/*
* 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.collections;
/**
* Defines a functor interface implemented by classes that transform one
* object into another.
* <p>
* A <code>Transformer</code> 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>
* Standard implementations of common transformers are provided by
* {@link TransformerUtils}. These include method invokation, returning a constant,
* cloning and returning the string value.
*
* @since Commons Collections 1.0
* @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
*
* @author James Strachan
* @author Stephen Colebourne
*/
public interface Transformer {
/**
* 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
*/
public Object transform(Object input);
}