sub parse_xls_file
{
    my ($data_folder,
        $filename,
        $materialmapping_table_xml,
        $materialmapping_table_xml_root) = @_;

    if (my $oBook = Spreadsheet::ParseExcel->
                    new()->parse($data_folder . $filename))
    {
        for (0 .. $oBook->{SheetCount} - 1)
        {
            process_sheet($oBook,
                          $_,
                          $materialmapping_table_xml,
                          $materialmapping_table_xml_root)
        }
    }

    print "Parsed $filename\n";
}