001package org.apache.maven.configuration;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *   http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022/**
023 * Preprocesses a value from a bean configuration before the bean configurator unmarshals it into a bean property. A
024 * common use case for such preprocessing is the evaluation of variables within the configuration value.
025 * 
026 * @author Benjamin Bentmann
027 */
028public interface BeanConfigurationValuePreprocessor
029{
030
031    /**
032     * Preprocesses the specified bean configuration value. The optional type provided to this method is a hint (not a
033     * requirement) for the preprocessor to resolve the value to a compatible value or a (string) value than can be
034     * unmarshalled into that type. The preprocessor is not required to perform any type conversion but should rather
035     * filter out incompatible values from its result.
036     * 
037     * @param value The configuration value to preprocess, must not be {@code null}.
038     * @param type The target type of the value, may be {@code null}.
039     * @return The processed configuration value or {@code null} if none.
040     * @throws BeanConfigurationException If an error occurred while preprocessing the value.
041     */
042    Object preprocessValue( String value, Class<?> type )
043        throws BeanConfigurationException;
044
045}