func (p *Properties) setEncAndDec(typ reflect.Type, lockGetProp bool) {
	p.enc = nil
	p.dec = nil
	p.size = nil
	switch t1 := typ; t1.Kind() {
	default:
		fmt.Fprintf(os.Stderr, "proto: no coders for %T\n", t1)
	case reflect.Ptr:
		switch t2 := t1.Elem(); t2.Kind() {
		default:
			fmt.Fprintf(os.Stderr, "proto: no encoder function for %T -> %T\n", t1, t2)
			break
		case reflect.Bool:
			p.enc = (*Buffer).enc_bool
			p.dec = (*Buffer).dec_bool
			p.size = size_bool
		case reflect.Int32:
			p.enc = (*Buffer).enc_int32
			p.dec = (*Buffer).dec_int32
			p.size = size_int32
		case reflect.Uint32:
			p.enc = (*Buffer).enc_uint32
			p.dec = (*Buffer).dec_int32  
			p.size = size_uint32
		case reflect.Int64, reflect.Uint64:
			p.enc = (*Buffer).enc_int64
			p.dec = (*Buffer).dec_int64
			p.size = size_int64
		case reflect.Float32:
			p.enc = (*Buffer).enc_uint32  
			p.dec = (*Buffer).dec_int32
			p.size = size_uint32
		case reflect.Float64:
			p.enc = (*Buffer).enc_int64  
			p.dec = (*Buffer).dec_int64
			p.size = size_int64
		case reflect.String:
			p.enc = (*Buffer).enc_string
			p.dec = (*Buffer).dec_string
			p.size = size_string
		case reflect.Struct:
			p.stype = t1.Elem()
			p.isMarshaler = isMarshaler(t1)
			p.isUnmarshaler = isUnmarshaler(t1)
			if p.Wire == "bytes" {
				p.enc = (*Buffer).enc_struct_message
				p.dec = (*Buffer).dec_struct_message
				p.size = size_struct_message
			} else {
				p.enc = (*Buffer).enc_struct_group
				p.dec = (*Buffer).dec_struct_group
				p.size = size_struct_group
			}
		}
	case reflect.Slice:
		switch t2 := t1.Elem(); t2.Kind() {
		default:
			logNoSliceEnc(t1, t2)
			break
		case reflect.Bool:
			if p.Packed {
				p.enc = (*Buffer).enc_slice_packed_bool
				p.size = size_slice_packed_bool
			} else {
				p.enc = (*Buffer).enc_slice_bool
				p.size = size_slice_bool
			}
			p.dec = (*Buffer).dec_slice_bool
			p.packedDec = (*Buffer).dec_slice_packed_bool
		case reflect.Int32:
			if p.Packed {
				p.enc = (*Buffer).enc_slice_packed_int32
				p.size = size_slice_packed_int32
			} else {
				p.enc = (*Buffer).enc_slice_int32
				p.size = size_slice_int32
			}
			p.dec = (*Buffer).dec_slice_int32
			p.packedDec = (*Buffer).dec_slice_packed_int32
		case reflect.Uint32:
			if p.Packed {
				p.enc = (*Buffer).enc_slice_packed_uint32
				p.size = size_slice_packed_uint32
			} else {
				p.enc = (*Buffer).enc_slice_uint32
				p.size = size_slice_uint32
			}
			p.dec = (*Buffer).dec_slice_int32
			p.packedDec = (*Buffer).dec_slice_packed_int32
		case reflect.Int64, reflect.Uint64:
			if p.Packed {
				p.enc = (*Buffer).enc_slice_packed_int64
				p.size = size_slice_packed_int64
			} else {
				p.enc = (*Buffer).enc_slice_int64
				p.size = size_slice_int64
			}
			p.dec = (*Buffer).dec_slice_int64
			p.packedDec = (*Buffer).dec_slice_packed_int64
		case reflect.Uint8:
			p.enc = (*Buffer).enc_slice_byte
			p.dec = (*Buffer).dec_slice_byte
			p.size = size_slice_byte
		case reflect.Float32, reflect.Float64:
			switch t2.Bits() {
			case 32:
				if p.Packed {
					p.enc = (*Buffer).enc_slice_packed_uint32
					p.size = size_slice_packed_uint32
				} else {
					p.enc = (*Buffer).enc_slice_uint32
					p.size = size_slice_uint32
				}
