147 lines
3.4 KiB
Go
147 lines
3.4 KiB
Go
// Copyright © 2016 Abcum Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package bytes
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import (
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"encoding"
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"encoding/binary"
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"errors"
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"io"
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"reflect"
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)
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type Decoder struct {
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Order binary.ByteOrder
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r *reader
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}
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func NewDecoder(r io.Reader) *Decoder {
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return &Decoder{
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Order: binary.BigEndian,
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r: &reader{r},
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}
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}
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func (d *Decoder) Decode(v interface{}) (err error) {
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// Check if the type implements the encoding.BinaryUnmarshaler interface, and use it if so.
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if i, ok := v.(encoding.BinaryUnmarshaler); ok {
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var l uint64
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if l, err = binary.ReadUvarint(d.r); err != nil {
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return
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}
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buf := make([]byte, l)
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_, err = d.r.Read(buf)
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return i.UnmarshalBinary(buf)
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}
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// Otherwise, use reflection.
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rv := reflect.Indirect(reflect.ValueOf(v))
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if !rv.CanAddr() {
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return errors.New("binary: can only Decode to pointer type")
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}
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t := rv.Type()
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switch t.Kind() {
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case reflect.Array:
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len := t.Len()
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for i := 0; i < int(len); i++ {
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if err = d.Decode(rv.Index(i).Addr().Interface()); err != nil {
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return
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}
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}
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case reflect.Slice:
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var l uint64
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if l, err = binary.ReadUvarint(d.r); err != nil {
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return
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}
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if t.Kind() == reflect.Slice {
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rv.Set(reflect.MakeSlice(t, int(l), int(l)))
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} else if int(l) != t.Len() {
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return errors.New("binary: encoded size != real size")
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}
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for i := 0; i < int(l); i++ {
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if err = d.Decode(rv.Index(i).Addr().Interface()); err != nil {
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return
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}
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}
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case reflect.Struct:
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l := rv.NumField()
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for i := 0; i < l; i++ {
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if v := rv.Field(i); v.CanSet() && t.Field(i).Name != "_" {
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if err = d.Decode(v.Addr().Interface()); err != nil {
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return
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}
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}
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}
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case reflect.Map:
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var l uint64
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if l, err = binary.ReadUvarint(d.r); err != nil {
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return
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}
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kt := t.Key()
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vt := t.Elem()
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rv.Set(reflect.MakeMap(t))
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for i := 0; i < int(l); i++ {
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kv := reflect.Indirect(reflect.New(kt))
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if err = d.Decode(kv.Addr().Interface()); err != nil {
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return
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}
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vv := reflect.Indirect(reflect.New(vt))
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if err = d.Decode(vv.Addr().Interface()); err != nil {
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return
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}
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rv.SetMapIndex(kv, vv)
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}
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case reflect.String:
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var l uint64
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if l, err = binary.ReadUvarint(d.r); err != nil {
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return
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}
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buf := make([]byte, l)
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_, err = d.r.Read(buf)
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rv.SetString(string(buf))
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case reflect.Bool:
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var out byte
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err = binary.Read(d.r, d.Order, &out)
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rv.SetBool(out != 0)
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case reflect.Int:
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var out int64
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err = binary.Read(d.r, d.Order, &out)
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rv.SetInt(out)
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case reflect.Uint:
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var out uint64
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err = binary.Read(d.r, d.Order, &out)
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rv.SetUint(out)
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case reflect.Int8, reflect.Uint8, reflect.Int16, reflect.Uint16,
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reflect.Int32, reflect.Uint32, reflect.Int64, reflect.Uint64,
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reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
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err = binary.Read(d.r, d.Order, v)
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default:
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return errors.New("binary: unsupported type " + t.String())
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}
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return
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}
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