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/*
* 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 implements Transformer, Serializable {
/** Serial version UID */
private static final long serialVersionUID = 862391807045468939L;
/** The map of data to lookup in */
private final Map iMap;
/**
* Factory to create the transformer.
*
* If the map is null, a transformer that always returns null is returned.
*
* @param the input type
* @param the output type
* @param map the map, not cloned
* @return the transformer
*/
public static Transformer mapTransformer(final Map map) {
if (map == null) {
return ConstantTransformer.nullTransformer();
}
return new MapTransformer<>(map);
}
/**
* Constructor that performs no validation.
* Use mapTransformer if you want that.
*
* @param map the map to use for lookup, not cloned
*/
private MapTransformer(final Map map) {
super();
iMap = map;
}
/**
* Transforms the input to result by looking it up in a Map.
*
* @param input the input object to transform
* @return the transformed result
*/
@Override
public O transform(final I input) {
return iMap.get(input);
}
/**
* Gets the map to lookup in.
*
* @return the map
* @since 3.1
*/
public Map getMap() {
return iMap;
}
}