Update #0 - First Release

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

@@ -0,0 +1,118 @@
+/*
+ * 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 java.util.Map;
+import java.util.Set;
+
+import javax.annotation.Nullable;
+
+import com.google.common.annotations.GwtCompatible;
+
+/**
+ * A bimap (or "bidirectional map") is a map that preserves the uniqueness of
+ * its values as well as that of its keys. This constraint enables bimaps to
+ * support an "inverse view", which is another bimap containing the same entries
+ * as this bimap but with reversed keys and values.
+ * 
+ * <p>
+ * See the Guava User Guide article on <a href=
+ * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
+ * {@code BiMap}</a>.
+ *
+ * @author Kevin Bourrillion
+ * @since 2.0 (imported from Google Collections Library)
+ */
+@GwtCompatible
+public interface BiMap<K, V> extends Map<K, V> {
+	// Modification Operations
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * @throws IllegalArgumentException if the given value is already bound to a
+	 *                                  different key in this bimap. The bimap will
+	 *                                  remain unmodified in this event. To avoid
+	 *                                  this exception, call {@link #forcePut}
+	 *                                  instead.
+	 */
+	@Override
+	V put(@Nullable K key, @Nullable V value);
+
+	/**
+	 * An alternate form of {@code put} that silently removes any existing entry
+	 * with the value {@code value} before proceeding with the {@link #put}
+	 * operation. If the bimap previously contained the provided key-value mapping,
+	 * this method has no effect.
+	 *
+	 * <p>
+	 * Note that a successful call to this method could cause the size of the bimap
+	 * to increase by one, stay the same, or even decrease by one.
+	 *
+	 * <p>
+	 * <b>Warning:</b> If an existing entry with this value is removed, the key for
+	 * that entry is discarded and not returned.
+	 *
+	 * @param key   the key with which the specified value is to be associated
+	 * @param value the value to be associated with the specified key
+	 * @return the value which was previously associated with the key, which may be
+	 *         {@code null}, or {@code null} if there was no previous entry
+	 */
+	V forcePut(@Nullable K key, @Nullable V value);
+
+	// Bulk Operations
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>
+	 * <b>Warning:</b> the results of calling this method may vary depending on the
+	 * iteration order of {@code map}.
+	 *
+	 * @throws IllegalArgumentException if an attempt to {@code put} any entry
+	 *                                  fails. Note that some map entries may have
+	 *                                  been added to the bimap before the exception
+	 *                                  was thrown.
+	 */
+	@Override
+	void putAll(Map<? extends K, ? extends V> map);
+
+	// Views
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>
+	 * Because a bimap has unique values, this method returns a {@link Set}, instead
+	 * of the {@link java.util.Collection} specified in the {@link Map} interface.
+	 */
+	@Override
+	Set<V> values();
+
+	/**
+	 * Returns the inverse view of this bimap, which maps each of this bimap's
+	 * values to its associated key. The two bimaps are backed by the same data; any
+	 * changes to one will appear in the other.
+	 *
+	 * <p>
+	 * <b>Note:</b>There is no guaranteed correspondence between the iteration order
+	 * of a bimap and that of its inverse.
+	 *
+	 * @return the inverse view of this bimap
+	 */
+	BiMap<V, K> inverse();
+}