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// ========================================================================
// Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================
package org.eclipse.jetty.rewrite.handler;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/**
 * Abstract rule to use as a base class for rules that match with a regular expression.
 */
public abstract class RegexRule extends Rule
{
    protected Pattern _regex; 

    /* ------------------------------------------------------------ */
    /**
     * Sets the regular expression string used to match with string URI.
     * 
     * @param regex the regular expression.
     */
    public void setRegex(String regex)
    {
        _regex=Pattern.compile(regex);
    }

    /* ------------------------------------------------------------ */
    /**
     * @return get the regular expression
     */
    public String getRegex()
    {
        return _regex==null?null:_regex.pattern();
    }
    

    /* ------------------------------------------------------------ */
    public String matchAndApply(String target, HttpServletRequest request, HttpServletResponse response) throws IOException
    {
        Matcher matcher=_regex.matcher(target);
        boolean matches = matcher.matches();
        if (matches)
            return apply(target,request,response, matcher);
        return null;
    }

    /* ------------------------------------------------------------ */
    /** 
     * Apply this rule to the request/response pair.
     * Called by {@link #matchAndApply(String, HttpServletRequest, HttpServletResponse)} if the regex matches.
     * @param target field to attempt match
     * @param request request object
     * @param response response object
     * @param matcher The Regex matcher that matched the request (with capture groups available for replacement).
     * @return The target (possible updated).
     * @throws IOException exceptions dealing with operating on request or response objects
     */
    protected abstract String apply(String target, HttpServletRequest request, HttpServletResponse response, Matcher matcher) throws IOException;
    

    /* ------------------------------------------------------------ */
    /**
     * Returns the regular expression string.
     */
    public String toString()
    {
        return super.toString()+"["+_regex+"]";
    }
}