Add registry implement

registry/network.go

@@ -0,0 +1,46 @@
+package registry
+
+import (
+	"io"
+
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+func (reg *Registry[E]) ReadFrom(r io.Reader) (int64, error) {
+	var length pk.VarInt
+
+	n, err := length.ReadFrom(r)
+	if err != nil {
+		return n, err
+	}
+
+	reg.Clear()
+
+	var key pk.Identifier
+	var hasData pk.Boolean
+	for i := 0; i < int(length); i++ {
+		var data E
+		var n1, n2, n3 int64
+
+		n1, err = key.ReadFrom(r)
+		if err != nil {
+			return n + n1, err
+		}
+
+		n2, err = hasData.ReadFrom(r)
+		if err != nil {
+			return n + n1 + n2, err
+		}
+
+		if hasData {
+			n3, err = pk.NBTField{V:&data, AllowUnknownFields: true}.ReadFrom(r)
+			if err != nil {
+				return n + n1 + n2 + n3, err
+			}
+			reg.Put(string(key), data)
+		}
+
+		n += n1 + n2 + n3
+	}
+	return n, nil
+}