    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.convert;
    018
    019
    020/**
    021 * <p>
    022 * Definition of an interface used by {@link ListDelimiterHandler} to perform
    023 * additional transformations on behalf of a configuration when a property value
    024 * is escaped.
    025 * </p>
    026 * <p>
    027 * Some {@code Configuration} implementations require a special encoding of
    028 * their property values before they get written on disk. In some
    029 * constellations, e.g. when a property with multiple values is to be forced on
    030 * a single line, this encoding has to be done together with the escaping of
    031 * list delimiter characters - which is in the responsibility of
    032 * {@link ListDelimiterHandler}.
    033 * </p>
    034 * <p>
    035 * In order to allow a proper collaboration between the parties involved, this
    036 * interface was introduced. A configuration object provides an implementation
    037 * of {@code ValueTransformer} and passes it to the {@code ListDelimiterHandler}
    038 * when escaping of properties is needed. The delimiter handler can then call
    039 * back to perform the additional encoding as its pleasure.
    040 * </p>
    041 *
    042 * @since 2.0
    043 */
    044public interface ValueTransformer
    045{
    046    /**
    047     * Performs an arbitrary encoding of the passed in value object. This method
    048     * is called by a {@link ListDelimiterHandler} implementation before or
    049     * after list delimiters have been escaped.
    050     *
    051     * @param value the property value to be transformed
    052     * @return the transformed property value
    053     */
    054    Object transformValue(Object value);
    055}