| /* |
| * 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); |
| } |
| } |