def rebuild()

in lib/dateutil/rrule.py [0:0]


    def rebuild(self, year, month):
        # Every mask is 7 days longer to handle cross-year weekly periods.
        rr = self.rrule
        if year != self.lastyear:
            self.yearlen = 365 + calendar.isleap(year)
            self.nextyearlen = 365 + calendar.isleap(year + 1)
            firstyday = datetime.date(year, 1, 1)
            self.yearordinal = firstyday.toordinal()
            self.yearweekday = firstyday.weekday()

            wday = datetime.date(year, 1, 1).weekday()
            if self.yearlen == 365:
                self.mmask = M365MASK
                self.mdaymask = MDAY365MASK
                self.nmdaymask = NMDAY365MASK
                self.wdaymask = WDAYMASK[wday:]
                self.mrange = M365RANGE
            else:
                self.mmask = M366MASK
                self.mdaymask = MDAY366MASK
                self.nmdaymask = NMDAY366MASK
                self.wdaymask = WDAYMASK[wday:]
                self.mrange = M366RANGE

            if not rr._byweekno:
                self.wnomask = None
            else:
                self.wnomask = [0]*(self.yearlen+7)
                # no1wkst = firstwkst = self.wdaymask.index(rr._wkst)
                no1wkst = firstwkst = (7-self.yearweekday+rr._wkst) % 7
                if no1wkst >= 4:
                    no1wkst = 0
                    # Number of days in the year, plus the days we got
                    # from last year.
                    wyearlen = self.yearlen+(self.yearweekday-rr._wkst) % 7
                else:
                    # Number of days in the year, minus the days we
                    # left in last year.
                    wyearlen = self.yearlen-no1wkst
                div, mod = divmod(wyearlen, 7)
                numweeks = div+mod//4
                for n in rr._byweekno:
                    if n < 0:
                        n += numweeks+1
                    if not (0 < n <= numweeks):
                        continue
                    if n > 1:
                        i = no1wkst+(n-1)*7
                        if no1wkst != firstwkst:
                            i -= 7-firstwkst
                    else:
                        i = no1wkst
                    for j in range(7):
                        self.wnomask[i] = 1
                        i += 1
                        if self.wdaymask[i] == rr._wkst:
                            break
                if 1 in rr._byweekno:
                    # Check week number 1 of next year as well
                    # TODO: Check -numweeks for next year.
                    i = no1wkst+numweeks*7
                    if no1wkst != firstwkst:
                        i -= 7-firstwkst
                    if i < self.yearlen:
                        # If week starts in next year, we
                        # don't care about it.
                        for j in range(7):
                            self.wnomask[i] = 1
                            i += 1
                            if self.wdaymask[i] == rr._wkst:
                                break
                if no1wkst:
                    # Check last week number of last year as
                    # well. If no1wkst is 0, either the year
                    # started on week start, or week number 1
                    # got days from last year, so there are no
                    # days from last year's last week number in
                    # this year.
                    if -1 not in rr._byweekno:
                        lyearweekday = datetime.date(year-1, 1, 1).weekday()
                        lno1wkst = (7-lyearweekday+rr._wkst) % 7
                        lyearlen = 365+calendar.isleap(year-1)
                        if lno1wkst >= 4:
                            lno1wkst = 0
                            lnumweeks = 52+(lyearlen +
                                            (lyearweekday-rr._wkst) % 7) % 7//4
                        else:
                            lnumweeks = 52+(self.yearlen-no1wkst) % 7//4
                    else:
                        lnumweeks = -1
                    if lnumweeks in rr._byweekno:
                        for i in range(no1wkst):
                            self.wnomask[i] = 1

        if (rr._bynweekday and (month != self.lastmonth or
                                year != self.lastyear)):
            ranges = []
            if rr._freq == YEARLY:
                if rr._bymonth:
                    for month in rr._bymonth:
                        ranges.append(self.mrange[month-1:month+1])
                else:
                    ranges = [(0, self.yearlen)]
            elif rr._freq == MONTHLY:
                ranges = [self.mrange[month-1:month+1]]
            if ranges:
                # Weekly frequency won't get here, so we may not
                # care about cross-year weekly periods.
                self.nwdaymask = [0]*self.yearlen
                for first, last in ranges:
                    last -= 1
                    for wday, n in rr._bynweekday:
                        if n < 0:
                            i = last+(n+1)*7
                            i -= (self.wdaymask[i]-wday) % 7
                        else:
                            i = first+(n-1)*7
                            i += (7-self.wdaymask[i]+wday) % 7
                        if first <= i <= last:
                            self.nwdaymask[i] = 1

        if rr._byeaster:
            self.eastermask = [0]*(self.yearlen+7)
            eyday = easter.easter(year).toordinal()-self.yearordinal
            for offset in rr._byeaster:
                self.eastermask[eyday+offset] = 1

        self.lastyear = year
        self.lastmonth = month