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

/**
 * A list iterator which forwards all its method calls to another list iterator. Subclasses should
 * override one or more methods to modify the behavior of the backing iterator as desired per the decorator pattern.
 *
 * {@code default} method warning: This class forwards calls to only some {@code
 * default} methods. Specifically, it forwards calls only for methods that existed before {@code
 * default} methods were introduced. For newer methods, like {@code forEachRemaining}, it
 * inherits their default implementations. When those implementations invoke methods, they invoke
 * methods on the {@code ForwardingListIterator}.
 *
 * @author Mike Bostock
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingListIterator
    extends ForwardingIterator implements ListIterator {

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

  @Override
  protected abstract ListIterator delegate();

  @Override
  public void add(@ParametricNullness E element) {
    delegate().add(element);
  }

  @Override
  public boolean hasPrevious() {
    return delegate().hasPrevious();
  }

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

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

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

  @Override
  public void set(@ParametricNullness E element) {
    delegate().set(element);
  }
}