/*
    * Copyright (C) 2009 The Guava Authors
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.common.collect.testing;
  
  import com.google.common.annotations.GwtCompatible;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.List;
  import java.util.Set;
  
  /**
   * A simplistic set which implements the bare minimum so that it can be used in
   * tests without relying on any specific Set implementations. Slow. Explicitly
   * allows null elements so that they can be used in the testers.
   *
   * @author Regina O'Dell
   */
  @GwtCompatible
  public class MinimalSet<E> extends MinimalCollection<E> implements Set<E> {
  
    @SuppressWarnings("unchecked") // empty Object[] as E[]
    public static <E> MinimalSet<E> of(E... contents) {
      return ofClassAndContents(
          Object.class, (E[]) new Object[0], Arrays.asList(contents));
    }
  
    @SuppressWarnings("unchecked") // empty Object[] as E[]
    public static <E> MinimalSet<E> from(Collection<? extends E> contents) {
      return ofClassAndContents(Object.class, (E[]) new Object[0], contents);
    }
  
    public static <E> MinimalSet<E> ofClassAndContents(
        Class<? super E> type, E[] emptyArrayForContents,
        Iterable<? extends E> contents) {
      List<E> setContents = new ArrayList<E>();
      for (E e : contents) {
        if (!setContents.contains(e)) {
          setContents.add(e);
        }
      }
      return new MinimalSet<E>(type, setContents.toArray(emptyArrayForContents));
    }
  
    private MinimalSet(Class<? super E> type, E... contents) {
      super(type, true, contents);
    }
  
    /*
     * equals() and hashCode() are more specific in the Set contract.
     */
  
    @Override public boolean equals(Object object) {
      if (object instanceof Set) {
        Set<?> that = (Set<?>) object;
        return (this.size() == that.size()) && this.containsAll(that);
      }
      return false;
    }
  
    @Override public int hashCode() {
      int hashCodeSum = 0;
      for (Object o : this) {
        hashCodeSum += (o == null) ? 0 : o.hashCode();
      }
      return hashCodeSum;
    }
  }