1/*
2 * Copyright (C) 2009 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.io.Serializable;
22import java.util.Collection;
23import java.util.EnumSet;
24
25/**
26 * Implementation of {@link ImmutableSet} backed by a non-empty {@link
27 * java.util.EnumSet}.
28 *
29 * @author Jared Levy
30 */
31@GwtCompatible(serializable = true, emulated = true)
32@SuppressWarnings("serial") // we're overriding default serialization
33final class ImmutableEnumSet<E extends Enum<E>> extends ImmutableSet<E> {
34  /*
35   * Notes on EnumSet and <E extends Enum<E>>:
36   *
37   * This class isn't an arbitrary ForwardingImmutableSet because we need to
38   * know that calling {@code clone()} during deserialization will return an
39   * object that no one else has a reference to, allowing us to guarantee
40   * immutability. Hence, we support only {@link EnumSet}.
41   */
42  private final transient EnumSet<E> delegate;
43
44  ImmutableEnumSet(EnumSet<E> delegate) {
45    this.delegate = delegate;
46  }
47
48  @Override boolean isPartialView() {
49    return false;
50  }
51
52  @Override public UnmodifiableIterator<E> iterator() {
53    return Iterators.unmodifiableIterator(delegate.iterator());
54  }
55
56  @Override
57  public int size() {
58    return delegate.size();
59  }
60
61  @Override public boolean contains(Object object) {
62    return delegate.contains(object);
63  }
64
65  @Override public boolean containsAll(Collection<?> collection) {
66    return delegate.containsAll(collection);
67  }
68
69  @Override public boolean isEmpty() {
70    return delegate.isEmpty();
71  }
72
73  @Override public Object[] toArray() {
74    return delegate.toArray();
75  }
76
77  @Override public <T> T[] toArray(T[] array) {
78    return delegate.toArray(array);
79  }
80
81  @Override public boolean equals(Object object) {
82    return object == this || delegate.equals(object);
83  }
84
85  private transient int hashCode;
86
87  @Override public int hashCode() {
88    int result = hashCode;
89    return (result == 0) ? hashCode = delegate.hashCode() : result;
90  }
91
92  @Override public String toString() {
93    return delegate.toString();
94  }
95
96  // All callers of the constructor are restricted to <E extends Enum<E>>.
97  @Override Object writeReplace() {
98    return new EnumSerializedForm<E>(delegate);
99  }
100
101  /*
102   * This class is used to serialize ImmutableEnumSet instances.
103   */
104  private static class EnumSerializedForm<E extends Enum<E>>
105      implements Serializable {
106    final EnumSet<E> delegate;
107    EnumSerializedForm(EnumSet<E> delegate) {
108      this.delegate = delegate;
109    }
110    Object readResolve() {
111      // EJ2 #76: Write readObject() methods defensively.
112      return new ImmutableEnumSet<E>(delegate.clone());
113    }
114    private static final long serialVersionUID = 0;
115  }
116}
117