Url Rewriter: Redirect requests according URL rewriting rules

URL Rewriter
Cesar D. Rodas <cesar@sixdegrees.com>

This class provides an easy mechanism to manage URL rewriting, avoiding to write and manage the  ".htaccess" file.
Another issue is that you can use a personalized regular expression for create friendlies URL.

I. Basic Structure
   <?php
        require "url_rewriter.php";
        $url = new url_rewriter('example/');
        $url->e404 = "error.php"; 
        // regular expression rules goes here
        $url->execute();
   ?>

II. Regular Expressions
    The regular expression are simple a set of constants, variable, and optionals parts.
    Example:
        $country=array('Argentina','Brasil','Paraguay');
        $url->add_rule("index.php","/[country]/{index.html}", array('country'=> $country) ); 
       
    If the first rule give true, "index.php" will be executed. For that country must be "Argentina", "Brasil" or "Paraguay" (this is because we force with the third parameter. "Country" must be in $country), and must exist an "index.html" or nothing.
    
        * /Paraguay/index.html  : Match
        * /Paraguay/                  : Match
        * /Paraguay/foo.html     : Mismatch
    
    The :numberX, where X is an identification, variable is an special variable that it must be numeric for match.
    
    Example:
        $country=array('Argentina','Brasil','Paraguay');
        $url->add_rule("foo.php","/[country]/[str]-[:number1]-site{-[:number2]}.[ext]", array('country'=> $country,':number2' => 2) );
        
        * /Paraguay/some_string-123-site.html                       :    Match
        * /Paraguay/some_other_string-123-site-456.html     :    Mismatch
        * /Paraguay/some_other_string-123-site-2.html         :    Match
        * /Paraguay/some_other_string-123-site-foo.html      :    Mismatch

III. Real life example
    Steps for  translate a page which is "foo.php?id=45" to its URL friendly mode.
    *   Download http://cesars.users.phpclasses.org/url_rewriter
    *   Edit url_handler.php
    *   Add a new rule
        $url->add_rule("foo.php","/entry-[:number1].html");
    *   Change all your links
        foo.php?id=45 for /entry-45.html
    * Edit foo.php adding an extra header
       <?php
            $id = $urlVars['number1'];
            //check if $id exist
             if ($id not exist) $urlHandler->error404();
            //handle request as you did before
        ?>