<?php

Route::get('group/{group_screenname}/project/{project_screenname}', array('before' => 'select:group_screenname', 'uses' => 'GroupController@show'));
Route::get('group/{group_screenname}/project/{project_screenname}/task/{id}', array('before' => 'select:group_screenname,id', 'uses' => 'GroupTaskController@show'));

Route::filter('select', function($route, $request, $value)
{
    $params = $route->parameters();
    $keys = explode(',', $value);

    foreach (array_keys($param) as $key)
    {
        $route->setParameter($key, null);
    }
    foreach ($keys as $key)
    {
        if (isset($param[$key])) {
            $route->setParameter('_'.$key, $param[$key]);
        }
    }
});