The CT Recurrence class gets future recurring dates based on given arguments. It also considers excluded dates. It is used for events in the Church Content plugin (and Pro add-on) and Church Theme Framework.
Version 2.0 adopted the use of php-rrule (MIT) for more sophisticted patterns. Earlier versions used more simplistic, proprietary calculations. get_dates(), calc_next_future_date() and their arguments are backwards-compatible.
Version 2.0 requires PHP 5.3+. Include ct-recurrence-load.php instead of ct-recurrence.php. Users of insufficient versions of PHP will have get_dates() return empty and calc_next_future_date() return false to prevent errors.
See example usage at bottom of ct-recurrence.php.