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-"""
-Class Date supplies date objects that support date arithmetic.
-
-Date(month,day,year) returns a Date object. An instance prints as,
-e.g., 'Mon 16 Aug 1993'.
-
-Addition, subtraction, comparison operators, min, max, and sorting
-all work as expected for date objects: int+date or date+int returns
-the date `int' days from `date'; date+date raises an exception;
-date-int returns the date `int' days before `date'; date2-date1 returns
-an integer, the number of days from date1 to date2; int-date raises an
-exception; date1 < date2 is true iff date1 occurs before date2 (&
-similarly for other comparisons); min(date1,date2) is the earlier of
-the two dates and max(date1,date2) the later; and date objects can be
-used as dictionary keys.
-
-Date objects support one visible method, date.weekday(). This returns
-the day of the week the date falls on, as a string.
-
-Date objects also have 4 read-only data attributes:
- .month in 1..12
- .day in 1..31
- .year int or long int
- .ord the ordinal of the date relative to an arbitrary staring point
-
-The Dates module also supplies function today(), which returns the
-current date as a date object.
-
-Those entranced by calendar trivia will be disappointed, as no attempt
-has been made to accommodate the Julian (etc) system. On the other
-hand, at least this package knows that 2000 is a leap year but 2100
-isn't, and works fine for years with a hundred decimal digits <wink>.
-
-Tim Peters tim@ksr.com
-not speaking for Kendall Square Research Corp
-
-Adapted to Python 1.1 (where some hacks to overcome coercion are unnecessary)
-by Guido van Rossum
-
-Note that as of Python 2.3, a datetime module is included in the stardard
-library.
-"""
-
-import functools
-
-_MONTH_NAMES = [ 'January', 'February', 'March', 'April', 'May',
- 'June', 'July', 'August', 'September', 'October',
- 'November', 'December' ]
-
-_DAY_NAMES = [ 'Friday', 'Saturday', 'Sunday', 'Monday',
- 'Tuesday', 'Wednesday', 'Thursday' ]
-
-_DAYS_IN_MONTH = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ]
-
-_DAYS_BEFORE_MONTH = []
-dbm = 0
-for dim in _DAYS_IN_MONTH:
- _DAYS_BEFORE_MONTH.append(dbm)
- dbm = dbm + dim
-del dbm, dim
-
-def _is_leap(year): # 1 if leap year, else 0
- if year % 4 != 0: return 0
- if year % 400 == 0: return 1
- return year % 100 != 0
-
-def _days_in_year(year): # number of days in year
- return 365 + _is_leap(year)
-
-def _days_before_year(year): # number of days before year
- return year*365 + (year+3)//4 - (year+99)//100 + (year+399)//400
-
-def _days_in_month(month, year): # number of days in month of year
- if month == 2 and _is_leap(year): return 29
- return _DAYS_IN_MONTH[month-1]
-
-def _days_before_month(month, year): # number of days in year before month
- return _DAYS_BEFORE_MONTH[month-1] + (month > 2 and _is_leap(year))
-
-def _date2num(date): # compute ordinal of date.month,day,year
- return _days_before_year(date.year) + \
- _days_before_month(date.month, date.year) + \
- date.day
-
-_DI400Y = _days_before_year(400) # number of days in 400 years
-
-def _num2date(n): # return date with ordinal n
- if not isinstance(n, int):
- raise TypeError('argument must be integer: %r' % type(n))
-
- # Get uninitialized Date object. This is necesary because once
- # attributes are set, they cannot be changed.
