/*
    * 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 static com.google.common.base.Preconditions.checkArgument;
  
  import com.google.common.annotations.Beta;
  import com.google.common.annotations.GwtCompatible;
  
  import java.util.Comparator;
  import java.util.NoSuchElementException;
  import java.util.SortedMap;
  
  import javax.annotation.Nullable;
  
  /**
   * A sorted map which forwards all its method calls to another sorted map.
   * Subclasses should override one or more methods to modify the behavior of
   * the backing sorted map as desired per the <a
   * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
   *
   * <p><i>Warning:</i> The methods of {@code ForwardingSortedMap} forward
   * <i>indiscriminately</i> to the methods of the delegate. For example,
   * overriding {@link #put} alone <i>will not</i> change the behavior of {@link
   * #putAll}, which can lead to unexpected behavior. In this case, you should
   * override {@code putAll} as well, either providing your own implementation, or
   * delegating to the provided {@code standardPutAll} method.
   *
   * <p>Each of the {@code standard} methods, where appropriate, use the
   * comparator of the map to test equality for both keys and values, unlike
   * {@code ForwardingMap}.
   *
   * <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 (imported from Google Collections Library)
   */
  @GwtCompatible
  public abstract class ForwardingSortedMap<K, V> extends ForwardingMap<K, V>
      implements SortedMap<K, V> {
    // TODO(user): identify places where thread safety is actually lost
  
    /** Constructor for use by subclasses. */
    protected ForwardingSortedMap() {}
  
    @Override protected abstract SortedMap<K, V> delegate();
  
    @Override
    public Comparator<? super K> comparator() {
      return delegate().comparator();
    }
  
    @Override
    public K firstKey() {
      return delegate().firstKey();
    }
  
    @Override
    public SortedMap<K, V> headMap(K toKey) {
      return delegate().headMap(toKey);
    }
  
    @Override
    public K lastKey() {
      return delegate().lastKey();
    }
  
    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      return delegate().subMap(fromKey, toKey);
    }
  
    @Override
    public SortedMap<K, V> tailMap(K fromKey) {
      return delegate().tailMap(fromKey);
    }
  
    /**
     * A sensible implementation of {@link SortedMap#keySet} in terms of the methods of
     * {@code ForwardingSortedMap}. In many cases, you may wish to override
     * {@link ForwardingSortedMap#keySet} to forward to this implementation or a subclass thereof.
     *
    * @since 15.0
    */
   @Beta
   protected class StandardKeySet extends Maps.SortedKeySet<K, V> {
     /** Constructor for use by subclasses. */
     public StandardKeySet() {
       super(ForwardingSortedMap.this);
     }
   }
 
   // unsafe, but worst case is a CCE is thrown, which callers will be expecting
   @SuppressWarnings("unchecked")
   private int unsafeCompare(Object k1, Object k2) {
     Comparator<? super K> comparator = comparator();
     if (comparator == null) {
       return ((Comparable<Object>) k1).compareTo(k2);
     } else {
       return ((Comparator<Object>) comparator).compare(k1, k2);
     }
   }
 
   /**
    * A sensible definition of {@link #containsKey} in terms of the {@code
    * firstKey()} method of {@link #tailMap}. If you override {@link #tailMap},
    * you may wish to override {@link #containsKey} to forward to this
    * implementation.
    *
    * @since 7.0
    */
   @Override @Beta protected boolean standardContainsKey(@Nullable Object key) {
     try {
       // any CCE will be caught
       @SuppressWarnings("unchecked")
       SortedMap<Object, V> self = (SortedMap<Object, V>) this;
       Object ceilingKey = self.tailMap(key).firstKey();
       return unsafeCompare(ceilingKey, key) == 0;
     } catch (ClassCastException e) {
       return false;
     } catch (NoSuchElementException e) {
       return false;
     } catch (NullPointerException e) {
       return false;
     }
   }
 
   /**
    * A sensible default implementation of {@link #subMap(Object, Object)} in
    * terms of {@link #headMap(Object)} and {@link #tailMap(Object)}. In some
    * situations, you may wish to override {@link #subMap(Object, Object)} to
    * forward to this implementation.
    *
    * @since 7.0
    */
   @Beta protected SortedMap<K, V> standardSubMap(K fromKey, K toKey) {
     checkArgument(unsafeCompare(fromKey, toKey) <= 0, "fromKey must be <= toKey");
     return tailMap(fromKey).headMap(toKey);
   }
 }