proto/text.go - third_party/golang/protobuf - Git at Google

 // Go support for Protocol Buffers - Google's data interchange format
 //
 // Copyright 2010 The Go Authors.  All rights reserved.
 // https://github.com/golang/protobuf
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
 // in the documentation and/or other materials provided with the
 // distribution.
 //     * Neither the name of Google Inc. nor the names of its
 // contributors may be used to endorse or promote products derived from
 // this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 package proto

 // Functions for writing the text protocol buffer format.

 import (
 	"bufio"
 	"bytes"
 	"encoding"
 	"errors"
 	"fmt"
 	"io"
 	"log"
 	"math"
 	"reflect"
 	"sort"
 	"strings"
 )

 var (
 	newline         = []byte("\n")
 	spaces          = []byte("                                        ")
 	gtNewline       = []byte(">\n")
 	endBraceNewline = []byte("}\n")
 	backslashN      = []byte{'\\', 'n'}
 	backslashR      = []byte{'\\', 'r'}
 	backslashT      = []byte{'\\', 't'}
 	backslashDQ     = []byte{'\\', '"'}
 	backslashBS     = []byte{'\\', '\\'}
 	posInf          = []byte("inf")
 	negInf          = []byte("-inf")
 	nan             = []byte("nan")
 )

 type writer interface {
 	io.Writer
 	WriteByte(byte) error
 }

 // textWriter is an io.Writer that tracks its indentation level.
 type textWriter struct {
 	ind      int
 	complete bool // if the current position is a complete line
 	compact  bool // whether to write out as a one-liner
 	w        writer
 }

 func (w *textWriter) WriteString(s string) (n int, err error) {
 	if !strings.Contains(s, "\n") {
 		if !w.compact && w.complete {
 			w.writeIndent()
 		}
 		w.complete = false
 		return io.WriteString(w.w, s)
 	}
 	// WriteString is typically called without newlines, so this
 	// codepath and its copy are rare.  We copy to avoid
 	// duplicating all of Write's logic here.
 	return w.Write([]byte(s))
 }

 func (w *textWriter) Write(p []byte) (n int, err error) {
 	newlines := bytes.Count(p, newline)
 	if newlines == 0 {
 		if !w.compact && w.complete {
 			w.writeIndent()
 		}
 		n, err = w.w.Write(p)
 		w.complete = false
 		return n, err
 	}

 	frags := bytes.SplitN(p, newline, newlines+1)
 	if w.compact {
 		for i, frag := range frags {
 			if i > 0 {
 				if err := w.w.WriteByte(' '); err != nil {
 					return n, err
 				}
 				n++
 			}
 			nn, err := w.w.Write(frag)
 			n += nn
 			if err != nil {
 				return n, err
 			}
 		}
 		return n, nil
 	}

 	for i, frag := range frags {
 		if w.complete {
 			w.writeIndent()
 		}
 		nn, err := w.w.Write(frag)
 		n += nn
 		if err != nil {
 			return n, err
 		}
 		if i+1 < len(frags) {
 			if err := w.w.WriteByte('\n'); err != nil {
 				return n, err
 			}
 			n++
 		}
 	}
 	w.complete = len(frags[len(frags)-1]) == 0
 	return n, nil
 }

 func (w *textWriter) WriteByte(c byte) error {
 	if w.compact && c == '\n' {
 		c = ' '
 	}
 	if !w.compact && w.complete {
 		w.writeIndent()
 	}
 	err := w.w.WriteByte(c)
 	w.complete = c == '\n'
 	return err
 }

 func (w *textWriter) indent() { w.ind++ }

 func (w *textWriter) unindent() {
 	if w.ind == 0 {
 		log.Print("proto: textWriter unindented too far")
 		return
 	}
 	w.ind--
 }

 func writeName(w *textWriter, props *Properties) error {
 	if _, err := w.WriteString(props.OrigName); err != nil {
 		return err
 	}
 	if props.Wire != "group" {
 		return w.WriteByte(':')
 	}
 	return nil
 }

 // raw is the interface satisfied by RawMessage.
 type raw interface {
 	Bytes() []byte
 }

 func requiresQuotes(u string) bool {
 	// When type URL contains any characters except [0-9A-Za-z./\-]*, it must be quoted.
 	for _, ch := range u {
 		switch {
 		case ch == '.' || ch == '/' || ch == '_':
 			continue
 		case '0' <= ch && ch <= '9':
 			continue
 		case 'A' <= ch && ch <= 'Z':
 			continue
 		case 'a' <= ch && ch <= 'z':
 			continue
 		default:
 			return true
 		}
 	}
 	return false
 }

 // isAny reports whether sv is a google.protobuf.Any message
 func isAny(sv reflect.Value) bool {
 	type wkt interface {
 		XXX_WellKnownType() string
 	}
 	t, ok := sv.Addr().Interface().(wkt)
 	return ok && t.XXX_WellKnownType() == "Any"
 }

