File::getSourceEncoding

public function getSourceEncoding(): string
{
	static $encodingCache = [];
	if (empty($this->sourceEncoding))
	{
		$language = $this->getLangId();
		if (isset($encodingCache[$language]))
		{
			$this->sourceEncoding = $encodingCache[$language];
		}
		else
		{
			$this->sourceEncoding = MainLocalizationTranslation::getSourceEncoding($language);
			$encodingCache[$language] = $this->sourceEncoding;
		}
	}

	return $this->sourceEncoding;
}