restfull output urls for code igniter

.htaccess

<IfModule mod_rewrite.c>
    RewriteEngine On
    
    #Checks to see if the user is attempting to access a valid file,
    #such as an image or css document, if this isn't true it sends the
    #request to index.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    #This last condition enables access to the images and css folders, and the robots.txt file
    #Submitted by Michael Radlmaier (mradlmaier)
    RewriteCond $1 !^(index\.php|public|images|robots\.txt|css)
    RewriteRule ^(.*)$ index.php/$1 [L,QSA]
</IfModule>

config.php

<?php
$config['index_page'] = '';
$config['uri_protocol']	= 'AUTO';
$config['url_suffix'] = '';//required

routes.php

<?php

//eg welcome/index
$route['([a-z]+)/([a-z]+)'] = "$1/$2";

//eg welcome/index.json
$route['([a-z]+)/([a-z]+).([a-z]+)'] = "$1/$2";

?>

welcome.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Welcome extends CI_Controller {

	public function index()
	{
		$this->load->helper('url');
		echo 'URL: ' . current_url().'<br/>';
		echo 'FORMAT: ' . $this->_format().'<br/>';
		echo 'Building a url: ' . site_url("welcome/local/123.html").'<br/>';
		
		echo 'INTERESTING OUTPUTS: .json, .xml, .html, .cache <br/>';
		echo 'ACTIONS:  .clear (->an action to clear cache)';
	}
	
        //this should be moved to a helper function
        //or a MY_Controller should be created
        //but it shows how this can be done
        //could also be done in MY_Model (a la rails)
        //as long as cache control is also there
	private function _format()
	{
	   $current_url = current_url();
	   $extension = substr(strrchr($current_url, '.'), 1);
	   if (empty($extension)) { 
	   	  return 'html';//default extension
	   }
	   return $extension;
	}
}

/* End of file welcome.php */
/* Location: ./application/controllers/welcome.php */

main logic in routes.php & welcome.php