001/*
002 * Copyright (C) 2007 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.collect;
018
019import com.google.common.annotations.GwtCompatible;
020import com.google.errorprone.annotations.CanIgnoreReturnValue;
021import com.google.errorprone.annotations.DoNotMock;
022import java.util.Map;
023import org.checkerframework.checker.nullness.qual.Nullable;
024
025/**
026 * A map, each entry of which maps a Java <a href="http://tinyurl.com/2cmwkz">raw type</a> to an
027 * instance of that type. In addition to implementing {@code Map}, the additional type-safe
028 * operations {@link #putInstance} and {@link #getInstance} are available.
029 *
030 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
031 * and a primitive type and its corresponding wrapper type may map to different values.
032 *
033 * <p>See the Guava User Guide article on <a href=
034 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
035 * ClassToInstanceMap}</a>.
036 *
037 * <p>To map a generic type to an instance of that type, use {@link
038 * com.google.common.reflect.TypeToInstanceMap} instead.
039 *
040 * @param <B> the common supertype that all entries must share; often this is simply {@link Object}
041 * @author Kevin Bourrillion
042 * @since 2.0
043 */
044@DoNotMock("Use ImmutableClassToInstanceMap or MutableClassToInstanceMap")
045@GwtCompatible
046public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
047  /**
048   * Returns the value the specified class is mapped to, or {@code null} if no entry for this class
049   * is present. This will only return a value that was bound to this specific class, not a value
050   * that may have been bound to a subtype.
051   */
052  <T extends B> T getInstance(Class<T> type);
053
054  /**
055   * Maps the specified class to the specified value. Does <i>not</i> associate this value with any
056   * of the class's supertypes.
057   *
058   * @return the value previously associated with this class (possibly {@code null}), or {@code
059   *     null} if there was no previous entry.
060   */
061  @CanIgnoreReturnValue
062  <T extends B> T putInstance(Class<T> type, @Nullable T value);
063}