TransformedMultiValuedMap.java
- /*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.apache.commons.collections4.multimap;
- import java.util.Iterator;
- import java.util.Map;
- import java.util.Objects;
- import org.apache.commons.collections4.CollectionUtils;
- import org.apache.commons.collections4.FluentIterable;
- import org.apache.commons.collections4.MultiValuedMap;
- import org.apache.commons.collections4.Transformer;
- /**
- * Decorates another {@code MultiValuedMap} to transform objects that are added.
- * <p>
- * This class affects the MultiValuedMap put methods. Thus objects must be
- * removed or searched for using their transformed form. For example, if the
- * transformation converts Strings to Integers, you must use the Integer form to
- * remove objects.
- * </p>
- * <p>
- * <strong>Note that TransformedMultiValuedMap is not synchronized and is not thread-safe.</strong>
- * </p>
- *
- * @param <K> the type of the keys in this map
- * @param <V> the type of the values in this map
- * @since 4.1
- */
- public class TransformedMultiValuedMap<K, V> extends AbstractMultiValuedMapDecorator<K, V> {
- /** Serialization Version */
- private static final long serialVersionUID = 20150612L;
- /**
- * Factory method to create a transforming MultiValuedMap that will
- * transform existing contents of the specified map.
- * <p>
- * If there are any elements already in the map being decorated, they will
- * be transformed by this method. Contrast this with
- * {@link #transformingMap(MultiValuedMap, Transformer, Transformer)}.
- * </p>
- *
- * @param <K> the key type
- * @param <V> the value type
- * @param map the MultiValuedMap to decorate, may not be null
- * @param keyTransformer the transformer to use for key conversion, null means no conversion
- * @param valueTransformer the transformer to use for value conversion, null means no conversion
- * @return a new transformed MultiValuedMap
- * @throws NullPointerException if map is null
- */
- public static <K, V> TransformedMultiValuedMap<K, V> transformedMap(final MultiValuedMap<K, V> map,
- final Transformer<? super K, ? extends K> keyTransformer,
- final Transformer<? super V, ? extends V> valueTransformer) {
- final TransformedMultiValuedMap<K, V> decorated =
- new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
- if (!map.isEmpty()) {
- final MultiValuedMap<K, V> mapCopy = new ArrayListValuedHashMap<>(map);
- decorated.clear();
- decorated.putAll(mapCopy);
- }
- return decorated;
- }
- /**
- * Factory method to create a transforming MultiValuedMap.
- * <p>
- * If there are any elements already in the map being decorated, they are
- * NOT transformed. Contrast this with
- * {@link #transformedMap(MultiValuedMap, Transformer, Transformer)}.
- * </p>
- *
- * @param <K> the key type
- * @param <V> the value type
- * @param map the MultiValuedMap to decorate, may not be null
- * @param keyTransformer the transformer to use for key conversion, null means no conversion
- * @param valueTransformer the transformer to use for value conversion, null means no conversion
- * @return a new transformed MultiValuedMap
- * @throws NullPointerException if map is null
- */
- public static <K, V> TransformedMultiValuedMap<K, V> transformingMap(final MultiValuedMap<K, V> map,
- final Transformer<? super K, ? extends K> keyTransformer,
- final Transformer<? super V, ? extends V> valueTransformer) {
- return new TransformedMultiValuedMap<>(map, keyTransformer, valueTransformer);
- }
- /** The key transformer */
- private final Transformer<? super K, ? extends K> keyTransformer;
- /** The value transformer */
- private final Transformer<? super V, ? extends V> valueTransformer;
- /**
- * Constructor that wraps (not copies).
- * <p>
- * If there are any elements already in the collection being decorated, they
- * are NOT transformed.
- * </p>
- *
- * @param map the MultiValuedMap to decorate, may not be null
- * @param keyTransformer the transformer to use for key conversion, null means no conversion
- * @param valueTransformer the transformer to use for value conversion, null means no conversion
- * @throws NullPointerException if map is null
- */
- protected TransformedMultiValuedMap(final MultiValuedMap<K, V> map,
- final Transformer<? super K, ? extends K> keyTransformer,
- final Transformer<? super V, ? extends V> valueTransformer) {
- super(map);
- this.keyTransformer = keyTransformer;
- this.valueTransformer = valueTransformer;
- }
- @Override
- public boolean put(final K key, final V value) {
- return decorated().put(transformKey(key), transformValue(value));
- }
- @Override
- public boolean putAll(final K key, final Iterable<? extends V> values) {
- Objects.requireNonNull(values, "values");
- final Iterable<V> transformedValues = FluentIterable.of(values).transform(valueTransformer);
- final Iterator<? extends V> it = transformedValues.iterator();
- return it.hasNext() && CollectionUtils.addAll(decorated().get(transformKey(key)), it);
- }
- @Override
- public boolean putAll(final Map<? extends K, ? extends V> map) {
- Objects.requireNonNull(map, "map");
- boolean changed = false;
- for (final Map.Entry<? extends K, ? extends V> entry : map.entrySet()) {
- changed |= put(entry.getKey(), entry.getValue());
- }
- return changed;
- }
- @Override
- public boolean putAll(final MultiValuedMap<? extends K, ? extends V> map) {
- Objects.requireNonNull(map, "map");
- boolean changed = false;
- for (final Map.Entry<? extends K, ? extends V> entry : map.entries()) {
- changed |= put(entry.getKey(), entry.getValue());
- }
- return changed;
- }
- /**
- * Transforms a key.
- * <p>
- * The transformer itself may throw an exception if necessary.
- * </p>
- *
- * @param object the object to transform
- * @return the transformed object
- */
- protected K transformKey(final K object) {
- if (keyTransformer == null) {
- return object;
- }
- return keyTransformer.apply(object);
- }
- /**
- * Transforms a value.
- * <p>
- * The transformer itself may throw an exception if necessary.
- * </p>
- *
- * @param object the object to transform
- * @return the transformed object
- */
- protected V transformValue(final V object) {
- if (valueTransformer == null) {
- return object;
- }
- return valueTransformer.apply(object);
- }
- }