Created
May 20, 2024 15:59
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func HookOpaqueTypeToFromMap(from reflect.Value, to reflect.Value) (v interface{}, err error) { | |
v = from.Interface() | |
anonMapType := reflect.TypeOf(map[string]interface{}{}) | |
// Passthrough if we are not mapping to/from map[string]interface{} | |
if (to.Type() != anonMapType && from.Type() != anonMapType) || to.Type() == from.Type() { | |
return | |
} | |
otherVal, otherType := from, from.Type() | |
if to.Type() != anonMapType { //Encode | |
otherVal, otherType = to, to.Type() | |
} | |
// Get rid of indirection | |
if otherType.Kind() == reflect.Pointer { | |
otherType = otherType.Elem() | |
} | |
if otherType.Kind() != reflect.Struct { | |
return | |
} | |
exportedFields := 0 | |
for i := 0; i < otherType.NumField(); i++ { | |
f := otherType.Field(i) | |
if f.PkgPath == "" { | |
exportedFields++ | |
} | |
} | |
// Type not opaque struct | |
if exportedFields != 0 { | |
return | |
} | |
anonMapKey := "EncGOB" | |
if from.Type() != anonMapType { //Encode | |
var encoded interface{} | |
if m := otherVal.MethodByName("GobEncode"); !m.IsZero() { | |
res := m.Call([]reflect.Value{}) | |
if res[1].IsNil() { | |
encoded = res[0].Interface() | |
} | |
} | |
return map[string]interface{}{"EncGOB": encoded}, nil | |
} else { //Decode | |
t := from.MapIndex(reflect.ValueOf(anonMapKey)) | |
if t.IsZero() { | |
return | |
} | |
dst := reflect.New(otherType) | |
if m := dst.MethodByName("GobDecode"); !m.IsZero() { | |
res := m.Call([]reflect.Value{t.Elem()}) | |
if !res[0].IsNil() { | |
return nil, res[0].Interface().(error) | |
} | |
} | |
return dst.Interface(), nil | |
} | |
} |
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