    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 *      https://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     * </p>
    057     *
    058     * @param <K> The key type
    059     * @param <V> The value type
    060     * @param map  The MultiValuedMap to decorate, may not be null
    061     * @param keyTransformer  The transformer to use for key conversion, null means no conversion
    062     * @param valueTransformer  The transformer to use for value conversion, null means no conversion
    063     * @return A new transformed MultiValuedMap
    064     * @throws NullPointerException if map is null
    065     */
    066    public static <K, V> TransformedMultiValuedMap<K, V> transformedMap(final MultiValuedMap<K, V> map,
    067            final Transformer<? super K, ? extends K> keyTransformer,
    068            final Transformer<? super V, ? extends V> valueTransformer) {
    069        final TransformedMultiValuedMap<K, V> decorated =
    070                new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
    071        if (!map.isEmpty()) {
    072            final MultiValuedMap<K, V> mapCopy = new ArrayListValuedHashMap<>(map);
    073            decorated.clear();
    074            decorated.putAll(mapCopy);
    075        }
    076        return decorated;
    077    }
    078
    079    /**
    080     * Factory method to create a transforming MultiValuedMap.
    081     * <p>
    082     * If there are any elements already in the map being decorated, they are
    083     * NOT transformed. Contrast this with
    084     * {@link #transformedMap(MultiValuedMap, Transformer, Transformer)}.
    085     * </p>
    086     *
    087     * @param <K> The key type
    088     * @param <V> The value type
    089     * @param map  The MultiValuedMap to decorate, may not be null
    090     * @param keyTransformer  The transformer to use for key conversion, null means no conversion
    091     * @param valueTransformer  The transformer to use for value conversion, null means no conversion
    092     * @return A new transformed MultiValuedMap
    093     * @throws NullPointerException if map is null
    094     */
    095    public static <K, V> TransformedMultiValuedMap<K, V> transformingMap(final MultiValuedMap<K, V> map,
    096            final Transformer<? super K, ? extends K> keyTransformer,
    097            final Transformer<? super V, ? extends V> valueTransformer) {
    098        return new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
    099    }
    100
    101    /** The key transformer */
    102    private final Transformer<? super K, ? extends K> keyTransformer;
    103
    104    /** The value transformer */
    105    private final Transformer<? super V, ? extends V> valueTransformer;
    106
    107    /**
    108     * Constructor that wraps (not copies).
    109     * <p>
    110     * If there are any elements already in the collection being decorated, they
    111     * are NOT transformed.
    112     * </p>
    113     *
    114     * @param map  The MultiValuedMap to decorate, may not be null
    115     * @param keyTransformer  The transformer to use for key conversion, null means no conversion
    116     * @param valueTransformer  The transformer to use for value conversion, null means no conversion
    117     * @throws NullPointerException if map is null
    118     */
    119    protected TransformedMultiValuedMap(final MultiValuedMap<K, V> map,
    120            final Transformer<? super K, ? extends K> keyTransformer,
    121            final Transformer<? super V, ? extends V> valueTransformer) {
    122        super(map);
    123        this.keyTransformer = keyTransformer;
    124        this.valueTransformer = valueTransformer;
    125    }
    126
    127    @Override
    128    public boolean put(final K key, final V value) {
    129        return decorated().put(transformKey(key), transformValue(value));
    130    }
    131
    132    @Override
    133    public boolean putAll(final K key, final Iterable<? extends V> values) {
    134        Objects.requireNonNull(values, "values");
    135
    136        final Iterable<V> transformedValues = FluentIterable.of(values).transform(valueTransformer);
    137        final Iterator<? extends V> it = transformedValues.iterator();
    138        return it.hasNext() && CollectionUtils.addAll(decorated().get(transformKey(key)), it);
    139    }
    140
    141    @Override
    142    public boolean putAll(final Map<? extends K, ? extends V> map) {
    143        Objects.requireNonNull(map, "map");
    144        boolean changed = false;
    145        for (final Map.Entry<? extends K, ? extends V> entry : map.entrySet()) {
    146            changed |= put(entry.getKey(), entry.getValue());
    147        }
    148        return changed;
    149    }
    150
    151    @Override
    152    public boolean putAll(final MultiValuedMap<? extends K, ? extends V> map) {
    153        Objects.requireNonNull(map, "map");
    154        boolean changed = false;
    155        for (final Map.Entry<? extends K, ? extends V> entry : map.entries()) {
    156            changed |= put(entry.getKey(), entry.getValue());
    157        }
    158        return changed;
    159    }
    160
    161    /**
    162     * Transforms a key.
    163     * <p>
    164     * The transformer itself may throw an exception if necessary.
    165     * </p>
    166     *
    167     * @param object  The object to transform
    168     * @return The transformed object
    169     */
    170    protected K transformKey(final K object) {
    171        if (keyTransformer == null) {
    172            return object;
    173        }
    174        return keyTransformer.apply(object);
    175    }
    176
    177    /**
    178     * Transforms a value.
    179     * <p>
    180     * The transformer itself may throw an exception if necessary.
    181     * </p>
    182     *
    183     * @param object  The object to transform
    184     * @return The transformed object
    185     */
    186    protected V transformValue(final V object) {
    187        if (valueTransformer == null) {
    188            return object;
    189        }
    190        return valueTransformer.apply(object);
    191    }
    192
    193}