# Format a datetime through its full proleptic Gregorian date range.
#
# >>> strftime(datetime.date(1850, 8, 2), "%Y/%M/%d was a %A")
# '1850/00/02 was a Friday'
# >>>
import re, datetime, time
# remove the unsupposed "%s" command. But don't
# do it if there's an even number of %s before the s
# because those are all escaped. Can't simply
# remove the s because the result of
# %sY
# should be %Y if %s isn't supported, not the
# 4 digit year.
_illegal_s = re.compile(r"((^|[^%])(%%)*%s)")
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
# Every 28 years the calendar repeats, except through century leap
# years where it's 6 years. But only if you're using the Gregorian
# calendar. ;)
def strftime(dt, fmt):
if _illegal_s.search(fmt):
raise TypeError("This strftime implementation does not handle %s")
if dt.year > 1900:
return dt.strftime(fmt)
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
# Make sure that the day names are in order
# from 1/1/1 until August 2000
def test():
s = strftime(datetime.date(1800, 9, 23),
"%Y has the same days as 1980 and 2008")
if s != "1800 has the same days as 1980 and 2008":
raise AssertionError(s)
print "Testing all day names from 0001/01/01 until 2000/08/01"
# Get the weekdays. Can't hard code them; they could be
# localized.
days = []
for i in range(1, 10):
days.append(datetime.date(2000, 1, i).strftime("%A"))
nextday = {}
for i in range(8):
nextday[days[i]] = days[i+1]
startdate = datetime.date(1, 1, 1)
enddate = datetime.date(2000, 8, 1)
prevday = strftime(startdate, "%A")
one_day = datetime.timedelta(1)
testdate = startdate + one_day
while testdate < enddate:
if (testdate.day == 1 and testdate.month == 1 and
(testdate.year % 100 == 0)):
print "Testing century", testdate.year
day = strftime(testdate, "%A")
if nextday[prevday] != day:
raise AssertionError(str(testdate))
prevday = day
testdate = testdate + one_day
if __name__ == "__main__":
test()
