = s[1:]
+			s = consume(s, 0)
+			for len(s) > 0 && isTypeNameChar(s[0]) {
+				name = append(name, s[0])
+				s = s[1:]
+			}
+			s = consume(s, 0)
+
+		default:
+			return Token{}, d.newSyntaxError(
+				"invalid type URL/extension field name: %s", d.orig[startPos:len(d.orig)-len(s)+1])
+		}
+	}
+
+	if !closed {
+		return Token{}, ErrUnexpectedEOF
+	}
+
+	// First character cannot be '.'. Last character cannot be '.' or '/'.
+	size := len(name)
+	if size == 0 || name[0] == '.' || name[size-1] == '.' || name[size-1] == '/' {
+		return Token{}, d.newSyntaxError("invalid type URL/extension field name: %s",
+			d.orig[startPos:len(d.orig)-len(s)])
+	}
+
+	d.in = s
+	endPos := len(d.orig) - len(d.in)
+	d.consume(0)
+
+	return Token{
+		kind:  Name,
+		attrs: uint8(TypeName),
+		pos:   startPos,
+		raw:   d.orig[startPos:endPos],
+		str:   string(name),
+	}, nil
+}
+
+func isTypeNameChar(b byte) bool {
+	return (b == '-' || b == '_' ||
+		('0' <= b && b <= '9') ||
+		('a' <= b && b <= 'z') ||
+		('A' <= b && b <= 'Z'))
+}
+
+func isWhiteSpace(b byte) bool {
+	switch b {
+	case ' ', '\n', '\r', '\t':
+		return true
+	default:
+		return false
+	}
+}
+
+// parseIdent parses an unquoted proto identifier and returns size.
+// If allowNeg is true, it allows '-' to be the first character in the
+// identifier. This is used when parsing literal values like -infinity, etc.
+// Regular expression matches an identifier: `^[_a-zA-Z][_a-zA-Z0-9]*`
+func parseIdent(input []byte, allowNeg bool) int {
+	var size int
+
+	s := input
+	if len(s) == 0 {
+		return 0
+	}
+
+	if allowNeg && s[0] == '-' {
+		s = s[1:]
+		size++
+		if len(s) == 0 {
+			return 0
+		}
+	}
+
+	switch {
+	case s[0] == '_',
+		'a' <= s[0] && s[0] <= 'z',
+		'A' <= s[0] && s[0] <= 'Z':
+		s = s[1:]
+		size++
+	default:
+		return 0
+	}
+
+	for len(s) > 0 && (s[0] == '_' ||
+		'a' <= s[0] && s[0] <= 'z' ||
+		'A' <= s[0] && s[0] <= 'Z' ||
+		'0' <= s[0] && s[0] <= '9') {
+		s = s[1:]
+		size++
+	}
+
+	if len(s) > 0 && !isDelim(s[0]) {
+		return 0
+	}
+
+	return size
+}
+
+// parseScalar parses for a string, literal or number value.
+func (d *Decoder) parseScalar() (Token, error) {
+	if d.in[0] == '"' || d.in[0] == '\'' {
+		return d.parseStringValue()
+	}
+
+	if tok, ok := d.parseLiteralValue(); ok {
+		return tok, nil
+	}
+
+	if tok, ok := d.parseNumberValue(); ok {
+		return tok, nil
+	}
+
+	return Token{}, d.newSyntaxError("invalid scalar value: %s", errRegexp.Find(d.in))
+}
+
+// parseLiteralValue parses a literal value. A literal value is used for
+// bools, special floats and enums. This function simply identifies that the
+// field value is a literal.
+func (d *Decoder) parseLiteralValue() (Token, bool) {
+	size := parseIdent(d.in, true)
+	if size == 0 {
+		return Token{}, false
+	}
+	return d.consumeToken(Scalar, size, literalValue), true
+}
+
+// consumeToken constructs a Token for given Kind from d.in and consumes given
+// size-length from it.
+func (d *Decoder) consumeToken(kind Kind, size int, attrs uint8) Token {
+	// Important to compute raw and pos before consuming.
+	tok := Token{
+		kind:  kind,
+		attrs: attrs,
+		pos:   len(d.orig) - len(d.in),
+		raw:   d.in[:size],
+	}
+	d.consume(size)
+	return tok
+}
+
+// newSyntaxError returns a syntax error with line and column information for
+// current position.
+func (d *Decoder) newSyntaxError(f string, x ...interface{}) error {
+	e := errors.New(f, x...)
+	line, column := d.Position(len(d.orig) - len(d.in))
+	return errors.New("syntax error (line %d:%d): %v", line, column, e)
+}
+
+// Position returns line and column number of given index of the original input.
+// It will panic if index is out of range.
