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 17 package com.google.common.collect; 18 19 import com.google.common.collect.MapConstraints.ConstrainedMap; 20 import com.google.common.primitives.Primitives; 21 22 import java.util.HashMap; 23 import java.util.Map; 24 25 /** 26 * A mutable class-to-instance map backed by an arbitrary user-provided map. 27 * See also {@link ImmutableClassToInstanceMap}. 28 * 29 * <p>See the Guava User Guide article on <a href= 30 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#ClassToInstanceMap"> 31 * {@code ClassToInstanceMap}</a>. 32 * 33 * @author Kevin Bourrillion 34 * @since 2.0 (imported from Google Collections Library) 35 */ 36 public final class MutableClassToInstanceMap<B> 37 extends ConstrainedMap<Class<? extends B>, B> 38 implements ClassToInstanceMap<B> { 39 40 /** 41 * Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link 42 * HashMap} using the default initial capacity and load factor. 43 */ create()44 public static <B> MutableClassToInstanceMap<B> create() { 45 return new MutableClassToInstanceMap<B>( 46 new HashMap<Class<? extends B>, B>()); 47 } 48 49 /** 50 * Returns a new {@code MutableClassToInstanceMap} instance backed by a given 51 * empty {@code backingMap}. The caller surrenders control of the backing map, 52 * and thus should not allow any direct references to it to remain accessible. 53 */ create( Map<Class<? extends B>, B> backingMap)54 public static <B> MutableClassToInstanceMap<B> create( 55 Map<Class<? extends B>, B> backingMap) { 56 return new MutableClassToInstanceMap<B>(backingMap); 57 } 58 MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate)59 private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) { 60 super(delegate, VALUE_CAN_BE_CAST_TO_KEY); 61 } 62 63 private static final MapConstraint<Class<?>, Object> VALUE_CAN_BE_CAST_TO_KEY 64 = new MapConstraint<Class<?>, Object>() { 65 @Override 66 public void checkKeyValue(Class<?> key, Object value) { 67 cast(key, value); 68 } 69 }; 70 71 @Override putInstance(Class<T> type, T value)72 public <T extends B> T putInstance(Class<T> type, T value) { 73 return cast(type, put(type, value)); 74 } 75 76 @Override getInstance(Class<T> type)77 public <T extends B> T getInstance(Class<T> type) { 78 return cast(type, get(type)); 79 } 80 cast(Class<T> type, B value)81 private static <B, T extends B> T cast(Class<T> type, B value) { 82 return Primitives.wrap(type).cast(value); 83 } 84 85 private static final long serialVersionUID = 0; 86 } 87