2153 lines
74 KiB
Python
2153 lines
74 KiB
Python
"""Concrete date/time and related types.
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See http://www.iana.org/time-zones/repository/tz-link.html for
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time zone and DST data sources.
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"""
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from __future__ import division
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from __future__ import unicode_literals
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from __future__ import print_function
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from __future__ import absolute_import
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from future.builtins import str
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from future.builtins import bytes
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from future.builtins import map
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from future.builtins import round
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from future.builtins import int
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from future.builtins import object
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from future.utils import native_str, PY2
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import time as _time
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import math as _math
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def _cmp(x, y):
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return 0 if x == y else 1 if x > y else -1
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MINYEAR = 1
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MAXYEAR = 9999
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_MAXORDINAL = 3652059 # date.max.toordinal()
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# Utility functions, adapted from Python's Demo/classes/Dates.py, which
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# also assumes the current Gregorian calendar indefinitely extended in
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# both directions. Difference: Dates.py calls January 1 of year 0 day
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# number 1. The code here calls January 1 of year 1 day number 1. This is
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# to match the definition of the "proleptic Gregorian" calendar in Dershowitz
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# and Reingold's "Calendrical Calculations", where it's the base calendar
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# for all computations. See the book for algorithms for converting between
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# proleptic Gregorian ordinals and many other calendar systems.
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_DAYS_IN_MONTH = [None, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
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_DAYS_BEFORE_MONTH = [None]
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dbm = 0
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for dim in _DAYS_IN_MONTH[1:]:
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_DAYS_BEFORE_MONTH.append(dbm)
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dbm += dim
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del dbm, dim
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def _is_leap(year):
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"year -> 1 if leap year, else 0."
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return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
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def _days_before_year(year):
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"year -> number of days before January 1st of year."
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y = year - 1
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return y*365 + y//4 - y//100 + y//400
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def _days_in_month(year, month):
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"year, month -> number of days in that month in that year."
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assert 1 <= month <= 12, month
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if month == 2 and _is_leap(year):
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return 29
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return _DAYS_IN_MONTH[month]
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def _days_before_month(year, month):
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"year, month -> number of days in year preceding first day of month."
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assert 1 <= month <= 12, 'month must be in 1..12'
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return _DAYS_BEFORE_MONTH[month] + (month > 2 and _is_leap(year))
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def _ymd2ord(year, month, day):
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"year, month, day -> ordinal, considering 01-Jan-0001 as day 1."
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assert 1 <= month <= 12, 'month must be in 1..12'
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dim = _days_in_month(year, month)
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assert 1 <= day <= dim, ('day must be in 1..%d' % dim)
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return (_days_before_year(year) +
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_days_before_month(year, month) +
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day)
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_DI400Y = _days_before_year(401) # number of days in 400 years
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_DI100Y = _days_before_year(101) # " " " " 100 "
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_DI4Y = _days_before_year(5) # " " " " 4 "
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# A 4-year cycle has an extra leap day over what we'd get from pasting
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# together 4 single years.
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assert _DI4Y == 4 * 365 + 1
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# Similarly, a 400-year cycle has an extra leap day over what we'd get from
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# pasting together 4 100-year cycles.
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assert _DI400Y == 4 * _DI100Y + 1
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# OTOH, a 100-year cycle has one fewer leap day than we'd get from
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# pasting together 25 4-year cycles.
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assert _DI100Y == 25 * _DI4Y - 1
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def _ord2ymd(n):
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"ordinal -> (year, month, day), considering 01-Jan-0001 as day 1."
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# n is a 1-based index, starting at 1-Jan-1. The pattern of leap years
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# repeats exactly every 400 years. The basic strategy is to find the
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# closest 400-year boundary at or before n, then work with the offset
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# from that boundary to n. Life is much clearer if we subtract 1 from
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# n first -- then the values of n at 400-year boundaries are exactly
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# those divisible by _DI400Y:
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#
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# D M Y n n-1
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# -- --- ---- ---------- ----------------
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# 31 Dec -400 -_DI400Y -_DI400Y -1
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# 1 Jan -399 -_DI400Y +1 -_DI400Y 400-year boundary
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# ...
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# 30 Dec 000 -1 -2
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# 31 Dec 000 0 -1
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# 1 Jan 001 1 0 400-year boundary
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# 2 Jan 001 2 1
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# 3 Jan 001 3 2
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# ...
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# 31 Dec 400 _DI400Y _DI400Y -1
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# 1 Jan 401 _DI400Y +1 _DI400Y 400-year boundary
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n -= 1
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n400, n = divmod(n, _DI400Y)
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year = n400 * 400 + 1 # ..., -399, 1, 401, ...
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# Now n is the (non-negative) offset, in days, from January 1 of year, to
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# the desired date. Now compute how many 100-year cycles precede n.
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# Note that it's possible for n100 to equal 4! In that case 4 full
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# 100-year cycles precede the desired day, which implies the desired
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# day is December 31 at the end of a 400-year cycle.
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n100, n = divmod(n, _DI100Y)
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# Now compute how many 4-year cycles precede it.
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n4, n = divmod(n, _DI4Y)
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# And now how many single years. Again n1 can be 4, and again meaning
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# that the desired day is December 31 at the end of the 4-year cycle.
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n1, n = divmod(n, 365)
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year += n100 * 100 + n4 * 4 + n1
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if n1 == 4 or n100 == 4:
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assert n == 0
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return year-1, 12, 31
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# Now the year is correct, and n is the offset from January 1. We find
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# the month via an estimate that's either exact or one too large.
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leapyear = n1 == 3 and (n4 != 24 or n100 == 3)
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assert leapyear == _is_leap(year)
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month = (n + 50) >> 5
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preceding = _DAYS_BEFORE_MONTH[month] + (month > 2 and leapyear)
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if preceding > n: # estimate is too large
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month -= 1
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preceding -= _DAYS_IN_MONTH[month] + (month == 2 and leapyear)
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n -= preceding
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assert 0 <= n < _days_in_month(year, month)
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# Now the year and month are correct, and n is the offset from the
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# start of that month: we're done!
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return year, month, n+1
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# Month and day names. For localized versions, see the calendar module.
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_MONTHNAMES = [None, "Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
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_DAYNAMES = [None, "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
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def _build_struct_time(y, m, d, hh, mm, ss, dstflag):
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wday = (_ymd2ord(y, m, d) + 6) % 7
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dnum = _days_before_month(y, m) + d
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return _time.struct_time((y, m, d, hh, mm, ss, wday, dnum, dstflag))
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def _format_time(hh, mm, ss, us):
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# Skip trailing microseconds when us==0.
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result = "%02d:%02d:%02d" % (hh, mm, ss)
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if us:
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result += ".%06d" % us
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return result
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# Correctly substitute for %z and %Z escapes in strftime formats.
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def _wrap_strftime(object, format, timetuple):
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# Don't call utcoffset() or tzname() unless actually needed.
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freplace = None # the string to use for %f
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zreplace = None # the string to use for %z
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Zreplace = None # the string to use for %Z
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# Scan format for %z and %Z escapes, replacing as needed.
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newformat = []
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push = newformat.append
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i, n = 0, len(format)
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while i < n:
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ch = format[i]
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i += 1
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if ch == '%':
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if i < n:
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ch = format[i]
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i += 1
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if ch == 'f':
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if freplace is None:
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freplace = '%06d' % getattr(object,
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'microsecond', 0)
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newformat.append(freplace)
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elif ch == 'z':
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if zreplace is None:
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zreplace = ""
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if hasattr(object, "utcoffset"):
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offset = object.utcoffset()
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if offset is not None:
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sign = '+'
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if offset.days < 0:
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offset = -offset
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sign = '-'
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h, m = divmod(offset, timedelta(hours=1))
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assert not m % timedelta(minutes=1), "whole minute"
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m //= timedelta(minutes=1)
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zreplace = '%c%02d%02d' % (sign, h, m)
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assert '%' not in zreplace
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newformat.append(zreplace)
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elif ch == 'Z':
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if Zreplace is None:
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Zreplace = ""
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if hasattr(object, "tzname"):
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s = object.tzname()
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if s is not None:
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# strftime is going to have at this: escape %
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Zreplace = s.replace('%', '%%')
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newformat.append(Zreplace)
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else:
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push('%')
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push(ch)
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else:
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push('%')
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else:
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push(ch)
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newformat = "".join(newformat)
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return _time.strftime(newformat, timetuple)
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def _call_tzinfo_method(tzinfo, methname, tzinfoarg):
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if tzinfo is None:
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return None
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return getattr(tzinfo, methname)(tzinfoarg)
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# Just raise TypeError if the arg isn't None or a string.
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def _check_tzname(name):
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if name is not None and not isinstance(name, str):
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raise TypeError("tzinfo.tzname() must return None or string, "
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"not '%s'" % type(name))
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# name is the offset-producing method, "utcoffset" or "dst".
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# offset is what it returned.
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# If offset isn't None or timedelta, raises TypeError.
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# If offset is None, returns None.
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# Else offset is checked for being in range, and a whole # of minutes.
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# If it is, its integer value is returned. Else ValueError is raised.
