| // Copyright (c) 2024, 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. |
| |
| /// Extension type that uses a list as a stack. |
| extension type LocalStack<T>(List<T> _list) { |
| /// Return `true` if the stack is not empty. |
| /// |
| /// ``` |
| /// DartDocTest(LocalStack<int>([]).hasCurrent, false) |
| /// DartDocTest(LocalStack<int>([0]).hasCurrent, true) |
| /// DartDocTest(LocalStack<int>([0, 1]).hasCurrent, true) |
| /// ``` |
| bool get hasCurrent => _list.isNotEmpty; |
| |
| /// Return the current top of the stack. |
| /// |
| /// ``` |
| /// DartDocTest(LocalStack<int>([0]).current, 0) |
| /// DartDocTest(LocalStack<int>([0, 1]).current, 1) |
| /// ``` |
| T get current => _list.last; |
| |
| /// Return `true` if the stack has more than one element. |
| /// |
| /// ``` |
| /// DartDocTest(LocalStack<int>([]).hasPrevious, false) |
| /// DartDocTest(LocalStack<int>([0]).hasPrevious, false) |
| /// DartDocTest(LocalStack<int>([0, 1]).hasPrevious, true) |
| /// ``` |
| bool get hasPrevious => _list.length > 1; |
| |
| /// Returns the second-most element on the stack. |
| /// |
| /// ``` |
| /// DartDocTest(LocalStack<int>([0, 1]).previous, 0) |
| /// DartDocTest(LocalStack<int>([0, 1, 2]).previous, 1) |
| /// ``` |
| T get previous => _list[_list.length - 2]; |
| |
| /// Puts [element] on the top of the stack. |
| /// |
| /// ``` |
| /// DartDocTest((LocalStack<int>([])..push(0)).current, 0) |
| /// DartDocTest((LocalStack<int>([])..push(0)..push(1)).current, 1) |
| /// DartDocTest( |
| /// (LocalStack<int>([])..push(0)..pop()..push(1)).hasPrevious, |
| /// false |
| /// ) |
| /// ``` |
| void push(T element) { |
| _list.add(element); |
| } |
| |
| /// Pops the top of the stack. |
| /// |
| /// ``` |
| /// DartDocTest(LocalStack<int>([0]).pop(), 0) |
| /// DartDocTest((LocalStack<int>([0, 1, 2])..pop()).pop(), 1) |
| /// ``` |
| T pop() { |
| return _list.removeLast(); |
| } |
| } |