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|
package msgpack
import (
"bytes"
"fmt"
"reflect"
"sync"
"github.com/vmihailenco/msgpack/codes"
)
var extTypes = make(map[int8]reflect.Type)
var bufferPool = &sync.Pool{
New: func() interface{} {
return new(bytes.Buffer)
},
}
// RegisterExt records a type, identified by a value for that type,
// under the provided id. That id will identify the concrete type of a value
// sent or received as an interface variable. Only types that will be
// transferred as implementations of interface values need to be registered.
// Expecting to be used only during initialization, it panics if the mapping
// between types and ids is not a bijection.
func RegisterExt(id int8, value interface{}) {
typ := reflect.TypeOf(value)
if typ.Kind() == reflect.Ptr {
typ = typ.Elem()
}
ptr := reflect.PtrTo(typ)
if _, ok := extTypes[id]; ok {
panic(fmt.Errorf("msgpack: ext with id=%d is already registered", id))
}
registerExt(id, ptr, getEncoder(ptr), getDecoder(ptr))
registerExt(id, typ, getEncoder(typ), getDecoder(typ))
}
func registerExt(id int8, typ reflect.Type, enc encoderFunc, dec decoderFunc) {
if dec != nil {
extTypes[id] = typ
}
if enc != nil {
typEncMap[typ] = makeExtEncoder(id, enc)
}
if dec != nil {
typDecMap[typ] = makeExtDecoder(id, dec)
}
}
func (e *Encoder) EncodeExtHeader(typeId int8, length int) error {
if err := e.encodeExtLen(length); err != nil {
return err
}
if err := e.w.WriteByte(byte(typeId)); err != nil {
return err
}
return nil
}
func makeExtEncoder(typeId int8, enc encoderFunc) encoderFunc {
return func(e *Encoder, v reflect.Value) error {
buf := bufferPool.Get().(*bytes.Buffer)
defer bufferPool.Put(buf)
buf.Reset()
oldw := e.w
e.w = buf
err := enc(e, v)
e.w = oldw
if err != nil {
return err
}
err = e.EncodeExtHeader(typeId, buf.Len())
if err != nil {
return err
}
return e.write(buf.Bytes())
}
}
func makeExtDecoder(typeId int8, dec decoderFunc) decoderFunc {
return func(d *Decoder, v reflect.Value) error {
c, err := d.PeekCode()
if err != nil {
return err
}
if !codes.IsExt(c) {
return dec(d, v)
}
id, extLen, err := d.DecodeExtHeader()
if err != nil {
return err
}
if id != typeId {
return fmt.Errorf("msgpack: got ext type=%d, wanted %d", int8(c), typeId)
}
d.extLen = extLen
return dec(d, v)
}
}
func (e *Encoder) encodeExtLen(l int) error {
switch l {
case 1:
return e.writeCode(codes.FixExt1)
case 2:
return e.writeCode(codes.FixExt2)
case 4:
return e.writeCode(codes.FixExt4)
case 8:
return e.writeCode(codes.FixExt8)
case 16:
return e.writeCode(codes.FixExt16)
}
if l < 256 {
return e.write1(codes.Ext8, uint8(l))
}
if l < 65536 {
return e.write2(codes.Ext16, uint16(l))
}
return e.write4(codes.Ext32, uint32(l))
}
func (d *Decoder) parseExtLen(c codes.Code) (int, error) {
switch c {
case codes.FixExt1:
return 1, nil
case codes.FixExt2:
return 2, nil
case codes.FixExt4:
return 4, nil
case codes.FixExt8:
return 8, nil
case codes.FixExt16:
return 16, nil
case codes.Ext8:
n, err := d.uint8()
return int(n), err
case codes.Ext16:
n, err := d.uint16()
return int(n), err
case codes.Ext32:
n, err := d.uint32()
return int(n), err
default:
return 0, fmt.Errorf("msgpack: invalid code=%x decoding ext length", c)
}
}
func (d *Decoder) decodeExtHeader(c codes.Code) (int8, int, error) {
length, err := d.parseExtLen(c)
if err != nil {
return 0, 0, err
}
typeId, err := d.readCode()
if err != nil {
return 0, 0, err
}
return int8(typeId), length, nil
}
func (d *Decoder) DecodeExtHeader() (typeId int8, length int, err error) {
c, err := d.readCode()
if err != nil {
return
}
return d.decodeExtHeader(c)
}
func (d *Decoder) extInterface(c codes.Code) (interface{}, error) {
extId, extLen, err := d.decodeExtHeader(c)
if err != nil {
return nil, err
}
typ, ok := extTypes[extId]
if !ok {
return nil, fmt.Errorf("msgpack: unregistered ext id=%d", extId)
}
v := reflect.New(typ)
d.extLen = extLen
err = d.DecodeValue(v.Elem())
d.extLen = 0
if err != nil {
return nil, err
}
return v.Interface(), nil
}
func (d *Decoder) skipExt(c codes.Code) error {
n, err := d.parseExtLen(c)
if err != nil {
return err
}
return d.skipN(n + 1)
}
func (d *Decoder) skipExtHeader(c codes.Code) error {
// Read ext type.
_, err := d.readCode()
if err != nil {
return err
}
// Read ext body len.
for i := 0; i < extHeaderLen(c); i++ {
_, err := d.readCode()
if err != nil {
return err
}
}
return nil
}
func extHeaderLen(c codes.Code) int {
switch c {
case codes.Ext8:
return 1
case codes.Ext16:
return 2
case codes.Ext32:
return 4
}
return 0
}
|