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def _check_utc_offset(name, offset):
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assert name in ("utcoffset", "dst")
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if offset is None:
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return
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if not isinstance(offset, timedelta):
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raise TypeError("tzinfo.%s() must return None "
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"or timedelta, not '%s'" % (name, type(offset)))
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if offset % timedelta(minutes=1) or offset.microseconds:
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raise ValueError("tzinfo.%s() must return a whole number "
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"of minutes, got %s" % (name, offset))
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if not -timedelta(1) < offset < timedelta(1):
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raise ValueError("%s()=%s, must be must be strictly between"
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" -timedelta(hours=24) and timedelta(hours=24)"
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% (name, offset))
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def _check_date_fields(year, month, day):
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if not isinstance(year, int):
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raise TypeError('int expected')
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if not MINYEAR <= year <= MAXYEAR:
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raise ValueError('year must be in %d..%d' % (MINYEAR, MAXYEAR), year)
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if not 1 <= month <= 12:
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raise ValueError('month must be in 1..12', month)
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dim = _days_in_month(year, month)
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if not 1 <= day <= dim:
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raise ValueError('day must be in 1..%d' % dim, day)
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def _check_time_fields(hour, minute, second, microsecond):
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if not isinstance(hour, int):
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raise TypeError('int expected')
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if not 0 <= hour <= 23:
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raise ValueError('hour must be in 0..23', hour)
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if not 0 <= minute <= 59:
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raise ValueError('minute must be in 0..59', minute)
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if not 0 <= second <= 59:
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raise ValueError('second must be in 0..59', second)
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if not 0 <= microsecond <= 999999:
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raise ValueError('microsecond must be in 0..999999', microsecond)
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def _check_tzinfo_arg(tz):
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if tz is not None and not isinstance(tz, tzinfo):
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raise TypeError("tzinfo argument must be None or of a tzinfo subclass")
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def _cmperror(x, y):
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raise TypeError("can't compare '%s' to '%s'" % (
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type(x).__name__, type(y).__name__))
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class timedelta(object):
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"""Represent the difference between two datetime objects.
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Supported operators:
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- add, subtract timedelta
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- unary plus, minus, abs
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- compare to timedelta
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- multiply, divide by int
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In addition, datetime supports subtraction of two datetime objects
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returning a timedelta, and addition or subtraction of a datetime
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and a timedelta giving a datetime.
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Representation: (days, seconds, microseconds). Why? Because I
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felt like it.
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"""
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__slots__ = '_days', '_seconds', '_microseconds'
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def __new__(cls, days=0, seconds=0, microseconds=0,
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milliseconds=0, minutes=0, hours=0, weeks=0):
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# Doing this efficiently and accurately in C is going to be difficult
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# and error-prone, due to ubiquitous overflow possibilities, and that
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# C double doesn't have enough bits of precision to represent
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# microseconds over 10K years faithfully. The code here tries to make
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# explicit where go-fast assumptions can be relied on, in order to
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# guide the C implementation; it's way more convoluted than speed-
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# ignoring auto-overflow-to-long idiomatic Python could be.
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# XXX Check that all inputs are ints or floats.
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# Final values, all integer.
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# s and us fit in 32-bit signed ints; d isn't bounded.
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d = s = us = 0
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# Normalize everything to days, seconds, microseconds.
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days += weeks*7
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seconds += minutes*60 + hours*3600
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microseconds += milliseconds*1000
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# Get rid of all fractions, and normalize s and us.
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# Take a deep breath <wink>.
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if isinstance(days, float):
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dayfrac, days = _math.modf(days)
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daysecondsfrac, daysecondswhole = _math.modf(dayfrac * (24.*3600.))
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assert daysecondswhole == int(daysecondswhole) # can't overflow
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s = int(daysecondswhole)
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assert days == int(days)
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d = int(days)
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else:
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daysecondsfrac = 0.0
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d = days
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assert isinstance(daysecondsfrac, float)
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assert abs(daysecondsfrac) <= 1.0
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assert isinstance(d, int)
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assert abs(s) <= 24 * 3600
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# days isn't referenced again before redefinition
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if isinstance(seconds, float):
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secondsfrac, seconds = _math.modf(seconds)
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assert seconds == int(seconds)
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seconds = int(seconds)
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secondsfrac += daysecondsfrac
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assert abs(secondsfrac) <= 2.0
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else:
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secondsfrac = daysecondsfrac
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# daysecondsfrac isn't referenced again
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assert isinstance(secondsfrac, float)
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assert abs(secondsfrac) <= 2.0
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assert isinstance(seconds, int)
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days, seconds = divmod(seconds, 24*3600)
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d += days
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s += int(seconds) # can't overflow
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assert isinstance(s, int)
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assert abs(s) <= 2 * 24 * 3600
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# seconds isn't referenced again before redefinition
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usdouble = secondsfrac * 1e6
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assert abs(usdouble) < 2.1e6 # exact value not critical
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# secondsfrac isn't referenced again
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if isinstance(microseconds, float):
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microseconds += usdouble
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microseconds = round(microseconds, 0)
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seconds, microseconds = divmod(microseconds, 1e6)
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assert microseconds == int(microseconds)
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assert seconds == int(seconds)
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days, seconds = divmod(seconds, 24.*3600.)
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assert days == int(days)
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assert seconds == int(seconds)
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d += int(days)
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s += int(seconds) # can't overflow
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assert isinstance(s, int)
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assert abs(s) <= 3 * 24 * 3600
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else:
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seconds, microseconds = divmod(microseconds, 1000000)
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days, seconds = divmod(seconds, 24*3600)
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d += days
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s += int(seconds) # can't overflow
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assert isinstance(s, int)
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assert abs(s) <= 3 * 24 * 3600
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microseconds = float(microseconds)
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microseconds += usdouble
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microseconds = round(microseconds, 0)
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assert abs(s) <= 3 * 24 * 3600
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assert abs(microseconds) < 3.1e6
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# Just a little bit of carrying possible for microseconds and seconds.
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assert isinstance(microseconds, float)
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assert int(microseconds) == microseconds
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us = int(microseconds)
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seconds, us = divmod(us, 1000000)
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s += seconds # cant't overflow
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assert isinstance(s, int)
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days, s = divmod(s, 24*3600)
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d += days
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assert isinstance(d, int)
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assert isinstance(s, int) and 0 <= s < 24*3600
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assert isinstance(us, int) and 0 <= us < 1000000
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self = object.__new__(cls)
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self._days = d
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self._seconds = s
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self._microseconds = us
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if abs(d) > 999999999:
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raise OverflowError("timedelta # of days is too large: %d" % d)
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return self
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def __repr__(self):
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if self._microseconds:
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return "%s(%d, %d, %d)" % ('datetime.' + self.__class__.__name__,
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self._days,
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self._seconds,
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self._microseconds)
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if self._seconds:
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return "%s(%d, %d)" % ('datetime.' + self.__class__.__name__,
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self._days,
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self._seconds)
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return "%s(%d)" % ('datetime.' + self.__class__.__name__, self._days)
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def __str__(self):
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mm, ss = divmod(self._seconds, 60)
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hh, mm = divmod(mm, 60)
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s = "%d:%02d:%02d" % (hh, mm, ss)
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if self._days:
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def plural(n):
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return n, abs(n) != 1 and "s" or ""
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s = ("%d day%s, " % plural(self._days)) + s
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if self._microseconds:
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s = s + ".%06d" % self._microseconds
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return s
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def total_seconds(self):
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"""Total seconds in the duration."""
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return ((self.days * 86400 + self.seconds)*10**6 +
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self.microseconds) / 10**6
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# Read-only field accessors
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@property
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def days(self):
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"""days"""
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return self._days
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@property
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def seconds(self):
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"""seconds"""
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return self._seconds
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@property
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def microseconds(self):
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"""microseconds"""
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return self._microseconds
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def __add__(self, other):
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if isinstance(other, timedelta):
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# for CPython compatibility, we cannot use
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# our __class__ here, but need a real timedelta
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return timedelta(self._days + other._days,
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self._seconds + other._seconds,
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self._microseconds + other._microseconds)
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return NotImplemented
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__radd__ = __add__
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|
|
def __sub__(self, other):
|
|
if isinstance(other, timedelta):
|
|
# for CPython compatibility, we cannot use
|
|
# our __class__ here, but need a real timedelta
|
|
return timedelta(self._days - other._days,
|
|
self._seconds - other._seconds,
|
|
self._microseconds - other._microseconds)
|
|
return NotImplemented
|
|
|
|
def __rsub__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return -self + other
|
|
return NotImplemented
|
|
|
|
def __neg__(self):
|
|
# for CPython compatibility, we cannot use
|
|
# our __class__ here, but need a real timedelta
|
|
return timedelta(-self._days,
|
|
-self._seconds,
|
|
-self._microseconds)
|
|
|
|
def __pos__(self):
|
|
return self
|
|
|
|
def __abs__(self):
|
|
if self._days < 0:
|
|
return -self
|
|
else:
|
|
return self
|
|
|
|
def __mul__(self, other):
|
|
if isinstance(other, int):
|
|
# for CPython compatibility, we cannot use
|
|
# our __class__ here, but need a real timedelta
|
|
return timedelta(self._days * other,
|
|
self._seconds * other,
|
|
self._microseconds * other)
|
|
if isinstance(other, float):
|
|
a, b = other.as_integer_ratio()
|
|
return self * a / b
|
|
return NotImplemented
|
|
|
|
__rmul__ = __mul__
|
|
|
|
def _to_microseconds(self):
|
|
return ((self._days * (24*3600) + self._seconds) * 1000000 +
|
|
self._microseconds)
|
|
|
|
def __floordiv__(self, other):
|
|
if not isinstance(other, (int, timedelta)):
|
|
return NotImplemented
|
|
usec = self._to_microseconds()
|
|
if isinstance(other, timedelta):
|
|
return usec // other._to_microseconds()
|
|
if isinstance(other, int):
|
|
return timedelta(0, 0, usec // other)
|
|
|
|
def __truediv__(self, other):
|
|
if not isinstance(other, (int, float, timedelta)):
|
|
return NotImplemented
|
|
usec = self._to_microseconds()
|
|
if isinstance(other, timedelta):
|
|
return usec / other._to_microseconds()
|
|
if isinstance(other, int):
|
|
return timedelta(0, 0, usec / other)
|
|
if isinstance(other, float):
|
|
a, b = other.as_integer_ratio()
|
|
return timedelta(0, 0, b * usec / a)
|
|
|
|
def __mod__(self, other):
|
|
if isinstance(other, timedelta):
|
|
r = self._to_microseconds() % other._to_microseconds()
|
|
return timedelta(0, 0, r)
|
|
return NotImplemented
|
|
|
|
def __divmod__(self, other):
|
|
if isinstance(other, timedelta):
|
|
q, r = divmod(self._to_microseconds(),
|
|
other._to_microseconds())
|
|
return q, timedelta(0, 0, r)