 // writeProto3Any writes an expanded google.protobuf.Any message.
 //
 // It returns (false, nil) if sv value can't be unmarshaled (e.g. because
 // required messages are not linked in).
 //
 // It returns (true, error) when sv was written in expanded format or an error
 // was encountered.
 func (tm *TextMarshaler) writeProto3Any(w *textWriter, sv reflect.Value) (bool, error) {
 	turl := sv.FieldByName("TypeUrl")
 	val := sv.FieldByName("Value")
 	if !turl.IsValid() || !val.IsValid() {
 		return true, errors.New("proto: invalid google.protobuf.Any message")
 	}

 	b, ok := val.Interface().([]byte)
 	if !ok {
 		return true, errors.New("proto: invalid google.protobuf.Any message")
 	}

 	parts := strings.Split(turl.String(), "/")
 	mt := MessageType(parts[len(parts)-1])
 	if mt == nil {
 		return false, nil
 	}
 	m := reflect.New(mt.Elem())
 	if err := Unmarshal(b, m.Interface().(Message)); err != nil {
 		return false, nil
 	}
 	w.Write([]byte("["))
 	u := turl.String()
 	if requiresQuotes(u) {
 		writeString(w, u)
 	} else {
 		w.Write([]byte(u))
 	}
 	if w.compact {
 		w.Write([]byte("]:<"))
 	} else {
 		w.Write([]byte("]: <\n"))
 		w.ind++
 	}
 	if err := tm.writeStruct(w, m.Elem()); err != nil {
 		return true, err
 	}
 	if w.compact {
 		w.Write([]byte("> "))
 	} else {
 		w.ind--
 		w.Write([]byte(">\n"))
 	}
 	return true, nil
 }

 func (tm *TextMarshaler) writeStruct(w *textWriter, sv reflect.Value) error {
 	if tm.ExpandAny && isAny(sv) {
 		if canExpand, err := tm.writeProto3Any(w, sv); canExpand {
 			return err
 		}
 	}
 	st := sv.Type()
 	sprops := GetProperties(st)
 	for i := 0; i < sv.NumField(); i++ {
 		fv := sv.Field(i)
 		props := sprops.Prop[i]
 		name := st.Field(i).Name

 		if strings.HasPrefix(name, "XXX_") {
 			// There are two XXX_ fields:
 			//   XXX_unrecognized []byte
 			//   XXX_extensions   map[int32]proto.Extension
 			// The first is handled here;
 			// the second is handled at the bottom of this function.
 			if name == "XXX_unrecognized" && !fv.IsNil() {
 				if err := writeUnknownStruct(w, fv.Interface().([]byte)); err != nil {
 					return err
 				}
 			}
 			continue
 		}
 		if fv.Kind() == reflect.Ptr && fv.IsNil() {
 			// Field not filled in. This could be an optional field or
 			// a required field that wasn't filled in. Either way, there
 			// isn't anything we can show for it.
 			continue
 		}
 		if fv.Kind() == reflect.Slice && fv.IsNil() {
 			// Repeated field that is empty, or a bytes field that is unused.
 			continue
 		}

 		if props.Repeated && fv.Kind() == reflect.Slice {
 			// Repeated field.
 			for j := 0; j < fv.Len(); j++ {
 				if err := writeName(w, props); err != nil {
 					return err
 				}
 				if !w.compact {
 					if err := w.WriteByte(' '); err != nil {
 						return err
 					}
 				}
 				v := fv.Index(j)
 				if v.Kind() == reflect.Ptr && v.IsNil() {
 					// A nil message in a repeated field is not valid,
 					// but we can handle that more gracefully than panicking.
 					if _, err := w.Write([]byte("<nil>\n")); err != nil {
 						return err
 					}
 					continue
 				}
 				if err := tm.writeAny(w, v, props); err != nil {
 					return err
 				}
 				if err := w.WriteByte('\n'); err != nil {
 					return err
 				}
 			}
 			continue
 		}
 		if fv.Kind() == reflect.Map {
 			// Map fields are rendered as a repeated struct with key/value fields.
 			keys := fv.MapKeys()
 			sort.Sort(mapKeys(keys))
 			for _, key := range keys {
 				val := fv.MapIndex(key)
 				if err := writeName(w, props); err != nil {
 					return err
 				}
 				if !w.compact {
 					if err := w.WriteByte(' '); err != nil {
 						return err
 					}
 				}
 				// open struct
 				if err := w.WriteByte('<'); err != nil {
 					return err
 				}
 				if !w.compact {
 					if err := w.WriteByte('\n'); err != nil {
 						return err
 					}
 				}
 				w.indent()
 				// key
 				if _, err := w.WriteString("key:"); err != nil {
 					return err
 				}
 				if !w.compact {
 					if err := w.WriteByte(' '); err != nil {
 						return err
 					}
 				}
 				if err := tm.writeAny(w, key, props.mkeyprop); err != nil {
 					return err
 				}
 				if err := w.WriteByte('\n'); err != nil {
 					return err
 				}
 				// nil values aren't legal, but we can avoid panicking because of them.
 				if val.Kind() != reflect.Ptr || !val.IsNil() {
 					// value
 					if _, err := w.WriteString("value:"); err != nil {
 						return err
 					}
 					if !w.compact {
 						if err := w.WriteByte(' '); err != nil {
 							return err
 						}
 					}
 					if err := tm.writeAny(w, val, props.mvalprop); err != nil {
 						return err
 					}
 					if err := w.WriteByte('\n'); err != nil {
 						return err
 					}
 				}
 				// close struct
 				w.unindent()
 				if err := w.WriteByte('>'); err != nil {
 					return err
 				}
 				if err := w.WriteByte('\n'); err != nil {
 					return err
 				}
 			}
 			continue
 		}
 		if props.proto3 && fv.Kind() == reflect.Slice && fv.Len() == 0 {
 			// empty bytes field
 			continue
 		}
 		if fv.Kind() != reflect.Ptr && fv.Kind() != reflect.Slice {
 			// proto3 non-repeated scalar field; skip if zero value
 			if isProto3Zero(fv) {
 				continue
 			}
 		}

 		if fv.Kind() == reflect.Interface {
 			// Check if it is a oneof.
 			if st.Field(i).Tag.Get("protobuf_oneof") != "" {
 				// fv is nil, or holds a pointer to generated struct.
 				// That generated struct has exactly one field,
 				// which has a protobuf struct tag.
 				if fv.IsNil() {
 					continue
 				}
 				inner := fv.Elem().Elem() // interface -> *T -> T
 				tag := inner.Type().Field(0).Tag.Get("protobuf")
 				props = new(Properties) // Overwrite the outer props var, but not its pointee.
 				props.Parse(tag)
 				// Write the value in the oneof, not the oneof itself.
 				fv = inner.Field(0)

