Update #0 - First Release

sources/main/java/com/google/common/collect/MutableClassToInstanceMap.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2007 The Guava Authors
+ *
+ * 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;
+
+import com.google.common.collect.MapConstraints.ConstrainedMap;
+import com.google.common.primitives.Primitives;
+
+/**
+ * A mutable class-to-instance map backed by an arbitrary user-provided map. See
+ * also {@link ImmutableClassToInstanceMap}.
+ * 
+ * <p>
+ * See the Guava User Guide article on <a href=
+ * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#ClassToInstanceMap">
+ * {@code ClassToInstanceMap}</a>.
+ *
+ * @author Kevin Bourrillion
+ * @since 2.0 (imported from Google Collections Library)
+ */
+public final class MutableClassToInstanceMap<B> extends ConstrainedMap<Class<? extends B>, B>
+		implements ClassToInstanceMap<B> {
+
+	/**
+	 * Returns a new {@code MutableClassToInstanceMap} instance backed by a
+	 * {@link HashMap} using the default initial capacity and load factor.
+	 */
+	public static <B> MutableClassToInstanceMap<B> create() {
+		return new MutableClassToInstanceMap<B>(new HashMap<Class<? extends B>, 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 <B> MutableClassToInstanceMap<B> create(Map<Class<? extends B>, B> backingMap) {
+		return new MutableClassToInstanceMap<B>(backingMap);
+	}
+
+	private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) {
+		super(delegate, VALUE_CAN_BE_CAST_TO_KEY);
+	}
+
+	private static final MapConstraint<Class<?>, Object> VALUE_CAN_BE_CAST_TO_KEY = new MapConstraint<Class<?>, Object>() {
+		@Override
+		public void checkKeyValue(Class<?> key, Object value) {
+			cast(key, value);
+		}
+	};
+
+	@Override
+	public <T extends B> T putInstance(Class<T> type, T value) {
+		return cast(type, put(type, value));
+	}
+
+	@Override
+	public <T extends B> T getInstance(Class<T> type) {
+		return cast(type, get(type));
+	}
+
+	private static <B, T extends B> T cast(Class<T> type, B value) {
+		return Primitives.wrap(type).cast(value);
+	}
+
+	private static final long serialVersionUID = 0;
+}