Can you help me add a feature? about coven HOT 8 CLOSED

type A struct {   
    D1 int64
}

type B struct {   
    D int64
}

type mapStructConverter struct {
	*convertType
	dFieldMap          map[string]*reflect.StructField
	sEmptyMapInterface *emptyInterface
}

func newMapStructConverter(convertType *convertType) (m converter) {
	_, dFieldMap := extractFields(convertType.dstTyp, 0)
	sEmpty := reflect.New(convertType.srcTyp).Interface()
	m = &mapStructConverter{
		convertType,
		dFieldMap,
		(*emptyInterface)(unsafe.Pointer(&sEmpty)),
	}
	return
}

// convert only affects destination map with keys that source map has, the rest will remain unchanged.
// dPtr and sPtr must pointed to a non-pointer value,
// it is assured by Converter.Convert() and elemConverter.convert()
func (m *mapStructConverter) convert(dPtr, sPtr unsafe.Pointer) {
	sv := ptrToMapValue(m.sEmptyMapInterface, sPtr)
	keys := sv.MapKeys()
	for _, sKey := range keys {
		if dValTyp, ok := m.dFieldMap[sKey.String()]; ok {
			dVal := reflect.New(dValTyp.Type).Elem()
			sValPtr := valuePtr(sv.MapIndex(sKey))
			if elemConverter, ok := newElemConverter(dValTyp.Type, sv.MapIndex(sKey).Elem().Type()); ok {
				elemConverter.convert(unsafe.Pointer(dVal.UnsafeAddr()), sValPtr)
			}
		}
	}
}

func ExampleConverter_Convert2() {
	type foobar struct {
		D int
	}
	type Bar struct {
		A []int
		D int64
	}
	foo := map[string]interface{}{"A": []interface{}{1, 2, 3}, "D": 1}
	var c = NewConverter(Bar{}, map[string]interface{}{})

	bar := Bar{}
	c.Convert(&bar, foo)
	bytes, _ := json.Marshal(bar)
	fmt.Println(string(bytes))

	// Output:
	// {"A":[1,2,3],"B":{"1":"ab","2":"ba","3":"cd"},"C":6,"D":11}
}