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/*
 * Copyright (C) 2007 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;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Basic implementation of the {@link SetMultimap} interface. It's a wrapper around {@link
 * AbstractMapBasedMultimap} that converts the returned collections into {@code Sets}. The {@link
 * #createCollection} method must return a {@code Set}.
 *
 * @author Jared Levy
 */
@GwtCompatible
abstract class AbstractSetMultimap extends AbstractMapBasedMultimap
    implements SetMultimap {
  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   */
  protected AbstractSetMultimap(Map> map) {
    super(map);
  }

  @Override
  abstract Set createCollection();

  @Override
  Set createUnmodifiableEmptyCollection() {
    return Collections.emptySet();
  }

  @Override
   Collection unmodifiableCollectionSubclass(Collection collection) {
    return Collections.unmodifiableSet((Set) collection);
  }

  @Override
  Collection wrapCollection(K key, Collection collection) {
    return new WrappedSet(key, (Set) collection);
  }

  // Following Javadoc copied from SetMultimap.

  /**
   * {@inheritDoc}
   *
   * Because a {@code SetMultimap} has unique values for a given key, this method returns a
   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   */
  @Override
  public Set get(@Nullable K key) {
    return (Set) super.get(key);
  }

  /**
   * {@inheritDoc}
   *
   * 
Because a {@code SetMultimap} has unique values for a given key, this method returns a
   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   */
  @Override
  public Set> entries() {
    return (Set>) super.entries();
  }

  /**
   * {@inheritDoc}
   *
   * 
Because a {@code SetMultimap} has unique values for a given key, this method returns a
   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   */
  @CanIgnoreReturnValue
  @Override
  public Set removeAll(@Nullable Object key) {
    return (Set) super.removeAll(key);
  }

  /**
   * {@inheritDoc}
   *
   * 
Because a {@code SetMultimap} has unique values for a given key, this method returns a
   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   *
   * 
Any duplicates in {@code values} will be stored in the multimap once.
   */
  @CanIgnoreReturnValue
  @Override
  public Set replaceValues(@Nullable K key, Iterable values) {
    return (Set) super.replaceValues(key, values);
  }

  /**
   * {@inheritDoc}
   *
   * 
Though the method signature doesn't say so explicitly, the returned map has {@link Set}
   * values.
   */
  @Override
  public Map> asMap() {
    return super.asMap();
  }

  /**
   * Stores a key-value pair in the multimap.
   *
   * @param key key to store in the multimap
   * @param value value to store in the multimap
   * @return {@code true} if the method increased the size of the multimap, or {@code false} if the
   *     multimap already contained the key-value pair
   */
  @CanIgnoreReturnValue
  @Override
  public boolean put(@Nullable K key, @Nullable V value) {
    return super.put(key, value);
  }

  /**
   * Compares the specified object to this multimap for equality.
   *
   * Two {@code SetMultimap} instances are equal if, for each key, they contain the same values.
   * Equality does not depend on the ordering of keys or values.
   */
  @Override
  public boolean equals(@Nullable Object object) {
    return super.equals(object);
  }

  private static final long serialVersionUID = 7431625294878419160L;
}