001/*
002 * Copyright (C) 2009 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.collect.testing;
018
019import com.google.common.annotations.GwtCompatible;
020import java.util.ArrayList;
021import java.util.Arrays;
022import java.util.Collection;
023import java.util.List;
024import java.util.Set;
025import org.checkerframework.checker.nullness.qual.Nullable;
026
027/**
028 * A simplistic set which implements the bare minimum so that it can be used in tests without
029 * relying on any specific Set implementations. Slow. Explicitly allows null elements so that they
030 * can be used in the testers.
031 *
032 * @author Regina O'Dell
033 */
034@GwtCompatible
035public class MinimalSet<E> extends MinimalCollection<E> implements Set<E> {
036
037  @SuppressWarnings("unchecked") // empty Object[] as E[]
038  public static <E> MinimalSet<E> of(E... contents) {
039    return ofClassAndContents(Object.class, (E[]) new Object[0], Arrays.asList(contents));
040  }
041
042  @SuppressWarnings("unchecked") // empty Object[] as E[]
043  public static <E> MinimalSet<E> from(Collection<? extends E> contents) {
044    return ofClassAndContents(Object.class, (E[]) new Object[0], contents);
045  }
046
047  public static <E> MinimalSet<E> ofClassAndContents(
048      Class<? super E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) {
049    List<E> setContents = new ArrayList<>();
050    for (E e : contents) {
051      if (!setContents.contains(e)) {
052        setContents.add(e);
053      }
054    }
055    return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents));
056  }
057
058  private MinimalSet(Class<? super E> type, E... contents) {
059    super(type, true, contents);
060  }
061
062  /*
063   * equals() and hashCode() are more specific in the Set contract.
064   */
065
066  @Override
067  public boolean equals(@Nullable Object object) {
068    if (object instanceof Set) {
069      Set<?> that = (Set<?>) object;
070      return (this.size() == that.size()) && this.containsAll(that);
071    }
072    return false;
073  }
074
075  @Override
076  public int hashCode() {
077    int hashCodeSum = 0;
078    for (Object o : this) {
079      hashCodeSum += (o == null) ? 0 : o.hashCode();
080    }
081    return hashCodeSum;
082  }
083}