+func (d *Decoder) Position(idx int) (line int, column int) {
+	b := d.orig[:idx]
+	line = bytes.Count(b, []byte("\n")) + 1
+	if i := bytes.LastIndexByte(b, '\n'); i >= 0 {
+		b = b[i+1:]
+	}
+	column = utf8.RuneCount(b) + 1 // ignore multi-rune characters
+	return line, column
+}
+
+func (d *Decoder) tryConsumeChar(c byte) bool {
+	if len(d.in) > 0 && d.in[0] == c {
+		d.consume(1)
+		return true
+	}
+	return false
+}
+
+// consume consumes n bytes of input and any subsequent whitespace or comments.
+func (d *Decoder) consume(n int) {
+	d.in = consume(d.in, n)
+	return
+}
+
+// consume consumes n bytes of input and any subsequent whitespace or comments.
+func consume(b []byte, n int) []byte {
+	b = b[n:]
+	for len(b) > 0 {
+		switch b[0] {
+		case ' ', '\n', '\r', '\t':
+			b = b[1:]
+		case '#':
+			if i := bytes.IndexByte(b, '\n'); i >= 0 {
+				b = b[i+len("\n"):]
+			} else {
+				b = nil
+			}
+		default:
+			return b
+		}
+	}
+	return b
+}
+
+// Any sequence that looks like a non-delimiter (for error reporting).
+var errRegexp = regexp.MustCompile(`^([-+._a-zA-Z0-9\/]+|.)`)
+
+// isDelim returns true if given byte is a delimiter character.
+func isDelim(c byte) bool {
+	return !(c == '-' || c == '+' || c == '.' || c == '_' ||
+		('a' <= c && c <= 'z') ||
+		('A' <= c && c <= 'Z') ||
+		('0' <= c && c <= '9'))
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/decode_number.go b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_number.go
new file mode 100644
index 00000000..f2d90b78
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_number.go
@@ -0,0 +1,190 @@
+// Copyright 2018 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 text
+
+// parseNumberValue parses a number from the input and returns a Token object.
+func (d *Decoder) parseNumberValue() (Token, bool) {
+	in := d.in
+	num := parseNumber(in)
+	if num.size == 0 {
+		return Token{}, false
+	}
+	numAttrs := num.kind
+	if num.neg {
+		numAttrs |= isNegative
+	}
+	strSize := num.size
+	last := num.size - 1
+	if num.kind == numFloat && (d.in[last] == 'f' || d.in[last] == 'F') {
+		strSize = last
+	}
+	tok := Token{
+		kind:     Scalar,
+		attrs:    numberValue,
+		pos:      len(d.orig) - len(d.in),
+		raw:      d.in[:num.size],
+		str:      string(d.in[:strSize]),
+		numAttrs: numAttrs,
+	}
+	d.consume(num.size)
+	return tok, true
+}
+
+const (
+	numDec uint8 = (1 << iota) / 2
+	numHex
+	numOct
+	numFloat
+)
+
+// number is the result of parsing out a valid number from parseNumber. It
+// contains data for doing float or integer conversion via the strconv package
+// in conjunction with the input bytes.
+type number struct {
+	kind uint8
+	neg  bool
+	size int
+}
+
+// parseNumber constructs a number object from given input. It allows for the
+// following patterns:
+//   integer: ^-?([1-9][0-9]*|0[xX][0-9a-fA-F]+|0[0-7]*)
+//   float: ^-?((0|[1-9][0-9]*)?([.][0-9]*)?([eE][+-]?[0-9]+)?[fF]?)
+// It also returns the number of parsed bytes for the given number, 0 if it is
+// not a number.
+func parseNumber(input []byte) number {
+	kind := numDec
+	var size int
+	var neg bool
+
+	s := input
+	if len(s) == 0 {
+		return number{}
+	}
+
+	// Optional -
+	if s[0] == '-' {
+		neg = true
+		s = s[1:]
+		size++
+		if len(s) == 0 {
+			return number{}
+		}
+	}
+
+	// C++ allows for whitespace and comments in between the negative sign and
+	// the rest of the number. This logic currently does not but is consistent
+	// with v1.
+
+	switch {
+	case s[0] == '0':
+		if len(s) > 1 {
+			switch {
+			case s[1] == 'x' || s[1] == 'X':
+				// Parse as hex number.
+				kind = numHex
+				n := 2
+				s = s[2:]
+				for len(s) > 0 && (('0' <= s[0] && s[0] <= '9') ||
+					('a' <= s[0] && s[0] <= 'f') ||
+					('A' <= s[0] && s[0] <= 'F')) {
+					s = s[1:]
+					n++
+				}
+				if n == 2 {
+					return number{}
+				}
+				size += n
+
+			case '0' <= s[1] && s[1] <= '7':
+				// Parse as octal number.
