001/*
002 * Copyright (C) 2012 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.reflect;
018
019import com.google.common.annotations.Beta;
020import com.google.common.collect.ForwardingMap;
021import com.google.common.collect.Maps;
022
023import java.util.Map;
024
025import javax.annotation.Nullable;
026
027/**
028 * A mutable type-to-instance map.
029 * See also {@link ImmutableTypeToInstanceMap}.
030 *
031 * @author Ben Yu
032 * @since 13.0
033 */
034@Beta
035public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
036    implements TypeToInstanceMap<B> {
037
038  private final Map<TypeToken<? extends B>, B> backingMap = Maps.newHashMap();
039
040  @Nullable
041  @Override
042  public <T extends B> T getInstance(Class<T> type) {
043    return trustedGet(TypeToken.of(type));
044  }
045
046  @Nullable
047  @Override
048  public <T extends B> T putInstance(Class<T> type, @Nullable T value) {
049    return trustedPut(TypeToken.of(type), value);
050  }
051
052  @Nullable
053  @Override
054  public <T extends B> T getInstance(TypeToken<T> type) {
055    return trustedGet(type.rejectTypeVariables());
056  }
057
058  @Nullable
059  @Override
060  public <T extends B> T putInstance(TypeToken<T> type, @Nullable T value) {
061    return trustedPut(type.rejectTypeVariables(), value);
062  }
063
064  /** Not supported. Use {@link #putInstance} instead. */
065  @Override public B put(TypeToken<? extends B> key, B value) {
066    throw new UnsupportedOperationException("Please use putInstance() instead.");
067  }
068
069  /** Not supported. Use {@link #putInstance} instead. */
070  @Override public void putAll(Map<? extends TypeToken<? extends B>, ? extends B> map) {
071    throw new UnsupportedOperationException("Please use putInstance() instead.");
072  }
073
074  @Override protected Map<TypeToken<? extends B>, B> delegate() {
075    return backingMap;
076  }
077
078  @SuppressWarnings("unchecked") // value could not get in if not a T
079  @Nullable
080  private <T extends B> T trustedPut(TypeToken<T> type, @Nullable T value) {
081    return (T) backingMap.put(type, value);
082  }
083
084  @SuppressWarnings("unchecked") // value could not get in if not a T
085  @Nullable
086  private <T extends B> T trustedGet(TypeToken<T> type) {
087    return (T) backingMap.get(type);
088  }
089}