protected function writeSharedStringsXML()
{
$temporary_filename = $this->tempFilename();
$file = new XLSXWriter_BuffererWriter($temporary_filename, $fd_flags = 'w', $check_utf8 = true);
$file->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n");
$file->write('<sst count="' . $this->shared_string_count . '" uniqueCount="' . count($this->shared_strings) . '" xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">');
foreach ($this->shared_strings as $s => $c) {
$file->write('<si><t>' . self::xmlspecialchars($s) . '</t></si>');
}
$file->write('</sst>');
$file->close();
return $temporary_filename;
}