/**
* Set the default namespace
*
* Set the default namespace to either a URI or the prefix of
* an already defined namespace.
*
* Example:
* EasyRdf_Namespace::setDefault('http://schema.org/');
*
* @param string $namespace The URI or prefix of a namespace (eg 'og')
*/
public static function setDefault($namespace)
{
if (is_null($namespace) or $namespace === '') {
self::$default = null;
} elseif (preg_match("/^\\w+\$/", $namespace)) {
if (isset(self::$namespaces[$namespace])) {
self::$default = self::$namespaces[$namespace];
} else {
throw new InvalidArgumentException("Unable to set default namespace to unknown prefix: {$namespace}");
}
} else {
self::$default = $namespace;
}
}
