/*
 * 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 com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import org.checkerframework.checker.nullness.qual.Nullable;

A list which forwards all its method calls to another list. Subclasses should override one or
more methods to modify the behavior of the backing list as desired per the decorator pattern.
This class does not implement RandomAccess. If the delegate supports random access, the ForwardingList subclass should implement the RandomAccess interface. 
Warning: The methods of ForwardingList forward indiscriminately to the methods of the delegate. For example, overriding ForwardingCollection.add alone will not change the behavior of ForwardingCollection.addAll, which can lead to unexpected behavior. In this case, you should override addAll as well, either providing your own implementation, or delegating to the provided standardAddAll method. 
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 ForwardingList. 
The standard methods and any collection views they return are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe. 
Author:
Mike Bostock, Louis Wasserman
Since:
2.0/**
 * A list which forwards all its method calls to another list. Subclasses should override one or
 * more methods to modify the behavior of the backing list as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>This class does not implement {@link java.util.RandomAccess}. If the delegate supports random
 * access, the {@code ForwardingList} subclass should implement the {@code RandomAccess} interface.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingList} 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 #addAll}, which can lead to unexpected behavior. In this case, you should
 * override {@code addAll} as well, either providing your own implementation, or delegating to the
 * provided {@code standardAddAll} method.
 *
 * <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 ForwardingList}.
 *
 * <p>The {@code standard} methods and any collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingList<E> extends ForwardingCollection<E> implements List<E> {
  // TODO(lowasser): identify places where thread safety is actually lost

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

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

  @Override
  public void add(int index, E element) {
    delegate().add(index, element);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean addAll(int index, Collection<? extends E> elements) {
    return delegate().addAll(index, elements);
  }

  @Override
  public E get(int index) {
    return delegate().get(index);
  }

  @Override
  public int indexOf(Object element) {
    return delegate().indexOf(element);
  }

  @Override
  public int lastIndexOf(Object element) {
    return delegate().lastIndexOf(element);
  }

  @Override
  public ListIterator<E> listIterator() {
    return delegate().listIterator();
  }

  @Override
  public ListIterator<E> listIterator(int index) {
    return delegate().listIterator(index);
  }

  @CanIgnoreReturnValue
  @Override
  public E remove(int index) {
    return delegate().remove(index);
  }

  @CanIgnoreReturnValue
  @Override
  public E set(int index, E element) {
    return delegate().set(index, element);
  }

  @Override
  public List<E> subList(int fromIndex, int toIndex) {
    return delegate().subList(fromIndex, toIndex);
  }

  @Override
  public boolean equals(@Nullable Object object) {
    return object == this || delegate().equals(object);
  }

  @Override
  public int hashCode() {
    return delegate().hashCode();
  }

  
A sensible default implementation of ForwardingCollection.add(Object), in terms of add(int, Object). If you override add(int, Object), you may wish to override ForwardingCollection.add(Object) to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #add(Object)}, in terms of {@link #add(int,
   * Object)}. If you override {@link #add(int, Object)}, you may wish to override {@link
   * #add(Object)} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardAdd(E element) {
    add(size(), element);
    return true;
  }

  
A sensible default implementation of addAll(int, Collection), in terms of the 
add method of listIterator(int). If you override listIterator(int), you may wish to override addAll(int, Collection) to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #addAll(int, Collection)}, in terms of the {@code
   * add} method of {@link #listIterator(int)}. If you override {@link #listIterator(int)}, you may
   * wish to override {@link #addAll(int, Collection)} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardAddAll(int index, Iterable<? extends E> elements) {
    return Lists.addAllImpl(this, index, elements);
  }

  
A sensible default implementation of indexOf, in terms of listIterator(). If you override listIterator(), you may wish to override indexOf to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #indexOf}, in terms of {@link #listIterator()}. If
   * you override {@link #listIterator()}, you may wish to override {@link #indexOf} to forward to
   * this implementation.
   *
   * @since 7.0
   */
  protected int standardIndexOf(@Nullable Object element) {
    return Lists.indexOfImpl(this, element);
  }

  
A sensible default implementation of lastIndexOf, in terms of listIterator(int). If you override listIterator(int), you may wish to override lastIndexOf to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #lastIndexOf}, in terms of {@link
   * #listIterator(int)}. If you override {@link #listIterator(int)}, you may wish to override
   * {@link #lastIndexOf} to forward to this implementation.
   *
   * @since 7.0
   */
  protected int standardLastIndexOf(@Nullable Object element) {
    return Lists.lastIndexOfImpl(this, element);
  }

  
A sensible default implementation of ForwardingCollection.iterator, in terms of listIterator(). If you override listIterator(), you may wish to override ForwardingCollection.iterator to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #iterator}, in terms of {@link #listIterator()}. If
   * you override {@link #listIterator()}, you may wish to override {@link #iterator} to forward to
   * this implementation.
   *
   * @since 7.0
   */
  protected Iterator<E> standardIterator() {
    return listIterator();
  }

  
A sensible default implementation of listIterator(), in terms of listIterator(int). If you override listIterator(int), you may wish to override listIterator() to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #listIterator()}, in terms of {@link
   * #listIterator(int)}. If you override {@link #listIterator(int)}, you may wish to override
   * {@link #listIterator()} to forward to this implementation.
   *
   * @since 7.0
   */
  protected ListIterator<E> standardListIterator() {
    return listIterator(0);
  }

  
A sensible default implementation of listIterator(int), in terms of ForwardingCollection.size, get(int), set(int, Object), add(int, Object), and remove(int). If you override any of these methods, you may wish to override listIterator(int) to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #listIterator(int)}, in terms of {@link #size},
   * {@link #get(int)}, {@link #set(int, Object)}, {@link #add(int, Object)}, and {@link
   * #remove(int)}. If you override any of these methods, you may wish to override {@link
   * #listIterator(int)} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected ListIterator<E> standardListIterator(int start) {
    return Lists.listIteratorImpl(this, start);
  }

  
A sensible default implementation of subList(int, int). If you override any other methods, you may wish to override subList(int, int) to forward to this implementation. 
Since:
7.0/**
   * A sensible default implementation of {@link #subList(int, int)}. If you override any other
   * methods, you may wish to override {@link #subList(int, int)} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected List<E> standardSubList(int fromIndex, int toIndex) {
    return Lists.subListImpl(this, fromIndex, toIndex);
  }

  
A sensible definition of equals(Object) in terms of ForwardingCollection.size and ForwardingCollection.iterator. If you override either of those methods, you may wish to override equals(Object) to forward to this implementation. 
Since:
7.0/**
   * A sensible definition of {@link #equals(Object)} in terms of {@link #size} and {@link
   * #iterator}. If you override either of those methods, you may wish to override {@link
   * #equals(Object)} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected boolean standardEquals(@Nullable Object object) {
    return Lists.equalsImpl(this, object);
  }

  
A sensible definition of hashCode in terms of ForwardingCollection.iterator. If you override ForwardingCollection.iterator, you may wish to override hashCode to forward to this implementation. 
Since:
7.0/**
   * A sensible definition of {@link #hashCode} in terms of {@link #iterator}. If you override
   * {@link #iterator}, you may wish to override {@link #hashCode} to forward to this
   * implementation.
   *
   * @since 7.0
   */
  @Beta
  protected int standardHashCode() {
    return Lists.hashCodeImpl(this);
  }
}