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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 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. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 library utf.list_range; | 5 library utf.list_range; |
6 | 6 |
7 import 'dart:collection'; | 7 import 'dart:collection'; |
8 | 8 |
9 /** | 9 /** |
10 * _ListRange in an internal type used to create a lightweight Interable on a | 10 * _ListRange in an internal type used to create a lightweight Interable on a |
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41 | 41 |
42 /** | 42 /** |
43 * The ListRangeIterator provides more capabilities than a standard iterator, | 43 * The ListRangeIterator provides more capabilities than a standard iterator, |
44 * including the ability to get the current position, count remaining items, | 44 * including the ability to get the current position, count remaining items, |
45 * and move forward/backward within the iterator. | 45 * and move forward/backward within the iterator. |
46 */ | 46 */ |
47 abstract class ListRangeIterator implements Iterator<int> { | 47 abstract class ListRangeIterator implements Iterator<int> { |
48 bool moveNext(); | 48 bool moveNext(); |
49 int get current; | 49 int get current; |
50 int get position; | 50 int get position; |
51 void backup([by]); | 51 void backup([int by]); |
52 int get remaining; | 52 int get remaining; |
53 void skip([count]); | 53 void skip([int count]); |
54 } | 54 } |
55 | 55 |
56 class _ListRangeIteratorImpl implements ListRangeIterator { | 56 class _ListRangeIteratorImpl implements ListRangeIterator { |
57 final List<int> _source; | 57 final List<int> _source; |
58 int _offset; | 58 int _offset; |
59 final int _end; | 59 final int _end; |
60 | 60 |
61 _ListRangeIteratorImpl(this._source, int offset, this._end) | 61 _ListRangeIteratorImpl(this._source, int offset, this._end) |
62 : _offset = offset - 1; | 62 : _offset = offset - 1; |
63 | 63 |
64 int get current => _source[_offset]; | 64 int get current => _source[_offset]; |
65 | 65 |
66 bool moveNext() => ++_offset < _end; | 66 bool moveNext() => ++_offset < _end; |
67 | 67 |
68 int get position => _offset; | 68 int get position => _offset; |
69 | 69 |
70 void backup([int by = 1]) { | 70 void backup([int by = 1]) { |
71 _offset -= by; | 71 _offset -= by; |
72 } | 72 } |
73 | 73 |
74 int get remaining => _end - _offset - 1; | 74 int get remaining => _end - _offset - 1; |
75 | 75 |
76 void skip([int count = 1]) { | 76 void skip([int count = 1]) { |
77 _offset += count; | 77 _offset += count; |
78 } | 78 } |
79 } | 79 } |
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