package org.apache.commons.digester3.examples.plugins.pipeline;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 

import org.apache.commons.digester3.Digester;

/**
 * An implementation of the Transform interface which replaces all occurrences
 * of a specified string with a different string.
 * <p>
 * Because this class wishes to configure instances via nested "from" and
 * "to" tags, it needs to define an addRules method to add rules to the
 * Digester dynamically. Note that there are different ways of defining the
 * rules though; for example they can be defined in a separate
 * SubstituteTransformRuleInfo class.
 */
public class SubstituteTransform
    implements Transform
{

    private String from;

    private String to;

    public void setFrom( String from )
    {
        this.from = from;
    }

    public void setTo( String to )
    {
        this.to = to;
    }

    public String transform( String s )
    {
        StringBuilder buf = new StringBuilder( s );
        while ( true )
        {
            int idx = buf.indexOf( from );
            if ( idx == -1 )
            {
                break;
            }

            buf.replace( idx, idx + from.length(), to );
        }
        return buf.toString();
    }

    public static void addRules( Digester d, String patternPrefix )
    {
        d.addCallMethod( patternPrefix + "/from", "setFrom", 0 );
        d.addCallMethod( patternPrefix + "/to", "setTo", 0 );
    }

}