    001    /* $Id: Substitutor.java 471661 2006-11-06 08:09:25Z skitching $
    002     *
    003     * Licensed to the Apache Software Foundation (ASF) under one or more
    004     * contributor license agreements.  See the NOTICE file distributed with
    005     * this work for additional information regarding copyright ownership.
    006     * The ASF licenses this file to You under the Apache License, Version 2.0
    007     * (the "License"); you may not use this file except in compliance with
    008     * the License.  You may obtain a copy of the License at
    009     *
    010     *      http://www.apache.org/licenses/LICENSE-2.0
    011     *
    012     * Unless required by applicable law or agreed to in writing, software
    013     * distributed under the License is distributed on an "AS IS" BASIS,
    014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    015     * See the License for the specific language governing permissions and
    016     * limitations under the License.
    017     */
    018
    019    package org.apache.commons.digester;
    020
    021    import org.xml.sax.Attributes;
    022
    023    /**
    024     * <p>(Logical) Interface for substitution strategies.
    025     * (It happens to be implemented as a Java abstract class to allow
    026     * future additions to be made without breaking backwards compatibility.)
    027     * </p>
    028     * <p>
    029     * Usage: When {@link Digester#setSubstitutor} is set, <code>Digester</code>
    030     * calls the methods in this interface to create substitute values which will
    031     * be passed into the Rule implementations.
    032     * Of course, it is perfectly acceptable for implementations not to make
    033     * substitutions and simply return the inputs.
    034     * </p>
    035     * <p>Different strategies are supported for attributes and body text.</p>
    036     *
    037     * @since 1.6
    038     */
    039    public abstract class Substitutor {
    040
    041        /**
    042         * <p>Substitutes the attributes (before they are passed to the
    043         * <code>Rule</code> implementations's).</p>
    044         *
    045         * <p><code>Digester</code> will only call this method a second time
    046         * once the original <code>Attributes</code> instance can be safely reused.
    047         * The implementation is therefore free to reuse the same <code>Attributes</code> instance
    048         * for all calls.</p>
    049         *
    050         * @param attributes the <code>Attributes</code> passed into <code>Digester</code> by the SAX parser,
    051         * not null (but may be empty)
    052         * @return <code>Attributes</code> to be passed to the <code>Rule</code> implementations.
    053         * This method may pass back the Attributes passed in.
    054         * Not null but possibly empty.
    055         */
    056        public abstract Attributes substitute(Attributes attributes);
    057
    058        /**
    059         * Substitutes for the body text.
    060         * This method may substitute values into the body text of the
    061         * elements that Digester parses.
    062         *
    063         * @param bodyText the body text (as passed to <code>Digester</code>)
    064         * @return the body text to be passed to the <code>Rule</code> implementations
    065         */
    066        public abstract String substitute(String bodyText);
    067    }