protected function isFormatCodeMatchingDateFormatPattern($formatCode)
{
// Remove extra formatting (what's between [ ], the brackets should not be preceded by a "\")
$pattern = '((?<!\\\\)\\[.+?(?<!\\\\)\\])';
$formatCode = preg_replace($pattern, '', $formatCode);
// custom date formats contain specific characters to represent the date:
// e - yy - m - d - h - s
// and all of their variants (yyyy - mm - dd...)
$dateFormatCharacters = ['e', 'yy', 'm', 'd', 'h', 's'];
$hasFoundDateFormatCharacter = false;
foreach ($dateFormatCharacters as $dateFormatCharacter) {
// character not preceded by "\" (case insensitive)
$pattern = '/(?<!\\\\)' . $dateFormatCharacter . '/i';
if (preg_match($pattern, $formatCode)) {
$hasFoundDateFormatCharacter = true;
break;
}
}
return $hasFoundDateFormatCharacter;
}