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