+				kind = numOct
+				n := 2
+				s = s[2:]
+				for len(s) > 0 && '0' <= s[0] && s[0] <= '7' {
+					s = s[1:]
+					n++
+				}
+				size += n
+			}
+
+			if kind&(numHex|numOct) > 0 {
+				if len(s) > 0 && !isDelim(s[0]) {
+					return number{}
+				}
+				return number{kind: kind, neg: neg, size: size}
+			}
+		}
+		s = s[1:]
+		size++
+
+	case '1' <= s[0] && s[0] <= '9':
+		n := 1
+		s = s[1:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+
+	case s[0] == '.':
+		// Set kind to numFloat to signify the intent to parse as float. And
+		// that it needs to have other digits after '.'.
+		kind = numFloat
+
+	default:
+		return number{}
+	}
+
+	// . followed by 0 or more digits.
+	if len(s) > 0 && s[0] == '.' {
+		n := 1
+		s = s[1:]
+		// If decimal point was before any digits, it should be followed by
+		// other digits.
+		if len(s) == 0 && kind == numFloat {
+			return number{}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+		kind = numFloat
+	}
+
+	// e or E followed by an optional - or + and 1 or more digits.
+	if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
+		kind = numFloat
+		s = s[1:]
+		n := 1
+		if s[0] == '+' || s[0] == '-' {
+			s = s[1:]
+			n++
+			if len(s) == 0 {
+				return number{}
+			}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+	}
+
+	// Optional suffix f or F for floats.
+	if len(s) > 0 && (s[0] == 'f' || s[0] == 'F') {
+		kind = numFloat
+		s = s[1:]
+		size++
+	}
+
+	// Check that next byte is a delimiter or it is at the end.
+	if len(s) > 0 && !isDelim(s[0]) {
+		return number{}
+	}
+
+	return number{kind: kind, neg: neg, size: size}
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/decode_string.go b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_string.go
new file mode 100644
index 00000000..d4d34902
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_string.go
@@ -0,0 +1,161 @@
+// Copyright 2018 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 text
+
+import (
+	"bytes"
+	"strconv"
+	"strings"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/internal/strs"
+)
+
+// parseStringValue parses string field token.
+// This differs from parseString since the text format allows
+// multiple back-to-back string literals where they are semantically treated
+// as a single large string with all values concatenated.
+//
+// E.g., `"foo" "bar" "baz"` => "foobarbaz"
+func (d *Decoder) parseStringValue() (Token, error) {
+	// Note that the ending quote is sufficient to unambiguously mark the end
+	// of a string. Thus, the text grammar does not require intervening
+	// whitespace or control characters in-between strings.
+	// Thus, the following is valid:
+	//	`"foo"'bar'"baz"` => "foobarbaz"
+	in0 := d.in
+	var ss []string
+	for len(d.in) > 0 && (d.in[0] == '"' || d.in[0] == '\'') {
+		s, err := d.parseString()
+		if err != nil {
+			return Token{}, err
+		}
+		ss = append(ss, s)
+	}
+	// d.in already points to the end of the value at this point.
+	return Token{
+		kind:  Scalar,
+		attrs: stringValue,
+		pos:   len(d.orig) - len(in0),
+		raw:   in0[:len(in0)-len(d.in)],
+		str:   strings.Join(ss, ""),
+	}, nil
+}
+
+// parseString parses a string value enclosed in " or '.
+func (d *Decoder) parseString() (string, error) {
+	in := d.in
+	if len(in) == 0 {
+		return "", ErrUnexpectedEOF
+	}
+	quote := in[0]
+	in = in[1:]
+	i := indexNeedEscapeInBytes(in)
+	in, out := in[i:], in[:i:i] // set cap to prevent mutations
+	for len(in) > 0 {
+		switch r, n := utf8.DecodeRune(in); {
+		case r == utf8.RuneError && n == 1:
+			return "", d.newSyntaxError("invalid UTF-8 detected")
+		case r == 0 || r == '\n':
+			return "", d.newSyntaxError("invalid character %q in string", r)
+		case r == rune(quote):
+			in = in[1:]
+			d.consume(len(d.in) - len(in))
+			return string(out), nil
+		case r == '\\':
+			if len(in) < 2 {
+				return "", ErrUnexpectedEOF
+			}
+			switch r := in[1]; r {
+			case '"', '\'', '\\', '?':
+				in, out = in[2:], append(out, r)
+			case 'a':
+				in, out = in[2:], append(out, '\a')
+			case 'b':
+				in, out = in[2:], append(out, '\b')
+			case 'n':
+				in, out = in[2:], append(out, '\n')
+			case 'r':
+				in, out = in[2:], append(out, '\r')
+			case 't':
+				in, out = in[2:], append(out, '\t')
+			case 'v':
+				in, out = in[2:], append(out, '\v')
+			case 'f':
+				in, out = in[2:], append(out, '\f')
+			case '0', '1', '2', '3', '4', '5', '6', '7':
+				// One, two, or three octal characters.
