+
+def unified_strdate(date_str):
+ """Return a string with the date in the format YYYYMMDD"""
+ upload_date = None
+ #Replace commas
+ date_str = date_str.replace(',',' ')
+ # %z (UTC offset) is only supported in python>=3.2
+ date_str = re.sub(r' (\+|-)[\d]*$', '', date_str)
+ format_expressions = ['%d %B %Y', '%B %d %Y', '%b %d %Y', '%Y-%m-%d', '%d/%m/%Y', '%Y/%m/%d %H:%M:%S']
+ for expression in format_expressions:
+ try:
+ upload_date = datetime.datetime.strptime(date_str, expression).strftime('%Y%m%d')
+ except:
+ pass
+ return upload_date
+
+def date_from_str(date_str):
+ """
+ Return a datetime object from a string in the format YYYYMMDD or
+ (now|today)[+-][0-9](day|week|month|year)(s)?"""
+ today = datetime.date.today()
+ if date_str == 'now'or date_str == 'today':
+ return today
+ match = re.match('(now|today)(?P<sign>[+-])(?P<time>\d+)(?P<unit>day|week|month|year)(s)?', date_str)
+ if match is not None:
+ sign = match.group('sign')
+ time = int(match.group('time'))
+ if sign == '-':
+ time = -time
+ unit = match.group('unit')
+ #A bad aproximation?
+ if unit == 'month':
+ unit = 'day'
+ time *= 30
+ elif unit == 'year':
+ unit = 'day'
+ time *= 365
+ unit += 's'
+ delta = datetime.timedelta(**{unit: time})
+ return today + delta
+ return datetime.datetime.strptime(date_str, "%Y%m%d").date()
+
+class DateRange(object):
+ """Represents a time interval between two dates"""
+ def __init__(self, start=None, end=None):
+ """start and end must be strings in the format accepted by date"""
+ if start is not None:
+ self.start = date_from_str(start)
+ else:
+ self.start = datetime.datetime.min.date()
+ if end is not None:
+ self.end = date_from_str(end)
+ else:
+ self.end = datetime.datetime.max.date()
+ if self.start > self.end:
+ raise ValueError('Date range: "%s" , the start date must be before the end date' % self)
+ @classmethod
+ def day(cls, day):
+ """Returns a range that only contains the given day"""
+ return cls(day,day)
+ def __contains__(self, date):
+ """Check if the date is in the range"""
+ if not isinstance(date, datetime.date):
+ date = date_from_str(date)
+ return self.start <= date <= self.end
+ def __str__(self):
+ return '%s - %s' % ( self.start.isoformat(), self.end.isoformat())