    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 *
    034 * @param <K> the type of the keys in this map
    035 * @param <V> the type of the values in this map
    036 * @since 3.0
    037 */
    038public final class UnmodifiableBidiMap<K, V>
    039        extends AbstractBidiMapDecorator<K, V> implements Unmodifiable {
    040
    041    /** The inverse unmodifiable map */
    042    private UnmodifiableBidiMap<V, K> inverse;
    043
    044    /**
    045     * Factory method to create an unmodifiable map.
    046     * <p>
    047     * If the map passed in is already unmodifiable, it is returned.
    048     *
    049     * @param <K> the key type
    050     * @param <V> the value type
    051     * @param map  the map to decorate, must not be null
    052     * @return an unmodifiable BidiMap
    053     * @throws NullPointerException if map is null
    054     * @since 4.0
    055     */
    056    public static <K, V> BidiMap<K, V> unmodifiableBidiMap(final BidiMap<? extends K, ? extends V> map) {
    057        if (map instanceof Unmodifiable) {
    058            @SuppressWarnings("unchecked") // safe to upcast
    059            final BidiMap<K, V> tmpMap = (BidiMap<K, V>) map;
    060            return tmpMap;
    061        }
    062        return new UnmodifiableBidiMap<>(map);
    063    }
    064
    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    //-----------------------------------------------------------------------
    078    @Override
    079    public void clear() {
    080        throw new UnsupportedOperationException();
    081    }
    082
    083    @Override
    084    public V put(final K key, final V value) {
    085        throw new UnsupportedOperationException();
    086    }
    087
    088    @Override
    089    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
    090        throw new UnsupportedOperationException();
    091    }
    092
    093    @Override
    094    public V remove(final Object key) {
    095        throw new UnsupportedOperationException();
    096    }
    097
    098    @Override
    099    public Set<Map.Entry<K, V>> entrySet() {
    100        final Set<Map.Entry<K, V>> set = super.entrySet();
    101        return UnmodifiableEntrySet.unmodifiableEntrySet(set);
    102    }
    103
    104    @Override
    105    public Set<K> keySet() {
    106        final Set<K> set = super.keySet();
    107        return UnmodifiableSet.unmodifiableSet(set);
    108    }
    109
    110    @Override
    111    public Set<V> values() {
    112        final Set<V> set = super.values();
    113        return UnmodifiableSet.unmodifiableSet(set);
    114    }
    115
    116    //-----------------------------------------------------------------------
    117    @Override
    118    public K removeValue(final Object value) {
    119        throw new UnsupportedOperationException();
    120    }
    121
    122    @Override
    123    public MapIterator<K, V> mapIterator() {
    124        final MapIterator<K, V> it = decorated().mapIterator();
    125        return UnmodifiableMapIterator.unmodifiableMapIterator(it);
    126    }
    127
    128    @Override
    129    public synchronized BidiMap<V, K> inverseBidiMap() {
    130        if (inverse == null) {
    131            inverse = new UnmodifiableBidiMap<>(decorated().inverseBidiMap());
    132            inverse.inverse = this;
    133        }
    134        return inverse;
    135    }
    136
    137}