+
−# Python's datetime strftime doesn't handle dates before 1900.
+
−# These classes override date and datetime to support the formatting of a date
+
−# through its full "proleptic Gregorian" date range.
+
−#
+
−# Based on code submitted to comp.lang.python by Andrew Dalke
+
−#
+
−# >>> datetime_safe.date(1850, 8, 2).strftime("%Y/%M/%d was a %A")
+
−# '1850/08/02 was a Friday'
+
−
+
−from datetime import date as real_date, datetime as real_datetime
+
−import re
+
−import time
+
−
+
−class date(real_date):
+
−    def strftime(self, fmt):
+
−        return strftime(self, fmt)
+
−
+
−class datetime(real_datetime):
+
−    def strftime(self, fmt):
+
−        return strftime(self, fmt)
+
−
+
−    def combine(self, date, time):
+
−        return datetime(date.year, date.month, date.day, time.hour, time.minute, time.microsecond, time.tzinfo)
+
−
+
−    def date(self):
+
−        return date(self.year, self.month, self.day)
+
−
+
−def new_date(d):
+
−    "Generate a safe date from a datetime.date object."
+
−    return date(d.year, d.month, d.day)
+
−
+
−def new_datetime(d):
+
−    """
+
−    Generate a safe datetime from a datetime.date or datetime.datetime object.
+
−    """
+
−    kw = [d.year, d.month, d.day]
+
−    if isinstance(d, real_datetime):
+
−        kw.extend([d.hour, d.minute, d.second, d.microsecond, d.tzinfo])
+
−    return datetime(*kw)
+
−
+
−# This library does not support strftime's "%s" or "%y" format strings.
+
−# Allowed if there's an even number of "%"s because they are escaped.
+
−_illegal_formatting = re.compile(r"((^|[^%])(%%)*%[sy])")
+
−
+
−def _findall(text, substr):
+
−    # Also finds overlaps
+
−    sites = []
+
−    i = 0
+
−    while 1:
+
−        j = text.find(substr, i)
+
−        if j == -1:
+
−            break
+
−        sites.append(j)
+
−        i=j+1
+
−    return sites
+
−
+
−def strftime(dt, fmt):
+
−    if dt.year >= 1900:
+
−        return super(type(dt), dt).strftime(fmt)
+
−    illegal_formatting = _illegal_formatting.search(fmt)
+
−    if illegal_formatting:
+
−        raise TypeError("strftime of dates before 1900 does not handle" + illegal_formatting.group(0))
+
−
+
−    year = dt.year
+
−    # For every non-leap year century, advance by
+
−    # 6 years to get into the 28-year repeat cycle
+
−    delta = 2000 - year
+
−    off = 6 * (delta // 100 + delta // 400)
+
−    year = year + off
+
−
+
−    # Move to around the year 2000
+
−    year = year + ((2000 - year) // 28) * 28
+
−    timetuple = dt.timetuple()
+
−    s1 = time.strftime(fmt, (year,) + timetuple[1:])
+
−    sites1 = _findall(s1, str(year))
+
−
+
−    s2 = time.strftime(fmt, (year+28,) + timetuple[1:])
+
−    sites2 = _findall(s2, str(year+28))
+
−
+
−    sites = []
+
−    for site in sites1:
+
−        if site in sites2:
+
−            sites.append(site)
+
−
+
−    s = s1
+
−    syear = "%4d" % (dt.year,)
+
−    for site in sites:
+
−        s = s[:site] + syear + s[site+4:]
+
−    return s