 				// Special case to cope with malformed messages gracefully:
 				// If the value in the oneof is a nil pointer, don't panic
 				// in writeAny.
 				if fv.Kind() == reflect.Ptr && fv.IsNil() {
 					// Use errors.New so writeAny won't render quotes.
 					msg := errors.New("/* nil */")
 					fv = reflect.ValueOf(&msg).Elem()
 				}
 			}
 		}

 		if err := writeName(w, props); err != nil {
 			return err
 		}
 		if !w.compact {
 			if err := w.WriteByte(' '); err != nil {
 				return err
 			}
 		}
 		if b, ok := fv.Interface().(raw); ok {
 			if err := writeRaw(w, b.Bytes()); err != nil {
 				return err
 			}
 			continue
 		}

 		// Enums have a String method, so writeAny will work fine.
 		if err := tm.writeAny(w, fv, props); err != nil {
 			return err
 		}

 		if err := w.WriteByte('\n'); err != nil {
 			return err
 		}
 	}

 	// Extensions (the XXX_extensions field).
 	pv := sv.Addr()
 	if _, ok := extendable(pv.Interface()); ok {
 		if err := tm.writeExtensions(w, pv); err != nil {
 			return err
 		}
 	}

 	return nil
 }

 // writeRaw writes an uninterpreted raw message.
 func writeRaw(w *textWriter, b []byte) error {
 	if err := w.WriteByte('<'); err != nil {
 		return err
 	}
 	if !w.compact {
 		if err := w.WriteByte('\n'); err != nil {
 			return err
 		}
 	}
 	w.indent()
 	if err := writeUnknownStruct(w, b); err != nil {
 		return err
 	}
 	w.unindent()
 	if err := w.WriteByte('>'); err != nil {
 		return err
 	}
 	return nil
 }

 // writeAny writes an arbitrary field.
 func (tm *TextMarshaler) writeAny(w *textWriter, v reflect.Value, props *Properties) error {
 	v = reflect.Indirect(v)

 	// Floats have special cases.
 	if v.Kind() == reflect.Float32 || v.Kind() == reflect.Float64 {
 		x := v.Float()
 		var b []byte
 		switch {
 		case math.IsInf(x, 1):
 			b = posInf
 		case math.IsInf(x, -1):
 			b = negInf
 		case math.IsNaN(x):
 			b = nan
 		}
 		if b != nil {
 			_, err := w.Write(b)
 			return err
 		}
 		// Other values are handled below.
 	}

 	// We don't attempt to serialise every possible value type; only those
 	// that can occur in protocol buffers.
 	switch v.Kind() {
 	case reflect.Slice:
 		// Should only be a []byte; repeated fields are handled in writeStruct.
 		if err := writeString(w, string(v.Bytes())); err != nil {
 			return err
 		}
 	case reflect.String:
 		if err := writeString(w, v.String()); err != nil {
 			return err
 		}
 	case reflect.Struct:
 		// Required/optional group/message.
 		var bra, ket byte = '<', '>'
 		if props != nil && props.Wire == "group" {
 			bra, ket = '{', '}'
 		}
 		if err := w.WriteByte(bra); err != nil {
 			return err
 		}
 		if !w.compact {
 			if err := w.WriteByte('\n'); err != nil {
 				return err
 			}
 		}
 		w.indent()
 		if etm, ok := v.Interface().(encoding.TextMarshaler); ok {
 			text, err := etm.MarshalText()
 			if err != nil {
 				return err
 			}
 			if _, err = w.Write(text); err != nil {
 				return err
 			}
 		} else if err := tm.writeStruct(w, v); err != nil {
 			return err
 		}
 		w.unindent()
 		if err := w.WriteByte(ket); err != nil {
 			return err
 		}
 	default:
 		_, err := fmt.Fprint(w, v.Interface())
 		return err
 	}
 	return nil
 }

 // equivalent to C's isprint.
 func isprint(c byte) bool {
 	return c >= 0x20 && c < 0x7f
 }

 // writeString writes a string in the protocol buffer text format.
 // It is similar to strconv.Quote except we don't use Go escape sequences,
 // we treat the string as a byte sequence, and we use octal escapes.
 // These differences are to maintain interoperability with the other
 // languages' implementations of the text format.
 func writeString(w *textWriter, s string) error {
 	// use WriteByte here to get any needed indent
 	if err := w.WriteByte('"'); err != nil {
 		return err
 	}
 	// Loop over the bytes, not the runes.
 	for i := 0; i < len(s); i++ {
 		var err error
 		// Divergence from C++: we don't escape apostrophes.
 		// There's no need to escape them, and the C++ parser
 		// copes with a naked apostrophe.
 		switch c := s[i]; c {
 		case '\n':
 			_, err = w.w.Write(backslashN)
 		case '\r':
 			_, err = w.w.Write(backslashR)
 		case '\t':
 			_, err = w.w.Write(backslashT)
 		case '"':
 			_, err = w.w.Write(backslashDQ)
 		case '\\':
 			_, err = w.w.Write(backslashBS)
 		default:
 			if isprint(c) {
 				err = w.w.WriteByte(c)
 			} else {
 				_, err = fmt.Fprintf(w.w, "\\%03o", c)
 			}
 		}
 		if err != nil {
 			return err
 		}
 	}
 	return w.WriteByte('"')
 }

