1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.configuration2.convert; 18 19 /** 20 * <p> 21 * Definition of an interface used by {@link ListDelimiterHandler} to perform additional transformations on behalf of a 22 * configuration when a property value is escaped. 23 * </p> 24 * <p> 25 * Some {@code Configuration} implementations require a special encoding of their property values before they get 26 * written on disk. In some constellations, e.g. when a property with multiple values is to be forced on a single line, 27 * this encoding has to be done together with the escaping of list delimiter characters - which is in the responsibility 28 * of {@link ListDelimiterHandler}. 29 * </p> 30 * <p> 31 * In order to allow a proper collaboration between the parties involved, this interface was introduced. A configuration 32 * object provides an implementation of {@code ValueTransformer} and passes it to the {@code ListDelimiterHandler} when 33 * escaping of properties is needed. The delimiter handler can then call back to perform the additional encoding as its 34 * pleasure. 35 * </p> 36 * 37 * @since 2.0 38 */ 39 public interface ValueTransformer { 40 /** 41 * Performs an arbitrary encoding of the passed in value object. This method is called by a {@link ListDelimiterHandler} 42 * implementation before or after list delimiters have been escaped. 43 * 44 * @param value the property value to be transformed 45 * @return the transformed property value 46 */ 47 Object transformValue(Object value); 48 }