OLD | NEW |
| (Empty) |
1 // Copyright (c) 2015, the Dartino project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 import 'node.dart' show | |
6 Node; | |
7 | |
8 class NodeStack { | |
9 List<Node> data = <Node>[]; | |
10 | |
11 int get size => data.length; | |
12 | |
13 // Stack interface. | |
14 void pushNode(Node node) { | |
15 data.add(node); | |
16 } | |
17 | |
18 Node popNode() { | |
19 return data.removeLast(); | |
20 } | |
21 | |
22 /// Returns the top of the stack or [null] if the stack is empty. | |
23 Node topNode() { | |
24 return data.isNotEmpty ? data.last : null; | |
25 } | |
26 } | |
27 | |
28 class Popper<T extends Node> { | |
29 NodeStack stack; | |
30 Popper(this.stack); | |
31 | |
32 T popNodeIfMatching() { | |
33 return (stack.topNode() is T) ? stack.popNode() : null; | |
34 } | |
35 | |
36 List<T> popNodesWhileMatching() { | |
37 List<T> result = <T>[]; | |
38 while (stack.topNode() is T) { | |
39 result.add(stack.popNode()); | |
40 } | |
41 return result; | |
42 } | |
43 | |
44 List<T> popNodes(int count) { | |
45 List<T> result = new List<T>(count); | |
46 assert(count <= stack.data.length); | |
47 int oldLength = stack.data.length; | |
48 int newLength = oldLength - count; | |
49 for (int i = newLength; i < oldLength; ++i) { | |
50 result[i - newLength] = stack.data[i]; | |
51 } | |
52 stack.data.length = newLength; | |
53 return result; | |
54 } | |
55 } | |
OLD | NEW |