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Google Collections Library is a suite of new collections and collection-related goodness for Java 5.0
/*
* Copyright (C) 2007 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect;
import java.util.HashMap;
import java.util.Map;
/**
* A mutable class-to-instance map backed by an arbitrary user-provided map.
* See also {@link ImmutableClassToInstanceMap}.
*
* @author Kevin Bourrillion
*/
public final class MutableClassToInstanceMap
extends ConstrainedMap, B>
implements ClassToInstanceMap {
/**
* Returns a new {@code MutableClassToInstanceMap} instance backed by a {@link
* HashMap} using the default initial capacity and load factor.
*/
public static MutableClassToInstanceMap create() {
return new MutableClassToInstanceMap(
new HashMap, B>());
}
/**
* Returns a new {@code MutableClassToInstanceMap} instance backed by a given
* empty {@code backingMap}. The caller surrenders control of the backing map,
* and thus should not allow any direct references to it to remain accessible.
*/
public static MutableClassToInstanceMap create(
Map, B> backingMap) {
return new MutableClassToInstanceMap(backingMap);
}
private MutableClassToInstanceMap(Map, B> delegate) {
super(delegate, VALUE_CAN_BE_CAST_TO_KEY);
}
private static final MapConstraint, Object> VALUE_CAN_BE_CAST_TO_KEY
= new MapConstraint, Object>() {
public void checkKeyValue(Class key, Object value) {
cast(key, value);
}
};
public T putInstance(Class type, T value) {
return cast(type, put(type, value));
}
public T getInstance(Class type) {
return cast(type, get(type));
}
// Default access so that ImmutableClassToInstanceMap can share it
static T cast(Class type, B value) {
// TODO: this should eventually use common.primitives.Primitives.wrap()
return wrap(type).cast(value);
}
// safe because both Long.class and long.class are of type Class
@SuppressWarnings("unchecked")
private static Class wrap(Class c) {
return c.isPrimitive() ? (Class) PRIMITIVES_TO_WRAPPERS.get(c) : c;
}
private static final Map, Class> PRIMITIVES_TO_WRAPPERS
= new ImmutableMap.Builder, Class>()
.put(boolean.class, Boolean.class)
.put(byte.class, Byte.class)
.put(char.class, Character.class)
.put(double.class, Double.class)
.put(float.class, Float.class)
.put(int.class, Integer.class)
.put(long.class, Long.class)
.put(short.class, Short.class)
.put(void.class, Void.class)
.build();
}