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decoder.go
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decoder.go
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// Copyright (c) 2023 RoseLoverX
package tl
import (
"bytes"
"fmt"
"reflect"
"github.com/pkg/errors"
)
func Decode(data []byte, res any) error {
if res == nil {
return errors.New("can't unmarshal to nil value")
}
if reflect.TypeOf(res).Kind() != reflect.Ptr {
return fmt.Errorf("res value is not pointer as expected. got %v", reflect.TypeOf(res))
}
d, err := NewDecoder(bytes.NewReader(data))
if err != nil {
return err
}
d.decodeValue(reflect.ValueOf(res))
if d.err != nil {
return errors.Wrapf(d.err, "decode %T", res)
}
return nil
}
// DecodeUnknownObject decodes object from message, when you don't actually know, what message contains.
// due to TL doesn't provide mechanism for understanding is message a int or string, you MUST guarantee, that
// input stream DOES NOT contains any type WITHOUT its CRC code. So, strings, ints, floats, etc. CAN'T BE
// automatically parsed.
//
// expectNextTypes is your predictions how decoder must parse objects hidden under interfaces.
// See Decoder.ExpectTypesInInterface description
func DecodeUnknownObject(data []byte, expectNextTypes ...reflect.Type) (Object, error) {
d, err := NewDecoder(bytes.NewReader(data))
if err != nil {
return nil, err
}
if len(expectNextTypes) > 0 {
d.ExpectTypesInInterface(expectNextTypes...)
}
obj := d.decodeRegisteredObject()
if d.err != nil {
return nil, errors.Wrap(d.err, "decoding predicted object")
}
return obj, nil
}
func (d *Decoder) decodeObject(o Object, ignoreCRC bool) {
if d.err != nil {
return
}
if !ignoreCRC {
crcCode := d.PopCRC()
if d.err != nil {
d.err = errors.Wrap(d.err, "read crc")
return
}
if crcCode != o.CRC() {
d.err = fmt.Errorf("invalid crc code: %#v, want: %#v", crcCode, o.CRC())
return
}
}
value := reflect.ValueOf(o)
if value.Kind() != reflect.Ptr {
panic("not a pointer")
}
value = reflect.Indirect(value)
if value.Kind() != reflect.Struct {
panic("not receiving on struct: " + value.Type().String() + " -> " + value.Kind().String())
}
vtyp := value.Type()
var optionalBitSet uint32
var flagsetIndex = -1
if haveFlag(value.Interface()) {
// getting new cause we need idempotent response
indexGetter, ok := reflect.New(vtyp).Interface().(FlagIndexGetter)
if !ok {
panic("type " + value.Type().String() + " has type bit flag tags, but doesn't inplement tl.FlagIndexGetter")
}
flagsetIndex = indexGetter.FlagIndex()
if flagsetIndex < 0 {
panic("flag index is below zero, must be index of parameters")
}
}
var bitsetParsed bool
loopCycles := value.NumField()
if flagsetIndex >= 0 {
loopCycles++
}
for i := 0; i < loopCycles; i++ {
// parsing flag is necessary
if flagsetIndex == i {
optionalBitSet = d.PopUint()
if d.err != nil {
d.err = errors.Wrap(d.err, "read bitset")
return
}
bitsetParsed = true
continue
}
fieldIndex := i
if bitsetParsed {
fieldIndex--
}
field := value.Field(fieldIndex)
if _, found := vtyp.Field(fieldIndex).Tag.Lookup(tagName); found {
info, err := parseTag(vtyp.Field(fieldIndex).Tag)
if err != nil {
d.err = errors.Wrap(err, "parse tag")
return
}
if optionalBitSet&(1<<info.index) == 0 {
continue
}
if info.encodedInBitflag {
field.Set(reflect.ValueOf(true).Convert(field.Type()))
continue
}
}
if field.Kind() == reflect.Ptr { // && field.IsNil()
val := reflect.New(field.Type().Elem())
field.Set(val)
}
d.decodeValue(field)
if d.err != nil {
d.err = errors.Wrapf(d.err, "decode field '%s'", vtyp.Field(fieldIndex).Name)
break
}
}
}
func (d *Decoder) decodeValue(value reflect.Value) {
if d.err != nil {
return
}
if m, ok := value.Interface().(Unmarshaler); ok {
err := m.UnmarshalTL(d)
if err != nil {
d.err = err
}
return
}