|
|
return NotImplemented
|
|
|
|
# Comparisons of timedelta objects with other.
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) == 0
|
|
else:
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) != 0
|
|
else:
|
|
return True
|
|
|
|
def __le__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) <= 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __lt__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) < 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __ge__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) >= 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __gt__(self, other):
|
|
if isinstance(other, timedelta):
|
|
return self._cmp(other) > 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def _cmp(self, other):
|
|
assert isinstance(other, timedelta)
|
|
return _cmp(self._getstate(), other._getstate())
|
|
|
|
def __hash__(self):
|
|
return hash(self._getstate())
|
|
|
|
def __bool__(self):
|
|
return (self._days != 0 or
|
|
self._seconds != 0 or
|
|
self._microseconds != 0)
|
|
|
|
# Pickle support.
|
|
|
|
def _getstate(self):
|
|
return (self._days, self._seconds, self._microseconds)
|
|
|
|
def __reduce__(self):
|
|
return (self.__class__, self._getstate())
|
|
|
|
timedelta.min = timedelta(-999999999)
|
|
timedelta.max = timedelta(days=999999999, hours=23, minutes=59, seconds=59,
|
|
microseconds=999999)
|
|
timedelta.resolution = timedelta(microseconds=1)
|
|
|
|
class date(object):
|
|
"""Concrete date type.
|
|
|
|
Constructors:
|
|
|
|
__new__()
|
|
fromtimestamp()
|
|
today()
|
|
fromordinal()
|
|
|
|
Operators:
|
|
|
|
__repr__, __str__
|
|
__cmp__, __hash__
|
|
__add__, __radd__, __sub__ (add/radd only with timedelta arg)
|
|
|
|
Methods:
|
|
|
|
timetuple()
|
|
toordinal()
|
|
weekday()
|
|
isoweekday(), isocalendar(), isoformat()
|
|
ctime()
|
|
strftime()
|
|
|
|
Properties (readonly):
|
|
year, month, day
|
|
"""
|
|
__slots__ = '_year', '_month', '_day'
|
|
|
|
def __new__(cls, year, month=None, day=None):
|
|
"""Constructor.
|
|
|
|
Arguments:
|
|
|
|
year, month, day (required, base 1)
|
|
"""
|
|
if (isinstance(year, bytes) and len(year) == 4 and
|
|
1 <= year[2] <= 12 and month is None): # Month is sane
|
|
# Pickle support
|
|
self = object.__new__(cls)
|
|
self.__setstate(year)
|
|
return self
|
|
_check_date_fields(year, month, day)
|
|
self = object.__new__(cls)
|
|
self._year = year
|
|
self._month = month
|
|
self._day = day
|
|
return self
|
|
|
|
# Additional constructors
|
|
|
|
@classmethod
|
|
def fromtimestamp(cls, t):
|
|
"Construct a date from a POSIX timestamp (like time.time())."
|
|
y, m, d, hh, mm, ss, weekday, jday, dst = _time.localtime(t)
|
|
return cls(y, m, d)
|
|
|
|
@classmethod
|
|
def today(cls):
|
|
"Construct a date from time.time()."
|
|
t = _time.time()
|
|
return cls.fromtimestamp(t)
|
|
|
|
@classmethod
|
|
def fromordinal(cls, n):
|
|
"""Contruct a date from a proleptic Gregorian ordinal.
|
|
|
|
January 1 of year 1 is day 1. Only the year, month and day are
|
|
non-zero in the result.
|
|
"""
|
|
y, m, d = _ord2ymd(n)
|
|
return cls(y, m, d)
|
|
|
|
# Conversions to string
|
|
|
|
def __repr__(self):
|
|
"""Convert to formal string, for repr().
|
|
|
|
>>> dt = datetime(2010, 1, 1)
|
|
>>> repr(dt)
|
|
'datetime.datetime(2010, 1, 1, 0, 0)'
|
|
|
|
>>> dt = datetime(2010, 1, 1, tzinfo=timezone.utc)
|
|
>>> repr(dt)
|
|
'datetime.datetime(2010, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)'
|
|
"""
|
|
return "%s(%d, %d, %d)" % ('datetime.' + self.__class__.__name__,
|
|
self._year,
|
|
self._month,
|
|
self._day)
|
|
# XXX These shouldn't depend on time.localtime(), because that
|
|
# clips the usable dates to [1970 .. 2038). At least ctime() is
|
|
# easily done without using strftime() -- that's better too because
|
|
# strftime("%c", ...) is locale specific.
|
|
|
|
|
|
def ctime(self):
|
|
"Return ctime() style string."
|
|
weekday = self.toordinal() % 7 or 7
|
|
return "%s %s %2d 00:00:00 %04d" % (
|
|
_DAYNAMES[weekday],
|
|
_MONTHNAMES[self._month],
|
|
self._day, self._year)
|
|
|
|
def strftime(self, fmt):
|
|
"Format using strftime()."
|
|
return _wrap_strftime(self, fmt, self.timetuple())
|
|
|
|
def __format__(self, fmt):
|
|
if len(fmt) != 0:
|
|
return self.strftime(fmt)
|
|
return str(self)
|
|
|
|
def isoformat(self):
|
|
"""Return the date formatted according to ISO.
|
|
|
|
This is 'YYYY-MM-DD'.
|
|
|
|
References:
|
|
- http://www.w3.org/TR/NOTE-datetime
|
|
- http://www.cl.cam.ac.uk/~mgk25/iso-time.html
|
|
"""
|
|
return "%04d-%02d-%02d" % (self._year, self._month, self._day)
|
|
|
|
__str__ = isoformat
|
|
|
|
# Read-only field accessors
|
|
@property
|
|
def year(self):
|
|
"""year (1-9999)"""
|
|
return self._year
|
|
|
|
@property
|
|
def month(self):
|
|
"""month (1-12)"""
|
|
return self._month
|
|
|
|
@property
|
|
def day(self):
|
|
"""day (1-31)"""
|
|
return self._day
|
|
|
|
# Standard conversions, __cmp__, __hash__ (and helpers)
|
|
|
|
def timetuple(self):
|
|
"Return local time tuple compatible with time.localtime()."
|
|
return _build_struct_time(self._year, self._month, self._day,
|
|
0, 0, 0, -1)
|
|
|
|
def toordinal(self):
|
|
"""Return proleptic Gregorian ordinal for the year, month and day.
|
|
|
|
January 1 of year 1 is day 1. Only the year, month and day values
|
|
contribute to the result.
|
|
"""
|
|
return _ymd2ord(self._year, self._month, self._day)
|
|
|
|
def replace(self, year=None, month=None, day=None):
|
|
"""Return a new date with new values for the specified fields."""
|
|
if year is None:
|
|
year = self._year
|
|
if month is None:
|
|
month = self._month
|
|
if day is None:
|
|
day = self._day
|
|
_check_date_fields(year, month, day)
|
|
return date(year, month, day)
|
|
|
|
# Comparisons of date objects with other.
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) == 0
|
|
return NotImplemented
|
|
|
|
def __ne__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) != 0
|
|
return NotImplemented
|
|
|
|
def __le__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) <= 0
|
|
return NotImplemented
|
|
|
|
def __lt__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) < 0
|
|
return NotImplemented
|
|
|
|
def __ge__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) >= 0
|
|
return NotImplemented
|
|
|
|
def __gt__(self, other):
|
|
if isinstance(other, date):
|
|
return self._cmp(other) > 0
|
|
return NotImplemented
|
|
|
|
def _cmp(self, other):
|
|
assert isinstance(other, date)
|
|
y, m, d = self._year, self._month, self._day
|
|
y2, m2, d2 = other._year, other._month, other._day
|
|
return _cmp((y, m, d), (y2, m2, d2))
|
|
|
|
def __hash__(self):
|
|
"Hash."
|
|
return hash(self._getstate())
|
|
|
|
# Computations
|
|
|
|
def __add__(self, other):
|
|
"Add a date to a timedelta."
|
|
if isinstance(other, timedelta):
|
|
o = self.toordinal() + other.days
|
|
if 0 < o <= _MAXORDINAL:
|
|
return date.fromordinal(o)
|
|
raise OverflowError("result out of range")
|
|
return NotImplemented
|
|
|
|
__radd__ = __add__
|
|
|
|
def __sub__(self, other):
|
|
"""Subtract two dates, or a date and a timedelta."""
|
|
if isinstance(other, timedelta):
|
|
return self + timedelta(-other.days)
|
|
if isinstance(other, date):
|
|
days1 = self.toordinal()
|
|
days2 = other.toordinal()
|
|
return timedelta(days1 - days2)
|
|
return NotImplemented
|
|
|
|
def weekday(self):
|
|
"Return day of the week, where Monday == 0 ... Sunday == 6."
|
|
return (self.toordinal() + 6) % 7
|
|
|
|
# Day-of-the-week and week-of-the-year, according to ISO
|
|
|
|
def isoweekday(self):
|
|
"Return day of the week, where Monday == 1 ... Sunday == 7."
|
|
# 1-Jan-0001 is a Monday
|
|
return self.toordinal() % 7 or 7
|
|
|
|
def isocalendar(self):
|
|
"""Return a 3-tuple containing ISO year, week number, and weekday.
|
|
|
|
The first ISO week of the year is the (Mon-Sun) week
|
|
containing the year's first Thursday; everything else derives
|
|
from that.
|
|
|
|
The first week is 1; Monday is 1 ... Sunday is 7.
