/*
* Copyright (C) 2011 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.GwtCompatible;
import java.util.Map;
import java.util.Set;
/**
* Workaround for
* <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6312706">
* EnumMap bug</a>. If you want to pass an {@code EnumMap}, with the
* intention of using its {@code entrySet()} method, you should
* wrap the {@code EnumMap} in this class instead.
*
* @author Dimitris Andreou
*/
@GwtCompatible
final class WellBehavedMap<K, V> extends ForwardingMap<K, V> {
private final Map<K, V> delegate;
private Set<Entry<K, V>> entrySet;
private WellBehavedMap(Map<K, V> delegate) {
this.delegate = delegate;
}
/**
* Wraps the given map into a {@code WellBehavedEntriesMap}, which
* intercepts its {@code entrySet()} method by taking the
* {@code Set<K> keySet()} and transforming it to
* {@code Set<Entry<K, V>>}. All other invocations are delegated as-is.
*/
static <K, V> WellBehavedMap<K, V> wrap(Map<K, V> delegate) {
return new WellBehavedMap<K, V>(delegate);
}
@Override protected Map<K, V> delegate() {
return delegate;
}
@Override public Set<Entry<K, V>> entrySet() {
Set<Entry<K, V>> es = entrySet;
if (es != null) {
return es;
}
return entrySet = Sets.transform(
delegate.keySet(), new KeyToEntryConverter<K, V>(this));
}
private static class KeyToEntryConverter<K, V>
extends Sets.InvertibleFunction<K, Map.Entry<K, V>> {
final Map<K, V> map;
KeyToEntryConverter(Map<K, V> map) {
this.map = map;
}
@Override public Map.Entry<K, V> apply(final K key) {
return new AbstractMapEntry<K, V>() {
@Override public K getKey() {
return key;
}
@Override public V getValue() {
return map.get(key);
}
@Override public V setValue(V value) {
return map.put(key, value);
}
};
}
@Override public K invert(Map.Entry<K, V> entry) {
return entry.getKey();
}
}
}
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