1/* 2 * Copyright (C) 2011 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.google.common.collect; 18 19import com.google.common.annotations.GwtCompatible; 20 21import java.util.Map; 22import java.util.Set; 23 24/** 25 * Workaround for 26 * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6312706"> 27 * EnumMap bug</a>. If you want to pass an {@code EnumMap}, with the 28 * intention of using its {@code entrySet()} method, you should 29 * wrap the {@code EnumMap} in this class instead. 30 * 31 * @author Dimitris Andreou 32 */ 33@GwtCompatible 34final class WellBehavedMap<K, V> extends ForwardingMap<K, V> { 35 private final Map<K, V> delegate; 36 private Set<Entry<K, V>> entrySet; 37 38 private WellBehavedMap(Map<K, V> delegate) { 39 this.delegate = delegate; 40 } 41 42 /** 43 * Wraps the given map into a {@code WellBehavedEntriesMap}, which 44 * intercepts its {@code entrySet()} method by taking the 45 * {@code Set<K> keySet()} and transforming it to 46 * {@code Set<Entry<K, V>>}. All other invocations are delegated as-is. 47 */ 48 static <K, V> WellBehavedMap<K, V> wrap(Map<K, V> delegate) { 49 return new WellBehavedMap<K, V>(delegate); 50 } 51 52 @Override protected Map<K, V> delegate() { 53 return delegate; 54 } 55 56 @Override public Set<Entry<K, V>> entrySet() { 57 Set<Entry<K, V>> es = entrySet; 58 if (es != null) { 59 return es; 60 } 61 return entrySet = Sets.transform( 62 delegate.keySet(), new KeyToEntryConverter<K, V>(this)); 63 } 64 65 private static class KeyToEntryConverter<K, V> 66 extends Sets.InvertibleFunction<K, Map.Entry<K, V>> { 67 final Map<K, V> map; 68 69 KeyToEntryConverter(Map<K, V> map) { 70 this.map = map; 71 } 72 73 @Override public Map.Entry<K, V> apply(final K key) { 74 return new AbstractMapEntry<K, V>() { 75 @Override public K getKey() { 76 return key; 77 } 78 @Override public V getValue() { 79 return map.get(key); 80 } 81 @Override public V setValue(V value) { 82 return map.put(key, value); 83 } 84 }; 85 } 86 87 @Override public K invert(Map.Entry<K, V> entry) { 88 return entry.getKey(); 89 } 90 } 91} 92