Function unstringifyMapKey

docstore/driver/codec.go:631–671

Given a map key encoded as a string, and the type of the map key, convert the key into the type. For example, if we are decoding the key "3" for a map[int]interface{}, then key is "3" and keyType is reflect.Int.

(key string, keyType reflect.Type)

// For example, if we are decoding the key "3" for a map[int]interface{}, then key is "3"
// and keyType is reflect.Int.
func unstringifyMapKey(key string, keyType reflect.Type) (reflect.Value, error) {
	// This code is mostly from the middle of decodeState.object in encoding/json/decode.go.
	// Except for literalStore, which I don't understand.
	// TODO(jba): understand literalStore.
	switch {
	case keyType.Kind() == reflect.String:
		return reflect.ValueOf(key).Convert(keyType), nil
	case reflect.PtrTo(keyType).Implements(textUnmarshalerType):
		tu := reflect.New(keyType)
		if err := tu.Interface().(encoding.TextUnmarshaler).UnmarshalText([]byte(key)); err != nil {
			return reflect.Value{}, err
		}
		return tu.Elem(), nil
	case keyType.Kind() == reflect.Interface && keyType.NumMethod() == 0:
		// TODO: remove this case? encoding/json doesn't support it.
		return reflect.ValueOf(key), nil
	default:
		switch keyType.Kind() {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			n, err := strconv.ParseInt(key, 10, 64)
			if err != nil {
				return reflect.Value{}, err
			}
			if reflect.Zero(keyType).OverflowInt(n) {
				return reflect.Value{}, overflowError(n, keyType)
			}
			return reflect.ValueOf(n).Convert(keyType), nil
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
			n, err := strconv.ParseUint(key, 10, 64)
			if err != nil {
				return reflect.Value{}, err
			}
			if reflect.Zero(keyType).OverflowUint(n) {
				return reflect.Value{}, overflowError(n, keyType)
			}
			return reflect.ValueOf(n).Convert(keyType), nil
		default:
			return reflect.Value{}, gcerr.Newf(gcerr.InvalidArgument, nil, "invalid key type %s", keyType)
		}
	}
}

func decodeStruct(v reflect.Value, d Decoder) error {
	fs, err := fieldCache.Fields(v.Type())