001package org.apache.commons.digester3.examples.plugins.pipeline;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one or more
005 * contributor license agreements.  See the NOTICE file distributed with
006 * this work for additional information regarding copyright ownership.
007 * The ASF licenses this file to You under the Apache License, Version 2.0
008 * (the "License"); you may not use this file except in compliance with
009 * the License.  You may obtain a copy of the License at
010 * 
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 * 
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */ 
019
020import org.apache.commons.digester3.Digester;
021
022/**
023 * An implementation of the Transform interface which replaces all occurrences
024 * of a specified string with a different string.
025 * <p>
026 * Because this class wishes to configure instances via nested "from" and
027 * "to" tags, it needs to define an addRules method to add rules to the
028 * Digester dynamically. Note that there are different ways of defining the
029 * rules though; for example they can be defined in a separate
030 * SubstituteTransformRuleInfo class.
031 */
032public class SubstituteTransform
033    implements Transform
034{
035
036    private String from;
037
038    private String to;
039
040    public void setFrom( String from )
041    {
042        this.from = from;
043    }
044
045    public void setTo( String to )
046    {
047        this.to = to;
048    }
049
050    public String transform( String s )
051    {
052        StringBuilder buf = new StringBuilder( s );
053        while ( true )
054        {
055            int idx = buf.indexOf( from );
056            if ( idx == -1 )
057            {
058                break;
059            }
060
061            buf.replace( idx, idx + from.length(), to );
062        }
063        return buf.toString();
064    }
065
066    public static void addRules( Digester d, String patternPrefix )
067    {
068        d.addCallMethod( patternPrefix + "/from", "setFrom", 0 );
069        d.addCallMethod( patternPrefix + "/to", "setTo", 0 );
070    }
071
072}