 func writeUnknownStruct(w *textWriter, data []byte) (err error) {
 	if !w.compact {
 		if _, err := fmt.Fprintf(w, "/* %d unknown bytes */\n", len(data)); err != nil {
 			return err
 		}
 	}
 	b := NewBuffer(data)
 	for b.index < len(b.buf) {
 		x, err := b.DecodeVarint()
 		if err != nil {
 			_, err := fmt.Fprintf(w, "/* %v */\n", err)
 			return err
 		}
 		wire, tag := x&7, x>>3
 		if wire == WireEndGroup {
 			w.unindent()
 			if _, err := w.Write(endBraceNewline); err != nil {
 				return err
 			}
 			continue
 		}
 		if _, err := fmt.Fprint(w, tag); err != nil {
 			return err
 		}
 		if wire != WireStartGroup {
 			if err := w.WriteByte(':'); err != nil {
 				return err
 			}
 		}
 		if !w.compact || wire == WireStartGroup {
 			if err := w.WriteByte(' '); err != nil {
 				return err
 			}
 		}
 		switch wire {
 		case WireBytes:
 			buf, e := b.DecodeRawBytes(false)
 			if e == nil {
 				_, err = fmt.Fprintf(w, "%q", buf)
 			} else {
 				_, err = fmt.Fprintf(w, "/* %v */", e)
 			}
 		case WireFixed32:
 			x, err = b.DecodeFixed32()
 			err = writeUnknownInt(w, x, err)
 		case WireFixed64:
 			x, err = b.DecodeFixed64()
 			err = writeUnknownInt(w, x, err)
 		case WireStartGroup:
 			err = w.WriteByte('{')
 			w.indent()
 		case WireVarint:
 			x, err = b.DecodeVarint()
 			err = writeUnknownInt(w, x, err)
 		default:
 			_, err = fmt.Fprintf(w, "/* unknown wire type %d */", wire)
 		}
 		if err != nil {
 			return err
 		}
 		if err = w.WriteByte('\n'); err != nil {
 			return err
 		}
 	}
 	return nil
 }

 func writeUnknownInt(w *textWriter, x uint64, err error) error {
 	if err == nil {
 		_, err = fmt.Fprint(w, x)
 	} else {
 		_, err = fmt.Fprintf(w, "/* %v */", err)
 	}
 	return err
 }

 type int32Slice []int32

 func (s int32Slice) Len() int           { return len(s) }
 func (s int32Slice) Less(i, j int) bool { return s[i] < s[j] }
 func (s int32Slice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

 // writeExtensions writes all the extensions in pv.
 // pv is assumed to be a pointer to a protocol message struct that is extendable.
 func (tm *TextMarshaler) writeExtensions(w *textWriter, pv reflect.Value) error {
 	emap := extensionMaps[pv.Type().Elem()]
 	ep, _ := extendable(pv.Interface())

 	// Order the extensions by ID.
 	// This isn't strictly necessary, but it will give us
 	// canonical output, which will also make testing easier.
 	m, mu := ep.extensionsRead()
 	if m == nil {
 		return nil
 	}
 	mu.Lock()
 	ids := make([]int32, 0, len(m))
 	for id := range m {
 		ids = append(ids, id)
 	}
 	sort.Sort(int32Slice(ids))
 	mu.Unlock()

 	for _, extNum := range ids {
 		ext := m[extNum]
 		var desc *ExtensionDesc
 		if emap != nil {
 			desc = emap[extNum]
 		}
 		if desc == nil {
 			// Unknown extension.
 			if err := writeUnknownStruct(w, ext.enc); err != nil {
 				return err
 			}
 			continue
 		}

 		pb, err := GetExtension(ep, desc)
 		if err != nil {
 			return fmt.Errorf("failed getting extension: %v", err)
 		}

 		// Repeated extensions will appear as a slice.
 		if !desc.repeated() {
 			if err := tm.writeExtension(w, desc.Name, pb); err != nil {
 				return err
 			}
 		} else {
 			v := reflect.ValueOf(pb)
 			for i := 0; i < v.Len(); i++ {
 				if err := tm.writeExtension(w, desc.Name, v.Index(i).Interface()); err != nil {
 					return err
 				}
 			}
 		}
 	}
 	return nil
 }

 func (tm *TextMarshaler) writeExtension(w *textWriter, name string, pb interface{}) error {
 	if _, err := fmt.Fprintf(w, "[%s]:", name); err != nil {
 		return err
 	}
 	if !w.compact {
 		if err := w.WriteByte(' '); err != nil {
 			return err
 		}
 	}
 	if err := tm.writeAny(w, reflect.ValueOf(pb), nil); err != nil {
 		return err
 	}
 	if err := w.WriteByte('\n'); err != nil {
 		return err
 	}
 	return nil
 }

 func (w *textWriter) writeIndent() {
 	if !w.complete {
 		return
 	}
 	remain := w.ind * 2
 	for remain > 0 {
 		n := remain
 		if n > len(spaces) {
 			n = len(spaces)
 		}
 		w.w.Write(spaces[:n])
 		remain -= n
 	}
 	w.complete = false
 }

 // TextMarshaler is a configurable text format marshaler.
 type TextMarshaler struct {
 	Compact   bool // use compact text format (one line).
 	ExpandAny bool // expand google.protobuf.Any messages of known types
 }

 // Marshal writes a given protocol buffer in text format.
 // The only errors returned are from w.
 func (tm *TextMarshaler) Marshal(w io.Writer, pb Message) error {
 	val := reflect.ValueOf(pb)
 	if pb == nil || val.IsNil() {
 		w.Write([]byte("<nil>"))
 		return nil
 	}
 	var bw *bufio.Writer
 	ww, ok := w.(writer)
 	if !ok {
 		bw = bufio.NewWriter(w)
 		ww = bw
 	}
 	aw := &textWriter{
 		w:        ww,
 		complete: true,
 		compact:  tm.Compact,
 	}

 	if etm, ok := pb.(encoding.TextMarshaler); ok {
 		text, err := etm.MarshalText()
 		if err != nil {
 			return err
 		}
 		if _, err = aw.Write(text); err != nil {
 			return err
 		}
 		if bw != nil {
 			return bw.Flush()
 		}
 		return nil
 	}
 	// Dereference the received pointer so we don't have outer < and >.
 	v := reflect.Indirect(val)
 	if err := tm.writeStruct(aw, v); err != nil {
 		return err
 	}
 	if bw != nil {
 		return bw.Flush()
 	}
 	return nil
 }