|
|
|
|
ISO calendar algorithm taken from
|
|
http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
|
|
"""
|
|
year = self._year
|
|
week1monday = _isoweek1monday(year)
|
|
today = _ymd2ord(self._year, self._month, self._day)
|
|
# Internally, week and day have origin 0
|
|
week, day = divmod(today - week1monday, 7)
|
|
if week < 0:
|
|
year -= 1
|
|
week1monday = _isoweek1monday(year)
|
|
week, day = divmod(today - week1monday, 7)
|
|
elif week >= 52:
|
|
if today >= _isoweek1monday(year+1):
|
|
year += 1
|
|
week = 0
|
|
return year, week+1, day+1
|
|
|
|
# Pickle support.
|
|
|
|
def _getstate(self):
|
|
yhi, ylo = divmod(self._year, 256)
|
|
return bytes([yhi, ylo, self._month, self._day]),
|
|
|
|
def __setstate(self, string):
|
|
if len(string) != 4 or not (1 <= string[2] <= 12):
|
|
raise TypeError("not enough arguments")
|
|
yhi, ylo, self._month, self._day = string
|
|
self._year = yhi * 256 + ylo
|
|
|
|
def __reduce__(self):
|
|
return (self.__class__, self._getstate())
|
|
|
|
_date_class = date # so functions w/ args named "date" can get at the class
|
|
|
|
date.min = date(1, 1, 1)
|
|
date.max = date(9999, 12, 31)
|
|
date.resolution = timedelta(days=1)
|
|
|
|
class tzinfo(object):
|
|
"""Abstract base class for time zone info classes.
|
|
|
|
Subclasses must override the name(), utcoffset() and dst() methods.
|
|
"""
|
|
__slots__ = ()
|
|
def tzname(self, dt):
|
|
"datetime -> string name of time zone."
|
|
raise NotImplementedError("tzinfo subclass must override tzname()")
|
|
|
|
def utcoffset(self, dt):
|
|
"datetime -> minutes east of UTC (negative for west of UTC)"
|
|
raise NotImplementedError("tzinfo subclass must override utcoffset()")
|
|
|
|
def dst(self, dt):
|
|
"""datetime -> DST offset in minutes east of UTC.
|
|
|
|
Return 0 if DST not in effect. utcoffset() must include the DST
|
|
offset.
|
|
"""
|
|
raise NotImplementedError("tzinfo subclass must override dst()")
|
|
|
|
def fromutc(self, dt):
|
|
"datetime in UTC -> datetime in local time."
|
|
|
|
if not isinstance(dt, datetime):
|
|
raise TypeError("fromutc() requires a datetime argument")
|
|
if dt.tzinfo is not self:
|
|
raise ValueError("dt.tzinfo is not self")
|
|
|
|
dtoff = dt.utcoffset()
|
|
if dtoff is None:
|
|
raise ValueError("fromutc() requires a non-None utcoffset() "
|
|
"result")
|
|
|
|
# See the long comment block at the end of this file for an
|
|
# explanation of this algorithm.
|
|
dtdst = dt.dst()
|
|
if dtdst is None:
|
|
raise ValueError("fromutc() requires a non-None dst() result")
|
|
delta = dtoff - dtdst
|
|
if delta:
|
|
dt += delta
|
|
dtdst = dt.dst()
|
|
if dtdst is None:
|
|
raise ValueError("fromutc(): dt.dst gave inconsistent "
|
|
"results; cannot convert")
|
|
return dt + dtdst
|
|
|
|
# Pickle support.
|
|
|
|
def __reduce__(self):
|
|
getinitargs = getattr(self, "__getinitargs__", None)
|
|
if getinitargs:
|
|
args = getinitargs()
|
|
else:
|
|
args = ()
|
|
getstate = getattr(self, "__getstate__", None)
|
|
if getstate:
|
|
state = getstate()
|
|
else:
|
|
state = getattr(self, "__dict__", None) or None
|
|
if state is None:
|
|
return (self.__class__, args)
|
|
else:
|
|
return (self.__class__, args, state)
|
|
|
|
_tzinfo_class = tzinfo
|
|
|
|
class time(object):
|
|
"""Time with time zone.
|
|
|
|
Constructors:
|
|
|
|
__new__()
|
|
|
|
Operators:
|
|
|
|
__repr__, __str__
|
|
__cmp__, __hash__
|
|
|
|
Methods:
|
|
|
|
strftime()
|
|
isoformat()
|
|
utcoffset()
|
|
tzname()
|
|
dst()
|
|
|
|
Properties (readonly):
|
|
hour, minute, second, microsecond, tzinfo
|
|
"""
|
|
|
|
def __new__(cls, hour=0, minute=0, second=0, microsecond=0, tzinfo=None):
|
|
"""Constructor.
|
|
|
|
Arguments:
|
|
|
|
hour, minute (required)
|
|
second, microsecond (default to zero)
|
|
tzinfo (default to None)
|
|
"""
|
|
self = object.__new__(cls)
|
|
if isinstance(hour, bytes) and len(hour) == 6:
|
|
# Pickle support
|
|
self.__setstate(hour, minute or None)
|
|
return self
|
|
_check_tzinfo_arg(tzinfo)
|
|
_check_time_fields(hour, minute, second, microsecond)
|
|
self._hour = hour
|
|
self._minute = minute
|
|
self._second = second
|
|
self._microsecond = microsecond
|
|
self._tzinfo = tzinfo
|
|
return self
|
|
|
|
# Read-only field accessors
|
|
@property
|
|
def hour(self):
|
|
"""hour (0-23)"""
|
|
return self._hour
|
|
|
|
@property
|
|
def minute(self):
|
|
"""minute (0-59)"""
|
|
return self._minute
|
|
|
|
@property
|
|
def second(self):
|
|
"""second (0-59)"""
|
|
return self._second
|
|
|
|
@property
|
|
def microsecond(self):
|
|
"""microsecond (0-999999)"""
|
|
return self._microsecond
|
|
|
|
@property
|
|
def tzinfo(self):
|
|
"""timezone info object"""
|
|
return self._tzinfo
|
|
|
|
# Standard conversions, __hash__ (and helpers)
|
|
|
|
# Comparisons of time objects with other.
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other, allow_mixed=True) == 0
|
|
else:
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other, allow_mixed=True) != 0
|
|
else:
|
|
return True
|
|
|
|
def __le__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other) <= 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __lt__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other) < 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __ge__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other) >= 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __gt__(self, other):
|
|
if isinstance(other, time):
|
|
return self._cmp(other) > 0
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def _cmp(self, other, allow_mixed=False):
|
|
assert isinstance(other, time)
|
|
mytz = self._tzinfo
|
|
ottz = other._tzinfo
|
|
myoff = otoff = None
|
|
|
|
if mytz is ottz:
|
|
base_compare = True
|
|
else:
|
|
myoff = self.utcoffset()
|
|
otoff = other.utcoffset()
|
|
base_compare = myoff == otoff
|
|
|
|
if base_compare:
|
|
return _cmp((self._hour, self._minute, self._second,
|
|
self._microsecond),
|
|
(other._hour, other._minute, other._second,
|
|
other._microsecond))
|
|
if myoff is None or otoff is None:
|
|
if allow_mixed:
|
|
return 2 # arbitrary non-zero value
|
|
else:
|
|
raise TypeError("cannot compare naive and aware times")
|
|
myhhmm = self._hour * 60 + self._minute - myoff//timedelta(minutes=1)
|
|
othhmm = other._hour * 60 + other._minute - otoff//timedelta(minutes=1)
|
|
return _cmp((myhhmm, self._second, self._microsecond),
|
|
(othhmm, other._second, other._microsecond))
|
|
|
|
def __hash__(self):
|
|
"""Hash."""
|
|
tzoff = self.utcoffset()
|
|
if not tzoff: # zero or None
|
|
return hash(self._getstate()[0])
|
|
h, m = divmod(timedelta(hours=self.hour, minutes=self.minute) - tzoff,
|
|
timedelta(hours=1))
|
|
assert not m % timedelta(minutes=1), "whole minute"
|
|
m //= timedelta(minutes=1)
|
|
if 0 <= h < 24:
|
|
return hash(time(h, m, self.second, self.microsecond))
|
|
return hash((h, m, self.second, self.microsecond))
|
|
|
|
# Conversion to string
|
|
|
|
def _tzstr(self, sep=":"):
|
|
"""Return formatted timezone offset (+xx:xx) or None."""
|
|
off = self.utcoffset()
|
|
if off is not None:
|
|
if off.days < 0:
|
|
sign = "-"
|
|
off = -off
|
|
else:
|
|
sign = "+"
|
|
hh, mm = divmod(off, timedelta(hours=1))
|
|
assert not mm % timedelta(minutes=1), "whole minute"
|
|
mm //= timedelta(minutes=1)
|
|
assert 0 <= hh < 24
|
|
off = "%s%02d%s%02d" % (sign, hh, sep, mm)
|
|
return off
|
|
|
|
def __repr__(self):
|
|
"""Convert to formal string, for repr()."""
|
|
if self._microsecond != 0:
|
|
s = ", %d, %d" % (self._second, self._microsecond)
|
|
elif self._second != 0:
|
|
s = ", %d" % self._second
|
|
else:
|
|
s = ""
|
|
s= "%s(%d, %d%s)" % ('datetime.' + self.__class__.__name__,
|
|
self._hour, self._minute, s)
|
|
if self._tzinfo is not None:
|
|
assert s[-1:] == ")"
|
|
s = s[:-1] + ", tzinfo=%r" % self._tzinfo + ")"
|
|
return s
|
|
|
|
def isoformat(self):
|
|
"""Return the time formatted according to ISO.
|
|
|
|
This is 'HH:MM:SS.mmmmmm+zz:zz', or 'HH:MM:SS+zz:zz' if
|
|
self.microsecond == 0.
