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    /** The inverse unmodifiable map */
043    private UnmodifiableBidiMap<V, K> inverse;
044
045    /**
046     * Factory method to create an unmodifiable map.
047     * <p>
048     * If the map passed in is already unmodifiable, it is returned.
049     *
050     * @param <K> the key type
051     * @param <V> the value type
052     * @param map  the map to decorate, must not be null
053     * @return an unmodifiable BidiMap
054     * @throws NullPointerException if map is null
055     * @since 4.0
056     */
057    public static <K, V> BidiMap<K, V> unmodifiableBidiMap(final BidiMap<? extends K, ? extends V> map) {
058        if (map instanceof Unmodifiable) {
059            @SuppressWarnings("unchecked") // safe to upcast
060            final BidiMap<K, V> tmpMap = (BidiMap<K, V>) map;
061            return tmpMap;
062        }
063        return new UnmodifiableBidiMap<>(map);
064    }
065
066    //-----------------------------------------------------------------------
067    /**
068     * Constructor that wraps (not copies).
069     *
070     * @param map  the map to decorate, must not be null
071     * @throws NullPointerException if map is null
072     */
073    @SuppressWarnings("unchecked") // safe to upcast
074    private UnmodifiableBidiMap(final BidiMap<? extends K, ? extends V> map) {
075        super((BidiMap<K, V>) map);
076    }
077
078    //-----------------------------------------------------------------------
079    @Override
080    public void clear() {
081        throw new UnsupportedOperationException();
082    }
083
084    @Override
085    public V put(final K key, final V value) {
086        throw new UnsupportedOperationException();
087    }
088
089    @Override
090    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
091        throw new UnsupportedOperationException();
092    }
093
094    @Override
095    public V remove(final Object key) {
096        throw new UnsupportedOperationException();
097    }
098
099    @Override
100    public Set<Map.Entry<K, V>> entrySet() {
101        final Set<Map.Entry<K, V>> set = super.entrySet();
102        return UnmodifiableEntrySet.unmodifiableEntrySet(set);
103    }
104
105    @Override
106    public Set<K> keySet() {
107        final Set<K> set = super.keySet();
108        return UnmodifiableSet.unmodifiableSet(set);
109    }
110
111    @Override
112    public Set<V> values() {
113        final Set<V> set = super.values();
114        return UnmodifiableSet.unmodifiableSet(set);
115    }
116
117    //-----------------------------------------------------------------------
118    @Override
119    public K removeValue(final Object value) {
120        throw new UnsupportedOperationException();
121    }
122
123    @Override
124    public MapIterator<K, V> mapIterator() {
125        final MapIterator<K, V> it = decorated().mapIterator();
126        return UnmodifiableMapIterator.unmodifiableMapIterator(it);
127    }
128
129    @Override
130    public synchronized BidiMap<V, K> inverseBidiMap() {
131        if (inverse == null) {
132            inverse = new UnmodifiableBidiMap<>(decorated().inverseBidiMap());
133            inverse.inverse = this;
134        }
135        return inverse;
136    }
137
138}