PresetAbstract::getPlainSort

private function getPlainSort()
{
	static $plainArray;

	if ($plainArray)
	{
		return $plainArray;
	}

	$flatten = function($value, $key) use (&$plainArray, &$flatten) {
		if (is_string($key))
		{
			$plainArray[] = $key;
		}
		if (is_array($value))
		{
			array_walk($value, $flatten);
		}
		else
		{
			$plainArray[] = strval($value);
		}
	};

	$structure = $this->getFinalStructure();
	array_walk($structure, $flatten);

	return $plainArray;
}