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 * @author Kevin Bourrillion 30 * @since 2.0 (imported from Google Collections Library) 31 */ 32 public final class MutableClassToInstanceMap<B> 33 extends ConstrainedMap<Class<? extends B>, B> 34 implements ClassToInstanceMap<B> { 35 36 /** 37 * Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link 38 * HashMap} using the default initial capacity and load factor. 39 */ 40 public static <B> MutableClassToInstanceMap<B> create() { 41 return new MutableClassToInstanceMap<B>( 42 new HashMap<Class<? extends B>, B>()); 43 } 44 45 /** 46 * Returns a new {@code MutableClassToInstanceMap} instance backed by a given 47 * empty {@code backingMap}. The caller surrenders control of the backing map, 48 * and thus should not allow any direct references to it to remain accessible. 49 */ 50 public static <B> MutableClassToInstanceMap<B> create( 51 Map<Class<? extends B>, B> backingMap) { 52 return new MutableClassToInstanceMap<B>(backingMap); 53 } 54 55 private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) { 56 super(delegate, VALUE_CAN_BE_CAST_TO_KEY); 57 } 58 59 private static final MapConstraint<Class<?>, Object> VALUE_CAN_BE_CAST_TO_KEY 60 = new MapConstraint<Class<?>, Object>() { 61 @Override 62 public void checkKeyValue(Class<?> key, Object value) { 63 cast(key, value); 64 } 65 }; 66 67 @Override 68 public <T extends B> T putInstance(Class<T> type, T value) { 69 return cast(type, put(type, value)); 70 } 71 72 @Override 73 public <T extends B> T getInstance(Class<T> type) { 74 return cast(type, get(type)); 75 } 76 77 private static <B, T extends B> T cast(Class<T> type, B value) { 78 return Primitives.wrap(type).cast(value); 79 } 80 81 private static final long serialVersionUID = 0; 82 } 83