+				n := len(in[1:]) - len(bytes.TrimLeft(in[1:], "01234567"))
+				if n > 3 {
+					n = 3
+				}
+				v, err := strconv.ParseUint(string(in[1:1+n]), 8, 8)
+				if err != nil {
+					return "", d.newSyntaxError("invalid octal escape code %q in string", in[:1+n])
+				}
+				in, out = in[1+n:], append(out, byte(v))
+			case 'x':
+				// One or two hexadecimal characters.
+				n := len(in[2:]) - len(bytes.TrimLeft(in[2:], "0123456789abcdefABCDEF"))
+				if n > 2 {
+					n = 2
+				}
+				v, err := strconv.ParseUint(string(in[2:2+n]), 16, 8)
+				if err != nil {
+					return "", d.newSyntaxError("invalid hex escape code %q in string", in[:2+n])
+				}
+				in, out = in[2+n:], append(out, byte(v))
+			case 'u', 'U':
+				// Four or eight hexadecimal characters
+				n := 6
+				if r == 'U' {
+					n = 10
+				}
+				if len(in) < n {
+					return "", ErrUnexpectedEOF
+				}
+				v, err := strconv.ParseUint(string(in[2:n]), 16, 32)
+				if utf8.MaxRune < v || err != nil {
+					return "", d.newSyntaxError("invalid Unicode escape code %q in string", in[:n])
+				}
+				in = in[n:]
+
+				r := rune(v)
+				if utf16.IsSurrogate(r) {
+					if len(in) < 6 {
+						return "", ErrUnexpectedEOF
+					}
+					v, err := strconv.ParseUint(string(in[2:6]), 16, 16)
+					r = utf16.DecodeRune(r, rune(v))
+					if in[0] != '\\' || in[1] != 'u' || r == unicode.ReplacementChar || err != nil {
+						return "", d.newSyntaxError("invalid Unicode escape code %q in string", in[:6])
+					}
+					in = in[6:]
+				}
+				out = append(out, string(r)...)
+			default:
+				return "", d.newSyntaxError("invalid escape code %q in string", in[:2])
+			}
+		default:
+			i := indexNeedEscapeInBytes(in[n:])
+			in, out = in[n+i:], append(out, in[:n+i]...)
+		}
+	}
+	return "", ErrUnexpectedEOF
+}
+
+// indexNeedEscapeInString returns the index of the character that needs
+// escaping. If no characters need escaping, this returns the input length.
+func indexNeedEscapeInBytes(b []byte) int { return indexNeedEscapeInString(strs.UnsafeString(b)) }
+
+// UnmarshalString returns an unescaped string given a textproto string value.
+// String value needs to contain single or double quotes. This is only used by
+// internal/encoding/defval package for unmarshaling bytes.
+func UnmarshalString(s string) (string, error) {
+	d := NewDecoder([]byte(s))
+	return d.parseString()
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/decode_token.go b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_token.go
new file mode 100644
index 00000000..83d2b0d5
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_token.go
@@ -0,0 +1,373 @@
+// Copyright 2018 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 text
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+
+	"google.golang.org/protobuf/internal/flags"
+)
+
+// Kind represents a token kind expressible in the textproto format.
+type Kind uint8
+
+// Kind values.
+const (
+	Invalid Kind = iota
+	EOF
+	Name   // Name indicates the field name.
+	Scalar // Scalar are scalar values, e.g. "string", 47, ENUM_LITERAL, true.
+	MessageOpen
+	MessageClose
+	ListOpen
+	ListClose
+
+	// comma and semi-colon are only for parsing in between values and should not be exposed.
+	comma
+	semicolon
+
+	// bof indicates beginning of file, which is the default token
+	// kind at the beginning of parsing.
+	bof = Invalid
+)
+
+func (t Kind) String() string {
+	switch t {
+	case Invalid:
+		return "<invalid>"
+	case EOF:
+		return "eof"
+	case Scalar:
+		return "scalar"
+	case Name:
+		return "name"
+	case MessageOpen:
+		return "{"
+	case MessageClose:
+		return "}"
+	case ListOpen:
+		return "["
+	case ListClose:
+		return "]"
+	case comma:
+		return ","
+	case semicolon:
+		return ";"
+	default:
+		return fmt.Sprintf("<invalid:%v>", uint8(t))
+	}
+}
+
+// NameKind represents different types of field names.
+type NameKind uint8
+
+// NameKind values.
+const (
+	IdentName NameKind = iota + 1
+	TypeName
+	FieldNumber
+)
+
+func (t NameKind) String() string {
+	switch t {
+	case IdentName:
+		return "IdentName"
+	case TypeName:
+		return "TypeName"
+	case FieldNumber:
+		return "FieldNumber"
+	default:
+		return fmt.Sprintf("<invalid:%v>", uint8(t))
+	}
+}
+
+// Bit mask in Token.attrs to indicate if a Name token is followed by the
+// separator char ':'. The field name separator char is optional for message
+// field or repeated message field, but required for all other types. Decoder
+// simply indicates whether a Name token is followed by separator or not.  It is
+// up to the prototext package to validate.
