/* * Copyright (C) 2012 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.collect.CollectPreconditions.checkRemove; import static com.google.common.collect.Maps.keyOrNull; import java.util.Iterator; import java.util.NavigableMap; import java.util.NavigableSet; import java.util.NoSuchElementException; import java.util.SortedMap; import com.google.common.annotations.Beta; /** * A navigable map which forwards all its method calls to another navigable map. * Subclasses should override one or more methods to modify the behavior of the * backing map as desired per the * decorator * pattern. * *

* Warning: The methods of {@code ForwardingNavigableMap} forward * indiscriminately to the methods of the delegate. For example, * overriding {@link #put} alone will not 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. * *

* Each of the {@code standard} methods uses the map'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 Map} contract. * *

* 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 Louis Wasserman * @since 12.0 */ public abstract class ForwardingNavigableMap extends ForwardingSortedMap implements NavigableMap { /** Constructor for use by subclasses. */ protected ForwardingNavigableMap() { } @Override protected abstract NavigableMap delegate(); @Override public Entry lowerEntry(K key) { return delegate().lowerEntry(key); } /** * A sensible definition of {@link #lowerEntry} in terms of the * {@code lastEntry()} of {@link #headMap(Object, boolean)}. If you override * {@code headMap}, you may wish to override {@code lowerEntry} to forward to * this implementation. */ protected Entry standardLowerEntry(K key) { return headMap(key, false).lastEntry(); } @Override public K lowerKey(K key) { return delegate().lowerKey(key); } /** * A sensible definition of {@link #lowerKey} in terms of {@code lowerEntry}. If * you override {@link #lowerEntry}, you may wish to override {@code lowerKey} * to forward to this implementation. */ protected K standardLowerKey(K key) { return keyOrNull(lowerEntry(key)); } @Override public Entry floorEntry(K key) { return delegate().floorEntry(key); } /** * A sensible definition of {@link #floorEntry} in terms of the * {@code lastEntry()} of {@link #headMap(Object, boolean)}. If you override * {@code headMap}, you may wish to override {@code floorEntry} to forward to * this implementation. */ protected Entry standardFloorEntry(K key) { return headMap(key, true).lastEntry(); } @Override public K floorKey(K key) { return delegate().floorKey(key); } /** * A sensible definition of {@link #floorKey} in terms of {@code floorEntry}. If * you override {@code floorEntry}, you may wish to override {@code floorKey} to * forward to this implementation. */ protected K standardFloorKey(K key) { return keyOrNull(floorEntry(key)); } @Override public Entry ceilingEntry(K key) { return delegate().ceilingEntry(key); } /** * A sensible definition of {@link #ceilingEntry} in terms of the * {@code firstEntry()} of {@link #tailMap(Object, boolean)}. If you override * {@code tailMap}, you may wish to override {@code ceilingEntry} to forward to * this implementation. */ protected Entry standardCeilingEntry(K key) { return tailMap(key, true).firstEntry(); } @Override public K ceilingKey(K key) { return delegate().ceilingKey(key); } /** * A sensible definition of {@link #ceilingKey} in terms of * {@code ceilingEntry}. If you override {@code ceilingEntry}, you may wish to * override {@code ceilingKey} to forward to this implementation. */ protected K standardCeilingKey(K key) { return keyOrNull(ceilingEntry(key)); } @Override public Entry higherEntry(K key) { return delegate().higherEntry(key); } /** * A sensible definition of {@link #higherEntry} in terms of the * {@code firstEntry()} of {@link #tailMap(Object, boolean)}. If you override * {@code tailMap}, you may wish to override {@code higherEntry} to forward to * this implementation. */ protected Entry standardHigherEntry(K key) { return tailMap(key, false).firstEntry(); } @Override public K higherKey(K key) { return delegate().higherKey(key); } /** * A sensible definition of {@link #higherKey} in terms of {@code higherEntry}. * If you override {@code higherEntry}, you may wish to override * {@code higherKey} to forward to this implementation. */ protected K standardHigherKey(K key) { return keyOrNull(higherEntry(key)); } @Override public Entry firstEntry() { return delegate().firstEntry(); } /** * A sensible definition of {@link #firstEntry} in terms of the * {@code iterator()} of {@link #entrySet}. If you override {@code entrySet}, * you may wish to override {@code firstEntry} to forward to this * implementation. */ protected Entry standardFirstEntry() { return Iterables.getFirst(entrySet(), null); } /** * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If * you override {@code firstEntry}, you may wish to override {@code firstKey} to * forward to this implementation. */ protected K standardFirstKey() { Entry entry = firstEntry(); if (entry == null) { throw new NoSuchElementException(); } else { return entry.getKey(); } } @Override public Entry lastEntry() { return delegate().lastEntry(); } /** * A sensible definition of {@link #lastEntry} in terms of the * {@code iterator()} of the {@link #entrySet} of {@link #descendingMap}. If you * override {@code descendingMap}, you may wish to override {@code lastEntry} to * forward to this implementation. */ protected Entry standardLastEntry() { return Iterables.getFirst(descendingMap().entrySet(), null); } /** * A sensible definition of {@link #lastKey} in terms of {@code lastEntry}. If * you override {@code lastEntry}, you may wish to override {@code lastKey} to * forward to this implementation. */ protected K standardLastKey() { Entry entry = lastEntry(); if (entry == null) { throw new NoSuchElementException(); } else { return entry.getKey(); } } @Override public Entry pollFirstEntry() { return delegate().pollFirstEntry(); } /** * A sensible definition of {@link #pollFirstEntry} in terms of the * {@code iterator} of {@code entrySet}. If you override {@code entrySet}, you * may wish to override {@code pollFirstEntry} to forward to this * implementation. */ protected Entry standardPollFirstEntry() { return Iterators.pollNext(entrySet().iterator()); } @Override public Entry pollLastEntry() { return delegate().pollLastEntry(); } /** * A sensible definition of {@link #pollFirstEntry} in terms of the * {@code iterator} of the {@code entrySet} of {@code descendingMap}. If you * override {@code descendingMap}, you may wish to override * {@code pollFirstEntry} to forward to this implementation. */ protected Entry standardPollLastEntry() { return Iterators.pollNext(descendingMap().entrySet().iterator()); } @Override public NavigableMap descendingMap() { return delegate().descendingMap(); } /** * A sensible implementation of {@link NavigableMap#descendingMap} in terms of * the methods of this {@code NavigableMap}. In many cases, you may wish to * override {@link ForwardingNavigableMap#descendingMap} to forward to this * implementation or a subclass thereof. * *

