| 1 | /*
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more
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| 3 | * contributor license agreements. See the NOTICE file distributed with
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| 4 | * this work for additional information regarding copyright ownership.
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| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0
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| 6 | * (the "License"); you may not use this file except in compliance with
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| 7 | * the License. You may obtain a copy of the License at
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| 8 | *
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| 9 | * http://www.apache.org/licenses/LICENSE-2.0
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| 10 | *
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| 11 | * Unless required by applicable law or agreed to in writing, software
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| 12 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 14 | * See the License for the specific language governing permissions and
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| 15 | * limitations under the License.
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| 16 | */
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| 17 | package org.apache.commons.collections;
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| 18 |
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| 19 | /**
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| 20 | * Defines a functor interface implemented by classes that transform one
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| 21 | * object into another.
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| 22 | * <p>
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| 23 | * A <code>Transformer</code> converts the input object to the output object.
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| 24 | * The input object should be left unchanged.
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| 25 | * Transformers are typically used for type conversions, or extracting data
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| 26 | * from an object.
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| 27 | * <p>
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| 28 | * Standard implementations of common transformers are provided by
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| 29 | * {@link TransformerUtils}. These include method invokation, returning a constant,
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| 30 | * cloning and returning the string value.
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| 31 | *
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| 32 | * @since Commons Collections 1.0
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| 33 | * @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (jeu., 10 avr. 2008) $
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| 34 | *
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| 35 | * @author James Strachan
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| 36 | * @author Stephen Colebourne
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| 37 | */
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| 38 | public interface Transformer {
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| 39 |
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| 40 | /**
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| 41 | * Transforms the input object (leaving it unchanged) into some output object.
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| 42 | *
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| 43 | * @param input the object to be transformed, should be left unchanged
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| 44 | * @return a transformed object
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| 45 | * @throws ClassCastException (runtime) if the input is the wrong class
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| 46 | * @throws IllegalArgumentException (runtime) if the input is invalid
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| 47 | * @throws FunctorException (runtime) if the transform cannot be completed
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| 48 | */
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| 49 | public Object transform(Object input);
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| 50 |
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| 51 | }
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