+const hasSeparator = 1 << 7
+
+// Scalar value types.
+const (
+	numberValue = iota + 1
+	stringValue
+	literalValue
+)
+
+// Bit mask in Token.numAttrs to indicate that the number is a negative.
+const isNegative = 1 << 7
+
+// Token provides a parsed token kind and value. Values are provided by the
+// different accessor methods.
+type Token struct {
+	// Kind of the Token object.
+	kind Kind
+	// attrs contains metadata for the following Kinds:
+	// Name: hasSeparator bit and one of NameKind.
+	// Scalar: one of numberValue, stringValue, literalValue.
+	attrs uint8
+	// numAttrs contains metadata for numberValue:
+	// - highest bit is whether negative or positive.
+	// - lower bits indicate one of numDec, numHex, numOct, numFloat.
+	numAttrs uint8
+	// pos provides the position of the token in the original input.
+	pos int
+	// raw bytes of the serialized token.
+	// This is a subslice into the original input.
+	raw []byte
+	// str contains parsed string for the following:
+	// - stringValue of Scalar kind
+	// - numberValue of Scalar kind
+	// - TypeName of Name kind
+	str string
+}
+
+// Kind returns the token kind.
+func (t Token) Kind() Kind {
+	return t.kind
+}
+
+// RawString returns the read value in string.
+func (t Token) RawString() string {
+	return string(t.raw)
+}
+
+// Pos returns the token position from the input.
+func (t Token) Pos() int {
+	return t.pos
+}
+
+// NameKind returns IdentName, TypeName or FieldNumber.
+// It panics if type is not Name.
+func (t Token) NameKind() NameKind {
+	if t.kind == Name {
+		return NameKind(t.attrs &^ hasSeparator)
+	}
+	panic(fmt.Sprintf("Token is not a Name type: %s", t.kind))
+}
+
+// HasSeparator returns true if the field name is followed by the separator char
+// ':', else false. It panics if type is not Name.
+func (t Token) HasSeparator() bool {
+	if t.kind == Name {
+		return t.attrs&hasSeparator != 0
+	}
+	panic(fmt.Sprintf("Token is not a Name type: %s", t.kind))
+}
+
+// IdentName returns the value for IdentName type.
+func (t Token) IdentName() string {
+	if t.kind == Name && t.attrs&uint8(IdentName) != 0 {
+		return string(t.raw)
+	}
+	panic(fmt.Sprintf("Token is not an IdentName: %s:%s", t.kind, NameKind(t.attrs&^hasSeparator)))
+}
+
+// TypeName returns the value for TypeName type.
+func (t Token) TypeName() string {
+	if t.kind == Name && t.attrs&uint8(TypeName) != 0 {
+		return t.str
+	}
+	panic(fmt.Sprintf("Token is not a TypeName: %s:%s", t.kind, NameKind(t.attrs&^hasSeparator)))
+}
+
+// FieldNumber returns the value for FieldNumber type. It returns a
+// non-negative int32 value. Caller will still need to validate for the correct
+// field number range.
+func (t Token) FieldNumber() int32 {
+	if t.kind != Name || t.attrs&uint8(FieldNumber) == 0 {
+		panic(fmt.Sprintf("Token is not a FieldNumber: %s:%s", t.kind, NameKind(t.attrs&^hasSeparator)))
+	}
+	// Following should not return an error as it had already been called right
+	// before this Token was constructed.
+	num, _ := strconv.ParseInt(string(t.raw), 10, 32)
+	return int32(num)
+}
+
+// String returns the string value for a Scalar type.
+func (t Token) String() (string, bool) {
+	if t.kind != Scalar || t.attrs != stringValue {
+		return "", false
+	}
+	return t.str, true
+}
+
+// Enum returns the literal value for a Scalar type for use as enum literals.
+func (t Token) Enum() (string, bool) {
+	if t.kind != Scalar || t.attrs != literalValue || (len(t.raw) > 0 && t.raw[0] == '-') {
+		return "", false
+	}
+	return string(t.raw), true
+}
+
+// Bool returns the bool value for a Scalar type.
+func (t Token) Bool() (bool, bool) {
+	if t.kind != Scalar {
+		return false, false
+	}
+	switch t.attrs {
+	case literalValue:
+		if b, ok := boolLits[string(t.raw)]; ok {
+			return b, true
+		}
+	case numberValue:
+		// Unsigned integer representation of 0 or 1 is permitted: 00, 0x0, 01,
+		// 0x1, etc.
+		n, err := strconv.ParseUint(t.str, 0, 64)
+		if err == nil {
+			switch n {
+			case 0:
+				return false, true
+			case 1:
+				return true, true
+			}
+		}
+	}
+	return false, false
+}
+
+// These exact boolean literals are the ones supported in C++.
