func transformBsoncoreDocument(registry *bsoncodec.Registry, val interface{}, mapAllowed bool, paramName string) (bsoncore.Document, error) {
if registry == nil {
registry = bson.DefaultRegistry
}
if val == nil {
return nil, ErrNilDocument
}
if bs, ok := val.([]byte); ok {
// Slight optimization so we'll just use MarshalBSON and not go through the codec machinery.
val = bson.Raw(bs)
}
if !mapAllowed {
refValue := reflect.ValueOf(val)
if refValue.Kind() == reflect.Map && refValue.Len() > 1 {
return nil, ErrMapForOrderedArgument{paramName}
}
}
// TODO(skriptble): Use a pool of these instead.
buf := make([]byte, 0, 256)
b, err := bson.MarshalAppendWithRegistry(registry, buf[:0], val)
if err != nil {
return nil, MarshalError{Value: val, Err: err}
}
return b, nil
}
Multiple conditional sort is not supported from the source code？why?