106 lines
2.8 KiB
Python
106 lines
2.8 KiB
Python
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# Python's datetime strftime doesn't handle dates before 1900.
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# These classes override date and datetime to support the formatting of a date
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# through its full "proleptic Gregorian" date range.
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#
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# Based on code submitted to comp.lang.python by Andrew Dalke
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#
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# >>> datetime_safe.date(1850, 8, 2).strftime("%Y/%m/%d was a %A")
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# '1850/08/02 was a Friday'
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import re
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import time as ttime
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from datetime import (
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date as real_date, datetime as real_datetime, time as real_time,
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)
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class date(real_date):
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def strftime(self, fmt):
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return strftime(self, fmt)
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class datetime(real_datetime):
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def strftime(self, fmt):
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return strftime(self, fmt)
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@classmethod
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def combine(cls, date, time):
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return cls(date.year, date.month, date.day,
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time.hour, time.minute, time.second,
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time.microsecond, time.tzinfo)
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def date(self):
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return date(self.year, self.month, self.day)
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class time(real_time):
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pass
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def new_date(d):
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"Generate a safe date from a datetime.date object."
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return date(d.year, d.month, d.day)
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def new_datetime(d):
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"""
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Generate a safe datetime from a datetime.date or datetime.datetime object.
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"""
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kw = [d.year, d.month, d.day]
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if isinstance(d, real_datetime):
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kw.extend([d.hour, d.minute, d.second, d.microsecond, d.tzinfo])
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return datetime(*kw)
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# This library does not support strftime's "%s" or "%y" format strings.
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# Allowed if there's an even number of "%"s because they are escaped.
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_illegal_formatting = re.compile(r"((^|[^%])(%%)*%[sy])")
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def _findall(text, substr):
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# Also finds overlaps
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sites = []
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i = 0
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while True:
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i = text.find(substr, i)
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if i == -1:
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break
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sites.append(i)
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i += 1
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return sites
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def strftime(dt, fmt):
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if dt.year >= 1900:
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return super(type(dt), dt).strftime(fmt)
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illegal_formatting = _illegal_formatting.search(fmt)
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if illegal_formatting:
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raise TypeError("strftime of dates before 1900 does not handle" + illegal_formatting.group(0))
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year = dt.year
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# For every non-leap year century, advance by
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# 6 years to get into the 28-year repeat cycle
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delta = 2000 - year
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off = 6 * (delta // 100 + delta // 400)
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year = year + off
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# Move to around the year 2000
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year = year + ((2000 - year) // 28) * 28
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timetuple = dt.timetuple()
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s1 = ttime.strftime(fmt, (year,) + timetuple[1:])
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sites1 = _findall(s1, str(year))
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s2 = ttime.strftime(fmt, (year + 28,) + timetuple[1:])
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sites2 = _findall(s2, str(year + 28))
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sites = []
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for site in sites1:
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if site in sites2:
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sites.append(site)
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s = s1
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syear = "%04d" % (dt.year,)
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for site in sites:
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s = s[:site] + syear + s[site + 4:]
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return s
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