add codec.RawMessage support

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

go.mod

@@ -1,10 +1,15 @@
 module go.unistack.org/micro-codec-xml/v3
 
-go 1.16
+go 1.21
+
+toolchain go1.23.4
 
 require (
-	github.com/imdario/mergo v0.3.13 // indirect
 	go.unistack.org/micro-proto/v3 v3.4.1
 	go.unistack.org/micro/v3 v3.10.88
-	google.golang.org/protobuf v1.34.2 // indirect
+)
+
+require (
+	github.com/google/go-cmp v0.6.0 // indirect
+	google.golang.org/protobuf v1.35.2 // indirect
 )

xml.go

@@ -40,6 +40,10 @@ func (c *xmlCodec) Marshal(v interface{}, opts ...codec.Option) ([]byte, error)
 		return m.Data, nil
 	case *pb.Frame:
 		return m.Data, nil
+	case codec.RawMessage:
+		return []byte(m), nil
+	case *codec.RawMessage:
+		return []byte(*m), nil
 	}
 
 	return xml.Marshal(v)
@@ -68,6 +72,12 @@ func (c *xmlCodec) Unmarshal(b []byte, v interface{}, opts ...codec.Option) erro
 	case *pb.Frame:
 		m.Data = b
 		return nil
+	case *codec.RawMessage:
+		*m = append((*m)[0:0], b...)
+		return nil
+	case codec.RawMessage:
+		copy(m, b)
+		return nil
 	}
 
 	return xml.Unmarshal(b, v)