+var boolLits = map[string]bool{
+	"t":     true,
+	"true":  true,
+	"True":  true,
+	"f":     false,
+	"false": false,
+	"False": false,
+}
+
+// Uint64 returns the uint64 value for a Scalar type.
+func (t Token) Uint64() (uint64, bool) {
+	if t.kind != Scalar || t.attrs != numberValue ||
+		t.numAttrs&isNegative > 0 || t.numAttrs&numFloat > 0 {
+		return 0, false
+	}
+	n, err := strconv.ParseUint(t.str, 0, 64)
+	if err != nil {
+		return 0, false
+	}
+	return n, true
+}
+
+// Uint32 returns the uint32 value for a Scalar type.
+func (t Token) Uint32() (uint32, bool) {
+	if t.kind != Scalar || t.attrs != numberValue ||
+		t.numAttrs&isNegative > 0 || t.numAttrs&numFloat > 0 {
+		return 0, false
+	}
+	n, err := strconv.ParseUint(t.str, 0, 32)
+	if err != nil {
+		return 0, false
+	}
+	return uint32(n), true
+}
+
+// Int64 returns the int64 value for a Scalar type.
+func (t Token) Int64() (int64, bool) {
+	if t.kind != Scalar || t.attrs != numberValue || t.numAttrs&numFloat > 0 {
+		return 0, false
+	}
+	if n, err := strconv.ParseInt(t.str, 0, 64); err == nil {
+		return n, true
+	}
+	// C++ accepts large positive hex numbers as negative values.
+	// This feature is here for proto1 backwards compatibility purposes.
+	if flags.ProtoLegacy && (t.numAttrs == numHex) {
+		if n, err := strconv.ParseUint(t.str, 0, 64); err == nil {
+			return int64(n), true
+		}
+	}
+	return 0, false
+}
+
+// Int32 returns the int32 value for a Scalar type.
+func (t Token) Int32() (int32, bool) {
+	if t.kind != Scalar || t.attrs != numberValue || t.numAttrs&numFloat > 0 {
+		return 0, false
+	}
+	if n, err := strconv.ParseInt(t.str, 0, 32); err == nil {
+		return int32(n), true
+	}
+	// C++ accepts large positive hex numbers as negative values.
+	// This feature is here for proto1 backwards compatibility purposes.
+	if flags.ProtoLegacy && (t.numAttrs == numHex) {
+		if n, err := strconv.ParseUint(t.str, 0, 32); err == nil {
+			return int32(n), true
+		}
+	}
+	return 0, false
+}
+
+// Float64 returns the float64 value for a Scalar type.
+func (t Token) Float64() (float64, bool) {
+	if t.kind != Scalar {
+		return 0, false
+	}
+	switch t.attrs {
+	case literalValue:
+		if f, ok := floatLits[strings.ToLower(string(t.raw))]; ok {
+			return f, true
+		}
+	case numberValue:
+		n, err := strconv.ParseFloat(t.str, 64)
+		if err == nil {
+			return n, true
+		}
+		nerr := err.(*strconv.NumError)
+		if nerr.Err == strconv.ErrRange {
+			return n, true
+		}
+	}
+	return 0, false
+}
+
+// Float32 returns the float32 value for a Scalar type.
+func (t Token) Float32() (float32, bool) {
+	if t.kind != Scalar {
+		return 0, false
+	}
+	switch t.attrs {
+	case literalValue:
+		if f, ok := floatLits[strings.ToLower(string(t.raw))]; ok {
+			return float32(f), true
+		}
+	case numberValue:
+		n, err := strconv.ParseFloat(t.str, 64)
+		if err == nil {
+			// Overflows are treated as (-)infinity.
+			return float32(n), true
+		}
+		nerr := err.(*strconv.NumError)
+		if nerr.Err == strconv.ErrRange {
+			return float32(n), true
+		}
+	}
+	return 0, false
+}
+
+// These are the supported float literals which C++ permits case-insensitive
+// variants of these.
+var floatLits = map[string]float64{
+	"nan":       math.NaN(),
+	"inf":       math.Inf(1),
+	"infinity":  math.Inf(1),
+	"-inf":      math.Inf(-1),
+	"-infinity": math.Inf(-1),
+}
+
+// TokenEquals returns true if given Tokens are equal, else false.
+func TokenEquals(x, y Token) bool {
+	return x.kind == y.kind &&
+		x.attrs == y.attrs &&
+		x.numAttrs == y.numAttrs &&
+		x.pos == y.pos &&
+		bytes.Equal(x.raw, y.raw) &&
+		x.str == y.str
+}
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/doc.go b/vendor/google.golang.org/protobuf/internal/encoding/text/doc.go
new file mode 100644
index 00000000..0ce8d6fb
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/doc.go
@@ -0,0 +1,29 @@
+// Copyright 2018 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 text implements the text format for protocol buffers.
+// This package has no semantic understanding for protocol buffers and is only
+// a parser and composer for the format.
