guava/src/com/google/common/collect/AbstractSortedSetMultimap.java

/*
 * 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.NavigableSet;
import java.util.SortedSet;
import org.checkerframework.checker.nullness.qual.Nullable;

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

  @Override
  abstract SortedSet<V> createCollection();

  @Override
  SortedSet<V> createUnmodifiableEmptyCollection() {
    return unmodifiableCollectionSubclass(createCollection());
  }

  @Override
  <E> SortedSet<E> unmodifiableCollectionSubclass(Collection<E> collection) {
    if (collection instanceof NavigableSet) {
      return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
    } else {
      return Collections.unmodifiableSortedSet((SortedSet<E>) collection);
    }
  }

  @Override
  Collection<V> wrapCollection(K key, Collection<V> collection) {
    if (collection instanceof NavigableSet) {
      return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
    } else {
      return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
    }
  }

  // Following Javadoc copied from Multimap and SortedSetMultimap.

  /**
   * Returns a collection view of all values associated with a key. If no mappings in the multimap
   * have the provided key, an empty collection is returned.
   *
   * <p>Changes to the returned collection will update the underlying multimap, and vice versa.
   *
   * <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
   * returns a {@link SortedSet}, instead of the {@link Collection} specified in the {@link
   * Multimap} interface.
   */
  @Override
  public SortedSet<V> get(@Nullable K key) {
    return (SortedSet<V>) super.get(key);
  }

  /**
   * Removes all values associated with a given key. The returned collection is immutable.
   *
   * <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
   * returns a {@link SortedSet}, instead of the {@link Collection} specified in the {@link
   * Multimap} interface.
   */
  @CanIgnoreReturnValue
  @Override
  public SortedSet<V> removeAll(@Nullable Object key) {
    return (SortedSet<V>) super.removeAll(key);
  }

  /**
   * Stores a collection of values with the same key, replacing any existing values for that key.
   * The returned collection is immutable.
   *
   * <p>Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
   * returns a {@link SortedSet}, instead of the {@link Collection} specified in the {@link
   * Multimap} interface.
   *
   * <p>Any duplicates in {@code values} will be stored in the multimap once.
   */
  @CanIgnoreReturnValue
  @Override
  public SortedSet<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
    return (SortedSet<V>) super.replaceValues(key, values);
  }

  /**
   * Returns a map view that associates each key with the corresponding values in the multimap.
   * Changes to the returned map, such as element removal, will update the underlying multimap. The
   * map does not support {@code setValue} on its entries, {@code put}, or {@code putAll}.
   *
   * <p>When passed a key that is present in the map, {@code asMap().get(Object)} has the same
   * behavior as {@link #get}, returning a live collection. When passed a key that is not present,
   * however, {@code asMap().get(Object)} returns {@code null} instead of an empty collection.
   *
   * <p>Though the method signature doesn't say so explicitly, the returned map has {@link
   * SortedSet} values.
   */
  @Override
  public Map<K, Collection<V>> asMap() {
    return super.asMap();
  }

  /**
   * {@inheritDoc}
   *
   * <p>Consequently, the values do not follow their natural ordering or the ordering of the value
   * comparator.
   */
  @Override
  public Collection<V> values() {
    return super.values();
  }

  private static final long serialVersionUID = 430848587173315748L;
}