- ans = Date.__new__(Date)
- ans.ord = n
-
- n400 = (n-1)//_DI400Y # # of 400-year blocks preceding
- year, n = 400 * n400, n - _DI400Y * n400
- more = n // 365
- dby = _days_before_year(more)
- if dby >= n:
- more = more - 1
- dby = dby - _days_in_year(more)
- year, n = year + more, n - dby
- month = min(n//29 + 1, 12)
- dbm = _days_before_month(month, year)
- if dbm >= n:
- month = month - 1
- dbm = dbm - _days_in_month(month, year)
-
- ans.month, ans.day, ans.year = month, n-dbm, year
- return ans
-
-def _num2day(n): # return weekday name of day with ordinal n
- return _DAY_NAMES[n % 7]
-
-@functools.total_ordering
-class Date:
- def __init__(self, month, day, year):
- if not 1 <= month <= 12:
- raise ValueError('month must be in 1..12: %r' % (month,))
- dim = _days_in_month(month, year)
- if not 1 <= day <= dim:
- raise ValueError('day must be in 1..%r: %r' % (dim, day))
- self.month, self.day, self.year = map(int, (month, day, year))
- self.ord = _date2num(self)
-
- # don't allow setting existing attributes
- def __setattr__(self, name, value):
- if name in self.__dict__:
- raise AttributeError('read-only attribute ' + name)
- self.__dict__[name] = value
-
- def __eq__(self, other):
- return self.ord == other.ord
-
- def __lt__(self, other):
- return self.ord < other.ord
-
- # define a hash function so dates can be used as dictionary keys
- def __hash__(self):
- return hash(self.ord)
-
- # print as, e.g., Mon 16 Aug 1993
- def __repr__(self):
- return '%.3s %2d %.3s %r' % (
- self.weekday(),
- self.day,
- _MONTH_NAMES[self.month-1],
- self.year)
-
- # Python 1.1 coerces neither int+date nor date+int
- def __add__(self, n):
- if not isinstance(n, int):
- raise TypeError('can\'t add %r to date' % type(n))
- return _num2date(self.ord + n)
- __radd__ = __add__ # handle int+date
-
- # Python 1.1 coerces neither date-int nor date-date
- def __sub__(self, other):
- if isinstance(other, int): # date-int
- return _num2date(self.ord - other)
- else:
- return self.ord - other.ord # date-date
-
- # complain about int-date
- def __rsub__(self, other):
- raise TypeError('Can\'t subtract date from integer')
-
- def weekday(self):
- return _num2day(self.ord)
-
-def today():
- import time
- local = time.localtime(time.time())
- return Date(local[1], local[2], local[0])
-
-class DateTestError(Exception):
- pass
-
-def test(firstyear, lastyear):
- a = Date(9,30,1913)
- b = Date(9,30,1914)
- if repr(a) != 'Tue 30 Sep 1913':
- raise DateTestError('__repr__ failure')
- if (not a < b) or a == b or a > b or b != b:
- raise DateTestError('__cmp__ failure')
- if a+365 != b or 365+a != b:
- raise DateTestError('__add__ failure')
- if b-a != 365 or b-365 != a:
- raise DateTestError('__sub__ failure')
- try:
- x = 1 - a
- raise DateTestError('int-date should have failed')
- except TypeError:
- pass
- try:
- x = a + b
- raise DateTestError('date+date should have failed')
- except TypeError:
- pass
- if a.weekday() != 'Tuesday':
- raise DateTestError('weekday() failure')
- if max(a,b) is not b or min(a,b) is not a:
- raise DateTestError('min/max failure')
- d = {a-1:b, b:a+1}
- if d[b-366] != b or d[a+(b-a)] != Date(10,1,1913):
- raise DateTestError('dictionary failure')
-
- # verify date<->number conversions for first and last days for
- # all years in firstyear .. lastyear
-
- lord = _days_before_year(firstyear)
- y = firstyear
- while y <= lastyear:
- ford = lord + 1
- lord = ford + _days_in_year(y) - 1
- fd, ld = Date(1,1,y), Date(12,31,y)
- if (fd.ord,ld.ord) != (ford,lord):
- raise DateTestError('date->num failed', y)
- fd, ld = _num2date(ford), _num2date(lord)
- if (1,1,y,12,31,y) != \
- (fd.month,fd.day,fd.year,ld.month,ld.day,ld.year):
- raise DateTestError('num->date failed', y)
- y = y + 1
-
-if __name__ == '__main__':
- test(1850, 2150)
generated by cgit v0.12 at 2025-08-31 13:00:56 (GMT)