1/*
2 * Copyright (C) 2012 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.reflect;
18
19import static com.google.common.base.Preconditions.checkNotNull;
20
21import com.google.common.annotations.Beta;
22import com.google.common.base.Function;
23import com.google.common.collect.ForwardingMap;
24import com.google.common.collect.ForwardingMapEntry;
25import com.google.common.collect.ForwardingSet;
26import com.google.common.collect.Iterators;
27import com.google.common.collect.Maps;
28
29import java.util.Iterator;
30import java.util.Map;
31import java.util.Set;
32
33import javax.annotation.Nullable;
34
35/**
36 * A mutable type-to-instance map.
37 * See also {@link ImmutableTypeToInstanceMap}.
38 *
39 * @author Ben Yu
40 * @since 13.0
41 */
42@Beta
43public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
44    implements TypeToInstanceMap<B> {
45
46  private final Map<TypeToken<? extends B>, B> backingMap = Maps.newHashMap();
47
48  @Nullable
49  @Override
50  public <T extends B> T getInstance(Class<T> type) {
51    return trustedGet(TypeToken.of(type));
52  }
53
54  @Nullable
55  @Override
56  public <T extends B> T putInstance(Class<T> type, @Nullable T value) {
57    return trustedPut(TypeToken.of(type), value);
58  }
59
60  @Nullable
61  @Override
62  public <T extends B> T getInstance(TypeToken<T> type) {
63    return trustedGet(type.rejectTypeVariables());
64  }
65
66  @Nullable
67  @Override
68  public <T extends B> T putInstance(TypeToken<T> type, @Nullable T value) {
69    return trustedPut(type.rejectTypeVariables(), value);
70  }
71
72  /** Not supported. Use {@link #putInstance} instead. */
73  @Override public B put(TypeToken<? extends B> key, B value) {
74    throw new UnsupportedOperationException("Please use putInstance() instead.");
75  }
76
77  /** Not supported. Use {@link #putInstance} instead. */
78  @Override public void putAll(Map<? extends TypeToken<? extends B>, ? extends B> map) {
79    throw new UnsupportedOperationException("Please use putInstance() instead.");
80  }
81
82  @Override public Set<Entry<TypeToken<? extends B>, B>> entrySet() {
83    return UnmodifiableEntry.transformEntries(super.entrySet());
84  }
85
86  @Override protected Map<TypeToken<? extends B>, B> delegate() {
87    return backingMap;
88  }
89
90  @SuppressWarnings("unchecked") // value could not get in if not a T
91  @Nullable
92  private <T extends B> T trustedPut(TypeToken<T> type, @Nullable T value) {
93    return (T) backingMap.put(type, value);
94  }
95
96  @SuppressWarnings("unchecked") // value could not get in if not a T
97  @Nullable
98  private <T extends B> T trustedGet(TypeToken<T> type) {
99    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}
144