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1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2014, 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 dart2js.util.emptyset; | 5 library dart2js.util.emptyset; |
6 | 6 |
7 import 'dart:collection' show IterableBase; | 7 import 'dart:collection' show IterableBase; |
8 | 8 |
9 class ImmutableEmptySet<E> extends IterableBase<E> implements Set<E> { | 9 class ImmutableEmptySet<E> extends IterableBase<E> implements Set<E> { |
10 const ImmutableEmptySet(); | 10 const ImmutableEmptySet(); |
11 | 11 |
12 get iterator => const _EmptySetIterator(); | 12 get iterator => const _EmptySetIterator(); |
13 int get length => 0; | 13 int get length => 0; |
14 bool get isEmpty => true; | 14 bool get isEmpty => true; |
15 | 15 |
16 get _immutableError => throw new UnsupportedError("EmptySet is immutable"); | 16 get _immutableError => throw new UnsupportedError("EmptySet is immutable"); |
17 | 17 |
18 bool add (E element) => _immutableError; | 18 bool add(E element) => _immutableError; |
19 void addAll(Iterable<E> elements) => _immutableError; | 19 void addAll(Iterable<E> elements) => _immutableError; |
20 | 20 |
21 E lookup(E element) => null; | 21 E lookup(E element) => null; |
22 bool remove(E element) => false; | 22 bool remove(E element) => false; |
23 void removeAll(Iterable<E> elements) {} | 23 void removeAll(Iterable<E> elements) {} |
24 void removeWhere(bool test(E element)) {} | 24 void removeWhere(bool test(E element)) {} |
25 void retainAll(Iterable<E> elements) {} | 25 void retainAll(Iterable<E> elements) {} |
26 void retainWhere(bool test(E element)) {} | 26 void retainWhere(bool test(E element)) {} |
27 void forEach(void action(E element)) {} | 27 void forEach(void action(E element)) {} |
28 void clear() {} | 28 void clear() {} |
29 | 29 |
30 bool contains(E element) => false; | 30 bool contains(E element) => false; |
31 bool containsAll(Iterable<E> other) => other.isEmpty; | 31 bool containsAll(Iterable<E> other) => other.isEmpty; |
32 | 32 |
33 Set<E> union(Set<E> other) => new Set.from(other); | 33 Set<E> union(Set<E> other) => new Set.from(other); |
34 Set<E> intersection(Set<E> other) => this; | 34 Set<E> intersection(Set<E> other) => this; |
35 Set<E> difference(Set<E> other) => this; | 35 Set<E> difference(Set<E> other) => this; |
36 Set<E> toSet() => new Set(); | 36 Set<E> toSet() => new Set(); |
37 } | 37 } |
38 | 38 |
39 class _EmptySetIterator<E> implements Iterator<E> { | 39 class _EmptySetIterator<E> implements Iterator<E> { |
40 const _EmptySetIterator(); | 40 const _EmptySetIterator(); |
41 | 41 |
42 E get current => null; | 42 E get current => null; |
43 bool moveNext() => false; | 43 bool moveNext() => false; |
44 } | 44 } |
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