offsets.py 文件源码

def apply(self, other):
        n = self.n
        wkday, days_in_month = tslib.monthrange(other.year, self.month)
        lastBDay = (days_in_month -
                    max(((wkday + days_in_month - 1) % 7) - 4, 0))

        years = n
        if n > 0:
            if (other.month < self.month or
                    (other.month == self.month and other.day < lastBDay)):
                years -= 1
        elif n <= 0:
            if (other.month > self.month or
                    (other.month == self.month and other.day > lastBDay)):
                years += 1

        other = other + relativedelta(years=years)

        _, days_in_month = tslib.monthrange(other.year, self.month)
        result = datetime(other.year, self.month, days_in_month,
                          other.hour, other.minute, other.second,
                          other.microsecond)

        if result.weekday() > 4:
            result = result - BDay()

        return result