001    package org.apache.commons.digester3;
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    import org.xml.sax.Attributes;
023    
024    /**
025     * <p>
026     * (Logical) Interface for substitution strategies. (It happens to be implemented as a Java abstract class to allow
027     * future additions to be made without breaking backwards compatibility.)
028     * </p>
029     * <p>
030     * Usage: When {@link Digester#setSubstitutor} is set, <code>Digester</code> calls the methods in this interface to
031     * create substitute values which will be passed into the Rule implementations. Of course, it is perfectly acceptable
032     * for implementations not to make substitutions and simply return the inputs.
033     * </p>
034     * <p>
035     * Different strategies are supported for attributes and body text.
036     * </p>
037     * 
038     * @since 1.6
039     */
040    public abstract class Substitutor
041    {
042    
043        /**
044         * <p>
045         * Substitutes the attributes (before they are passed to the <code>Rule</code> implementations's).
046         * </p>
047         * <p>
048         * <code>Digester</code> will only call this method a second time once the original <code>Attributes</code> instance
049         * can be safely reused. The implementation is therefore free to reuse the same <code>Attributes</code> instance for
050         * all calls.
051         * </p>
052         * 
053         * @param attributes the <code>Attributes</code> passed into <code>Digester</code> by the SAX parser, not null (but
054         *            may be empty)
055         * @return <code>Attributes</code> to be passed to the <code>Rule</code> implementations. This method may pass back
056         *         the Attributes passed in. Not null but possibly empty.
057         */
058        public abstract Attributes substitute( Attributes attributes );
059    
060        /**
061         * Substitutes for the body text. This method may substitute values into the body text of the elements that Digester
062         * parses.
063         * 
064         * @param bodyText the body text (as passed to <code>Digester</code>)
065         * @return the body text to be passed to the <code>Rule</code> implementations
066         */
067        public abstract String substitute( String bodyText );
068    
069    }