|
|
"""
|
|
s = _format_time(self._hour, self._minute, self._second,
|
|
self._microsecond)
|
|
tz = self._tzstr()
|
|
if tz:
|
|
s += tz
|
|
return s
|
|
|
|
__str__ = isoformat
|
|
|
|
def strftime(self, fmt):
|
|
"""Format using strftime(). The date part of the timestamp passed
|
|
to underlying strftime should not be used.
|
|
"""
|
|
# The year must be >= 1000 else Python's strftime implementation
|
|
# can raise a bogus exception.
|
|
timetuple = (1900, 1, 1,
|
|
self._hour, self._minute, self._second,
|
|
0, 1, -1)
|
|
return _wrap_strftime(self, fmt, timetuple)
|
|
|
|
def __format__(self, fmt):
|
|
if len(fmt) != 0:
|
|
return self.strftime(fmt)
|
|
return str(self)
|
|
|
|
# Timezone functions
|
|
|
|
def utcoffset(self):
|
|
"""Return the timezone offset in minutes east of UTC (negative west of
|
|
UTC)."""
|
|
if self._tzinfo is None:
|
|
return None
|
|
offset = self._tzinfo.utcoffset(None)
|
|
_check_utc_offset("utcoffset", offset)
|
|
return offset
|
|
|
|
def tzname(self):
|
|
"""Return the timezone name.
|
|
|
|
Note that the name is 100% informational -- there's no requirement that
|
|
it mean anything in particular. For example, "GMT", "UTC", "-500",
|
|
"-5:00", "EDT", "US/Eastern", "America/New York" are all valid replies.
|
|
"""
|
|
if self._tzinfo is None:
|
|
return None
|
|
name = self._tzinfo.tzname(None)
|
|
_check_tzname(name)
|
|
return name
|
|
|
|
def dst(self):
|
|
"""Return 0 if DST is not in effect, or the DST offset (in minutes
|
|
eastward) if DST is in effect.
|
|
|
|
This is purely informational; the DST offset has already been added to
|
|
the UTC offset returned by utcoffset() if applicable, so there's no
|
|
need to consult dst() unless you're interested in displaying the DST
|
|
info.
|
|
"""
|
|
if self._tzinfo is None:
|
|
return None
|
|
offset = self._tzinfo.dst(None)
|
|
_check_utc_offset("dst", offset)
|
|
return offset
|
|
|
|
def replace(self, hour=None, minute=None, second=None, microsecond=None,
|
|
tzinfo=True):
|
|
"""Return a new time with new values for the specified fields."""
|
|
if hour is None:
|
|
hour = self.hour
|
|
if minute is None:
|
|
minute = self.minute
|
|
if second is None:
|
|
second = self.second
|
|
if microsecond is None:
|
|
microsecond = self.microsecond
|
|
if tzinfo is True:
|
|
tzinfo = self.tzinfo
|
|
_check_time_fields(hour, minute, second, microsecond)
|
|
_check_tzinfo_arg(tzinfo)
|
|
return time(hour, minute, second, microsecond, tzinfo)
|
|
|
|
def __bool__(self):
|
|
if self.second or self.microsecond:
|
|
return True
|
|
offset = self.utcoffset() or timedelta(0)
|
|
return timedelta(hours=self.hour, minutes=self.minute) != offset
|
|
|
|
# Pickle support.
|
|
|
|
def _getstate(self):
|
|
us2, us3 = divmod(self._microsecond, 256)
|
|
us1, us2 = divmod(us2, 256)
|
|
basestate = bytes([self._hour, self._minute, self._second,
|
|
us1, us2, us3])
|
|
if self._tzinfo is None:
|
|
return (basestate,)
|
|
else:
|
|
return (basestate, self._tzinfo)
|
|
|
|
def __setstate(self, string, tzinfo):
|
|
if len(string) != 6 or string[0] >= 24:
|
|
raise TypeError("an integer is required")
|
|
(self._hour, self._minute, self._second,
|
|
us1, us2, us3) = string
|
|
self._microsecond = (((us1 << 8) | us2) << 8) | us3
|
|
if tzinfo is None or isinstance(tzinfo, _tzinfo_class):
|
|
self._tzinfo = tzinfo
|
|
else:
|
|
raise TypeError("bad tzinfo state arg %r" % tzinfo)
|
|
|
|
def __reduce__(self):
|
|
return (time, self._getstate())
|
|
|
|
_time_class = time # so functions w/ args named "time" can get at the class
|
|
|
|
time.min = time(0, 0, 0)
|
|
time.max = time(23, 59, 59, 999999)
|
|
time.resolution = timedelta(microseconds=1)
|
|
|
|
class datetime(date):
|
|
"""datetime(year, month, day[, hour[, minute[, second[, microsecond[,tzinfo]]]]])
|
|
|
|
The year, month and day arguments are required. tzinfo may be None, or an
|
|
instance of a tzinfo subclass. The remaining arguments may be ints.
|
|
"""
|
|
|
|
__slots__ = date.__slots__ + (
|
|
'_hour', '_minute', '_second',
|
|
'_microsecond', '_tzinfo')
|
|
def __new__(cls, year, month=None, day=None, hour=0, minute=0, second=0,
|
|
microsecond=0, tzinfo=None):
|
|
if isinstance(year, bytes) and len(year) == 10:
|
|
# Pickle support
|
|
self = date.__new__(cls, year[:4])
|
|
self.__setstate(year, month)
|
|
return self
|
|
_check_tzinfo_arg(tzinfo)
|
|
_check_time_fields(hour, minute, second, microsecond)
|
|
self = date.__new__(cls, year, month, day)
|
|
self._hour = hour
|
|
self._minute = minute
|
|
self._second = second
|
|
self._microsecond = microsecond
|
|
self._tzinfo = tzinfo
|
|
return self
|
|
|
|
# Read-only field accessors
|
|
@property
|
|
def hour(self):
|
|
"""hour (0-23)"""
|
|
return self._hour
|
|
|
|
@property
|
|
def minute(self):
|
|
"""minute (0-59)"""
|
|
return self._minute
|
|
|
|
@property
|
|
def second(self):
|
|
"""second (0-59)"""
|
|
return self._second
|
|
|
|
@property
|
|
def microsecond(self):
|
|
"""microsecond (0-999999)"""
|
|
return self._microsecond
|
|
|
|
@property
|
|
def tzinfo(self):
|
|
"""timezone info object"""
|
|
return self._tzinfo
|
|
|
|
@classmethod
|
|
def fromtimestamp(cls, t, tz=None):
|
|
"""Construct a datetime from a POSIX timestamp (like time.time()).
|
|
|
|
A timezone info object may be passed in as well.
|
|
"""
|
|
|
|
_check_tzinfo_arg(tz)
|
|
|
|
converter = _time.localtime if tz is None else _time.gmtime
|
|
|
|
t, frac = divmod(t, 1.0)
|
|
us = int(frac * 1e6)
|
|
|
|
# If timestamp is less than one microsecond smaller than a
|
|
# full second, us can be rounded up to 1000000. In this case,
|
|
# roll over to seconds, otherwise, ValueError is raised
|
|
# by the constructor.
|
|
if us == 1000000:
|
|
t += 1
|
|
us = 0
|
|
y, m, d, hh, mm, ss, weekday, jday, dst = converter(t)
|
|
ss = min(ss, 59) # clamp out leap seconds if the platform has them
|
|
result = cls(y, m, d, hh, mm, ss, us, tz)
|
|
if tz is not None:
|
|
result = tz.fromutc(result)
|
|
return result
|
|
|
|
@classmethod
|
|
def utcfromtimestamp(cls, t):
|
|
"Construct a UTC datetime from a POSIX timestamp (like time.time())."
|
|
t, frac = divmod(t, 1.0)
|
|
us = int(frac * 1e6)
|
|
|
|
# If timestamp is less than one microsecond smaller than a
|
|
# full second, us can be rounded up to 1000000. In this case,
|
|
# roll over to seconds, otherwise, ValueError is raised
|
|
# by the constructor.
|
|
if us == 1000000:
|
|
t += 1
|
|
us = 0
|
|
y, m, d, hh, mm, ss, weekday, jday, dst = _time.gmtime(t)
|
|
ss = min(ss, 59) # clamp out leap seconds if the platform has them
|
|
return cls(y, m, d, hh, mm, ss, us)
|
|
|
|
# XXX This is supposed to do better than we *can* do by using time.time(),
|
|
# XXX if the platform supports a more accurate way. The C implementation
|
|
# XXX uses gettimeofday on platforms that have it, but that isn't
|
|
# XXX available from Python. So now() may return different results
|
|
# XXX across the implementations.
|
|
@classmethod
|
|
def now(cls, tz=None):
|
|
"Construct a datetime from time.time() and optional time zone info."
|
|
t = _time.time()
|
|
return cls.fromtimestamp(t, tz)
|
|
|
|
@classmethod
|
|
def utcnow(cls):
|
|
"Construct a UTC datetime from time.time()."
|
|
t = _time.time()
|
|
return cls.utcfromtimestamp(t)
|
|
|
|
@classmethod
|
|
def combine(cls, date, time):
|
|
"Construct a datetime from a given date and a given time."
|
|
if not isinstance(date, _date_class):
|
|
raise TypeError("date argument must be a date instance")
|
|
if not isinstance(time, _time_class):
|
|
raise TypeError("time argument must be a time instance")
|
|
return cls(date.year, date.month, date.day,
|
|
time.hour, time.minute, time.second, time.microsecond,
|
|
time.tzinfo)
|
|
|
|
def timetuple(self):
|
|
"Return local time tuple compatible with time.localtime()."
