001/* 002 * Copyright (C) 2012 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.reflect; 016 017import com.google.errorprone.annotations.CanIgnoreReturnValue; 018import com.google.errorprone.annotations.DoNotMock; 019import java.util.Map; 020import javax.annotation.CheckForNull; 021import org.checkerframework.checker.nullness.qual.NonNull; 022import org.checkerframework.checker.nullness.qual.Nullable; 023 024/** 025 * A map, each entry of which maps a {@link TypeToken} to an instance of that type. In addition to 026 * implementing {@code Map}, the additional type-safe operations {@link #putInstance} and {@link 027 * #getInstance} are available. 028 * 029 * <p>Generally, implementations don't support {@link #put} and {@link #putAll} because there is no 030 * way to check an object at runtime to be an instance of a {@link TypeToken}. Instead, caller 031 * should use the type safe {@link #putInstance}. 032 * 033 * <p>Also, if caller suppresses unchecked warnings and passes in an {@code Iterable<String>} for 034 * type {@code Iterable<Integer>}, the map won't be able to detect and throw type error. 035 * 036 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types, 037 * and a primitive type and its corresponding wrapper type may map to different values. 038 * 039 * @param <B> the common supertype that all entries must share; often this is simply {@link Object} 040 * @author Ben Yu 041 * @since 13.0 042 */ 043@DoNotMock("Use ImmutableTypeToInstanceMap or MutableTypeToInstanceMap") 044@ElementTypesAreNonnullByDefault 045public interface TypeToInstanceMap<B extends @Nullable Object> 046 extends Map<TypeToken<? extends @NonNull B>, B> { 047 048 /** 049 * Returns the value the specified class is mapped to, or {@code null} if no entry for this class 050 * is present. This will only return a value that was bound to this specific class, not a value 051 * that may have been bound to a subtype. 052 * 053 * <p>{@code getInstance(Foo.class)} is equivalent to {@code 054 * getInstance(TypeToken.of(Foo.class))}. 055 */ 056 @CheckForNull 057 <T extends @NonNull B> T getInstance(Class<T> type); 058 059 /** 060 * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is 061 * present. This will only return a value that was bound to this specific type, not a value that 062 * may have been bound to a subtype. 063 */ 064 @CheckForNull 065 <T extends @NonNull B> T getInstance(TypeToken<T> type); 066 067 /** 068 * Maps the specified class to the specified value. Does <i>not</i> associate this value with any 069 * of the class's supertypes. 070 * 071 * <p>{@code putInstance(Foo.class, foo)} is equivalent to {@code 072 * putInstance(TypeToken.of(Foo.class), foo)}. 073 * 074 * @return the value previously associated with this class (possibly {@code null}), or {@code 075 * null} if there was no previous entry. 076 */ 077 @CanIgnoreReturnValue 078 @CheckForNull 079 <T extends B> T putInstance(Class<@NonNull T> type, @ParametricNullness T value); 080 081 /** 082 * Maps the specified type to the specified value. Does <i>not</i> associate this value with any 083 * of the type's supertypes. 084 * 085 * @return the value previously associated with this type (possibly {@code null}), or {@code null} 086 * if there was no previous entry. 087 */ 088 @CanIgnoreReturnValue 089 @CheckForNull 090 <T extends B> T putInstance(TypeToken<@NonNull T> type, @ParametricNullness T value); 091}