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This project contains some of the configurable modules used within the Heritrix application to crawl the web. The modules in this project can be used in applications other than Heritrix, however.

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/*
 *  This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA 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.
 */
package org.archive.modules.canonicalize;

import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


/**
 * General conversion rule.
 * @author stack
 * @version $Date$, $Revision$
 */
public class RegexRule
extends BaseRule {

    private static final long serialVersionUID = -3L;

    protected static Logger logger =
        Logger.getLogger(BaseRule.class.getName());

//    private static final String DESCRIPTION = "General regex rule. " +
//        "Specify a matching regex and a format string used outputting" +
//        " result if a match was found.  If problem compiling regex or" +
//        " interpreting format, problem is logged, and this rule does" +
//        " nothing.  See User Manual for example usage.";

    
    /**
     * The regular expression to use to match.
     */
    {
        setRegex(Pattern.compile("(.*)"));
    }
    public Pattern getRegex() {
        return (Pattern) kp.get("regex");
    }
    public void setRegex(Pattern regex) {
        kp.put("regex",regex);
    }
    
    /**
     * The format string to use when a match is found.
     */
    {
        setFormat("$1");
    }
    public String getFormat() {
        return (String) kp.get("format");
    }
    public void setFormat(String format) {
        kp.put("format",format);
    }

    public RegexRule() {
    }
    

    public String canonicalize(String url) {
        Pattern pattern = getRegex();
        Matcher matcher = pattern.matcher(url);
        if (!matcher.matches()) {
            return url;
        }
        StringBuffer buffer = new StringBuffer(url.length() * 2);
        matcher.appendReplacement(buffer,getFormat());
        return buffer.toString();
    }
}