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

Go to download
Show more of this group Show more artifacts with this name
Show all versions of guava Show documentation
Builds the guava lib. Requires the jsr305 be built first.
There is a newer version: 33.3.0-jre-r3
/*
 * Copyright (C) 2012 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 com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Deque;
import java.util.Iterator;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A deque which forwards all its method calls to another deque. Subclasses should override one or
 * more methods to modify the behavior of the backing deque as desired per the decorator pattern.
 *
 * Warning: The methods of {@code ForwardingDeque} forward indiscriminately to the
 * methods of the delegate. For example, overriding {@link #add} alone will not change the
 * behavior of {@link #offer} which can lead to unexpected behavior. In this case, you should
 * override {@code offer} as well.
 *
 * {@code default} method warning: This class does not forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingDeque}.
 *
 * @author Kurt Alfred Kluever
 * @since 12.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingDeque extends ForwardingQueue
    implements Deque {

  /** Constructor for use by subclasses. */
  protected ForwardingDeque() {}

  @Override
  protected abstract Deque delegate();

  @Override
  public void addFirst(@ParametricNullness E e) {
    delegate().addFirst(e);
  }

  @Override
  public void addLast(@ParametricNullness E e) {
    delegate().addLast(e);
  }

  @Override
  public Iterator descendingIterator() {
    return delegate().descendingIterator();
  }

  @Override
  @ParametricNullness
  public E getFirst() {
    return delegate().getFirst();
  }

  @Override
  @ParametricNullness
  public E getLast() {
    return delegate().getLast();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public boolean offerFirst(@ParametricNullness E e) {
    return delegate().offerFirst(e);
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public boolean offerLast(@ParametricNullness E e) {
    return delegate().offerLast(e);
  }

  @Override
  @CheckForNull
  public E peekFirst() {
    return delegate().peekFirst();
  }

  @Override
  @CheckForNull
  public E peekLast() {
    return delegate().peekLast();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  @CheckForNull
  public E pollFirst() {
    return delegate().pollFirst();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  @CheckForNull
  public E pollLast() {
    return delegate().pollLast();
  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E pop() {
    return delegate().pop();
  }

  @Override
  public void push(@ParametricNullness E e) {
    delegate().push(e);
  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E removeFirst() {
    return delegate().removeFirst();
  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E removeLast() {
    return delegate().removeLast();
  }

  @CanIgnoreReturnValue
  @Override
  public boolean removeFirstOccurrence(@CheckForNull Object o) {
    return delegate().removeFirstOccurrence(o);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean removeLastOccurrence(@CheckForNull Object o) {
    return delegate().removeLastOccurrence(o);
  }
}