001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.bidimap;
018
019import java.util.Map;
020import java.util.Set;
021
022import org.apache.commons.collections4.BidiMap;
023import org.apache.commons.collections4.MapIterator;
024import org.apache.commons.collections4.Unmodifiable;
025import org.apache.commons.collections4.iterators.UnmodifiableMapIterator;
026import org.apache.commons.collections4.map.UnmodifiableEntrySet;
027import org.apache.commons.collections4.set.UnmodifiableSet;
028
029/**
030 * Decorates another {@link BidiMap} to ensure it can't be altered.
031 * <p>
032 * Attempts to modify it will result in an UnsupportedOperationException.
033 * </p>
034 *
035 * @param <K> the type of the keys in this map
036 * @param <V> the type of the values in this map
037 * @since 3.0
038 */
039public final class UnmodifiableBidiMap<K, V>
040        extends AbstractBidiMapDecorator<K, V> implements Unmodifiable {
041
042    /**
043     * Factory method to create an unmodifiable map.
044     * <p>
045     * If the map passed in is already unmodifiable, it is returned.
046     *
047     * @param <K> the key type
048     * @param <V> the value type
049     * @param map  the map to decorate, must not be null
050     * @return an unmodifiable BidiMap
051     * @throws NullPointerException if map is null
052     * @since 4.0
053     */
054    public static <K, V> BidiMap<K, V> unmodifiableBidiMap(final BidiMap<? extends K, ? extends V> map) {
055        if (map instanceof Unmodifiable) {
056            @SuppressWarnings("unchecked") // safe to upcast
057            final BidiMap<K, V> tmpMap = (BidiMap<K, V>) map;
058            return tmpMap;
059        }
060        return new UnmodifiableBidiMap<>(map);
061    }
062
063    /** The inverse unmodifiable map */
064    private UnmodifiableBidiMap<V, K> inverse;
065
066    /**
067     * Constructor that wraps (not copies).
068     *
069     * @param map  the map to decorate, must not be null
070     * @throws NullPointerException if map is null
071     */
072    @SuppressWarnings("unchecked") // safe to upcast
073    private UnmodifiableBidiMap(final BidiMap<? extends K, ? extends V> map) {
074        super((BidiMap<K, V>) map);
075    }
076
077    @Override
078    public void clear() {
079        throw new UnsupportedOperationException();
080    }
081
082    @Override
083    public Set<Map.Entry<K, V>> entrySet() {
084        final Set<Map.Entry<K, V>> set = super.entrySet();
085        return UnmodifiableEntrySet.unmodifiableEntrySet(set);
086    }
087
088    @Override
089    public synchronized BidiMap<V, K> inverseBidiMap() {
090        if (inverse == null) {
091            inverse = new UnmodifiableBidiMap<>(decorated().inverseBidiMap());
092            inverse.inverse = this;
093        }
094        return inverse;
095    }
096
097    @Override
098    public Set<K> keySet() {
099        final Set<K> set = super.keySet();
100        return UnmodifiableSet.unmodifiableSet(set);
101    }
102
103    @Override
104    public MapIterator<K, V> mapIterator() {
105        final MapIterator<K, V> it = decorated().mapIterator();
106        return UnmodifiableMapIterator.unmodifiableMapIterator(it);
107    }
108
109    @Override
110    public V put(final K key, final V value) {
111        throw new UnsupportedOperationException();
112    }
113
114    @Override
115    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
116        throw new UnsupportedOperationException();
117    }
118
119    @Override
120    public V remove(final Object key) {
121        throw new UnsupportedOperationException();
122    }
123
124    @Override
125    public K removeValue(final Object value) {
126        throw new UnsupportedOperationException();
127    }
128
129    @Override
130    public Set<V> values() {
131        final Set<V> set = super.values();
132        return UnmodifiableSet.unmodifiableSet(set);
133    }
134
135}