001    package org.apache.commons.digester3.substitution;
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     * <p>
024     * An Interface describing a class capable of expanding strings which may contain variable references. The exact syntax
025     * of the "reference", and the mechanism for determining the corresponding value to be used is up to the concrete
026     * implementation.
027     * </p>
028     * 
029     * @since 1.6
030     */
031    public interface VariableExpander
032    {
033    
034        /**
035         * Return the input string with any variables replaced by their corresponding value. If there are no variables in
036         * the string, then the input parameter is returned unaltered.
037         *
038         * @param param the string containing variables to be replaced.
039         * @return the input string with any variables replaced by their corresponding value.
040         */
041        String expand( String param );
042    
043    }