xgo/objects/builtin_len.go

package objects

// len(obj object) => int
func builtinLen(args ...Object) (Object, error) {
	if len(args) != 1 {
		return nil, ErrWrongNumArguments
	}

	switch arg := args[0].(type) {
	case *Array:
		return &Int{Value: int64(len(arg.Value))}, nil
	case *ImmutableArray:
		return &Int{Value: int64(len(arg.Value))}, nil
	case *String:
		return &Int{Value: int64(len(arg.Value))}, nil
	case *Bytes:
		return &Int{Value: int64(len(arg.Value))}, nil
	case *Map:
		return &Int{Value: int64(len(arg.Value))}, nil
	case *ImmutableMap:
		return &Int{Value: int64(len(arg.Value))}, nil
	default:
		return nil, ErrInvalidArgumentType{
			Name:     "first",
			Expected: "array/string/bytes/map",
			Found:    arg.TypeName(),
		}
	}
}