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package nbt
import (
"encoding/binary"
"errors"
"github.com/kch42/kagus"
"io"
)
type Tag struct {
Type TagType
Payload interface{}
}
type TagList struct {
Type TagType
Elems []interface{}
}
type TagCompound map[string]Tag
func readTagData(r io.Reader, tt TagType) (interface{}, error) {
switch tt {
case TAG_End:
case TAG_Byte:
var v uint8
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Short:
var v int16
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Int:
var v int32
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Long:
var v int64
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Float:
var v float32
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Double:
var v float64
err := binary.Read(r, binary.BigEndian, &v)
return v, err
case TAG_Byte_Array:
var l int32
if err := binary.Read(r, binary.BigEndian, &l); err != nil {
return nil, err
}
if l < 0 {
return nil, errors.New("Byte array has negative length?")
}
data := make([]byte, l)
_, err := io.ReadFull(r, data)
return data, err
case TAG_String:
var l int16
if err := binary.Read(r, binary.BigEndian, &l); err != nil {
return nil, err
}
if l < 0 {
return nil, errors.New("String has negative length?")
}
data := make([]byte, l)
_, err := io.ReadFull(r, data)
return string(data), err
case TAG_List:
_ltt, err := kagus.ReadByte(r)
if err != nil {
return nil, err
}
ltt := TagType(_ltt)
var l int32
if err := binary.Read(r, binary.BigEndian, &l); err != nil {
return nil, err
}
if l < 0 {
return nil, errors.New("List has negative length?")
}
tl := TagList{Type: ltt, Elems: make([]interface{}, l)}
for i := 0; i < int(l); i++ {
if tl.Elems[i], err = readTagData(r, ltt); err != nil {
return nil, err
}
}
return tl, nil
case TAG_Compound:
comp := make(TagCompound)
for {
tag, name, err := ReadNamedTag(r)
if err != nil {
return nil, err
}
if tag.Type == TAG_End {
break
}
comp[name] = tag
}
return comp, nil
case TAG_Int_Array:
var l int32
if err := binary.Read(r, binary.BigEndian, &l); err != nil {
return nil, err
}
if l < 0 {
return nil, errors.New("Int Array has negative length?")
}
data := make([]int32, l)
for i := 0; i < int(l); i++ {
var e int32
if err := binary.Read(r, binary.BigEndian, &e); err != nil {
return nil, err
}
data[i] = e
}
return data, nil
}
return nil, errors.New("Unknown tag type")
}
func ReadNamedTag(r io.Reader) (Tag, string, error) {
_tt, err := kagus.ReadByte(r)
if err != nil {
return Tag{}, "", err
}
tt := TagType(_tt)
if tt == TAG_End {
return Tag{Type: tt}, "", nil
}
name, err := readTagData(r, TAG_String)
if err != nil {
return Tag{}, "", err
}
td, err := readTagData(r, tt)
return Tag{Type: tt, Payload: td}, name.(string), err
}
func writeByte(w io.Writer, b byte) error {
_, err := w.Write([]byte{b})
return err
}
func writeTagData(w io.Writer, tt TagType, data interface{}) error {
switch tt {
case TAG_End:
return nil
case TAG_Byte:
return writeByte(w, data.(byte))
case TAG_Short:
return binary.Write(w, binary.BigEndian, data.(int16))
case TAG_Int:
return binary.Write(w, binary.BigEndian, data.(int32))
case TAG_Long:
return binary.Write(w, binary.BigEndian, data.(int64))
case TAG_Float:
return binary.Write(w, binary.BigEndian, data.(float32))
case TAG_Double:
return binary.Write(w, binary.BigEndian, data.(float64))
case TAG_Byte_Array:
slice := data.([]byte)
if err := binary.Write(w, binary.BigEndian, int32(len(slice))); err != nil {
return err
}
_, err := w.Write(slice)
return err
case TAG_String:
strEnc := []byte(data.(string))
if err := binary.Write(w, binary.BigEndian, int16(len(strEnc))); err != nil {
return err
}
_, err := w.Write(strEnc)
return err
case TAG_List:
list := data.(TagList)
if err := writeByte(w, byte(list.Type)); err != nil {
return err
}
if err := binary.Write(w, binary.BigEndian, int32(len(list.Elems))); err != nil {
return err
}
for _, el := range list.Elems {
if err := writeTagData(w, list.Type, el); err != nil {
return err
}
}
return nil
case TAG_Compound:
comp := data.(TagCompound)
for name, tag := range comp {
if err := WriteNamedTag(w, name, tag); err != nil {
return err
}
}
return writeByte(w, TAG_End)
case TAG_Int_Array:
slice := data.([]int32)
if err := binary.Write(w, binary.BigEndian, int32(len(slice))); err != nil {
return err
}
for _, el := range slice {
if err := binary.Write(w, binary.BigEndian, el); err != nil {
return err
}
}
return nil
}
return errors.New("Unknown tage type")
}
func WriteNamedTag(w io.Writer, name string, tag Tag) error {
if err := writeByte(w, byte(tag.Type)); err != nil {
return err
}
if err := writeTagData(w, TAG_String, name); err != nil {
return err
}
return writeTagData(w, tag.Type, tag.Payload)
}
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