/*
 * 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.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Deque;
import java.util.Iterator;

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 ForwardingDeque forward indiscriminately to the methods of the delegate. For example, overriding ForwardingCollection.add alone will not change the behavior of ForwardingQueue.offer which can lead to unexpected behavior. In this case, you should override offer as well. 
default method warning: This class does not forward calls to 
default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingDeque. 
Author:
Kurt Alfred Kluever
Since:
12.0/**
 * 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 <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingDeque} forward <b>indiscriminately</b> to the
 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the
 * behavior of {@link #offer} which can lead to unexpected behavior. In this case, you should
 * override {@code offer} as well.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> 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
 */
@GwtIncompatible
public abstract class ForwardingDeque<E> extends ForwardingQueue<E> implements Deque<E> {

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

  @Override
  protected abstract Deque<E> delegate();

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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