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; 021 022/** 023 * A map, each entry of which maps a {@link TypeToken} to an instance of that type. In addition to 024 * implementing {@code Map}, the additional type-safe operations {@link #putInstance} and {@link 025 * #getInstance} are available. 026 * 027 * <p>Generally, implementations don't support {@link #put} and {@link #putAll} because there is no 028 * way to check an object at runtime to be an instance of a {@link TypeToken}. Instead, caller 029 * should use the type safe {@link #putInstance}. 030 * 031 * <p>Also, if caller suppresses unchecked warnings and passes in an {@code Iterable<String>} for 032 * type {@code Iterable<Integer>}, the map won't be able to detect and throw type error. 033 * 034 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types, 035 * and a primitive type and its corresponding wrapper type may map to different values. 036 * 037 * <p>This class's support for {@code null} requires some explanation. For details, see {@link 038 * com.google.common.collect.ClassToInstanceMap}. Its explanation applies equally well to {@code 039 * TypeToInstanceMap}. 040 * 041 * @param <B> the common supertype that all entries must share; often this is simply {@link Object} 042 * @author Ben Yu 043 * @since 13.0 044 */ 045@DoNotMock("Use ImmutableTypeToInstanceMap or MutableTypeToInstanceMap") 046@ElementTypesAreNonnullByDefault 047public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> { 048 049 /** 050 * Returns the value the specified class is mapped to, or {@code null} if no entry for this class 051 * is present. This will only return a value that was bound to this specific class, not a value 052 * that may have been bound to a subtype. 053 * 054 * <p>{@code getInstance(Foo.class)} is equivalent to {@code 055 * getInstance(TypeToken.of(Foo.class))}. 056 */ 057 @CheckForNull 058 <T extends B> T getInstance(Class<T> type); 059 060 /** 061 * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is 062 * present. This will only return a value that was bound to this specific type, not a value that 063 * may have been bound to a subtype. 064 */ 065 @CheckForNull 066 <T extends B> T getInstance(TypeToken<T> type); 067 068 /** 069 * Maps the specified class to the specified value. Does <i>not</i> associate this value with any 070 * of the class's supertypes. 071 * 072 * <p>{@code putInstance(Foo.class, foo)} is equivalent to {@code 073 * putInstance(TypeToken.of(Foo.class), foo)}. 074 * 075 * @return the value previously associated with this class (possibly {@code null}), or {@code 076 * null} if there was no previous entry. 077 */ 078 @CanIgnoreReturnValue 079 @CheckForNull 080 <T extends B> T putInstance(Class<T> type, T value); 081 082 /** 083 * Maps the specified type to the specified value. Does <i>not</i> associate this value with any 084 * of the type's supertypes. 085 * 086 * @return the value previously associated with this type (possibly {@code null}), or {@code null} 087 * if there was no previous entry. 088 */ 089 @CanIgnoreReturnValue 090 @CheckForNull 091 <T extends B> T putInstance(TypeToken<T> type, T value); 092}