001    package 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     */
028    public 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    }