feat(pkg/scale): Use New() receiver function for construction of cu…

…stom `VaryingDataType` (#3315)
ChainSafe · Jun 13, 2023 · 9688f6c · 9688f6c
1 parent 1a34972
commit 9688f6c
Show file tree

Hide file tree

Showing 2 changed files with 55 additions and 0 deletions.
diff --git a/pkg/scale/decode.go b/pkg/scale/decode.go
@@ -344,6 +344,22 @@ func (ds *decodeState) decodeVaryingDataTypeSlice(dstv reflect.Value) (err error
 
 func (ds *decodeState) decodeCustomVaryingDataType(dstv reflect.Value) (err error) {
 	initialType := dstv.Type()
+
+	methodVal := dstv.MethodByName("New")
+	if methodVal.IsValid() && !methodVal.IsZero() {
+		if methodVal.Type().Out(0).String() != dstv.Type().String() {
+			return fmt.Errorf("%s.New() returns %s instead of %s", dstv.Type(), methodVal.Type().Out(0), dstv.Type())
+		}
+
+		values := methodVal.Call(nil)
+		if len(values) > 1 {
+			return fmt.Errorf("%s.New() returns too many values", dstv.Type())
+		} else if len(values) == 0 {
+			return fmt.Errorf("%s.New() does not return a value", dstv.Type())
+		}
+		dstv.Set(values[0])
+	}
+
 	converted := dstv.Convert(reflect.TypeOf(VaryingDataType{}))
 	tempVal := reflect.New(converted.Type())
 	tempVal.Elem().Set(converted)

diff --git a/pkg/scale/varying_data_type_test.go b/pkg/scale/varying_data_type_test.go
@@ -32,6 +32,12 @@ func mustNewVaryingDataTypeAndSet(value VaryingDataTypeValue, values ...VaryingD
 
 type customVDT VaryingDataType
 
+type customVDTWithNew VaryingDataType
+
+func (cvwn customVDTWithNew) New() customVDTWithNew {
+	return customVDTWithNew(mustNewVaryingDataType(VDTValue{}, VDTValue1{}, VDTValue2{}, VDTValue3(0)))
+}
+
 type VDTValue struct {
 	A *big.Int
 	B int
@@ -406,6 +412,39 @@ func Test_decodeState_decodeCustomVaryingDataType(t *testing.T) {
 	}
 }
 
+func Test_decodeState_decodeCustomVaryingDataTypeWithNew(t *testing.T) {
+	for _, tt := range varyingDataTypeTests {
+		t.Run(tt.name, func(t *testing.T) {
+			dst := customVDTWithNew{}
+			if err := Unmarshal(tt.want, &dst); (err != nil) != tt.wantErr {
+				t.Errorf("decodeState.unmarshal() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			dstVDT := reflect.ValueOf(tt.in).Convert(reflect.TypeOf(VaryingDataType{})).Interface().(VaryingDataType)
+			inVDT := reflect.ValueOf(tt.in).Convert(reflect.TypeOf(VaryingDataType{})).Interface().(VaryingDataType)
+			dstVDTVal, err := dstVDT.Value()
+			if err != nil {
+				t.Errorf("%v", err)
+				return
+			}
+			inVDTVal, err := inVDT.Value()
+			if err != nil {
+				t.Errorf("%v", err)
+				return
+			}
+			diff := cmp.Diff(dstVDTVal, inVDTVal,
+				cmpopts.IgnoreUnexported(big.Int{}, VDTValue2{}, MyStructWithIgnore{}))
+			if diff != "" {
+				t.Errorf("decodeState.unmarshal() = %s", diff)
+			}
+			if reflect.TypeOf(dst) != reflect.TypeOf(customVDTWithNew{}) {
+				t.Errorf("types mismatch dst: %v expected: %v", reflect.TypeOf(dst), reflect.TypeOf(customVDT{}))
+			}
+		})
+	}
+}
+
 func TestNewVaryingDataType(t *testing.T) {
 	type args struct {
 		values []VaryingDataTypeValue