+//
+// There is no formal specification for the protobuf text format, as such the
+// C++ implementation (see google::protobuf::TextFormat) is the reference
+// implementation of the text format.
+//
+// This package is neither a superset nor a subset of the C++ implementation.
+// This implementation permits a more liberal grammar in some cases to be
+// backwards compatible with the historical Go implementation.
+// Future parsings unique to Go should not be added.
+// Some grammars allowed by the C++ implementation are deliberately
+// not implemented here because they are considered a bug by the protobuf team
+// and should not be replicated.
+//
+// The Go implementation should implement a sufficient amount of the C++
+// grammar such that the default text serialization by C++ can be parsed by Go.
+// However, just because the C++ parser accepts some input does not mean that
+// the Go implementation should as well.
+//
+// The text format is almost a superset of JSON except:
+//	* message keys are not quoted strings, but identifiers
+//	* the top-level value must be a message without the delimiters
+package text
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/text/encode.go b/vendor/google.golang.org/protobuf/internal/encoding/text/encode.go
new file mode 100644
index 00000000..c4ba1c59
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/encode.go
@@ -0,0 +1,267 @@
+// Copyright 2018 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 text
+
+import (
+	"math"
+	"math/bits"
+	"strconv"
+	"strings"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/internal/detrand"
+	"google.golang.org/protobuf/internal/errors"
+)
+
+// encType represents an encoding type.
+type encType uint8
+
+const (
+	_ encType = (1 << iota) / 2
+	name
+	scalar
+	messageOpen
+	messageClose
+)
+
+// Encoder provides methods to write out textproto constructs and values. The user is
+// responsible for producing valid sequences of constructs and values.
+type Encoder struct {
+	encoderState
+
+	indent      string
+	newline     string // set to "\n" if len(indent) > 0
+	delims      [2]byte
+	outputASCII bool
+}
+
+type encoderState struct {
+	lastType encType
+	indents  []byte
+	out      []byte
+}
+
+// NewEncoder returns an Encoder.
+//
+// If indent is a non-empty string, it causes every entry in a List or Message
+// to be preceded by the indent and trailed by a newline.
+//
+// If delims is not the zero value, it controls the delimiter characters used
+// for messages (e.g., "{}" vs "<>").
+//
+// If outputASCII is true, strings will be serialized in such a way that
+// multi-byte UTF-8 sequences are escaped. This property ensures that the
+// overall output is ASCII (as opposed to UTF-8).
+func NewEncoder(indent string, delims [2]byte, outputASCII bool) (*Encoder, error) {
+	e := &Encoder{}
+	if len(indent) > 0 {
+		if strings.Trim(indent, " \t") != "" {
+			return nil, errors.New("indent may only be composed of space and tab characters")
+		}
+		e.indent = indent
+		e.newline = "\n"
+	}
+	switch delims {
+	case [2]byte{0, 0}:
+		e.delims = [2]byte{'{', '}'}
+	case [2]byte{'{', '}'}, [2]byte{'<', '>'}:
+		e.delims = delims
+	default:
+		return nil, errors.New("delimiters may only be \"{}\" or \"<>\"")
+	}
+	e.outputASCII = outputASCII
+
+	return e, nil
+}
+
+// Bytes returns the content of the written bytes.
+func (e *Encoder) Bytes() []byte {
+	return e.out
+}
+
+// StartMessage writes out the '{' or '<' symbol.
+func (e *Encoder) StartMessage() {
+	e.prepareNext(messageOpen)
+	e.out = append(e.out, e.delims[0])
+}
+
+// EndMessage writes out the '}' or '>' symbol.
+func (e *Encoder) EndMessage() {
+	e.prepareNext(messageClose)
+	e.out = append(e.out, e.delims[1])
+}
+
+// WriteName writes out the field name and the separator ':'.
+func (e *Encoder) WriteName(s string) {
+	e.prepareNext(name)
+	e.out = append(e.out, s...)
+	e.out = append(e.out, ':')
+}
+
+// WriteBool writes out the given boolean value.
+func (e *Encoder) WriteBool(b bool) {
+	if b {
+		e.WriteLiteral("true")
+	} else {
+		e.WriteLiteral("false")
+	}
+}
+
+// WriteString writes out the given string value.
+func (e *Encoder) WriteString(s string) {
+	e.prepareNext(scalar)
+	e.out = appendString(e.out, s, e.outputASCII)
+}
+
+func appendString(out []byte, in string, outputASCII bool) []byte {
+	out = append(out, '"')
+	i := indexNeedEscapeInString(in)
+	in, out = in[i:], append(out, in[:i]...)
+	for len(in) > 0 {
+		switch r, n := utf8.DecodeRuneInString(in); {
+		case r == utf8.RuneError && n == 1:
+			// We do not report invalid UTF-8 because strings in the text format
+			// are used to represent both the proto string and bytes type.
