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/*
 * Copyright (C) 2009 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 static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.primitives.Primitives;

import java.io.Serializable;
import java.util.Map;

import javax.annotation.Nullable;

/**
 * A {@link ClassToInstanceMap} whose contents will never change, with many
 * other important properties detailed at {@link ImmutableCollection}.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
public final class ImmutableClassToInstanceMap extends ForwardingMap, B>
    implements ClassToInstanceMap, Serializable {

  private static final ImmutableClassToInstanceMap EMPTY =
      new ImmutableClassToInstanceMap(ImmutableMap., Object>of());

  /**
   * Returns an empty {@code ImmutableClassToInstanceMap}.
   *
   * @since 19.0
   */
  @SuppressWarnings("unchecked")
  public static  ImmutableClassToInstanceMap of() {
    return (ImmutableClassToInstanceMap) EMPTY;
  }

  /**
   * Returns an {@code ImmutableClassToInstanceMap} containing a single entry.
   *
   * @since 19.0
   */
  public static  ImmutableClassToInstanceMap of(Class type, T value) {
    ImmutableMap, B> map = ImmutableMap., B>of(type, value);
    return new ImmutableClassToInstanceMap(map);
  }

  /**
   * Returns a new builder. The generated builder is equivalent to the builder
   * created by the {@link Builder} constructor.
   */
  public static  Builder builder() {
    return new Builder();
  }

  /**
   * A builder for creating immutable class-to-instance maps. Example:
   * 
   {@code
   *
   *   static final ImmutableClassToInstanceMap HANDLERS =
   *       new ImmutableClassToInstanceMap.Builder()
   *           .put(FooHandler.class, new FooHandler())
   *           .put(BarHandler.class, new SubBarHandler())
   *           .put(Handler.class, new QuuxHandler())
   *           .build();}
* *

After invoking {@link #build()} it is still possible to add more entries * and build again. Thus each map generated by this builder will be a superset * of any map generated before it. * * @since 2.0 */ public static final class Builder { private final ImmutableMap.Builder, B> mapBuilder = ImmutableMap.builder(); /** * Associates {@code key} with {@code value} in the built map. Duplicate * keys are not allowed, and will cause {@link #build} to fail. */ public Builder put(Class key, T value) { mapBuilder.put(key, value); return this; } /** * Associates all of {@code map's} keys and values in the built map. * Duplicate keys are not allowed, and will cause {@link #build} to fail. * * @throws NullPointerException if any key or value in {@code map} is null * @throws ClassCastException if any value is not an instance of the type * specified by its key */ public Builder putAll(Map, ? extends T> map) { for (Entry, ? extends T> entry : map.entrySet()) { Class type = entry.getKey(); T value = entry.getValue(); mapBuilder.put(type, cast(type, value)); } return this; } private static T cast(Class type, B value) { return Primitives.wrap(type).cast(value); } /** * Returns a new immutable class-to-instance map containing the entries * provided to this builder. * * @throws IllegalArgumentException if duplicate keys were added */ public ImmutableClassToInstanceMap build() { ImmutableMap, B> map = mapBuilder.build(); if (map.isEmpty()) { return of(); } else { return new ImmutableClassToInstanceMap(map); } } } /** * Returns an immutable map containing the same entries as {@code map}. If * {@code map} somehow contains entries with duplicate keys (for example, if * it is a {@code SortedMap} whose comparator is not consistent with * equals), the results of this method are undefined. * *

Note: Despite what the method name suggests, if {@code map} is * an {@code ImmutableClassToInstanceMap}, no copy will actually be performed. * * @throws NullPointerException if any key or value in {@code map} is null * @throws ClassCastException if any value is not an instance of the type * specified by its key */ public static ImmutableClassToInstanceMap copyOf( Map, ? extends S> map) { if (map instanceof ImmutableClassToInstanceMap) { @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable) // Eclipse won't compile if we cast to the parameterized type. ImmutableClassToInstanceMap cast = (ImmutableClassToInstanceMap) map; return cast; } return new Builder().putAll(map).build(); } private final ImmutableMap, B> delegate; private ImmutableClassToInstanceMap(ImmutableMap, B> delegate) { this.delegate = delegate; } @Override protected Map, B> delegate() { return delegate; } @Override @SuppressWarnings("unchecked") // value could not get in if not a T @Nullable public T getInstance(Class type) { return (T) delegate.get(checkNotNull(type)); } /** * Guaranteed to throw an exception and leave the map unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @Deprecated @Override public T putInstance(Class type, T value) { throw new UnsupportedOperationException(); } Object readResolve() { return isEmpty() ? of() : this; } }