001 /* $Id: Substitutor.java 992060 2010-09-02 19:09:47Z simonetripodi $
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 }