protected function libFunctionExists($args)
{
$string = $this->coerceString($args[0]);
$name = $this->compileStringContent($string);
// user defined functions
if ($this->has(static::$namespaces['function'] . $name)) {
return true;
}
$name = $this->normalizeName($name);
if (isset($this->userFunctions[$name])) {
return true;
}
// built-in functions
$f = $this->getBuiltinFunction($name);
return $this->toBool(is_callable($f));
}