goext/reflectext/primitiveStringSerializer.go
2023-06-07 17:45:45 +02:00

93 lines
2.4 KiB
Go

package reflectext
import (
"errors"
"fmt"
"gogs.mikescher.com/BlackForestBytes/goext/langext"
"reflect"
)
// PrimitiveStringSerializer is used to serialize primitive types (and a few more) from and to string
// This is not really intended to be user facing, and more as a simple building block for other mechanisms
// supports:
// - golang primitives (ints, uints, floats, bool, string)
// - type aliases
// - time.Time
// - primitive.ObjectID
type PrimitiveStringSerializer struct{}
func (pss PrimitiveStringSerializer) ValueToString(v any) (string, error) {
inType := reflect.TypeOf(v)
if inType.Kind() == reflect.Ptr && langext.IsNil(v) {
return "", nil
}
if inType.Kind() == reflect.Ptr {
rval1 := reflect.ValueOf(v)
rval2 := rval1.Elem()
rval3 := rval2.Interface()
return pss.ValueToString(rval3)
}
if conv, ok := primitiveSerializer[inType]; ok {
return conv.ToString(v)
}
for convType, conv := range primitiveSerializer {
if castV, ok := TryCastType(v, convType); ok {
return conv.ToString(castV)
}
}
return "", errors.New(fmt.Sprintf("failed to find a matching generic <toString> conversion fo type %T", v))
}
func (pss PrimitiveStringSerializer) ValueFromString(str string, outType reflect.Type) (any, error) {
if outType.Kind() == reflect.Ptr && str == "" {
return reflect.Zero(outType).Interface(), nil // = nil.(outType), nil
}
if str == "" {
return reflect.Zero(outType).Interface(), nil // = <default>(outType), nil
}
if outType.Kind() == reflect.Ptr {
innerValue, err := pss.ValueFromString(str, outType.Elem())
if err != nil {
return nil, err
}
// this weird piece of shit converts innerValue to &innerValue (while keeping types)
rval1 := reflect.ValueOf(innerValue)
rval2 := rval1.Convert(outType.Elem())
rval3 := reflect.New(outType.Elem())
rval3.Elem().Set(rval2)
rval4 := rval3.Interface()
return rval4, nil
}
if conv, ok := primitiveSerializer[outType]; ok {
return conv.FromString(str)
}
emptyResultVal := reflect.Zero(outType).Interface()
for convType, conv := range primitiveSerializer {
if _, ok := TryCastType(emptyResultVal, convType); ok {
if convVal, err := conv.FromString(str); err == nil {
if resVal, ok := TryCastType(convVal, outType); ok {
return resVal, nil
}
}
}
}
return "", errors.New(fmt.Sprintf("failed to find a matching generic <toString> conversion fo type %s", outType.String()))
}