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