001/*
002 * Copyright (C) 2007 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;
018
019import static com.google.common.base.Preconditions.checkNotNull;
020
021import com.google.common.annotations.GwtIncompatible;
022import com.google.common.annotations.J2ktIncompatible;
023import com.google.common.primitives.Primitives;
024import com.google.errorprone.annotations.CanIgnoreReturnValue;
025import java.io.InvalidObjectException;
026import java.io.ObjectInputStream;
027import java.io.Serializable;
028import java.util.HashMap;
029import java.util.Iterator;
030import java.util.LinkedHashMap;
031import java.util.Map;
032import java.util.Set;
033import java.util.Spliterator;
034import javax.annotation.CheckForNull;
035import org.checkerframework.checker.nullness.qual.NonNull;
036import org.checkerframework.checker.nullness.qual.Nullable;
037
038/**
039 * A mutable class-to-instance map backed by an arbitrary user-provided map. See also {@link
040 * ImmutableClassToInstanceMap}.
041 *
042 * <p>See the Guava User Guide article on <a href=
043 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
044 * ClassToInstanceMap}</a>.
045 *
046 * @author Kevin Bourrillion
047 * @since 2.0
048 */
049@J2ktIncompatible
050@GwtIncompatible
051@SuppressWarnings("serial") // using writeReplace instead of standard serialization
052@ElementTypesAreNonnullByDefault
053public final class MutableClassToInstanceMap<B extends @Nullable Object>
054    extends ForwardingMap<Class<? extends @NonNull B>, B>
055    implements ClassToInstanceMap<B>, Serializable {
056
057  /**
058   * Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link HashMap} using the
059   * default initial capacity and load factor.
060   */
061  public static <B extends @Nullable Object> MutableClassToInstanceMap<B> create() {
062    return new MutableClassToInstanceMap<B>(new HashMap<Class<? extends @NonNull B>, B>());
063  }
064
065  /**
066   * Returns a new {@code MutableClassToInstanceMap} instance backed by a given empty {@code
067   * backingMap}. The caller surrenders control of the backing map, and thus should not allow any
068   * direct references to it to remain accessible.
069   */
070  public static <B extends @Nullable Object> MutableClassToInstanceMap<B> create(
071      Map<Class<? extends @NonNull B>, B> backingMap) {
072    return new MutableClassToInstanceMap<B>(backingMap);
073  }
074
075  private final Map<Class<? extends @NonNull B>, B> delegate;
076
077  private MutableClassToInstanceMap(Map<Class<? extends @NonNull B>, B> delegate) {
078    this.delegate = checkNotNull(delegate);
079  }
080
081  @Override
082  protected Map<Class<? extends @NonNull B>, B> delegate() {
083    return delegate;
084  }
085
086  /**
087   * Wraps the {@code setValue} implementation of an {@code Entry} to enforce the class constraint.
088   */
089  private static <B extends @Nullable Object> Entry<Class<? extends @NonNull B>, B> checkedEntry(
090      final Entry<Class<? extends @NonNull B>, B> entry) {
091    return new ForwardingMapEntry<Class<? extends @NonNull B>, B>() {
092      @Override
093      protected Entry<Class<? extends @NonNull B>, B> delegate() {
094        return entry;
095      }
096
097      @Override
098      @ParametricNullness
099      public B setValue(@ParametricNullness B value) {
100        cast(getKey(), value);
101        return super.setValue(value);
102      }
103    };
104  }
105
106  @Override
107  public Set<Entry<Class<? extends @NonNull B>, B>> entrySet() {
108    return new ForwardingSet<Entry<Class<? extends @NonNull B>, B>>() {
109
110      @Override
111      protected Set<Entry<Class<? extends @NonNull B>, B>> delegate() {
112        return MutableClassToInstanceMap.this.delegate().entrySet();
113      }
114
115      @Override
116      public Spliterator<Entry<Class<? extends @NonNull B>, B>> spliterator() {
117        return CollectSpliterators.map(
118            delegate().spliterator(), MutableClassToInstanceMap::checkedEntry);
119      }
120
121      @Override
122      public Iterator<Entry<Class<? extends @NonNull B>, B>> iterator() {
123        return new TransformedIterator<
124            Entry<Class<? extends @NonNull B>, B>, Entry<Class<? extends @NonNull B>, B>>(
125            delegate().iterator()) {
126          @Override
127          Entry<Class<? extends @NonNull B>, B> transform(
128              Entry<Class<? extends @NonNull B>, B> from) {
129            return checkedEntry(from);
130          }
131        };
132      }
133
134      @Override
135      public Object[] toArray() {
136        /*
137         * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
138         * can be used with collections that may contain null. This collection is a collection of
139         * non-null Entry objects (Entry objects that might contain null values but are not
140         * themselves null), so we can treat it as a plain `Object[]`.
141         */
142        @SuppressWarnings("nullness")
143        Object[] result = standardToArray();
144        return result;
145      }
146
147      @Override
148      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
149      public <T extends @Nullable Object> T[] toArray(T[] array) {
150        return standardToArray(array);
151      }
152    };
153  }
154
155  @Override
156  @CanIgnoreReturnValue
157  @CheckForNull
158  public B put(Class<? extends @NonNull B> key, @ParametricNullness B value) {
159    cast(key, value);
160    return super.put(key, value);
161  }
162
163  @Override
164  public void putAll(Map<? extends Class<? extends @NonNull B>, ? extends B> map) {
165    Map<Class<? extends @NonNull B>, B> copy = new LinkedHashMap<>(map);
166    for (Entry<? extends Class<? extends @NonNull B>, B> entry : copy.entrySet()) {
167      cast(entry.getKey(), entry.getValue());
168    }
169    super.putAll(copy);
170  }
171
172  @CanIgnoreReturnValue
173  @Override
174  @CheckForNull
175  public <T extends B> T putInstance(Class<@NonNull T> type, @ParametricNullness T value) {
176    return cast(type, put(type, value));
177  }
178
179  @Override
180  @CheckForNull
181  public <T extends @NonNull B> T getInstance(Class<T> type) {
182    return cast(type, get(type));
183  }
184
185  @CanIgnoreReturnValue
186  @CheckForNull
187  private static <T> T cast(Class<T> type, @CheckForNull Object value) {
188    return Primitives.wrap(type).cast(value);
189  }
190
191  private Object writeReplace() {
192    return new SerializedForm<>(delegate());
193  }
194
195  private void readObject(ObjectInputStream stream) throws InvalidObjectException {
196    throw new InvalidObjectException("Use SerializedForm");
197  }
198
199  /** Serialized form of the map, to avoid serializing the constraint. */
200  private static final class SerializedForm<B extends @Nullable Object> implements Serializable {
201    private final Map<Class<? extends @NonNull B>, B> backingMap;
202
203    SerializedForm(Map<Class<? extends @NonNull B>, B> backingMap) {
204      this.backingMap = backingMap;
205    }
206
207    Object readResolve() {
208      return create(backingMap);
209    }
210
211    private static final long serialVersionUID = 0;
212  }
213}