Deep Copy

deepcopy.go

func deepCopy(rv reflect.Value) reflect.Value {
	switch rv.Kind() {
	case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128, reflect.String:
		return rv
	case reflect.Slice:
		if rv.IsNil() {
			return rv
		}
		sliceCpy := reflect.MakeSlice(rv.Type(), rv.Len(), rv.Cap())
		for i := 0; i < sliceCpy.Len(); i++ {
			sliceCpy.Index(i).Set(deepCopy(rv.Index(i)))
		}
		return sliceCpy
	case reflect.Array:
		arrCpy := reflect.New(rv.Type()).Elem()
		for i := 0; i < arrCpy.Len(); i++ {
			arrCpy.Index(i).Set(deepCopy(rv.Index(i)))
		}
		return arrCpy
	case reflect.Map:
		if rv.IsNil() {
			return rv
		}
		mapCpy := reflect.MakeMap(rv.Type())
		for _, key := range rv.MapKeys() {
			mapCpy.SetMapIndex(key, deepCopy(rv.MapIndex(key)))
		}
		return mapCpy
	case reflect.Struct:
		structCpy := reflect.New(rv.Type()).Elem()
		for i := 0; i < rv.NumField(); i++ {
			for _, r := range rv.Type().Field(i).Name {
				if !unicode.IsUpper(r) {
					panic(fmt.Sprintf("Unexported field name on type %v: %s", rv.Type(), rv.Type().Field(i).Name))
				}
				break
			}
			structCpy.Field(i).Set(deepCopy(rv.Field(i)))
		}
		return structCpy
	case reflect.Interface, reflect.Ptr:
		if rv.IsNil() {
			return rv
		}
		slice := reflect.MakeSlice(reflect.SliceOf(rv.Type()), 1, 1)
		cpy := slice.Index(0)
		cpy.Set(deepCopy(rv.Elem()))
		return cpy
	default:
		panic(fmt.Sprintf("Unimplemented kind: %v", rv.Kind()))
	}
}