1/*
2 * Copyright (C) 2007 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.collect;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.util.Map;
22
23import javax.annotation.Nullable;
24
25/**
26 * A map, each entry of which maps a Java
27 * <a href="http://tinyurl.com/2cmwkz">raw type</a> to an instance of that type.
28 * In addition to implementing {@code Map}, the additional type-safe operations
29 * {@link #putInstance} and {@link #getInstance} are available.
30 *
31 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries
32 * for primitive types, and a primitive type and its corresponding wrapper type
33 * may map to different values.
34 *
35 * <p>See the Guava User Guide article on <a href=
36 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#ClassToInstanceMap">
37 * {@code ClassToInstanceMap}</a>.
38 *
39 * <p>To map a generic type to an instance of that type, use {@link
40 * com.google.common.reflect.TypeToInstanceMap} instead.
41 *
42 * @param <B> the common supertype that all entries must share; often this is
43 *     simply {@link Object}
44 *
45 * @author Kevin Bourrillion
46 * @since 2.0 (imported from Google Collections Library)
47 */
48@GwtCompatible
49public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
50  /**
51   * Returns the value the specified class is mapped to, or {@code null} if no
52   * entry for this class is present. This will only return a value that was
53   * bound to this specific class, not a value that may have been bound to a
54   * subtype.
55   */
56  <T extends B> T getInstance(Class<T> type);
57
58  /**
59   * Maps the specified class to the specified value. Does <i>not</i> associate
60   * this value with any of the class's supertypes.
61   *
62   * @return the value previously associated with this class (possibly {@code
63   *     null}), or {@code null} if there was no previous entry.
64   */
65  <T extends B> T putInstance(Class<T> type, @Nullable T value);
66}
67