| /* |
| * 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; |
| |
| /** |
| * Defines a functor interface implemented by classes that transform one |
| * object into another. |
| * <p> |
| * A {@code Transformer} converts the input object to the output object. |
| * The input object should be left unchanged. |
| * Transformers are typically used for type conversions, or extracting data |
| * from an object. |
| * </p> |
| * <p> |
| * Standard implementations of common transformers are provided by |
| * {@link TransformerUtils}. These include method invocation, returning a constant, |
| * cloning and returning the string value. |
| * </p> |
| * |
| * @param <I> the input type to the transformer |
| * @param <O> the output type from the transformer |
| * |
| * @since 1.0 |
| */ |
| @FunctionalInterface |
| public interface Transformer<I, O> { |
| |
| /** |
| * Transforms the input object (leaving it unchanged) into some output object. |
| * |
| * @param input the object to be transformed, should be left unchanged |
| * @return a transformed object |
| * @throws ClassCastException (runtime) if the input is the wrong class |
| * @throws IllegalArgumentException (runtime) if the input is invalid |
| * @throws FunctorException (runtime) if the transform cannot be completed |
| */ |
| O transform(I input); |
| |
| } |