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.testing;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.util.ArrayList;
22import java.util.Arrays;
23import java.util.Collection;
24import java.util.List;
25import java.util.Set;
26
27/**
28 * A simplistic set which implements the bare minimum so that it can be used in
29 * tests without relying on any specific Set implementations. Slow. Explicitly
30 * allows null elements so that they can be used in the testers.
31 *
32 * @author Regina O'Dell
33 */
34@GwtCompatible
35public class MinimalSet<E> extends MinimalCollection<E> implements Set<E> {
36
37  @SuppressWarnings("unchecked") // empty Object[] as E[]
38  public static <E> MinimalSet<E> of(E... contents) {
39    return ofClassAndContents(
40        Object.class, (E[]) new Object[0], Arrays.asList(contents));
41  }
42
43  @SuppressWarnings("unchecked") // empty Object[] as E[]
44  public static <E> MinimalSet<E> from(Collection<? extends E> contents) {
45    return ofClassAndContents(Object.class, (E[]) new Object[0], contents);
46  }
47
48  public static <E> MinimalSet<E> ofClassAndContents(
49      Class<? super E> type, E[] emptyArrayForContents,
50      Iterable<? extends E> contents) {
51    List<E> setContents = new ArrayList<E>();
52    for (E e : contents) {
53      if (!setContents.contains(e)) {
54        setContents.add(e);
55      }
56    }
57    return new MinimalSet<E>(type, setContents.toArray(emptyArrayForContents));
58  }
59
60  private MinimalSet(Class<? super E> type, E... contents) {
61    super(type, true, contents);
62  }
63
64  /*
65   * equals() and hashCode() are more specific in the Set contract.
66   */
67
68  @Override public boolean equals(Object object) {
69    if (object instanceof Set) {
70      Set<?> that = (Set<?>) object;
71      return (this.size() == that.size()) && this.containsAll(that);
72    }
73    return false;
74  }
75
76  @Override public int hashCode() {
77    int hashCodeSum = 0;
78    for (Object o : this) {
79      hashCodeSum += (o == null) ? 0 : o.hashCode();
80    }
81    return hashCodeSum;
82  }
83}
84