|
|
dst = self.dst()
|
|
if dst is None:
|
|
dst = -1
|
|
elif dst:
|
|
dst = 1
|
|
else:
|
|
dst = 0
|
|
return _build_struct_time(self.year, self.month, self.day,
|
|
self.hour, self.minute, self.second,
|
|
dst)
|
|
|
|
def timestamp(self):
|
|
"Return POSIX timestamp as float"
|
|
if self._tzinfo is None:
|
|
return _time.mktime((self.year, self.month, self.day,
|
|
self.hour, self.minute, self.second,
|
|
-1, -1, -1)) + self.microsecond / 1e6
|
|
else:
|
|
return (self - _EPOCH).total_seconds()
|
|
|
|
def utctimetuple(self):
|
|
"Return UTC time tuple compatible with time.gmtime()."
|
|
offset = self.utcoffset()
|
|
if offset:
|
|
self -= offset
|
|
y, m, d = self.year, self.month, self.day
|
|
hh, mm, ss = self.hour, self.minute, self.second
|
|
return _build_struct_time(y, m, d, hh, mm, ss, 0)
|
|
|
|
def date(self):
|
|
"Return the date part."
|
|
return date(self._year, self._month, self._day)
|
|
|
|
def time(self):
|
|
"Return the time part, with tzinfo None."
|
|
return time(self.hour, self.minute, self.second, self.microsecond)
|
|
|
|
def timetz(self):
|
|
"Return the time part, with same tzinfo."
|
|
return time(self.hour, self.minute, self.second, self.microsecond,
|
|
self._tzinfo)
|
|
|
|
def replace(self, year=None, month=None, day=None, hour=None,
|
|
minute=None, second=None, microsecond=None, tzinfo=True):
|
|
"""Return a new datetime with new values for the specified fields."""
|
|
if year is None:
|
|
year = self.year
|
|
if month is None:
|
|
month = self.month
|
|
if day is None:
|
|
day = self.day
|
|
if hour is None:
|
|
hour = self.hour
|
|
if minute is None:
|
|
minute = self.minute
|
|
if second is None:
|
|
second = self.second
|
|
if microsecond is None:
|
|
microsecond = self.microsecond
|
|
if tzinfo is True:
|
|
tzinfo = self.tzinfo
|
|
_check_date_fields(year, month, day)
|
|
_check_time_fields(hour, minute, second, microsecond)
|
|
_check_tzinfo_arg(tzinfo)
|
|
return datetime(year, month, day, hour, minute, second,
|
|
microsecond, tzinfo)
|
|
|
|
def astimezone(self, tz=None):
|
|
if tz is None:
|
|
if self.tzinfo is None:
|
|
raise ValueError("astimezone() requires an aware datetime")
|
|
ts = (self - _EPOCH) // timedelta(seconds=1)
|
|
localtm = _time.localtime(ts)
|
|
local = datetime(*localtm[:6])
|
|
try:
|
|
# Extract TZ data if available
|
|
gmtoff = localtm.tm_gmtoff
|
|
zone = localtm.tm_zone
|
|
except AttributeError:
|
|
# Compute UTC offset and compare with the value implied
|
|
# by tm_isdst. If the values match, use the zone name
|
|
# implied by tm_isdst.
|
|
delta = local - datetime(*_time.gmtime(ts)[:6])
|
|
dst = _time.daylight and localtm.tm_isdst > 0
|
|
gmtoff = -(_time.altzone if dst else _time.timezone)
|
|
if delta == timedelta(seconds=gmtoff):
|
|
tz = timezone(delta, _time.tzname[dst])
|
|
else:
|
|
tz = timezone(delta)
|
|
else:
|
|
tz = timezone(timedelta(seconds=gmtoff), zone)
|
|
|
|
elif not isinstance(tz, tzinfo):
|
|
raise TypeError("tz argument must be an instance of tzinfo")
|
|
|
|
mytz = self.tzinfo
|
|
if mytz is None:
|
|
raise ValueError("astimezone() requires an aware datetime")
|
|
|
|
if tz is mytz:
|
|
return self
|
|
|
|
# Convert self to UTC, and attach the new time zone object.
|
|
myoffset = self.utcoffset()
|
|
if myoffset is None:
|
|
raise ValueError("astimezone() requires an aware datetime")
|
|
utc = (self - myoffset).replace(tzinfo=tz)
|
|
|
|
# Convert from UTC to tz's local time.
|
|
return tz.fromutc(utc)
|
|
|
|
# Ways to produce a string.
|
|
|
|
def ctime(self):
|
|
"Return ctime() style string."
|
|
weekday = self.toordinal() % 7 or 7
|
|
return "%s %s %2d %02d:%02d:%02d %04d" % (
|
|
_DAYNAMES[weekday],
|
|
_MONTHNAMES[self._month],
|
|
self._day,
|
|
self._hour, self._minute, self._second,
|
|
self._year)
|
|
|
|
def isoformat(self, sep='T'):
|
|
"""Return the time formatted according to ISO.
|
|
|
|
This is 'YYYY-MM-DD HH:MM:SS.mmmmmm', or 'YYYY-MM-DD HH:MM:SS' if
|
|
self.microsecond == 0.
|
|
|
|
If self.tzinfo is not None, the UTC offset is also attached, giving
|
|
'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM' or 'YYYY-MM-DD HH:MM:SS+HH:MM'.
|
|
|
|
Optional argument sep specifies the separator between date and
|
|
time, default 'T'.
|
|
"""
|
|
s = ("%04d-%02d-%02d%c" % (self._year, self._month, self._day,
|
|
sep) +
|
|
_format_time(self._hour, self._minute, self._second,
|
|
self._microsecond))
|
|
off = self.utcoffset()
|
|
if off is not None:
|
|
if off.days < 0:
|
|
sign = "-"
|
|
off = -off
|
|
else:
|
|
sign = "+"
|
|
hh, mm = divmod(off, timedelta(hours=1))
|
|
assert not mm % timedelta(minutes=1), "whole minute"
|
|
mm //= timedelta(minutes=1)
|
|
s += "%s%02d:%02d" % (sign, hh, mm)
|
|
return s
|
|
|
|
def __repr__(self):
|
|
"""Convert to formal string, for repr()."""
|
|
L = [self._year, self._month, self._day, # These are never zero
|
|
self._hour, self._minute, self._second, self._microsecond]
|
|
if L[-1] == 0:
|
|
del L[-1]
|
|
if L[-1] == 0:
|
|
del L[-1]
|
|
s = ", ".join(map(str, L))
|
|
s = "%s(%s)" % ('datetime.' + self.__class__.__name__, s)
|
|
if self._tzinfo is not None:
|
|
assert s[-1:] == ")"
|
|
s = s[:-1] + ", tzinfo=%r" % self._tzinfo + ")"
|
|
return s
|
|
|
|
def __str__(self):
|
|
"Convert to string, for str()."
|
|
return self.isoformat(sep=' ')
|
|
|
|
@classmethod
|
|
def strptime(cls, date_string, format):
|
|
'string, format -> new datetime parsed from a string (like time.strptime()).'
|
|
import _strptime
|
|
return _strptime._strptime_datetime(cls, date_string, format)
|
|
|
|
def utcoffset(self):
|
|
"""Return the timezone offset in minutes east of UTC (negative west of
|
|
UTC)."""
|
|
if self._tzinfo is None:
|
|
return None
|
|
offset = self._tzinfo.utcoffset(self)
|
|
_check_utc_offset("utcoffset", offset)
|
|
return offset
|
|
|
|
def tzname(self):
|
|
"""Return the timezone name.
|
|
|
|
Note that the name is 100% informational -- there's no requirement that
|
|
it mean anything in particular. For example, "GMT", "UTC", "-500",
|
|
"-5:00", "EDT", "US/Eastern", "America/New York" are all valid replies.
|
|
"""
|
|
name = _call_tzinfo_method(self._tzinfo, "tzname", self)
|
|
_check_tzname(name)
|
|
return name
|
|
|
|
def dst(self):
|
|
"""Return 0 if DST is not in effect, or the DST offset (in minutes
|
|
eastward) if DST is in effect.
|
|
|
|
This is purely informational; the DST offset has already been added to
|
|
the UTC offset returned by utcoffset() if applicable, so there's no
|
|
need to consult dst() unless you're interested in displaying the DST
|
|
info.
|
|
"""
|
|
if self._tzinfo is None:
|
|
return None
|
|
offset = self._tzinfo.dst(self)
|
|
_check_utc_offset("dst", offset)
|
|
return offset
|
|
|
|
# Comparisons of datetime objects with other.
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other, allow_mixed=True) == 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other, allow_mixed=True) != 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
return True
|
|
|
|
def __le__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other) <= 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __lt__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other) < 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __ge__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other) >= 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def __gt__(self, other):
|
|
if isinstance(other, datetime):
|
|
return self._cmp(other) > 0
|
|
elif not isinstance(other, date):
|
|
return NotImplemented
|
|
else:
|
|
_cmperror(self, other)
|
|
|
|
def _cmp(self, other, allow_mixed=False):
|
|
assert isinstance(other, datetime)
|
|
mytz = self._tzinfo
|
|
ottz = other._tzinfo
|
|
myoff = otoff = None
|
|
|
|
if mytz is ottz:
|
|
base_compare = True
|
|
else:
|
|
myoff = self.utcoffset()
|
|
otoff = other.utcoffset()
|
|
base_compare = myoff == otoff
|
|
|
|
if base_compare:
|
|
return _cmp((self._year, self._month, self._day,
|
|
self._hour, self._minute, self._second,
|
|
self._microsecond),
|
|
(other._year, other._month, other._day,
|
|
other._hour, other._minute, other._second,
|
|
other._microsecond))
|
|
if myoff is None or otoff is None:
|
|
if allow_mixed:
|
|
return 2 # arbitrary non-zero value
|
|
else:
|
|
raise TypeError("cannot compare naive and aware datetimes")
|
|
# XXX What follows could be done more efficiently...
|
|
diff = self - other # this will take offsets into account
|
|
if diff.days < 0:
|
|
return -1
|
|
return diff and 1 or 0
|
|
|
|
def __add__(self, other):
|
|
"Add a datetime and a timedelta."