val := d.decodeValueGeneral(value)
if val != nil {
value.Set(reflect.ValueOf(val).Convert(value.Type()))
return
}
switch value.Kind() { //nolint:exhaustive has default case + more types checked
// Float64,Int64,Uint32,Int32,Bool,String,Chan, Func, Uintptr, UnsafePointer,Struct,Map,Array,Int,
// Int8,Int16,Uint,Uint8,Uint16,Uint64,Float32,Complex64,Complex128
// these values are checked already
case reflect.Slice:
if _, ok := value.Interface().([]byte); ok {
val = d.PopMessage()
} else {
val = d.PopVector(value.Type().Elem())
}
case reflect.Ptr:
if o, ok := value.Interface().(Object); ok {
d.decodeObject(o, false)
} else {
d.decodeValue(value.Elem())
}
return
case reflect.Interface:
val = d.decodeRegisteredObject()
// if we got slice, we must unwrap it, cause WrappedSlice allowed to exist ONLY in root of returned object
if v, ok := val.(*WrappedSlice); ok {
if reflect.TypeOf(v.data).ConvertibleTo(value.Type()) {
val = v.data
}
}
if d.err != nil {
d.err = errors.Wrap(d.err, "decode interface")
return
}
default:
panic("неизвестная штука: " + value.Type().String())
}
if d.err != nil {
return
}
value.Set(reflect.ValueOf(val).Convert(value.Type()))
}
// декодирует базовые типы, строчки числа, вот это. если тип не найден возвращает nil
func (d *Decoder) decodeValueGeneral(value reflect.Value) any {
// value, which is setting into value arg
var val any
switch value.Kind() { //nolint:exhaustive has default case
case reflect.Float64:
val = d.PopDouble()
case reflect.Int64:
val = d.PopLong()
case reflect.Uint32: // это применимо так же к енумам
val = d.PopUint()
case reflect.Int32:
val = int32(d.PopUint())
case reflect.Bool:
val = d.PopBool()
case reflect.String:
val = string(d.PopMessage())
case reflect.Chan, reflect.Func, reflect.Uintptr, reflect.UnsafePointer:
panic(value.Kind().String() + " does not supported")
case reflect.Struct:
d.err = fmt.Errorf("%v must implement tl.Object for decoding (also it must be pointer)", value.Type())
case reflect.Map:
d.err = errors.New("map is not ordered object (must order like structs)")
case reflect.Array:
d.err = errors.New("array must be slice")
case reflect.Int, reflect.Int8, reflect.Int16,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint64:
d.err = fmt.Errorf("int kind: %v (must converted to int32, int64 or uint32 explicitly)", value.Kind())
return nil
case reflect.Float32, reflect.Complex64, reflect.Complex128:
d.err = fmt.Errorf("float kind: %s (must be converted to float64 explicitly)", value.Kind())
return nil
default:
// not basic type
return nil
}
return val
}
func (d *Decoder) decodeRegisteredObject() Object {
crc := d.PopCRC()
if d.err != nil {
d.err = errors.Wrap(d.err, "read crc")
}
var _typ reflect.Type
// firstly, we are checking specific crc situations.
// See https://github.com/jwillp/gogram/issues/51
switch crc {
case CrcVector:
if len(d.expectedTypes) == 0 {
d.err = &ErrMustParseSlicesExplicitly{}
return nil
}
_typ = d.expectedTypes[0]
d.expectedTypes = d.expectedTypes[1:]
res := d.popVector(_typ.Elem(), true)
if d.err != nil {
return nil
}
return &WrappedSlice{res}
case CrcFalse:
return &PseudoFalse{}
case CrcTrue:
return &PseudoTrue{}
case CrcNull:
return &PseudoNil{}
}
// in other ways we're trying to get object from registred crcs
var ok bool
_typ, ok = objectByCrc[crc]
if !ok {
msg, err := d.DumpWithoutRead()
if err != nil {
return nil
}
d.err = &ErrRegisteredObjectNotFound{
Crc: crc,
Data: msg,
}
return nil
}
o := reflect.New(_typ.Elem()).Interface().(Object)
if m, ok := o.(Unmarshaler); ok {
err := m.UnmarshalTL(d)
if err != nil {
d.err = err
return nil
}
return o
}
if _, isEnum := enumCrcs[crc]; !isEnum {
d.decodeObject(o, true)
if d.err != nil {
d.err = errors.Wrapf(d.err, "decode registered object %T", o)
return nil
}
}
return o
}