				p.dec = (*Buffer).dec_slice_int32
				p.packedDec = (*Buffer).dec_slice_packed_int32
			case 64:
				if p.Packed {
					p.enc = (*Buffer).enc_slice_packed_int64
					p.size = size_slice_packed_int64
				} else {
					p.enc = (*Buffer).enc_slice_int64
					p.size = size_slice_int64
				}
				p.dec = (*Buffer).dec_slice_int64
				p.packedDec = (*Buffer).dec_slice_packed_int64
			default:
				logNoSliceEnc(t1, t2)
				break
			}
		case reflect.String:
			p.enc = (*Buffer).enc_slice_string
			p.dec = (*Buffer).dec_slice_string
			p.size = size_slice_string
		case reflect.Ptr:
			switch t3 := t2.Elem(); t3.Kind() {
			default:
				fmt.Fprintf(os.Stderr, "proto: no ptr oenc for %T -> %T -> %T\n", t1, t2, t3)
				break
			case reflect.Struct:
				p.stype = t2.Elem()
				p.isMarshaler = isMarshaler(t2)
				p.isUnmarshaler = isUnmarshaler(t2)
				if p.Wire == "bytes" {
					p.enc = (*Buffer).enc_slice_struct_message
					p.dec = (*Buffer).dec_slice_struct_message
					p.size = size_slice_struct_message
				} else {
					p.enc = (*Buffer).enc_slice_struct_group
					p.dec = (*Buffer).dec_slice_struct_group
					p.size = size_slice_struct_group
				}
			}
		case reflect.Slice:
			switch t2.Elem().Kind() {
			default:
				fmt.Fprintf(os.Stderr, "proto: no slice elem oenc for %T -> %T -> %T\n", t1, t2, t2.Elem())
				break
			case reflect.Uint8:
				p.enc = (*Buffer).enc_slice_slice_byte
				p.dec = (*Buffer).dec_slice_slice_byte
				p.size = size_slice_slice_byte
			}
		}
	}
	wire := p.WireType
	if p.Packed {
		wire = WireBytes
	}
	x := uint32(p.Tag)<<3 | uint32(wire)
	i := 0
	for i = 0; x > 127; i++ {
		p.tagbuf[i] = 0x80 | uint8(x&0x7F)
		x >>= 7
	}
	p.tagbuf[i] = uint8(x)
	p.tagcode = p.tagbuf[0 : i+1]
	if p.stype != nil {
		if lockGetProp {
			p.sprop = GetProperties(p.stype)
		} else {
			p.sprop = getPropertiesLocked(p.stype)
		}
	}
}
Initialize the fields for encoding and decoding.
package proto
import (
	"fmt"
	"os"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"sync"
)
const debug bool = false
const (
	WireVarint     = 0
	WireFixed64    = 1
	WireBytes      = 2
	WireStartGroup = 3
	WireEndGroup   = 4
	WireFixed32    = 5
)
const startSize = 10  
type encoder func(p *Buffer, prop *Properties, base structPointer) error
type valueEncoder func(o *Buffer, x uint64) error
type sizer func(prop *Properties, base structPointer) int
type valueSizer func(x uint64) int
type decoder func(p *Buffer, prop *Properties, base structPointer) error
type valueDecoder func(o *Buffer) (x uint64, err error)
type tagMap struct {
	fastTags []int
	slowTags map[int]int
}
const tagMapFastLimit = 1024
func (p *tagMap) get(t int) (int, bool) {
	if t > 0 && t < tagMapFastLimit {
		if t >= len(p.fastTags) {
			return 0, false
		}
		fi := p.fastTags[t]
		return fi, fi >= 0
	}
	fi, ok := p.slowTags[t]
	return fi, ok
}
func (p *tagMap) put(t int, fi int) {
	if t > 0 && t < tagMapFastLimit {
		for len(p.fastTags) < t+1 {
			p.fastTags = append(p.fastTags, -1)
		}
		p.fastTags[t] = fi
		return
	}
	if p.slowTags == nil {
		p.slowTags = make(map[int]int)
	}
	p.slowTags[t] = fi
}
type StructProperties struct {
	Prop             []*Properties   
	reqCount         int             
	decoderTags      tagMap          
