Symfony 2: use GET parameter _path to determine route

app.php

use Package\MyBundle\Component\HttpFoundation\Request;

Request.php

<?php

    namespace Package\MyBundle\Component\HttpFoundation;

    use Symfony\Component\HttpFoundation\Request as BaseRequest;

    /**
     * Represents HTTP request.
     * Replaces actual path with GET _path parameter (if present)
     *
     * @author Ilya A. Sanosyan
     */
    class Request extends BaseRequest
    {

        /**
         * Returns the path being requested relative to the executed script.
         * If _path GET parameter is present, returns value of this parameter.
         *
         * The path info should always start with a /.
         *
         * Suppose this request is instantiated from /mysite on localhost:
         *
         *  * http://localhost/mysite                       returns an empty string
         *  * http://localhost/mysite/about                 returns '/about'
         *  * http://localhost/mysite/about?var=1           returns '/about'
         *  * http://localhost/mysite/about?var=1&_path=/my returns '/my'
         *
         * @return string
         */
        function getPathInfo ()
        {
            $getQueryElements = array ();
            parse_str ($this->server->get ('QUERY_STRING'), $getQueryElements);

            if (isset ($getQueryElements ['_path']))
                return $getQueryElements ['_path'];

            return parent::getPathInfo ();
        }

    }

services.yml

parameters:
    router.options.generator_base_class: Package\MyBundle\Component\Routing\Generator\UrlGenerator

UrlGenerator.php

<?php

    namespace Package\MyBundle\Component\Routing\Generator;

    use Symfony\Component\Routing\Generator\UrlGenerator as BaseUrlGenerator;

    /**
     * Will be base url generator class for Router.
     * Enables genrator to work with our type of URIs:
     *  /app.php?_path=/my/path&param1=v1&...
     *
     * @author Ilya A. Sanosyan
     */
    class UrlGenerator extends BaseUrlGenerator
    {

        /**
         * Asks parent class to generate URL and transforms it:
         *  - adds GET parameter _path holding path
         *  - replaces path with base url
         *  - adds app.php if no front controller was specified.
         */
        protected function doGenerate ($variables, $defaults, $requirements, $tokens, $parameters, $name, $absolute)
        {
            // asking parent to generate URL and parsing it
            $url      = str_replace ($base = $this->context->getBaseUrl (),
                                     '',
                                     parent::doGenerate ($variables, $defaults, $requirements, $tokens, $parameters, $name, $absolute)
            );
            $urlParts = parse_url ($url);

            // adding _path GET parameter
            if (isset ($urlParts ['query']))
                parse_str ($urlParts ['query'], $queryParameters);
            else
                $queryParameters = array ();
            if (isset ($urlParts ['path']))
                $queryParameters ['_path'] = $urlParts ['path'];

            // adding base url and front controller name
            if (!$base || mb_substr ($base, -1) == '/')
                $base .= 'app.php';

            // path should be empty
            $urlParts ['path'] = $base;

            // building uri back
            $urlParts ['query'] = urldecode (http_build_query ($queryParameters));

            return http_build_url ($urlParts);
        }

    }