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Supplement document of nbt API

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This commit is contained in:
Tnze
2021-07-06 09:41:32 +08:00
parent 870b4b1a0f
commit 08d2c03a58
4 changed files with 98 additions and 31 deletions
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24
nbt/decode.go
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@ -14,6 +14,14 @@ func Unmarshal(data []byte, v interface{}) error {
return err
}
// Decode method decodes an NBT value from the reader underline the Decoder into v.
// Internally try to handle all possible v by reflection,
// but the type of v must matches the NBT value logically.
// For example, you can decode an NBT value which root tag is TagCompound(0x0a)
// into a struct or map, but not a string.
//
// This method also return tag name of the root tag.
// In real world, it is often empty, but the API should allows you to get it when ever you want.
func (d *Decoder) Decode(v interface{}) (string, error) {
val := reflect.ValueOf(v)
if val.Kind() != reflect.Ptr {
@ -31,7 +39,7 @@ func (d *Decoder) Decode(v interface{}) (string, error) {
// We decode val not val.Elem because the NBTDecoder interface
// test must be applied at the top level of the value.
err = d.unmarshal(val, tagType, tagName)
err = d.unmarshal(val, tagType)
if err != nil {
return tagName, fmt.Errorf("nbt: fail to decode tag %q: %w", tagName, err)
}
@ -51,7 +59,7 @@ func (d *Decoder) checkCompressed(head byte) (compress string) {
// ErrEND error will be returned when reading a NBT with only Tag_End
var ErrEND = errors.New("unexpected TAG_End")
func (d *Decoder) unmarshal(val reflect.Value, tagType byte, tagName string) error {
func (d *Decoder) unmarshal(val reflect.Value, tagType byte) error {
u, val := indirect(val, tagType == TagEnd)
if u != nil {
return u.Decode(tagType, d.r)
@ -271,13 +279,13 @@ func (d *Decoder) unmarshal(val reflect.Value, tagType byte, tagName string) err
case reflect.Array:
if vl := val.Len(); vl < int(listLen) {
return fmt.Errorf(
"TagList %s has len %d, but array %v only has len %d",
tagName, listLen, val.Type(), vl)
"TagList has len %d, but array %v only has len %d",
listLen, val.Type(), vl)
}
buf = val
}
for i := 0; i < int(listLen); i++ {
if err := d.unmarshal(buf.Index(i), listType, ""); err != nil {
if err := d.unmarshal(buf.Index(i), listType); err != nil {
return err
}
}
@ -302,7 +310,7 @@ func (d *Decoder) unmarshal(val reflect.Value, tagType byte, tagName string) err
}
field := tinfo.findIndexByName(tn)
if field != -1 {
err = d.unmarshal(val.Field(field), tt, tn)
err = d.unmarshal(val.Field(field), tt)
if err != nil {
return fmt.Errorf("fail to decode tag %q: %w", tn, err)
}
@ -328,7 +336,7 @@ func (d *Decoder) unmarshal(val reflect.Value, tagType byte, tagName string) err
break
}
v := reflect.New(val.Type().Elem())
if err = d.unmarshal(v.Elem(), tt, tn); err != nil {
if err = d.unmarshal(v.Elem(), tt); err != nil {
return fmt.Errorf("fail to decode tag %q: %w", tn, err)
}
val.SetMapIndex(reflect.ValueOf(tn), v.Elem())
@ -344,7 +352,7 @@ func (d *Decoder) unmarshal(val reflect.Value, tagType byte, tagName string) err
break
}
var value interface{}
if err = d.unmarshal(reflect.ValueOf(&value).Elem(), tt, tn); err != nil {
if err = d.unmarshal(reflect.ValueOf(&value).Elem(), tt); err != nil {
return fmt.Errorf("fail to decode tag %q: %w", tn, err)
}
buf[tn] = value