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}