| // Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| // @dart = 2.9 |
| |
| /// @assertion We extend the list grammar to allow spread elements in addition to |
| /// regular elements: |
| /// listLiteral: |
| /// const? typeArguments? '[' spreadableList? ']' |
| /// ; |
| /// |
| /// spreadableList: |
| /// spreadableExpression ( ',' spreadableExpression )* ','? |
| /// ; |
| /// |
| /// spreadableExpression: |
| /// expression | |
| /// spread |
| /// ; |
| /// |
| /// spread: |
| /// ( '...' | '...?' ) expression |
| /// ; |
| /// |
| /// Instead of [expressionList], this uses a new [spreadableList] rule since |
| /// [expressionList] is used elsewhere in the grammar where spreads aren't |
| /// allowed. Each element in a list is either a normal expression or a spread |
| /// element. If the spread element starts with [...?], it's a null-aware spread |
| /// element. |
| /// @description Checks that spreadable element can be null-aware |
| /// @author iarkh@unipro.ru |
| |
| |
| import "../../Utils/expect.dart"; |
| |
| main() { |
| List list1 = null; |
| List list2 = [14, 18, 99]; |
| List list3 = [0, 2, 4, 6, 8]; |
| |
| List a; |
| |
| Expect.listEquals([], [...?list1]); |
| Expect.throws(() => a = [...list1]); |
| |
| Expect.listEquals([12], [12, ...?list1]); |
| Expect.throws(() => a = [12, ...list1]); |
| |
| Expect.listEquals([12], [...?list1, 12]); |
| Expect.throws(() => a = [...list1, 12]); |
| |
| Expect.listEquals([14, 18, 99, 0, 2, 4, 6, 8], |
| [14, 18, 99, ...?list1, 0, 2, 4, 6, 8]); |
| Expect.throws(() => a = [...list2, ...list1, ...list3]); |
| } |