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 static com.google.common.base.Preconditions.checkNotNull;
020
021import com.google.common.annotations.Beta;
022import com.google.common.base.Function;
023import com.google.common.collect.ForwardingMap;
024import com.google.common.collect.ForwardingMapEntry;
025import com.google.common.collect.ForwardingSet;
026import com.google.common.collect.Iterators;
027import com.google.common.collect.Maps;
028
029import java.util.Iterator;
030import java.util.Map;
031import java.util.Set;
032
033import javax.annotation.Nullable;
034
035/**
036 * A mutable type-to-instance map.
037 * See also {@link ImmutableTypeToInstanceMap}.
038 *
039 * @author Ben Yu
040 * @since 13.0
041 */
042@Beta
043public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
044    implements TypeToInstanceMap<B> {
045
046  private final Map<TypeToken<? extends B>, B> backingMap = Maps.newHashMap();
047
048  @Nullable
049  @Override
050  public <T extends B> T getInstance(Class<T> type) {
051    return trustedGet(TypeToken.of(type));
052  }
053
054  @Nullable
055  @Override
056  public <T extends B> T putInstance(Class<T> type, @Nullable T value) {
057    return trustedPut(TypeToken.of(type), value);
058  }
059
060  @Nullable
061  @Override
062  public <T extends B> T getInstance(TypeToken<T> type) {
063    return trustedGet(type.rejectTypeVariables());
064  }
065
066  @Nullable
067  @Override
068  public <T extends B> T putInstance(TypeToken<T> type, @Nullable T value) {
069    return trustedPut(type.rejectTypeVariables(), value);
070  }
071
072  /** Not supported. Use {@link #putInstance} instead. */
073  @Override public B put(TypeToken<? extends B> key, B value) {
074    throw new UnsupportedOperationException("Please use putInstance() instead.");
075  }
076
077  /** Not supported. Use {@link #putInstance} instead. */
078  @Override public void putAll(Map<? extends TypeToken<? extends B>, ? extends B> map) {
079    throw new UnsupportedOperationException("Please use putInstance() instead.");
080  }
081
082  @Override public Set<Entry<TypeToken<? extends B>, B>> entrySet() {
083    return UnmodifiableEntry.transformEntries(super.entrySet());
084  }
085
086  @Override protected Map<TypeToken<? extends B>, B> delegate() {
087    return backingMap;
088  }
089
090  @SuppressWarnings("unchecked") // value could not get in if not a T
091  @Nullable
092  private <T extends B> T trustedPut(TypeToken<T> type, @Nullable T value) {
093    return (T) backingMap.put(type, value);
094  }
095
096  @SuppressWarnings("unchecked") // value could not get in if not a T
097  @Nullable
098  private <T extends B> T trustedGet(TypeToken<T> type) {
099    return (T) backingMap.get(type);
100  }
101
102  private static final class UnmodifiableEntry<K, V> extends ForwardingMapEntry<K, V> {
103
104    private final Entry<K, V> delegate;
105
106    static <K, V> Set<Entry<K, V>> transformEntries(final Set<Entry<K, V>> entries) {
107      return new ForwardingSet<Map.Entry<K, V>>() {
108        @Override protected Set<Entry<K, V>> delegate() {
109          return entries;
110        }
111        @Override public Iterator<Entry<K, V>> iterator() {
112          return UnmodifiableEntry.transformEntries(super.iterator());
113        }
114        @Override public Object[] toArray() {
115          return standardToArray();
116        }
117        @Override public <T> T[] toArray(T[] array) {
118          return standardToArray(array);
119        }
120      };
121    }
122  
123    private static <K, V> Iterator<Entry<K, V>> transformEntries(Iterator<Entry<K, V>> entries) {
124      return Iterators.transform(entries, new Function<Entry<K, V>, Entry<K, V>>() {
125        @Override public Entry<K, V> apply(Entry<K, V> entry) {
126          return new UnmodifiableEntry<K, V>(entry);
127        }
128      });
129    }
130
131    private UnmodifiableEntry(java.util.Map.Entry<K, V> delegate) {
132      this.delegate = checkNotNull(delegate);
133    }
134
135    @Override protected Entry<K, V> delegate() {
136      return delegate;
137    }
138
139    @Override public V setValue(V value) {
140      throw new UnsupportedOperationException();
141    }
142  }
143}