 // Text is the same as Marshal, but returns the string directly.
 func (tm *TextMarshaler) Text(pb Message) string {
 	var buf bytes.Buffer
 	tm.Marshal(&buf, pb)
 	return buf.String()
 }

 var (
 	defaultTextMarshaler = TextMarshaler{}
 	compactTextMarshaler = TextMarshaler{Compact: true}
 )

 // TODO: consider removing some of the Marshal functions below.

 // MarshalText writes a given protocol buffer in text format.
 // The only errors returned are from w.
 func MarshalText(w io.Writer, pb Message) error { return defaultTextMarshaler.Marshal(w, pb) }

 // MarshalTextString is the same as MarshalText, but returns the string directly.
 func MarshalTextString(pb Message) string { return defaultTextMarshaler.Text(pb) }

 // CompactText writes a given protocol buffer in compact text format (one line).
 func CompactText(w io.Writer, pb Message) error { return compactTextMarshaler.Marshal(w, pb) }

 // CompactTextString is the same as CompactText, but returns the string directly.
 func CompactTextString(pb Message) string { return compactTextMarshaler.Text(pb) }
	// Go support for Protocol Buffers - Google's data interchange format
	//
	// Copyright 2010 The Go Authors. All rights reserved.
	// https://github.com/golang/protobuf
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are
	// met:
	//
	// * Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above
	// copyright notice, this list of conditions and the following disclaimer
	// in the documentation and/or other materials provided with the
	// distribution.
	// * Neither the name of Google Inc. nor the names of its
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	package proto

	// Functions for writing the text protocol buffer format.

	import (
	"bufio"
	"bytes"
	"encoding"
	"errors"
	"fmt"
	"io"
	"log"
	"math"
	"reflect"
	"sort"
	"strings"
	)

	var (
	newline = []byte("\n")
	spaces = []byte(" ")
	gtNewline = []byte(">\n")
	endBraceNewline = []byte("}\n")
	backslashN = []byte{'\\', 'n'}
	backslashR = []byte{'\\', 'r'}
	backslashT = []byte{'\\', 't'}
	backslashDQ = []byte{'\\', '"'}
	backslashBS = []byte{'\\', '\\'}
	posInf = []byte("inf")
	negInf = []byte("-inf")
	nan = []byte("nan")
	)

	type writer interface {
	io.Writer
	WriteByte(byte) error
	}

	// textWriter is an io.Writer that tracks its indentation level.
	type textWriter struct {
	ind int
	complete bool // if the current position is a complete line
	compact bool // whether to write out as a one-liner
	w writer
	}

	func (w *textWriter) WriteString(s string) (n int, err error) {
	if !strings.Contains(s, "\n") {
	if !w.compact && w.complete {
	w.writeIndent()
	}
	w.complete = false
	return io.WriteString(w.w, s)
	}
	// WriteString is typically called without newlines, so this
	// codepath and its copy are rare. We copy to avoid
	// duplicating all of Write's logic here.
	return w.Write([]byte(s))
	}

	func (w *textWriter) Write(p []byte) (n int, err error) {
	newlines := bytes.Count(p, newline)
	if newlines == 0 {
	if !w.compact && w.complete {
	w.writeIndent()
	}
	n, err = w.w.Write(p)
	w.complete = false
	return n, err
	}

	frags := bytes.SplitN(p, newline, newlines+1)
	if w.compact {
	for i, frag := range frags {
	if i > 0 {
	if err := w.w.WriteByte(' '); err != nil {
	return n, err
	}
	n++
	}
	nn, err := w.w.Write(frag)
	n += nn
	if err != nil {
	return n, err
	}
	}
	return n, nil
	}

	for i, frag := range frags {
	if w.complete {
	w.writeIndent()
	}
	nn, err := w.w.Write(frag)
	n += nn
	if err != nil {
	return n, err
	}
	if i+1 < len(frags) {
	if err := w.w.WriteByte('\n'); err != nil {
	return n, err
	}
	n++
	}
	}
	w.complete = len(frags[len(frags)-1]) == 0
	return n, nil
	}

	func (w *textWriter) WriteByte(c byte) error {
	if w.compact && c == '\n' {
	c = ' '
	}
	if !w.compact && w.complete {
	w.writeIndent()
	}
	err := w.w.WriteByte(c)
	w.complete = c == '\n'
	return err
	}

	func (w *textWriter) indent() { w.ind++ }

	func (w *textWriter) unindent() {
	if w.ind == 0 {
	log.Print("proto: textWriter unindented too far")
	return
	}
	w.ind--
	}

	func writeName(w textWriter, props Properties) error {
	if _, err := w.WriteString(props.OrigName); err != nil {
	return err
	}
	if props.Wire != "group" {
	return w.WriteByte(':')
	}
	return nil
	}

	// raw is the interface satisfied by RawMessage.
	type raw interface {
	Bytes() []byte
	}

	func requiresQuotes(u string) bool {
	// When type URL contains any characters except [0-9A-Za-z./\-]*, it must be quoted.
	for _, ch := range u {
	switch {
	case ch == '.' \|\| ch == '/' \|\| ch == '_':
	continue
	case '0' <= ch && ch <= '9':
	continue
	case 'A' <= ch && ch <= 'Z':
	continue
	case 'a' <= ch && ch <= 'z':
	continue
	default:
	return true
	}
	}
	return false
	}

