1/*
2 * Copyright (C) 2012 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.List;
23
24import javax.annotation.Nullable;
25
26/**
27 * An ordering that treats all references as equals, even nulls.
28 *
29 * @author Emily Soldal
30 */
31@GwtCompatible(serializable = true)
32final class AllEqualOrdering extends Ordering<Object> implements Serializable {
33  static final AllEqualOrdering INSTANCE = new AllEqualOrdering();
34
35  @Override
36  public int compare(@Nullable Object left, @Nullable Object right) {
37    return 0;
38  }
39
40  @Override
41  public <E> List<E> sortedCopy(Iterable<E> iterable) {
42    return Lists.newArrayList(iterable);
43  }
44
45  @Override
46  public <E> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
47    return ImmutableList.copyOf(iterable);
48  }
49
50  @SuppressWarnings("unchecked")
51  @Override
52  public <S> Ordering<S> reverse() {
53    return (Ordering<S>) this;
54  }
55
56  private Object readResolve() {
57    return INSTANCE;
58  }
59
60  @Override
61  public String toString() {
62    return "Ordering.allEqual()";
63  }
64
65  private static final long serialVersionUID = 0;
66}
67