|
|
if not isinstance(other, timedelta):
|
|
return NotImplemented
|
|
delta = timedelta(self.toordinal(),
|
|
hours=self._hour,
|
|
minutes=self._minute,
|
|
seconds=self._second,
|
|
microseconds=self._microsecond)
|
|
delta += other
|
|
hour, rem = divmod(delta.seconds, 3600)
|
|
minute, second = divmod(rem, 60)
|
|
if 0 < delta.days <= _MAXORDINAL:
|
|
return datetime.combine(date.fromordinal(delta.days),
|
|
time(hour, minute, second,
|
|
delta.microseconds,
|
|
tzinfo=self._tzinfo))
|
|
raise OverflowError("result out of range")
|
|
|
|
__radd__ = __add__
|
|
|
|
def __sub__(self, other):
|
|
"Subtract two datetimes, or a datetime and a timedelta."
|
|
if not isinstance(other, datetime):
|
|
if isinstance(other, timedelta):
|
|
return self + -other
|
|
return NotImplemented
|
|
|
|
days1 = self.toordinal()
|
|
days2 = other.toordinal()
|
|
secs1 = self._second + self._minute * 60 + self._hour * 3600
|
|
secs2 = other._second + other._minute * 60 + other._hour * 3600
|
|
base = timedelta(days1 - days2,
|
|
secs1 - secs2,
|
|
self._microsecond - other._microsecond)
|
|
if self._tzinfo is other._tzinfo:
|
|
return base
|
|
myoff = self.utcoffset()
|
|
otoff = other.utcoffset()
|
|
if myoff == otoff:
|
|
return base
|
|
if myoff is None or otoff is None:
|
|
raise TypeError("cannot mix naive and timezone-aware time")
|
|
return base + otoff - myoff
|
|
|
|
def __hash__(self):
|
|
tzoff = self.utcoffset()
|
|
if tzoff is None:
|
|
return hash(self._getstate()[0])
|
|
days = _ymd2ord(self.year, self.month, self.day)
|
|
seconds = self.hour * 3600 + self.minute * 60 + self.second
|
|
return hash(timedelta(days, seconds, self.microsecond) - tzoff)
|
|
|
|
# Pickle support.
|
|
|
|
def _getstate(self):
|
|
yhi, ylo = divmod(self._year, 256)
|
|
us2, us3 = divmod(self._microsecond, 256)
|
|
us1, us2 = divmod(us2, 256)
|
|
basestate = bytes([yhi, ylo, self._month, self._day,
|
|
self._hour, self._minute, self._second,
|
|
us1, us2, us3])
|
|
if self._tzinfo is None:
|
|
return (basestate,)
|
|
else:
|
|
return (basestate, self._tzinfo)
|
|
|
|
def __setstate(self, string, tzinfo):
|
|
(yhi, ylo, self._month, self._day, self._hour,
|
|
self._minute, self._second, us1, us2, us3) = string
|
|
self._year = yhi * 256 + ylo
|
|
self._microsecond = (((us1 << 8) | us2) << 8) | us3
|
|
if tzinfo is None or isinstance(tzinfo, _tzinfo_class):
|
|
self._tzinfo = tzinfo
|
|
else:
|
|
raise TypeError("bad tzinfo state arg %r" % tzinfo)
|
|
|
|
def __reduce__(self):
|
|
return (self.__class__, self._getstate())
|
|
|
|
|
|
datetime.min = datetime(1, 1, 1)
|
|
datetime.max = datetime(9999, 12, 31, 23, 59, 59, 999999)
|
|
datetime.resolution = timedelta(microseconds=1)
|
|
|
|
|
|
def _isoweek1monday(year):
|
|
# Helper to calculate the day number of the Monday starting week 1
|
|
# XXX This could be done more efficiently
|
|
THURSDAY = 3
|
|
firstday = _ymd2ord(year, 1, 1)
|
|
firstweekday = (firstday + 6) % 7 # See weekday() above
|
|
week1monday = firstday - firstweekday
|
|
if firstweekday > THURSDAY:
|
|
week1monday += 7
|
|
return week1monday
|
|
|
|
class timezone(tzinfo):
|
|
__slots__ = '_offset', '_name'
|
|
|
|
# Sentinel value to disallow None
|
|
_Omitted = object()
|
|
def __new__(cls, offset, name=_Omitted):
|
|
if not isinstance(offset, timedelta):
|
|
raise TypeError("offset must be a timedelta")
|
|
if name is cls._Omitted:
|
|
if not offset:
|
|
return cls.utc
|
|
name = None
|
|
elif not isinstance(name, str):
|
|
###
|
|
# For Python-Future:
|
|
if PY2 and isinstance(name, native_str):
|
|
name = name.decode()
|
|
else:
|
|
raise TypeError("name must be a string")
|
|
###
|
|
if not cls._minoffset <= offset <= cls._maxoffset:
|
|
raise ValueError("offset must be a timedelta"
|
|
" strictly between -timedelta(hours=24) and"
|
|
" timedelta(hours=24).")
|
|
if (offset.microseconds != 0 or
|
|
offset.seconds % 60 != 0):
|
|
raise ValueError("offset must be a timedelta"
|
|
" representing a whole number of minutes")
|
|
return cls._create(offset, name)
|
|
|
|
@classmethod
|
|
def _create(cls, offset, name=None):
|
|
self = tzinfo.__new__(cls)
|
|
self._offset = offset
|
|
self._name = name
|
|
return self
|
|
|
|
def __getinitargs__(self):
|
|
"""pickle support"""
|
|
if self._name is None:
|
|
return (self._offset,)
|
|
return (self._offset, self._name)
|
|
|
|
def __eq__(self, other):
|
|
if type(other) != timezone:
|
|
return False
|
|
return self._offset == other._offset
|
|
|
|
def __hash__(self):
|
|
return hash(self._offset)
|
|
|
|
def __repr__(self):
|
|
"""Convert to formal string, for repr().
|
|
|
|
>>> tz = timezone.utc
|
|
>>> repr(tz)
|
|
'datetime.timezone.utc'
|
|
>>> tz = timezone(timedelta(hours=-5), 'EST')
|
|
>>> repr(tz)
|
|
"datetime.timezone(datetime.timedelta(-1, 68400), 'EST')"
|
|
"""
|
|
if self is self.utc:
|
|
return 'datetime.timezone.utc'
|
|
if self._name is None:
|
|
return "%s(%r)" % ('datetime.' + self.__class__.__name__,
|
|
self._offset)
|
|
return "%s(%r, %r)" % ('datetime.' + self.__class__.__name__,
|
|
self._offset, self._name)
|
|
|
|
def __str__(self):
|
|
return self.tzname(None)
|
|
|
|
def utcoffset(self, dt):
|
|
if isinstance(dt, datetime) or dt is None:
|
|
return self._offset
|
|
raise TypeError("utcoffset() argument must be a datetime instance"
|
|
" or None")
|
|
|
|
def tzname(self, dt):
|
|
if isinstance(dt, datetime) or dt is None:
|
|
if self._name is None:
|
|
return self._name_from_offset(self._offset)
|
|
return self._name
|
|
raise TypeError("tzname() argument must be a datetime instance"
|
|
" or None")
|
|
|
|
def dst(self, dt):
|
|
if isinstance(dt, datetime) or dt is None:
|
|
return None
|
|
raise TypeError("dst() argument must be a datetime instance"
|
|
" or None")
|
|
|
|
def fromutc(self, dt):
|
|
if isinstance(dt, datetime):
|
|
if dt.tzinfo is not self:
|
|
raise ValueError("fromutc: dt.tzinfo "
|
|
"is not self")
|
|
return dt + self._offset
|
|
raise TypeError("fromutc() argument must be a datetime instance"
|
|
" or None")
|
|
|
|
_maxoffset = timedelta(hours=23, minutes=59)
|
|
_minoffset = -_maxoffset
|
|
|
|
@staticmethod
|
|
def _name_from_offset(delta):
|
|
if delta < timedelta(0):
|
|
sign = '-'
|
|
delta = -delta
|
|
else:
|
|
sign = '+'
|
|
hours, rest = divmod(delta, timedelta(hours=1))
|
|
minutes = rest // timedelta(minutes=1)
|
|
return 'UTC{}{:02d}:{:02d}'.format(sign, hours, minutes)
|
|
|
|
timezone.utc = timezone._create(timedelta(0))
|
|
timezone.min = timezone._create(timezone._minoffset)
|
|
timezone.max = timezone._create(timezone._maxoffset)
|
|
_EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)
|
|
"""
|
|
Some time zone algebra. For a datetime x, let
|
|
x.n = x stripped of its timezone -- its naive time.
|
|
x.o = x.utcoffset(), and assuming that doesn't raise an exception or
|
|
return None
|
|
x.d = x.dst(), and assuming that doesn't raise an exception or
|
|
return None
|
|
x.s = x's standard offset, x.o - x.d
|
|
|
|
Now some derived rules, where k is a duration (timedelta).
|
|
|
|
1. x.o = x.s + x.d
|
|
This follows from the definition of x.s.
|
|
|
|
2. If x and y have the same tzinfo member, x.s = y.s.
|
|
This is actually a requirement, an assumption we need to make about
|
|
sane tzinfo classes.
|
|
|
|
3. The naive UTC time corresponding to x is x.n - x.o.
|
|
This is again a requirement for a sane tzinfo class.
|
|
|
|
4. (x+k).s = x.s
|
|
This follows from #2, and that datimetimetz+timedelta preserves tzinfo.
|
|
|
|
5. (x+k).n = x.n + k
|
|
Again follows from how arithmetic is defined.