	decoderOrigNames map[string]int  
	order            []int           
	unrecField       field           
	extendable       bool            
}
func (sp *StructProperties) Len() int { return len(sp.order) }
func (sp *StructProperties) Less(i, j int) bool {
	return sp.Prop[sp.order[i]].Tag < sp.Prop[sp.order[j]].Tag
}
func (sp *StructProperties) Swap(i, j int) { sp.order[i], sp.order[j] = sp.order[j], sp.order[i] }
type Properties struct {
	Name     string  
	OrigName string  
	Wire     string
	WireType int
	Tag      int
	Required bool
	Optional bool
	Repeated bool
	Packed   bool    
	Enum     string  
	Default    string  
	HasDefault bool    
	def_uint64 uint64
	enc           encoder
	valEnc        valueEncoder  
	field         field
	tagcode       []byte  
	tagbuf        [8]byte
	stype         reflect.Type       
	sprop         *StructProperties  
	isMarshaler   bool
	isUnmarshaler bool
	size    sizer
	valSize valueSizer  
	dec    decoder
	valDec valueDecoder  
	packedDec decoder
}
func (p *Properties) String() string {
	s := p.Wire
	s = ","
	s += strconv.Itoa(p.Tag)
	if p.Required {
		s += ",req"
	}
	if p.Optional {
		s += ",opt"
	}
	if p.Repeated {
		s += ",rep"
	}
	if p.Packed {
		s += ",packed"
	}
	if p.OrigName != p.Name {
		s += ",name=" + p.OrigName
	}
	if len(p.Enum) > 0 {
		s += ",enum=" + p.Enum
	}
	if p.HasDefault {
		s += ",def=" + p.Default
	}
	return s
}
func (p *Properties) Parse(s string) {
	fields := strings.Split(s, ",")  
	if len(fields) < 2 {
		fmt.Fprintf(os.Stderr, "proto: tag has too few fields: %q\n", s)
		return
	}
	p.Wire = fields[0]
	switch p.Wire {
	case "varint":
		p.WireType = WireVarint
		p.valEnc = (*Buffer).EncodeVarint
		p.valDec = (*Buffer).DecodeVarint
		p.valSize = sizeVarint
	case "fixed32":
		p.WireType = WireFixed32
		p.valEnc = (*Buffer).EncodeFixed32
		p.valDec = (*Buffer).DecodeFixed32
		p.valSize = sizeFixed32
	case "fixed64":
		p.WireType = WireFixed64
		p.valEnc = (*Buffer).EncodeFixed64
		p.valDec = (*Buffer).DecodeFixed64
		p.valSize = sizeFixed64
	case "zigzag32":
		p.WireType = WireVarint
		p.valEnc = (*Buffer).EncodeZigzag32
		p.valDec = (*Buffer).DecodeZigzag32
		p.valSize = sizeZigzag32
	case "zigzag64":
		p.WireType = WireVarint
		p.valEnc = (*Buffer).EncodeZigzag64
		p.valDec = (*Buffer).DecodeZigzag64
		p.valSize = sizeZigzag64
	case "bytes", "group":
		p.WireType = WireBytes
	default:
		fmt.Fprintf(os.Stderr, "proto: tag has unknown wire type: %q\n", s)
		return
	}
	var err error
	p.Tag, err = strconv.Atoi(fields[1])
	if err != nil {
		return
	}
	for i := 2; i < len(fields); i++ {
		f := fields[i]
		switch {
		case f == "req":
			p.Required = true
		case f == "opt":
			p.Optional = true
		case f == "rep":
			p.Repeated = true
		case f == "packed":
			p.Packed = true
		case strings.HasPrefix(f, "name="):
			p.OrigName = f[5:]
		case strings.HasPrefix(f, "enum="):
			p.Enum = f[5:]
		case strings.HasPrefix(f, "def="):
			p.HasDefault = true
			p.Default = f[4:]  
			if i+1 < len(fields) {
				p.Default += "," + strings.Join(fields[i+1:], ",")
				break
			}
		}
	}
}
func logNoSliceEnc(t1, t2 reflect.Type) {
	fmt.Fprintf(os.Stderr, "proto: no slice oenc for %T = []%T\n", t1, t2)
}
var protoMessageType = reflect.TypeOf((*Message)(nil)).Elem()