dirty & quick php router only for xerver platform

xerver.php

<?php namespace xerver;

	// sort the _SERVER array based on its keys
	ksort($_SERVER);

	// normalize our path-info
	$_SERVER["PATH_INFO"] = preg_replace("~/+~", "/", "/" . $_SERVER["PATH_INFO"] . "/");

	// start the output buffer
	ob_start();

	// defer the output buffer flusher at the end of the script
	register_shutdown_function("ob_end_flush");

	/*
	 * pretty print the specified data
	 *
	 * @param 	mixed 		$data
	 *
	 * @return 	void
	 */
	function dump($data) {
		echo "<pre>" . print_r($data, 1) . "</pre>";
	}

	/*
	 * get a customized url using the specified info
	 *
	 * @param 	string 	$path 		the path to append to the url, (default "")
	 * @param 	string 	$hostname 	the hostname of the url, (default HTTP_HOST)
	 * @param 	bool 	$secure 	whether to be https url ornot, (default autodected)
	 *
	 * @return 	void
	 */
	function url($path = null, $hostname = null, $secure = null) {
		$url = "";
		if ( null === $secure ) {
			$url = $_SERVER["HTTPS"] ? "https://" : "http://";
		} else {
			$url = $secure ? "https://" : "http://";
		}
		if ( null === $hostname ) {
			$url .= $_SERVER["HTTP_HOST"];
		} else {
			$url .= $hostname;
		}
		return $url . "/" . ltrim($path, "/");
	}

	/*
	 * rewrite a pathinfo to a new pathinfo
	 *
	 * @param 	regexp 	$from
	 * @param 	string 	$to
	 *
	 * @return 	void
	 */
	function rewrite($from, $to) {
		$_SERVER["PATH_INFO"] = preg_replace($from, $to, $_SERVER["PATH_INFO"]);
		$_SERVER["PATH_INFO"] = preg_replace("~/+~", "/", "/" . $_SERVER["PATH_INFO"] . "/");
	}

	/*
	 * handle the specified path "pathinfo" using the specified callback
	 *
	 * @param 	string 		$path
	 * @param 	callable 	$fn
	 *
	 * @return 	void
	 */
	function on($path, callable $fn) {
		if ( preg_match("~^" . preg_replace("~/+~", "/", "/" . $path . "/") . "$~", $_SERVER["PATH_INFO"], $matches) ) {
			array_shift($matches);
			call_user_func_array($fn, $matches);
		}
	}

	/*
	 * handle the specified domain "hostname" using the specified callback
	 *
	 * @param 	string 		$hostname
	 * @param 	callable 	$fn
	 *
	 * @return 	void
	 */
	function vhost($hostname, callable $fn) {
		if ( preg_match($path, split(":", $_SERVER["HTTP_HOST"])[0] ?? "localhost", $matches) ) {
			array_shift($matches);
			call_user_func_array($fn, $matches);
		}
	}

	/*
	 * Send the specified file/directory to the browser using internal xerver action .
	 *
	 * @param 	string 		$path
	 *
	 * @return 	void
	 */
	function sendfile($filename) {
		header("Xerver-Internal-FileServer: " . $filename);
		exit;
	}