| // Copyright (c) 2023, 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. | |
| /// A mixin for marking classes. | |
| mixin Markable { | |
| bool _isMarked = false; | |
| bool mark() { | |
| if (_isMarked) return false; | |
| _isMarked = true; | |
| return true; | |
| } | |
| bool get isMarked => _isMarked; | |
| void unmark() { | |
| _isMarked = false; | |
| } | |
| } |