private function validateScopeToken($scopeToken)
{
if (!is_string($scopeToken) || 0 >= strlen($scopeToken)) {
throw new ScopeException('scope token must be a non-empty string');
}
$scopeTokenRegExp = '/^(?:\\x21|[\\x23-\\x5B]|[\\x5D-\\x7E])+$/';
$result = preg_match($scopeTokenRegExp, $scopeToken);
return 1 === $result;
}