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
017 package com.google.common.reflect;
018
019 import com.google.common.annotations.Beta;
020 import com.google.common.collect.ForwardingMap;
021 import com.google.common.collect.Maps;
022
023 import java.util.Map;
024
025 import 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
035 public 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 }