| /* |
| * 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.functors; |
| |
| import java.io.Serializable; |
| import java.util.Map; |
| |
| import org.apache.commons.collections4.Transformer; |
| |
| /** |
| * Transformer implementation that returns the value held in a specified map |
| * using the input parameter as a key. |
| * |
| * @since 3.0 |
| */ |
| public final class MapTransformer<I, O> implements Transformer<I, O>, Serializable { |
| |
| /** Serial version UID */ |
| private static final long serialVersionUID = 862391807045468939L; |
| |
| /** |
| * Factory to create the transformer. |
| * <p> |
| * If the map is null, a transformer that always returns null is returned. |
| * |
| * @param <I> the input type |
| * @param <O> the output type |
| * @param map the map, not cloned |
| * @return the transformer |
| */ |
| public static <I, O> Transformer<I, O> mapTransformer(final Map<? super I, ? extends O> map) { |
| if (map == null) { |
| return ConstantTransformer.<I, O>nullTransformer(); |
| } |
| return new MapTransformer<>(map); |
| } |
| |
| /** The map of data to lookup in */ |
| private final Map<? super I, ? extends O> iMap; |
| |
| /** |
| * Constructor that performs no validation. |
| * Use {@code mapTransformer} if you want that. |
| * |
| * @param map the map to use for lookup, not cloned |
| */ |
| private MapTransformer(final Map<? super I, ? extends O> map) { |
| iMap = map; |
| } |
| |
| /** |
| * Gets the map to lookup in. |
| * |
| * @return the map |
| * @since 3.1 |
| */ |
| public Map<? super I, ? extends O> getMap() { |
| return iMap; |
| } |
| |
| /** |
| * Transforms the input to result by looking it up in a {@code Map}. |
| * |
| * @param input the input object to transform |
| * @return the transformed result |
| */ |
| @Override |
| public O transform(final I input) { |
| return iMap.get(input); |
| } |
| |
| } |