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 com.google.common.collect.MapConstraints.ConstrainedMap;
020import com.google.common.primitives.Primitives;
021
022import java.util.HashMap;
023import java.util.Map;
024
025/**
026 * A mutable class-to-instance map backed by an arbitrary user-provided map.
027 * See also {@link ImmutableClassToInstanceMap}.
028 *
029 * @author Kevin Bourrillion
030 * @since 2 (imported from Google Collections Library)
031 */
032public final class MutableClassToInstanceMap<B>
033    extends ConstrainedMap<Class<? extends B>, B>
034    implements ClassToInstanceMap<B> {
035
036  /**
037   * Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link
038   * HashMap} using the default initial capacity and load factor.
039   */
040  public static <B> MutableClassToInstanceMap<B> create() {
041    return new MutableClassToInstanceMap<B>(
042        new HashMap<Class<? extends B>, B>());
043  }
044
045  /**
046   * Returns a new {@code MutableClassToInstanceMap} instance backed by a given
047   * empty {@code backingMap}. The caller surrenders control of the backing map,
048   * and thus should not allow any direct references to it to remain accessible.
049   */
050  public static <B> MutableClassToInstanceMap<B> create(
051      Map<Class<? extends B>, B> backingMap) {
052    return new MutableClassToInstanceMap<B>(backingMap);
053  }
054
055  private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) {
056    super(delegate, VALUE_CAN_BE_CAST_TO_KEY);
057  }
058
059  private static final MapConstraint<Class<?>, Object> VALUE_CAN_BE_CAST_TO_KEY
060      = new MapConstraint<Class<?>, Object>() {
061    @Override
062    public void checkKeyValue(Class<?> key, Object value) {
063      cast(key, value);
064    }
065  };
066
067  @Override
068  public <T extends B> T putInstance(Class<T> type, T value) {
069    return cast(type, put(type, value));
070  }
071
072  @Override
073  public <T extends B> T getInstance(Class<T> type) {
074    return cast(type, get(type));
075  }
076
077  private static <B, T extends B> T cast(Class<T> type, B value) {
078    return Primitives.wrap(type).cast(value);
079  }
080
081  private static final long serialVersionUID = 0;
082}