	// isAny reports whether sv is a google.protobuf.Any message
	func isAny(sv reflect.Value) bool {
	type wkt interface {
	XXX_WellKnownType() string
	}
	t, ok := sv.Addr().Interface().(wkt)
	return ok && t.XXX_WellKnownType() == "Any"
	}

	// writeProto3Any writes an expanded google.protobuf.Any message.
	//
	// It returns (false, nil) if sv value can't be unmarshaled (e.g. because
	// required messages are not linked in).
	//
	// It returns (true, error) when sv was written in expanded format or an error
	// was encountered.
	func (tm TextMarshaler) writeProto3Any(w textWriter, sv reflect.Value) (bool, error) {
	turl := sv.FieldByName("TypeUrl")
	val := sv.FieldByName("Value")
	if !turl.IsValid() \|\| !val.IsValid() {
	return true, errors.New("proto: invalid google.protobuf.Any message")
	}

	b, ok := val.Interface().([]byte)
	if !ok {
	return true, errors.New("proto: invalid google.protobuf.Any message")
	}

	parts := strings.Split(turl.String(), "/")
	mt := MessageType(parts[len(parts)-1])
	if mt == nil {
	return false, nil
	}
	m := reflect.New(mt.Elem())
	if err := Unmarshal(b, m.Interface().(Message)); err != nil {
	return false, nil
	}
	w.Write([]byte("["))
	u := turl.String()
	if requiresQuotes(u) {
	writeString(w, u)
	} else {
	w.Write([]byte(u))
	}
	if w.compact {
	w.Write([]byte("]:<"))
	} else {
	w.Write([]byte("]: <\n"))
	w.ind++
	}
	if err := tm.writeStruct(w, m.Elem()); err != nil {
	return true, err
	}
	if w.compact {
	w.Write([]byte("> "))
	} else {
	w.ind--
	w.Write([]byte(">\n"))
	}
	return true, nil
	}

	func (tm TextMarshaler) writeStruct(w textWriter, sv reflect.Value) error {
	if tm.ExpandAny && isAny(sv) {
	if canExpand, err := tm.writeProto3Any(w, sv); canExpand {
	return err
	}
	}
	st := sv.Type()
	sprops := GetProperties(st)
	for i := 0; i < sv.NumField(); i++ {
	fv := sv.Field(i)
	props := sprops.Prop[i]
	name := st.Field(i).Name

	if strings.HasPrefix(name, "XXX_") {
	// There are two XXX_ fields:
	// XXX_unrecognized []byte
	// XXX_extensions map[int32]proto.Extension
	// The first is handled here;
	// the second is handled at the bottom of this function.
	if name == "XXX_unrecognized" && !fv.IsNil() {
	if err := writeUnknownStruct(w, fv.Interface().([]byte)); err != nil {
	return err
	}
	}
	continue
	}
	if fv.Kind() == reflect.Ptr && fv.IsNil() {
	// Field not filled in. This could be an optional field or
	// a required field that wasn't filled in. Either way, there
	// isn't anything we can show for it.
	continue
	}
	if fv.Kind() == reflect.Slice && fv.IsNil() {
	// Repeated field that is empty, or a bytes field that is unused.
	continue
	}

	if props.Repeated && fv.Kind() == reflect.Slice {
	// Repeated field.
	for j := 0; j < fv.Len(); j++ {
	if err := writeName(w, props); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	v := fv.Index(j)
	if v.Kind() == reflect.Ptr && v.IsNil() {
	// A nil message in a repeated field is not valid,
	// but we can handle that more gracefully than panicking.
	if _, err := w.Write([]byte("<nil>\n")); err != nil {
	return err
	}
	continue
	}
	if err := tm.writeAny(w, v, props); err != nil {
	return err
	}
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	continue
	}
	if fv.Kind() == reflect.Map {
	// Map fields are rendered as a repeated struct with key/value fields.
	keys := fv.MapKeys()
	sort.Sort(mapKeys(keys))
	for _, key := range keys {
	val := fv.MapIndex(key)
	if err := writeName(w, props); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	// open struct
	if err := w.WriteByte('<'); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	w.indent()
	// key
	if _, err := w.WriteString("key:"); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	if err := tm.writeAny(w, key, props.mkeyprop); err != nil {
	return err
	}
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	// nil values aren't legal, but we can avoid panicking because of them.
	if val.Kind() != reflect.Ptr \|\| !val.IsNil() {
	// value
	if _, err := w.WriteString("value:"); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	if err := tm.writeAny(w, val, props.mvalprop); err != nil {
	return err
	}
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	// close struct
	w.unindent()
	if err := w.WriteByte('>'); err != nil {
	return err
	}
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	continue
	}
	if props.proto3 && fv.Kind() == reflect.Slice && fv.Len() == 0 {
	// empty bytes field
	continue
	}
	if fv.Kind() != reflect.Ptr && fv.Kind() != reflect.Slice {
	// proto3 non-repeated scalar field; skip if zero value
	if isProto3Zero(fv) {
	continue
	}
	}

	if fv.Kind() == reflect.Interface {
	// Check if it is a oneof.
	if st.Field(i).Tag.Get("protobuf_oneof") != "" {
	// fv is nil, or holds a pointer to generated struct.
	// That generated struct has exactly one field,
	// which has a protobuf struct tag.
	if fv.IsNil() {
	continue
	}
	inner := fv.Elem().Elem() // interface -> *T -> T
	tag := inner.Type().Field(0).Tag.Get("protobuf")
	props = new(Properties) // Overwrite the outer props var, but not its pointee.
	props.Parse(tag)
	// Write the value in the oneof, not the oneof itself.
	fv = inner.Field(0)

