    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.multimap;
    018
    019import java.util.Iterator;
    020import java.util.Map;
    021
    022import org.apache.commons.collections4.CollectionUtils;
    023import org.apache.commons.collections4.FluentIterable;
    024import org.apache.commons.collections4.MultiValuedMap;
    025import org.apache.commons.collections4.Transformer;
    026
    027/**
    028 * Decorates another <code>MultiValuedMap</code> to transform objects that are added.
    029 * <p>
    030 * This class affects the MultiValuedMap put methods. Thus objects must be
    031 * removed or searched for using their transformed form. For example, if the
    032 * transformation converts Strings to Integers, you must use the Integer form to
    033 * remove objects.
    034 * <p>
    035 * <strong>Note that TransformedMultiValuedMap is not synchronized and is not thread-safe.</strong>
    036 *
    037 * @param <K> the type of the keys in this map
    038 * @param <V> the type of the values in this map
    039 * @since 4.1
    040 */
    041public class TransformedMultiValuedMap<K, V> extends AbstractMultiValuedMapDecorator<K, V> {
    042
    043    /** Serialization Version */
    044    private static final long serialVersionUID = 20150612L;
    045
    046    /** The key transformer */
    047    private final Transformer<? super K, ? extends K> keyTransformer;
    048
    049    /** The value transformer */
    050    private final Transformer<? super V, ? extends V> valueTransformer;
    051
    052    /**
    053     * Factory method to create a transforming MultiValuedMap.
    054     * <p>
    055     * If there are any elements already in the map being decorated, they are
    056     * NOT transformed. Contrast this with
    057     * {@link #transformedMap(MultiValuedMap, Transformer, Transformer)}.
    058     *
    059     * @param <K> the key type
    060     * @param <V> the value type
    061     * @param map  the MultiValuedMap to decorate, may not be null
    062     * @param keyTransformer  the transformer to use for key conversion, null means no conversion
    063     * @param valueTransformer  the transformer to use for value conversion, null means no conversion
    064     * @return a new transformed MultiValuedMap
    065     * @throws NullPointerException if map is null
    066     */
    067    public static <K, V> TransformedMultiValuedMap<K, V> transformingMap(final MultiValuedMap<K, V> map,
    068            final Transformer<? super K, ? extends K> keyTransformer,
    069            final Transformer<? super V, ? extends V> valueTransformer) {
    070        return new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
    071    }
    072
    073    /**
    074     * Factory method to create a transforming MultiValuedMap that will
    075     * transform existing contents of the specified map.
    076     * <p>
    077     * If there are any elements already in the map being decorated, they will
    078     * be transformed by this method. Contrast this with
    079     * {@link #transformingMap(MultiValuedMap, Transformer, Transformer)}.
    080     *
    081     * @param <K> the key type
    082     * @param <V> the value type
    083     * @param map  the MultiValuedMap to decorate, may not be null
    084     * @param keyTransformer  the transformer to use for key conversion, null means no conversion
    085     * @param valueTransformer  the transformer to use for value conversion, null means no conversion
    086     * @return a new transformed MultiValuedMap
    087     * @throws NullPointerException if map is null
    088     */
    089    public static <K, V> TransformedMultiValuedMap<K, V> transformedMap(final MultiValuedMap<K, V> map,
    090            final Transformer<? super K, ? extends K> keyTransformer,
    091            final Transformer<? super V, ? extends V> valueTransformer) {
    092        final TransformedMultiValuedMap<K, V> decorated =
    093                new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
    094        if (!map.isEmpty()) {
    095            final MultiValuedMap<K, V> mapCopy = new ArrayListValuedHashMap<>(map);
    096            decorated.clear();
    097            decorated.putAll(mapCopy);
    098        }
    099        return decorated;
    100    }
    101
    102    // -----------------------------------------------------------------------
    103    /**
    104     * Constructor that wraps (not copies).
    105     * <p>
    106     * If there are any elements already in the collection being decorated, they
    107     * are NOT transformed.
    108     *
    109     * @param map  the MultiValuedMap to decorate, may not be null
    110     * @param keyTransformer  the transformer to use for key conversion, null means no conversion
    111     * @param valueTransformer  the transformer to use for value conversion, null means no conversion
    112     * @throws NullPointerException if map is null
    113     */
    114    protected TransformedMultiValuedMap(final MultiValuedMap<K, V> map,
    115            final Transformer<? super K, ? extends K> keyTransformer,
    116            final Transformer<? super V, ? extends V> valueTransformer) {
    117        super(map);
    118        this.keyTransformer = keyTransformer;
    119        this.valueTransformer = valueTransformer;
    120    }
    121
    122    /**
    123     * Transforms a key.
    124     * <p>
    125     * The transformer itself may throw an exception if necessary.
    126     *
    127     * @param object  the object to transform
    128     * @return the transformed object
    129     */
    130    protected K transformKey(final K object) {
    131        if (keyTransformer == null) {
    132            return object;
    133        }
    134        return keyTransformer.transform(object);
    135    }
    136
    137    /**
    138     * Transforms a value.
    139     * <p>
    140     * The transformer itself may throw an exception if necessary.
    141     *
    142     * @param object  the object to transform
    143     * @return the transformed object
    144     */
    145    protected V transformValue(final V object) {
    146        if (valueTransformer == null) {
    147            return object;
    148        }
    149        return valueTransformer.transform(object);
    150    }
    151
    152    @Override
    153    public boolean put(final K key, final V value) {
    154        return decorated().put(transformKey(key), transformValue(value));
    155    }
    156
    157    @Override
    158    public boolean putAll(final K key, final Iterable<? extends V> values) {
    159        if (values == null) {
    160            throw new NullPointerException("Values must not be null.");
    161        }
    162
    163        final Iterable<V> transformedValues = FluentIterable.of(values).transform(valueTransformer);
    164        final Iterator<? extends V> it = transformedValues.iterator();
    165        return it.hasNext() && CollectionUtils.addAll(decorated().get(transformKey(key)), it);
    166    }
    167
    168    @Override
    169    public boolean putAll(final Map<? extends K, ? extends V> map) {
    170        if (map == null) {
    171            throw new NullPointerException("Map must not be null.");
    172        }
    173        boolean changed = false;
    174        for (final Map.Entry<? extends K, ? extends V> entry : map.entrySet()) {
    175            changed |= put(entry.getKey(), entry.getValue());
    176        }
    177        return changed;
    178    }
    179
    180    @Override
    181    public boolean putAll(final MultiValuedMap<? extends K, ? extends V> map) {
    182        if (map == null) {
    183            throw new NullPointerException("Map must not be null.");
    184        }
    185        boolean changed = false;
    186        for (final Map.Entry<? extends K, ? extends V> entry : map.entries()) {
    187            changed |= put(entry.getKey(), entry.getValue());
    188        }
    189        return changed;
    190    }
    191
    192}