framework/helpers/BaseStringHelper.php
public static function dirname($path)
    {
        $pos = mb_strrpos(str_replace('\\', '/', $path), '/');
        if ($pos !== false) {
            return mb_substr($path, 0, $pos);
        }

        return '';
    }
public static function dirname($path)
    {
        $pos = mb_strrpos(str_replace('\\', '/', $path), '/');
        if ($pos !== false) {
            return mb_substr($path, 0, $pos);
        }

        return '';
    }
Returns parent directory's path.
This method is similar to `dirname()` except that it will treat
both \ and / as directory separators, independent of the operating system.

@param string $path A path string.
@return string the parent directory's path.
@see https://secure.php.net/manual/en/function.basename.php