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.NonNull; 026import org.checkerframework.checker.nullness.qual.Nullable; 027 028/** 029 * A simplistic set which implements the bare minimum so that it can be used in tests without 030 * relying on any specific Set implementations. Slow. Explicitly allows null elements so that they 031 * can be used in the testers. 032 * 033 * @author Regina O'Dell 034 */ 035@GwtCompatible 036@ElementTypesAreNonnullByDefault 037public class MinimalSet<E extends @Nullable Object> extends MinimalCollection<E> implements Set<E> { 038 039 @SuppressWarnings("unchecked") // empty Object[] as E[] 040 public static <E extends @Nullable Object> MinimalSet<E> of(E... contents) { 041 return ofClassAndContents(Object.class, (E[]) new Object[0], Arrays.asList(contents)); 042 } 043 044 @SuppressWarnings("unchecked") // empty Object[] as E[] 045 public static <E extends @Nullable Object> MinimalSet<E> from(Collection<? extends E> contents) { 046 return ofClassAndContents(Object.class, (E[]) new Object[0], contents); 047 } 048 049 public static <E extends @Nullable Object> MinimalSet<E> ofClassAndContents( 050 Class<? super @NonNull E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) { 051 List<E> setContents = new ArrayList<>(); 052 for (E e : contents) { 053 if (!setContents.contains(e)) { 054 setContents.add(e); 055 } 056 } 057 return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents)); 058 } 059 060 private MinimalSet(Class<? super @NonNull E> type, E... contents) { 061 super(type, true, contents); 062 } 063 064 /* 065 * equals() and hashCode() are more specific in the Set contract. 066 */ 067 068 @Override 069 public boolean equals(@Nullable Object object) { 070 if (object instanceof Set) { 071 Set<?> that = (Set<?>) object; 072 return (this.size() == that.size()) && this.containsAll(that); 073 } 074 return false; 075 } 076 077 @Override 078 public int hashCode() { 079 int hashCodeSum = 0; 080 for (Object o : this) { 081 hashCodeSum += (o == null) ? 0 : o.hashCode(); 082 } 083 return hashCodeSum; 084 } 085}