wp-routes.php

<?php
/**
 * Plugin Name: WP Routes
 * Plugin URI: http://theAverageDev.com
 * Description: Easy WordPress routing
 * Version: 1.0
 * Author: Luca Tumedei
 * Author URI: http://theAverageDev.com
 * License: GPL 2.0
 */

require_once dirname( __FILE__ ) . '/vendor/lucatume/klein52/wp_klein.php';

if ( ! function_exists( 'wp_routes_do_parse_request' ) ) {
	/**
	 * Filters the request parsing process before WordPress does.
	 *
	 * @param bool         $continue
	 * @param WP           $wp
	 * @param string|array $extra_query_vars
	 *
	 * @return bool Either a bool for the `$continue` value or void if the parse request is stopped.
	 */
	function wp_routes_do_parse_request( $continue, WP $wp, $extra_query_vars ) {
		/**
		 * Allows plugin and theme developers to register custom routes to be handled before WordPress
		 * parses the request.
		 *
		 * @since 1.0.0
		 *
		 * @param bool         $bool             Whether or not to parse the request. Defaults to `true`.
		 * @param WP           $this             Current WordPress environment instance.
		 * @param array|string $extra_query_vars Extra passed query variables.
		 */
		do_action( 'wp-routes/register_routes', $continue, $wp, $extra_query_vars );

		/**
		 * If no echo was produced or the only echo produced is from "*" routes
		 * then continue and let WordPress handle the request; otherwise output the
		 * route output and `die`.
		 */
		klein_dispatch_or_continue();

		// if we got here WordPress should handle the request
		return $continue;
	}
}

add_filter( 'do_parse_request', 'wp_routes_do_parse_request', 1, 3 );