/*
 * 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
decorator pattern.
Warning: The methods of ForwardingSortedSet 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 ForwardingSortedSet. 
Each of the 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 Set contract. 
The 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, Louis Wasserman
Since:
2.0/**
 * 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. /** 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 ForwardingCollection.contains in terms of the first() method of tailSet. If you override tailSet, you may wish to override ForwardingCollection.contains to forward to this implementation. 
Since:
7.0/**
   * 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 ForwardingCollection.remove in terms of the iterator() method of tailSet. If you override tailSet, you may wish to override ForwardingCollection.remove to forward to this implementation. 
Since:
7.0/**
   * 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 subSet(Object, Object) in terms of headSet(Object) and tailSet(Object). In some situations, you may wish to override subSet(Object, Object) to forward to this implementation. 
Since:
7.0/**
   * 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);
  }
}