<?php
function parse_url_relative($url, $component = NULL){
  $full_rx = '!^
    (?P<scheme>[a-z][a-z0-9\+\-\.]*):/*         # scheme
    (?:(?P<user>[^:@]*)(?::(?P<pass>[^@]*))?@)? # user and password
    (?P<host>[^/\?\#:]*)                        # host
    (?::(?P<port>[0-9]+))?                      # port
    (?P<path>[^\?\#]*)                          # path
    (?:\?(?P<query>[^\#]*))?                    # query
    (?:\#(?P<fragment>.*))?                     # fragment
  $!ix';

  $path_rx = '!^
    (?P<path>[^\?\#]*)                          # path
    (?:\?(?P<query>[^\#]*))?                    # query
    (?:\#(?P<fragment>.*))?                     # fragment
  $!ix';

  if (!preg_match($full_rx, $url, $m)) {
    preg_match($path_rx, $url, $m);
  }

  $return = array(
    'scheme'    => isset($m['scheme'])    ? $m['scheme']    : NULL,
    'user'      => isset($m['user'])      ? $m['user']      : NULL,
    'pass'      => isset($m['pass'])      ? $m['pass']      : NULL,
    'host'      => isset($m['host'])      ? $m['host']      : NULL,
    'port'      => isset($m['port'])      ? $m['port']      : NULL,
    'path'      => isset($m['path'])      ? $m['path']      : '',
    'query'     => isset($m['query'])     ? $m['query']     : '',
    'fragment'  => isset($m['fragment'])  ? $m['fragment']  : '',
  );

  switch ($component) {
    case NULL:
      return $return;
    case PHP_URL_SCHEME:
      return $return['scheme'];
    case PHP_URL_HOST:
      return $return['host'];
    case PHP_URL_PORT:
      return $return['port'];
    case PHP_URL_USER:
      return $return['user'];
    case PHP_URL_PASS:
      return $return['pass'];
    case PHP_URL_PATH:
      return $return['path'];
    case PHP_URL_QUERY:
      return $return['query'];
    case PHP_URL_FRAGMENT:
      return $return['fragment'];
  }
}
?>