Drupal code implements URL rewriting_PHP tutorial

/*
* Pseudo address to original address (url_alter )
*/
function example_url_inbound_alter(&$path, $original_path, $path_language)
{
if (preg_match('|^article(/.*)|', $path, $matches )) {
$path = 'node'. $matches[1];
}
}
/*
* Original address to pseudo address (url_alter)
*/
function example_url_outbound_alter(&$path, &$options, $original_path)
{
if (preg_match('|^node(/.*)|', $path, $matches)) {
$path = 'article' . $matches[1];
}
}