| // Copyright (c) 2015, 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. |
| |
| // Evaluation of an if-null expression e of the form e1 ?? e2 is equivalent to |
| // the evaluation of the expression ((x) => x == null ? e2 : x)(e1). |
| // |
| // Therefore, e1 should be evaluated first; if it is non-null, e2 should not |
| // be evaluated. |
| |
| import "package:expect/expect.dart"; |
| |
| bad() { |
| throw new Exception(); |
| } |
| |
| bool firstExecuted = false; |
| |
| first() { |
| firstExecuted = true; |
| return null; |
| } |
| |
| second() { |
| Expect.isTrue(firstExecuted); |
| return 2; |
| } |
| |
| main() { |
| var one = 1 as int?; |
| Expect.equals(1, one ?? bad()); |
| Expect.equals(2, first() ?? second()); |
| } |