+			r = rune(in[0])
+			fallthrough
+		case r < ' ' || r == '"' || r == '\\':
+			out = append(out, '\\')
+			switch r {
+			case '"', '\\':
+				out = append(out, byte(r))
+			case '\n':
+				out = append(out, 'n')
+			case '\r':
+				out = append(out, 'r')
+			case '\t':
+				out = append(out, 't')
+			default:
+				out = append(out, 'x')
+				out = append(out, "00"[1+(bits.Len32(uint32(r))-1)/4:]...)
+				out = strconv.AppendUint(out, uint64(r), 16)
+			}
+			in = in[n:]
+		case outputASCII && r >= utf8.RuneSelf:
+			out = append(out, '\\')
+			if r <= math.MaxUint16 {
+				out = append(out, 'u')
+				out = append(out, "0000"[1+(bits.Len32(uint32(r))-1)/4:]...)
+				out = strconv.AppendUint(out, uint64(r), 16)
+			} else {
+				out = append(out, 'U')
+				out = append(out, "00000000"[1+(bits.Len32(uint32(r))-1)/4:]...)
+				out = strconv.AppendUint(out, uint64(r), 16)
+			}
+			in = in[n:]
+		default:
+			i := indexNeedEscapeInString(in[n:])
+			in, out = in[n+i:], append(out, in[:n+i]...)
+		}
+	}
+	out = append(out, '"')
+	return out
+}
+
+// indexNeedEscapeInString returns the index of the character that needs
+// escaping. If no characters need escaping, this returns the input length.
+func indexNeedEscapeInString(s string) int {
+	for i := 0; i < len(s); i++ {
+		if c := s[i]; c < ' ' || c == '"' || c == '\'' || c == '\\' || c >= utf8.RuneSelf {
+			return i
+		}
+	}
+	return len(s)
+}
+
+// WriteFloat writes out the given float value for given bitSize.
+func (e *Encoder) WriteFloat(n float64, bitSize int) {
+	e.prepareNext(scalar)
+	e.out = appendFloat(e.out, n, bitSize)
+}
+
+func appendFloat(out []byte, n float64, bitSize int) []byte {
+	switch {
+	case math.IsNaN(n):
+		return append(out, "nan"...)
+	case math.IsInf(n, +1):
+		return append(out, "inf"...)
+	case math.IsInf(n, -1):
+		return append(out, "-inf"...)
+	default:
+		return strconv.AppendFloat(out, n, 'g', -1, bitSize)
+	}
+}
+
+// WriteInt writes out the given signed integer value.
+func (e *Encoder) WriteInt(n int64) {
+	e.prepareNext(scalar)
+	e.out = append(e.out, strconv.FormatInt(n, 10)...)
+}
+
+// WriteUint writes out the given unsigned integer value.
+func (e *Encoder) WriteUint(n uint64) {
+	e.prepareNext(scalar)
+	e.out = append(e.out, strconv.FormatUint(n, 10)...)
+}
+
+// WriteLiteral writes out the given string as a literal value without quotes.
+// This is used for writing enum literal strings.
+func (e *Encoder) WriteLiteral(s string) {
+	e.prepareNext(scalar)
+	e.out = append(e.out, s...)
+}
+
+// prepareNext adds possible space and indentation for the next value based
+// on last encType and indent option. It also updates e.lastType to next.
+func (e *Encoder) prepareNext(next encType) {
+	defer func() {
+		e.lastType = next
+	}()
+
+	// Single line.
+	if len(e.indent) == 0 {
+		// Add space after each field before the next one.
+		if e.lastType&(scalar|messageClose) != 0 && next == name {
+			e.out = append(e.out, ' ')
+			// Add a random extra space to make output unstable.
+			if detrand.Bool() {
+				e.out = append(e.out, ' ')
+			}
+		}
+		return
+	}
+
+	// Multi-line.
+	switch {
+	case e.lastType == name:
+		e.out = append(e.out, ' ')
+		// Add a random extra space after name: to make output unstable.
+		if detrand.Bool() {
+			e.out = append(e.out, ' ')
+		}
+
+	case e.lastType == messageOpen && next != messageClose:
+		e.indents = append(e.indents, e.indent...)
+		e.out = append(e.out, '\n')
+		e.out = append(e.out, e.indents...)
+
+	case e.lastType&(scalar|messageClose) != 0:
+		if next == messageClose {
+			e.indents = e.indents[:len(e.indents)-len(e.indent)]
+		}
+		e.out = append(e.out, '\n')
+		e.out = append(e.out, e.indents...)
+	}
+}
+
+// Snapshot returns the current snapshot for use in Reset.
+func (e *Encoder) Snapshot() encoderState {
+	return e.encoderState
+}
+
+// Reset resets the Encoder to the given encoderState from a Snapshot.
+func (e *Encoder) Reset(es encoderState) {
+	e.encoderState = es
+}