Update #0 - First Release

sources/main/java/com/google/common/collect/WellBehavedMap.java

@@ -0,0 +1,101 @@
+/*
+ * 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 java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+
+import com.google.common.annotations.GwtCompatible;
+
+/**
+ * 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.
+ *
+ * <p>
+ * This class is not thread-safe even if the underlying map is.
+ *
+ * @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 = new EntrySet();
+	}
+
+	private final class EntrySet extends Maps.EntrySet<K, V> {
+		@Override
+		Map<K, V> map() {
+			return WellBehavedMap.this;
+		}
+
+		@Override
+		public Iterator<Entry<K, V>> iterator() {
+			return new TransformedIterator<K, Entry<K, V>>(keySet().iterator()) {
+				@Override
+				Entry<K, V> transform(final K key) {
+					return new AbstractMapEntry<K, V>() {
+						@Override
+						public K getKey() {
+							return key;
+						}
+
+						@Override
+						public V getValue() {
+							return get(key);
+						}
+
+						@Override
+						public V setValue(V value) {
+							return put(key, value);
+						}
+					};
+				}
+			};
+		}
+	}
+}