which::autoLoad

static function autoLoad($className)
{
	// fix web env
	$className = ltrim($className, "\");

	$classLower = strtolower($className);

	static $documentRoot = null;
	if ($documentRoot === null)
	{
		$documentRoot = self::getDocumentRoot();
	}

	//optimization via direct paths
	if (isset(self::$autoLoadClasses[$classLower]))
	{
		$pathInfo = self::$autoLoadClasses[$classLower];
		if ($pathInfo["module"] != "")
		{
			$module = $pathInfo["module"];
			$holder = (self::$modulesHolders[$module] ?? self::BITRIX_HOLDER);

			$filePath = (defined('REPOSITORY_ROOT'))
				? REPOSITORY_ROOT
				: "{$documentRoot}/{$holder}/modules";

			$filePath .= '/'.$module."/".$pathInfo["file"];

			require_once($filePath);
		}
		else
		{
			require_once($documentRoot.$pathInfo["file"]);
		}
		return;
	}

	if (preg_match("#[^\\/a-zA-Z0-9_]#", $className))
	{
		return;
	}

	$tryFiles = [[
		"real" => $className,
		"lower" => $classLower,
	]];

	if (substr($classLower, -5) == "table")
	{
		// old *Table stored in reserved files
		$tryFiles[] = [
			"real" => substr($className, 0, -5),
			"lower" => substr($classLower, 0, -5),
		];
	}

	foreach ($tryFiles as $classInfo)
	{
		$classParts = explode("\", $classInfo["lower"]);

		//remove class name
		array_pop($classParts);

		while (!empty($classParts))
		{
			//go from the end
			$namespace = implode("\", $classParts)."\";

			if (isset(self::$namespaces[$namespace]))
			{
				//found
				foreach (self::$namespaces[$namespace] as $namespaceLocation)
				{
					$depth = $namespaceLocation["depth"];
					$path = $namespaceLocation["path"];

					$fileParts = explode("\", $classInfo["real"]);

					for ($i=0; $i <= $depth; $i++)
					{
						array_shift($fileParts);
					}

					$classPath = implode("/", $fileParts);

					$classPathLower = strtolower($classPath);

					// final path lower case
					$filePath = $path.'/'.$classPathLower.".php";

					if (file_exists($filePath))
					{
						require_once($filePath);
						break 3;
					}

					// final path original case
					$filePath = $path.'/'.$classPath.".php";

					if (file_exists($filePath))
					{
						require_once($filePath);
						break 3;
					}
				}
			}

			//try the shorter namespace
			array_pop($classParts);
		}
	}
}