All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.common.collect.ImmutableClassToInstanceMap Maven / Gradle / Ivy

Go to download

Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more.

There is a newer version: 33.3.0-jre
Show newest version
/*
 * 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.annotations.GwtIncompatible;
import com.google.common.primitives.Primitives;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.DoNotCall;
import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import java.util.Map;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.NonNull;

/**
 * A {@link ClassToInstanceMap} whose contents will never change, with many other important
 * properties detailed at {@link ImmutableCollection}.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@Immutable(containerOf = "B")
@GwtIncompatible
@ElementTypesAreNonnullByDefault
// TODO(b/278589132): Remove the redundant "@NonNull" on B once it's no longer required by J2KT.
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}.
   *
   * 

Performance note: the instance returned is a singleton. * * @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. */ @CanIgnoreReturnValue 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 */ @CanIgnoreReturnValue 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, Object 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.buildOrThrow(); 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("rawtypes") // JDT-based J2KT Java frontend does not permit the direct cast Map rawMap = map; @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable) ImmutableClassToInstanceMap cast = (ImmutableClassToInstanceMap) rawMap; 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 @CheckForNull 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. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") @CheckForNull public T putInstance(Class type, T value) { throw new UnsupportedOperationException(); } Object readResolve() { return isEmpty() ? of() : this; } }