	// Special case to cope with malformed messages gracefully:
	// If the value in the oneof is a nil pointer, don't panic
	// in writeAny.
	if fv.Kind() == reflect.Ptr && fv.IsNil() {
	// Use errors.New so writeAny won't render quotes.
	msg := errors.New("/* nil */")
	fv = reflect.ValueOf(&msg).Elem()
	}
	}
	}

	if err := writeName(w, props); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	if b, ok := fv.Interface().(raw); ok {
	if err := writeRaw(w, b.Bytes()); err != nil {
	return err
	}
	continue
	}

	// Enums have a String method, so writeAny will work fine.
	if err := tm.writeAny(w, fv, props); err != nil {
	return err
	}

	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}

	// Extensions (the XXX_extensions field).
	pv := sv.Addr()
	if _, ok := extendable(pv.Interface()); ok {
	if err := tm.writeExtensions(w, pv); err != nil {
	return err
	}
	}

	return nil
	}

	// writeRaw writes an uninterpreted raw message.
	func writeRaw(w *textWriter, b []byte) error {
	if err := w.WriteByte('<'); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	w.indent()
	if err := writeUnknownStruct(w, b); err != nil {
	return err
	}
	w.unindent()
	if err := w.WriteByte('>'); err != nil {
	return err
	}
	return nil
	}

	// writeAny writes an arbitrary field.
	func (tm TextMarshaler) writeAny(w textWriter, v reflect.Value, props *Properties) error {
	v = reflect.Indirect(v)

	// Floats have special cases.
	if v.Kind() == reflect.Float32 \|\| v.Kind() == reflect.Float64 {
	x := v.Float()
	var b []byte
	switch {
	case math.IsInf(x, 1):
	b = posInf
	case math.IsInf(x, -1):
	b = negInf
	case math.IsNaN(x):
	b = nan
	}
	if b != nil {
	_, err := w.Write(b)
	return err
	}
	// Other values are handled below.
	}

	// We don't attempt to serialise every possible value type; only those
	// that can occur in protocol buffers.
	switch v.Kind() {
	case reflect.Slice:
	// Should only be a []byte; repeated fields are handled in writeStruct.
	if err := writeString(w, string(v.Bytes())); err != nil {
	return err
	}
	case reflect.String:
	if err := writeString(w, v.String()); err != nil {
	return err
	}
	case reflect.Struct:
	// Required/optional group/message.
	var bra, ket byte = '<', '>'
	if props != nil && props.Wire == "group" {
	bra, ket = '{', '}'
	}
	if err := w.WriteByte(bra); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	}
	w.indent()
	if etm, ok := v.Interface().(encoding.TextMarshaler); ok {
	text, err := etm.MarshalText()
	if err != nil {
	return err
	}
	if _, err = w.Write(text); err != nil {
	return err
	}
	} else if err := tm.writeStruct(w, v); err != nil {
	return err
	}
	w.unindent()
	if err := w.WriteByte(ket); err != nil {
	return err
	}
	default:
	_, err := fmt.Fprint(w, v.Interface())
	return err
	}
	return nil
	}

	// equivalent to C's isprint.
	func isprint(c byte) bool {
	return c >= 0x20 && c < 0x7f
	}

	// writeString writes a string in the protocol buffer text format.
	// It is similar to strconv.Quote except we don't use Go escape sequences,
	// we treat the string as a byte sequence, and we use octal escapes.
	// These differences are to maintain interoperability with the other
	// languages' implementations of the text format.
	func writeString(w *textWriter, s string) error {
	// use WriteByte here to get any needed indent
	if err := w.WriteByte('"'); err != nil {
	return err
	}
	// Loop over the bytes, not the runes.
	for i := 0; i < len(s); i++ {
	var err error
	// Divergence from C++: we don't escape apostrophes.
	// There's no need to escape them, and the C++ parser
	// copes with a naked apostrophe.
	switch c := s[i]; c {
	case '\n':
	_, err = w.w.Write(backslashN)
	case '\r':
	_, err = w.w.Write(backslashR)
	case '\t':
	_, err = w.w.Write(backslashT)
	case '"':
	_, err = w.w.Write(backslashDQ)
	case '\\':
	_, err = w.w.Write(backslashBS)
	default:
	if isprint(c) {
	err = w.w.WriteByte(c)
	} else {
	_, err = fmt.Fprintf(w.w, "\\%03o", c)
	}
	}
	if err != nil {
	return err
	}
	}
	return w.WriteByte('"')
	}

	func writeUnknownStruct(w *textWriter, data []byte) (err error) {
	if !w.compact {
	if _, err := fmt.Fprintf(w, "/* %d unknown bytes */\n", len(data)); err != nil {
	return err
	}
	}
	b := NewBuffer(data)
	for b.index < len(b.buf) {
	x, err := b.DecodeVarint()
	if err != nil {
	_, err := fmt.Fprintf(w, "/* %v */\n", err)
	return err
	}
	wire, tag := x&7, x>>3
	if wire == WireEndGroup {
	w.unindent()
	if _, err := w.Write(endBraceNewline); err != nil {
	return err
	}
	continue
	}
	if _, err := fmt.Fprint(w, tag); err != nil {
	return err
	}
	if wire != WireStartGroup {
	if err := w.WriteByte(':'); err != nil {
	return err
	}
	}
	if !w.compact \|\| wire == WireStartGroup {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	switch wire {
	case WireBytes:
	buf, e := b.DecodeRawBytes(false)
	if e == nil {
	_, err = fmt.Fprintf(w, "%q", buf)
	} else {
	_, err = fmt.Fprintf(w, "/* %v */", e)
	}
	case WireFixed32:
	x, err = b.DecodeFixed32()
	err = writeUnknownInt(w, x, err)
	case WireFixed64:
	x, err = b.DecodeFixed64()
	err = writeUnknownInt(w, x, err)
	case WireStartGroup:
	err = w.WriteByte('{')
	w.indent()
	case WireVarint:
	x, err = b.DecodeVarint()
	err = writeUnknownInt(w, x, err)
	default:
	_, err = fmt.Fprintf(w, "/* unknown wire type %d */", wire)
	}
	if err != nil {
	return err
	}
	if err = w.WriteByte('\n'); err != nil {
	return err
	}
	}
	return nil
	}

