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- # 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'
-
- import re
- import time as ttime
- from datetime import (
- date as real_date, datetime as real_datetime, time as real_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)
-
- @classmethod
- def combine(cls, date, time):
- return cls(date.year, date.month, date.day,
- time.hour, time.minute, time.second,
- time.microsecond, time.tzinfo)
-
- def date(self):
- return date(self.year, self.month, self.day)
-
-
- class time(real_time):
- pass
-
-
- 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 = ttime.strftime(fmt, (year,) + timetuple[1:])
- sites1 = _findall(s1, str(year))
-
- s2 = ttime.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 = "%04d" % (dt.year,)
- for site in sites:
- s = s[:site] + syear + s[site + 4:]
- return s
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