| /* |
| * 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.compatqual.NullableDecl; |
| |
| /** |
| * 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. */ |
| 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(@NullableDecl Object object) { |
| return object == this || delegate().equals(object); |
| } |
| |
| @Override |
| public int hashCode() { |
| return delegate().hashCode(); |
| } |
| |
| /** |
| * 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 {@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 {@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(@NullableDecl Object element) { |
| return Lists.indexOfImpl(this, element); |
| } |
| |
| /** |
| * 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(@NullableDecl Object element) { |
| return Lists.lastIndexOfImpl(this, element); |
| } |
| |
| /** |
| * 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 {@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 {@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 {@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 {@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(@NullableDecl Object object) { |
| return Lists.equalsImpl(this, object); |
| } |
| |
| /** |
| * 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); |
| } |
| } |