	func writeUnknownInt(w *textWriter, x uint64, err error) error {
	if err == nil {
	_, err = fmt.Fprint(w, x)
	} else {
	_, err = fmt.Fprintf(w, "/* %v */", err)
	}
	return err
	}

	type int32Slice []int32

	func (s int32Slice) Len() int { return len(s) }
	func (s int32Slice) Less(i, j int) bool { return s[i] < s[j] }
	func (s int32Slice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

	// writeExtensions writes all the extensions in pv.
	// pv is assumed to be a pointer to a protocol message struct that is extendable.
	func (tm TextMarshaler) writeExtensions(w textWriter, pv reflect.Value) error {
	emap := extensionMaps[pv.Type().Elem()]
	ep, _ := extendable(pv.Interface())

	// Order the extensions by ID.
	// This isn't strictly necessary, but it will give us
	// canonical output, which will also make testing easier.
	m, mu := ep.extensionsRead()
	if m == nil {
	return nil
	}
	mu.Lock()
	ids := make([]int32, 0, len(m))
	for id := range m {
	ids = append(ids, id)
	}
	sort.Sort(int32Slice(ids))
	mu.Unlock()

	for _, extNum := range ids {
	ext := m[extNum]
	var desc *ExtensionDesc
	if emap != nil {
	desc = emap[extNum]
	}
	if desc == nil {
	// Unknown extension.
	if err := writeUnknownStruct(w, ext.enc); err != nil {
	return err
	}
	continue
	}

	pb, err := GetExtension(ep, desc)
	if err != nil {
	return fmt.Errorf("failed getting extension: %v", err)
	}

	// Repeated extensions will appear as a slice.
	if !desc.repeated() {
	if err := tm.writeExtension(w, desc.Name, pb); err != nil {
	return err
	}
	} else {
	v := reflect.ValueOf(pb)
	for i := 0; i < v.Len(); i++ {
	if err := tm.writeExtension(w, desc.Name, v.Index(i).Interface()); err != nil {
	return err
	}
	}
	}
	}
	return nil
	}

	func (tm TextMarshaler) writeExtension(w textWriter, name string, pb interface{}) error {
	if _, err := fmt.Fprintf(w, "[%s]:", name); err != nil {
	return err
	}
	if !w.compact {
	if err := w.WriteByte(' '); err != nil {
	return err
	}
	}
	if err := tm.writeAny(w, reflect.ValueOf(pb), nil); err != nil {
	return err
	}
	if err := w.WriteByte('\n'); err != nil {
	return err
	}
	return nil
	}

	func (w *textWriter) writeIndent() {
	if !w.complete {
	return
	}
	remain := w.ind * 2
	for remain > 0 {
	n := remain
	if n > len(spaces) {
	n = len(spaces)
	}
	w.w.Write(spaces[:n])
	remain -= n
	}
	w.complete = false
	}

	// TextMarshaler is a configurable text format marshaler.
	type TextMarshaler struct {
	Compact bool // use compact text format (one line).
	ExpandAny bool // expand google.protobuf.Any messages of known types
	}

	// Marshal writes a given protocol buffer in text format.
	// The only errors returned are from w.
	func (tm *TextMarshaler) Marshal(w io.Writer, pb Message) error {
	val := reflect.ValueOf(pb)
	if pb == nil \|\| val.IsNil() {
	w.Write([]byte("<nil>"))
	return nil
	}
	var bw *bufio.Writer
	ww, ok := w.(writer)
	if !ok {
	bw = bufio.NewWriter(w)
	ww = bw
	}
	aw := &textWriter{
	w: ww,
	complete: true,
	compact: tm.Compact,
	}

	if etm, ok := pb.(encoding.TextMarshaler); ok {
	text, err := etm.MarshalText()
	if err != nil {
	return err
	}
	if _, err = aw.Write(text); err != nil {
	return err
	}
	if bw != nil {
	return bw.Flush()
	}
	return nil
	}
	// Dereference the received pointer so we don't have outer < and >.
	v := reflect.Indirect(val)
	if err := tm.writeStruct(aw, v); err != nil {
	return err
	}
	if bw != nil {
	return bw.Flush()
	}
	return nil
	}

	// Text is the same as Marshal, but returns the string directly.
	func (tm *TextMarshaler) Text(pb Message) string {
	var buf bytes.Buffer
	tm.Marshal(&buf, pb)
	return buf.String()
	}

	var (
	defaultTextMarshaler = TextMarshaler{}
	compactTextMarshaler = TextMarshaler{Compact: true}
	)

	// TODO: consider removing some of the Marshal functions below.

	// MarshalText writes a given protocol buffer in text format.
	// The only errors returned are from w.
	func MarshalText(w io.Writer, pb Message) error { return defaultTextMarshaler.Marshal(w, pb) }

	// MarshalTextString is the same as MarshalText, but returns the string directly.
	func MarshalTextString(pb Message) string { return defaultTextMarshaler.Text(pb) }

	// CompactText writes a given protocol buffer in compact text format (one line).
	func CompactText(w io.Writer, pb Message) error { return compactTextMarshaler.Marshal(w, pb) }

	// CompactTextString is the same as CompactText, but returns the string directly.
	func CompactTextString(pb Message) string { return compactTextMarshaler.Text(pb) }