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 * https://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, for example 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 }