Apply "network nbt" format for net/packet.

examples and tests are updated

nbt/encode.go

@@ -47,9 +47,14 @@ func (e *Encoder) NetworkFormat(enable bool) {
 // expect `[]int8`, `[]int32`, `[]int64`, `[]uint8`, `[]uint32` and `[]uint64`,
 // which TagByteArray, TagIntArray and TagLongArray.
 // To force encode them as TagList, add a struct field tag.
-func (e *Encoder) Encode(v any, tagName string) error {
+func (e *Encoder) Encode(v any, tagName string) (err error) {
 	t, val := getTagType(reflect.ValueOf(v))
-	if err := writeTag(e.w, t, tagName); err != nil {
+	if e.networkFormat {
+		_, err = e.w.Write([]byte{t})
+	} else {
+		err = writeTag(e.w, t, tagName)
+	}
+	if err != nil {
 		return err
 	}
 	return e.marshal(val, t)

net/packet/packet_test.go

@@ -77,7 +77,7 @@ func ExampleMarshal_setSlot() {
 	// Output:
 	// 15 00 00 05 00
 	// 15 00 00 05 01 01 01 00
-	// 15 00 00 05 01 01 01 03 00 00 12 34 56 78
+	// 15 00 00 05 01 01 01 03 12 34 56 78
 }
 
 func BenchmarkPacket_Pack_packWithoutCompression(b *testing.B) {

net/packet/types.go

@@ -469,16 +469,15 @@ func (d *Double) ReadFrom(r io.Reader) (n int64, err error) {
 //
 // When using as [FieldDecoder], unknown fields are not allowed by default.
 // For allow unknown fields, using [NBTField] instead.
-func NBT(v any, optionalTagName ...string) Field {
-	if len(optionalTagName) > 0 {
-		return NBTField{V: v, TagName: optionalTagName[0]}
-	}
+func NBT(v any) Field {
 	return NBTField{V: v}
 }
 
+// NBTField is a NBT warpper for convert any type into a Field, allowing to be pack or unpack with network packets.
+//
+// After v1.20.2, the "network format" is used. The root tag nolonger have a tag name anymore.
 type NBTField struct {
-	TagName string
-	V       any
+	V any
 
 	AllowUnknownFields bool
 }
@@ -491,25 +490,27 @@ func (n NBTField) WriteTo(w io.Writer) (int64, error) {
 	// nbt Encode method does not count written bytes,
 	// so we warp the writer to count it.
 	cw := countingWriter{w: w}
-	err := nbt.NewEncoder(&cw).Encode(n.V, n.TagName)
+	enc := nbt.NewEncoder(&cw)
+	enc.NetworkFormat(true)
+	err := enc.Encode(n.V, "")
 	return cw.n, err
 }
 
 func (n NBTField) ReadFrom(r io.Reader) (int64, error) {
 	// LimitReader is used to count reader length
 	cr := countingReader{r: r}
-	decoder := nbt.NewDecoder(&cr)
+	dec := nbt.NewDecoder(&cr)
+	dec.NetworkFormat(true)
 	if !n.AllowUnknownFields {
-		decoder.DisallowUnknownFields()
+		dec.DisallowUnknownFields()
 	}
-	tagName, err := decoder.Decode(n.V)
+	_, err := dec.Decode(n.V)
 	if err != nil {
 		if !errors.Is(err, nbt.ErrEND) {
 			return cr.n, err
 		}
 		err = nil
 	}
-	n.TagName = tagName
 	return cr.n, nil
 }
 

net/packet/types_test.go

@@ -145,8 +145,7 @@ func ExampleNBT() {
 	p := pk.Marshal(
 		packetid.ServerboundPacketID(0),
 		//...
-		pk.NBT(send),           // without tag name
-		pk.NBT(send, "player"), // with tag name
+		pk.NBT(send),
 		//...
 	)
 	fmt.Println("Marshal:")
@@ -156,16 +155,13 @@ func ExampleNBT() {
 	_ = p.Scan(
 		//...
 		pk.NBT(&recv),
-		// pk.NBT(&recv) // The tag name are going to be ignored. To receive the tag name, pk.NBTField has to be used.
 		//...
 	)
 	fmt.Println("Scan:", recv.Name)
 
 	// Output:
 	// Marshal:
-	// 00000000  0a 00 00 08 00 04 6e 61  6d 65 00 04 54 6e 7a 65  |......name..Tnze|
-	// 00000010  00 0a 00 06 70 6c 61 79  65 72 08 00 04 6e 61 6d  |....player...nam|
-	// 00000020  65 00 04 54 6e 7a 65 00                           |e..Tnze.|
+	// 00000000  0a 08 00 04 6e 61 6d 65  00 04 54 6e 7a 65 00     |....name..Tnze.|
 	//
 	// Scan: Tnze
 }
@@ -184,7 +180,7 @@ func TestNBTField_ReadFrom(t *testing.T) {
 		pk.NBTField{V: send},
 	)
 
-	err := p.Scan(pk.NBTField{V: &recv})
+	err := p.Scan(&pk.NBTField{V: &recv})
 	if err == nil {
 		t.Errorf("should be a unknown field error here")
 	}
@@ -194,7 +190,7 @@ func TestNBTField_ReadFrom(t *testing.T) {
 		t.Errorf("disallow unknown field by default")
 	}
 
-	err = p.Scan(pk.NBTField{V: &recv, AllowUnknownFields: true})
+	err = p.Scan(&pk.NBTField{V: &recv, AllowUnknownFields: true})
 	if err != nil {
 		t.Errorf("should allow the unknown field here: %v", err)
 	}