|
|
|
|
Now we can explain tz.fromutc(x). Let's assume it's an interesting case
|
|
(meaning that the various tzinfo methods exist, and don't blow up or return
|
|
None when called).
|
|
|
|
The function wants to return a datetime y with timezone tz, equivalent to x.
|
|
x is already in UTC.
|
|
|
|
By #3, we want
|
|
|
|
y.n - y.o = x.n [1]
|
|
|
|
The algorithm starts by attaching tz to x.n, and calling that y. So
|
|
x.n = y.n at the start. Then it wants to add a duration k to y, so that [1]
|
|
becomes true; in effect, we want to solve [2] for k:
|
|
|
|
(y+k).n - (y+k).o = x.n [2]
|
|
|
|
By #1, this is the same as
|
|
|
|
(y+k).n - ((y+k).s + (y+k).d) = x.n [3]
|
|
|
|
By #5, (y+k).n = y.n + k, which equals x.n + k because x.n=y.n at the start.
|
|
Substituting that into [3],
|
|
|
|
x.n + k - (y+k).s - (y+k).d = x.n; the x.n terms cancel, leaving
|
|
k - (y+k).s - (y+k).d = 0; rearranging,
|
|
k = (y+k).s - (y+k).d; by #4, (y+k).s == y.s, so
|
|
k = y.s - (y+k).d
|
|
|
|
On the RHS, (y+k).d can't be computed directly, but y.s can be, and we
|
|
approximate k by ignoring the (y+k).d term at first. Note that k can't be
|
|
very large, since all offset-returning methods return a duration of magnitude
|
|
less than 24 hours. For that reason, if y is firmly in std time, (y+k).d must
|
|
be 0, so ignoring it has no consequence then.
|
|
|
|
In any case, the new value is
|
|
|
|
z = y + y.s [4]
|
|
|
|
It's helpful to step back at look at [4] from a higher level: it's simply
|
|
mapping from UTC to tz's standard time.
|
|
|
|
At this point, if
|
|
|
|
z.n - z.o = x.n [5]
|
|
|
|
we have an equivalent time, and are almost done. The insecurity here is
|
|
at the start of daylight time. Picture US Eastern for concreteness. The wall
|
|
time jumps from 1:59 to 3:00, and wall hours of the form 2:MM don't make good
|
|
sense then. The docs ask that an Eastern tzinfo class consider such a time to
|
|
be EDT (because it's "after 2"), which is a redundant spelling of 1:MM EST
|
|
on the day DST starts. We want to return the 1:MM EST spelling because that's
|
|
the only spelling that makes sense on the local wall clock.
|
|
|
|
In fact, if [5] holds at this point, we do have the standard-time spelling,
|
|
but that takes a bit of proof. We first prove a stronger result. What's the
|
|
difference between the LHS and RHS of [5]? Let
|
|
|
|
diff = x.n - (z.n - z.o) [6]
|
|
|
|
Now
|
|
z.n = by [4]
|
|
(y + y.s).n = by #5
|
|
y.n + y.s = since y.n = x.n
|
|
x.n + y.s = since z and y are have the same tzinfo member,
|
|
y.s = z.s by #2
|
|
x.n + z.s
|
|
|
|
Plugging that back into [6] gives
|
|
|
|
diff =
|
|
x.n - ((x.n + z.s) - z.o) = expanding
|
|
x.n - x.n - z.s + z.o = cancelling
|
|
- z.s + z.o = by #2
|
|
z.d
|
|
|
|
So diff = z.d.
|
|
|
|
If [5] is true now, diff = 0, so z.d = 0 too, and we have the standard-time
|
|
spelling we wanted in the endcase described above. We're done. Contrarily,
|
|
if z.d = 0, then we have a UTC equivalent, and are also done.
|
|
|
|
If [5] is not true now, diff = z.d != 0, and z.d is the offset we need to
|
|
add to z (in effect, z is in tz's standard time, and we need to shift the
|
|
local clock into tz's daylight time).
|
|
|
|
Let
|
|
|
|
z' = z + z.d = z + diff [7]
|
|
|
|
and we can again ask whether
|
|
|
|
z'.n - z'.o = x.n [8]
|
|
|
|
If so, we're done. If not, the tzinfo class is insane, according to the
|
|
assumptions we've made. This also requires a bit of proof. As before, let's
|
|
compute the difference between the LHS and RHS of [8] (and skipping some of
|
|
the justifications for the kinds of substitutions we've done several times
|
|
already):
|
|
|
|
diff' = x.n - (z'.n - z'.o) = replacing z'.n via [7]
|
|
x.n - (z.n + diff - z'.o) = replacing diff via [6]
|
|
x.n - (z.n + x.n - (z.n - z.o) - z'.o) =
|
|
x.n - z.n - x.n + z.n - z.o + z'.o = cancel x.n
|
|
- z.n + z.n - z.o + z'.o = cancel z.n
|
|
- z.o + z'.o = #1 twice
|
|
-z.s - z.d + z'.s + z'.d = z and z' have same tzinfo
|
|
z'.d - z.d
|
|
|
|
So z' is UTC-equivalent to x iff z'.d = z.d at this point. If they are equal,
|
|
we've found the UTC-equivalent so are done. In fact, we stop with [7] and
|
|
return z', not bothering to compute z'.d.
|
|
|
|
How could z.d and z'd differ? z' = z + z.d [7], so merely moving z' by
|
|
a dst() offset, and starting *from* a time already in DST (we know z.d != 0),
|
|
would have to change the result dst() returns: we start in DST, and moving
|
|
a little further into it takes us out of DST.
|
|
|
|
There isn't a sane case where this can happen. The closest it gets is at
|
|
the end of DST, where there's an hour in UTC with no spelling in a hybrid
|
|
tzinfo class. In US Eastern, that's 5:MM UTC = 0:MM EST = 1:MM EDT. During
|
|
that hour, on an Eastern clock 1:MM is taken as being in standard time (6:MM
|
|
UTC) because the docs insist on that, but 0:MM is taken as being in daylight
|
|
time (4:MM UTC). There is no local time mapping to 5:MM UTC. The local
|
|
clock jumps from 1:59 back to 1:00 again, and repeats the 1:MM hour in
|
|
standard time. Since that's what the local clock *does*, we want to map both
|
|
UTC hours 5:MM and 6:MM to 1:MM Eastern. The result is ambiguous
|
|
in local time, but so it goes -- it's the way the local clock works.
|
|
|
|
When x = 5:MM UTC is the input to this algorithm, x.o=0, y.o=-5 and y.d=0,
|
|
so z=0:MM. z.d=60 (minutes) then, so [5] doesn't hold and we keep going.
|
|
z' = z + z.d = 1:MM then, and z'.d=0, and z'.d - z.d = -60 != 0 so [8]
|
|
(correctly) concludes that z' is not UTC-equivalent to x.
|
|
|
|
Because we know z.d said z was in daylight time (else [5] would have held and
|
|
we would have stopped then), and we know z.d != z'.d (else [8] would have held
|
|
and we have stopped then), and there are only 2 possible values dst() can
|
|
return in Eastern, it follows that z'.d must be 0 (which it is in the example,
|
|
but the reasoning doesn't depend on the example -- it depends on there being
|
|
two possible dst() outcomes, one zero and the other non-zero). Therefore
|
|
z' must be in standard time, and is the spelling we want in this case.
|
|
|
|
Note again that z' is not UTC-equivalent as far as the hybrid tzinfo class is
|
|
concerned (because it takes z' as being in standard time rather than the
|
|
daylight time we intend here), but returning it gives the real-life "local
|
|
clock repeats an hour" behavior when mapping the "unspellable" UTC hour into
|
|
tz.
|
|
|
|
When the input is 6:MM, z=1:MM and z.d=0, and we stop at once, again with
|
|
the 1:MM standard time spelling we want.
|
|
|
|
So how can this break? One of the assumptions must be violated. Two
|
|
possibilities:
|
|
|
|
1) [2] effectively says that y.s is invariant across all y belong to a given
|
|
time zone. This isn't true if, for political reasons or continental drift,
|
|
a region decides to change its base offset from UTC.
|
|
|
|
2) There may be versions of "double daylight" time where the tail end of
|
|
the analysis gives up a step too early. I haven't thought about that
|
|
enough to say.
|
|
|
|
In any case, it's clear that the default fromutc() is strong enough to handle
|
|
"almost all" time zones: so long as the standard offset is invariant, it
|
|
doesn't matter if daylight time transition points change from year to year, or
|
|
if daylight time is skipped in some years; it doesn't matter how large or
|
|
small dst() may get within its bounds; and it doesn't even matter if some
|
|
perverse time zone returns a negative dst()). So a breaking case must be
|
|
pretty bizarre, and a tzinfo subclass can override fromutc() if it is.
|
|
"""
|
|
try:
|
|
from _datetime import *
|
|
except ImportError:
|
|
pass
|
|
else:
|
|
# Clean up unused names
|
|
del (_DAYNAMES, _DAYS_BEFORE_MONTH, _DAYS_IN_MONTH,
|
|
_DI100Y, _DI400Y, _DI4Y, _MAXORDINAL, _MONTHNAMES,
|
|
_build_struct_time, _call_tzinfo_method, _check_date_fields,
|
|
_check_time_fields, _check_tzinfo_arg, _check_tzname,
|
|
_check_utc_offset, _cmp, _cmperror, _date_class, _days_before_month,
|
|
_days_before_year, _days_in_month, _format_time, _is_leap,
|
|
_isoweek1monday, _math, _ord2ymd, _time, _time_class, _tzinfo_class,
|
|
_wrap_strftime, _ymd2ord)
|
|
# XXX Since import * above excludes names that start with _,
|
|
# docstring does not get overwritten. In the future, it may be
|
|
# appropriate to maintain a single module level docstring and
|
|
# remove the following line.
|
|
from _datetime import __doc__
|