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.primitives.Primitives;
023import com.google.errorprone.annotations.CanIgnoreReturnValue;
024import java.io.Serializable;
025import java.util.HashMap;
026import java.util.Iterator;
027import java.util.LinkedHashMap;
028import java.util.Map;
029import java.util.Set;
030
031/**
032 * A mutable class-to-instance map backed by an arbitrary user-provided map. See also {@link
033 * ImmutableClassToInstanceMap}.
034 *
035 * <p>See the Guava User Guide article on <a href=
036 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
037 * ClassToInstanceMap}</a>.
038 *
039 * @author Kevin Bourrillion
040 * @since 2.0
041 */
042@GwtIncompatible
043@SuppressWarnings("serial") // using writeReplace instead of standard serialization
044public final class MutableClassToInstanceMap<B> extends ForwardingMap<Class<? extends B>, B>
045    implements ClassToInstanceMap<B>, Serializable {
046
047  /**
048   * Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link
049   * HashMap} using the default initial capacity and load factor.
050   */
051  public static <B> MutableClassToInstanceMap<B> create() {
052    return new MutableClassToInstanceMap<B>(new HashMap<Class<? extends B>, B>());
053  }
054
055  /**
056   * Returns a new {@code MutableClassToInstanceMap} instance backed by a given
057   * empty {@code backingMap}. The caller surrenders control of the backing map,
058   * and thus should not allow any direct references to it to remain accessible.
059   */
060  public static <B> MutableClassToInstanceMap<B> create(Map<Class<? extends B>, B> backingMap) {
061    return new MutableClassToInstanceMap<B>(backingMap);
062  }
063
064  private final Map<Class<? extends B>, B> delegate;
065
066  private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) {
067    this.delegate = checkNotNull(delegate);
068  }
069
070  @Override
071  protected Map<Class<? extends B>, B> delegate() {
072    return delegate;
073  }
074
075  static <B> Entry<Class<? extends B>, B> checkedEntry(final Entry<Class<? extends B>, B> entry) {
076    return new ForwardingMapEntry<Class<? extends B>, B>() {
077      @Override
078      protected Entry<Class<? extends B>, B> delegate() {
079        return entry;
080      }
081
082      @Override
083      public B setValue(B value) {
084        return super.setValue(cast(getKey(), value));
085      }
086    };
087  }
088
089  @Override
090  public Set<Entry<Class<? extends B>, B>> entrySet() {
091    return new ForwardingSet<Entry<Class<? extends B>, B>>() {
092
093      @Override
094      protected Set<Entry<Class<? extends B>, B>> delegate() {
095        return MutableClassToInstanceMap.this.delegate().entrySet();
096      }
097
098      @Override
099      public Iterator<Entry<Class<? extends B>, B>> iterator() {
100        return new TransformedIterator<Entry<Class<? extends B>, B>, Entry<Class<? extends B>, B>>(
101            delegate().iterator()) {
102          @Override
103          Entry<Class<? extends B>, B> transform(Entry<Class<? extends B>, B> from) {
104            return checkedEntry(from);
105          }
106        };
107      }
108
109      @Override
110      public Object[] toArray() {
111        return standardToArray();
112      }
113
114      @Override
115      public <T> T[] toArray(T[] array) {
116        return standardToArray(array);
117      }
118    };
119  }
120
121  @Override
122  @CanIgnoreReturnValue
123  public B put(Class<? extends B> key, B value) {
124    return super.put(key, cast(key, value));
125  }
126
127  @Override
128  public void putAll(Map<? extends Class<? extends B>, ? extends B> map) {
129    Map<Class<? extends B>, B> copy = new LinkedHashMap<Class<? extends B>, B>(map);
130    for (Entry<? extends Class<? extends B>, B> entry : copy.entrySet()) {
131      cast(entry.getKey(), entry.getValue());
132    }
133    super.putAll(copy);
134  }
135
136  @CanIgnoreReturnValue
137  @Override
138  public <T extends B> T putInstance(Class<T> type, T value) {
139    return cast(type, put(type, value));
140  }
141
142  @Override
143  public <T extends B> T getInstance(Class<T> type) {
144    return cast(type, get(type));
145  }
146
147  @CanIgnoreReturnValue
148  private static <B, T extends B> T cast(Class<T> type, B value) {
149    return Primitives.wrap(type).cast(value);
150  }
151
152  private Object writeReplace() {
153    return new SerializedForm(delegate());
154  }
155
156  /**
157   * Serialized form of the map, to avoid serializing the constraint.
158   */
159  private static final class SerializedForm<B> implements Serializable {
160    private final Map<Class<? extends B>, B> backingMap;
161
162    SerializedForm(Map<Class<? extends B>, B> backingMap) {
163      this.backingMap = backingMap;
164    }
165
166    Object readResolve() {
167      return create(backingMap);
168    }
169
170    private static final long serialVersionUID = 0;
171  }
172}