| /* |
| * 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 java.util.Comparator; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| import java.util.SortedSet; |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| |
| /** |
| * A sorted set which forwards all its method calls to another sorted set. Subclasses should |
| * override one or more methods to modify the behavior of the backing sorted set as desired per the |
| * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. |
| * |
| * <p><b>Warning:</b> The methods of {@code ForwardingSortedSet} forward <i>indiscriminately</i> to |
| * the methods of the delegate. For example, overriding {@link #add} alone <i>will not</i> 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 ForwardingSortedSet}. |
| * |
| * <p>Each of the {@code standard} methods, where appropriate, uses the set's comparator (or the |
| * natural ordering of the elements, if there is no comparator) to test element equality. As a |
| * result, if the comparator is not consistent with equals, some of the standard implementations may |
| * violate the {@code Set} contract. |
| * |
| * <p>The {@code standard} methods and the 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 ForwardingSortedSet<E> extends ForwardingSet<E> implements SortedSet<E> { |
| |
| /** Constructor for use by subclasses. */ |
| protected ForwardingSortedSet() {} |
| |
| @Override |
| protected abstract SortedSet<E> delegate(); |
| |
| @Override |
| public Comparator<? super E> comparator() { |
| return delegate().comparator(); |
| } |
| |
| @Override |
| public E first() { |
| return delegate().first(); |
| } |
| |
| @Override |
| public SortedSet<E> headSet(E toElement) { |
| return delegate().headSet(toElement); |
| } |
| |
| @Override |
| public E last() { |
| return delegate().last(); |
| } |
| |
| @Override |
| public SortedSet<E> subSet(E fromElement, E toElement) { |
| return delegate().subSet(fromElement, toElement); |
| } |
| |
| @Override |
| public SortedSet<E> tailSet(E fromElement) { |
| return delegate().tailSet(fromElement); |
| } |
| |
| // unsafe, but worst case is a CCE is thrown, which callers will be expecting |
| @SuppressWarnings("unchecked") |
| private int unsafeCompare(@Nullable Object o1, @Nullable Object o2) { |
| Comparator<? super E> comparator = comparator(); |
| return (comparator == null) |
| ? ((Comparable<Object>) o1).compareTo(o2) |
| : ((Comparator<Object>) comparator).compare(o1, o2); |
| } |
| |
| /** |
| * A sensible definition of {@link #contains} in terms of the {@code first()} method of {@link |
| * #tailSet}. If you override {@link #tailSet}, you may wish to override {@link #contains} to |
| * forward to this implementation. |
| * |
| * @since 7.0 |
| */ |
| @Override |
| @Beta |
| protected boolean standardContains(@Nullable Object object) { |
| try { |
| // any ClassCastExceptions are caught |
| @SuppressWarnings("unchecked") |
| SortedSet<Object> self = (SortedSet<Object>) this; |
| Object ceiling = self.tailSet(object).first(); |
| return unsafeCompare(ceiling, object) == 0; |
| } catch (ClassCastException | NoSuchElementException | NullPointerException e) { |
| return false; |
| } |
| } |
| |
| /** |
| * A sensible definition of {@link #remove} in terms of the {@code iterator()} method of {@link |
| * #tailSet}. If you override {@link #tailSet}, you may wish to override {@link #remove} to |
| * forward to this implementation. |
| * |
| * @since 7.0 |
| */ |
| @Override |
| @Beta |
| protected boolean standardRemove(@Nullable Object object) { |
| try { |
| // any ClassCastExceptions are caught |
| @SuppressWarnings("unchecked") |
| SortedSet<Object> self = (SortedSet<Object>) this; |
| Iterator<Object> iterator = self.tailSet(object).iterator(); |
| if (iterator.hasNext()) { |
| Object ceiling = iterator.next(); |
| if (unsafeCompare(ceiling, object) == 0) { |
| iterator.remove(); |
| return true; |
| } |
| } |
| } catch (ClassCastException | NullPointerException e) { |
| return false; |
| } |
| return false; |
| } |
| |
| /** |
| * A sensible default implementation of {@link #subSet(Object, Object)} in terms of {@link |
| * #headSet(Object)} and {@link #tailSet(Object)}. In some situations, you may wish to override |
| * {@link #subSet(Object, Object)} to forward to this implementation. |
| * |
| * @since 7.0 |
| */ |
| @Beta |
| protected SortedSet<E> standardSubSet(E fromElement, E toElement) { |
| return tailSet(fromElement).headSet(toElement); |
| } |
| } |