* In particular, this map iterates over entries with repeated calls to * {@link NavigableMap#lowerEntry}. If a more efficient means of iteration is * available, you may wish to override the {@code entryIterator()} method of * this class. * * @since 12.0 */ @Beta protected class StandardDescendingMap extends Maps.DescendingMap { /** Constructor for use by subclasses. */ public StandardDescendingMap() { } @Override NavigableMap forward() { return ForwardingNavigableMap.this; } @Override protected Iterator> entryIterator() { return new Iterator>() { private Entry toRemove = null; private Entry nextOrNull = forward().lastEntry(); @Override public boolean hasNext() { return nextOrNull != null; } @Override public java.util.Map.Entry next() { if (!hasNext()) { throw new NoSuchElementException(); } try { return nextOrNull; } finally { toRemove = nextOrNull; nextOrNull = forward().lowerEntry(nextOrNull.getKey()); } } @Override public void remove() { checkRemove(toRemove != null); forward().remove(toRemove.getKey()); toRemove = null; } }; } } @Override public NavigableSet navigableKeySet() { return delegate().navigableKeySet(); } /** * A sensible implementation of {@link NavigableMap#navigableKeySet} in terms of * the methods of this {@code NavigableMap}. In many cases, you may wish to * override {@link ForwardingNavigableMap#navigableKeySet} to forward to this * implementation or a subclass thereof. * * @since 12.0 */ @Beta protected class StandardNavigableKeySet extends Maps.NavigableKeySet { /** Constructor for use by subclasses. */ public StandardNavigableKeySet() { super(ForwardingNavigableMap.this); } } @Override public NavigableSet descendingKeySet() { return delegate().descendingKeySet(); } /** * A sensible definition of {@link #descendingKeySet} as the * {@code navigableKeySet} of {@link #descendingMap}. (The * {@link StandardDescendingMap} implementation implements * {@code navigableKeySet} on its own, so as not to cause an infinite loop.) If * you override {@code descendingMap}, you may wish to override * {@code descendingKeySet} to forward to this implementation. */ @Beta protected NavigableSet standardDescendingKeySet() { return descendingMap().navigableKeySet(); } /** * A sensible definition of {@link #subMap(Object, Object)} in terms of * {@link #subMap(Object, boolean, Object, boolean)}. If you override * {@code subMap(K, boolean, K, boolean)}, you may wish to override * {@code subMap} to forward to this implementation. */ @Override protected SortedMap standardSubMap(K fromKey, K toKey) { return subMap(fromKey, true, toKey, false); } @Override public NavigableMap subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) { return delegate().subMap(fromKey, fromInclusive, toKey, toInclusive); } @Override public NavigableMap headMap(K toKey, boolean inclusive) { return delegate().headMap(toKey, inclusive); } @Override public NavigableMap tailMap(K fromKey, boolean inclusive) { return delegate().tailMap(fromKey, inclusive); } /** * A sensible definition of {@link #headMap(Object)} in terms of * {@link #headMap(Object, boolean)}. If you override * {@code headMap(K, boolean)}, you may wish to override {@code headMap} to * forward to this implementation. */ protected SortedMap standardHeadMap(K toKey) { return headMap(toKey, false); } /** * A sensible definition of {@link #tailMap(Object)} in terms of * {@link #tailMap(Object, boolean)}. If you override * {@code tailMap(K, boolean)}, you may wish to override {@code tailMap} to * forward to this implementation. */ protected SortedMap standardTailMap(K fromKey) { return tailMap(fromKey, true); } }