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462 lines
20 KiB
Python
462 lines
20 KiB
Python
"""Strptime-related classes and functions.
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CLASSES:
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LocaleTime -- Discovers and stores locale-specific time information
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TimeRE -- Creates regexes for pattern matching a string of text containing
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time information
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FUNCTIONS:
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_getlang -- Figure out what language is being used for the locale
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strptime -- Calculates the time struct represented by the passed-in string
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"""
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import time
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import locale
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import calendar
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from re import compile as re_compile
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from re import IGNORECASE, ASCII
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from re import escape as re_escape
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from datetime import date as datetime_date
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try:
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from _thread import allocate_lock as _thread_allocate_lock
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except:
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from _dummy_thread import allocate_lock as _thread_allocate_lock
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__all__ = []
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def _getlang():
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# Figure out what the current language is set to.
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return locale.getlocale(locale.LC_TIME)
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class LocaleTime(object):
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"""Stores and handles locale-specific information related to time.
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ATTRIBUTES:
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f_weekday -- full weekday names (7-item list)
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a_weekday -- abbreviated weekday names (7-item list)
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f_month -- full month names (13-item list; dummy value in [0], which
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is added by code)
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a_month -- abbreviated month names (13-item list, dummy value in
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[0], which is added by code)
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am_pm -- AM/PM representation (2-item list)
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LC_date_time -- format string for date/time representation (string)
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LC_date -- format string for date representation (string)
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LC_time -- format string for time representation (string)
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timezone -- daylight- and non-daylight-savings timezone representation
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(2-item list of sets)
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lang -- Language used by instance (2-item tuple)
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"""
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def __init__(self):
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"""Set all attributes.
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Order of methods called matters for dependency reasons.
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The locale language is set at the offset and then checked again before
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exiting. This is to make sure that the attributes were not set with a
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mix of information from more than one locale. This would most likely
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happen when using threads where one thread calls a locale-dependent
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function while another thread changes the locale while the function in
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the other thread is still running. Proper coding would call for
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locks to prevent changing the locale while locale-dependent code is
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running. The check here is done in case someone does not think about
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doing this.
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Only other possible issue is if someone changed the timezone and did
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not call tz.tzset . That is an issue for the programmer, though,
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since changing the timezone is worthless without that call.
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"""
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self.lang = _getlang()
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self.__calc_weekday()
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self.__calc_month()
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self.__calc_am_pm()
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self.__calc_timezone()
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self.__calc_date_time()
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if _getlang() != self.lang:
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raise ValueError("locale changed during initialization")
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def __pad(self, seq, front):
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# Add '' to seq to either the front (is True), else the back.
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seq = list(seq)
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if front:
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seq.insert(0, '')
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else:
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seq.append('')
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return seq
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def __calc_weekday(self):
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# Set self.a_weekday and self.f_weekday using the calendar
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# module.
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a_weekday = [calendar.day_abbr[i].lower() for i in range(7)]
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f_weekday = [calendar.day_name[i].lower() for i in range(7)]
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self.a_weekday = a_weekday
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self.f_weekday = f_weekday
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def __calc_month(self):
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# Set self.f_month and self.a_month using the calendar module.
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a_month = [calendar.month_abbr[i].lower() for i in range(13)]
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f_month = [calendar.month_name[i].lower() for i in range(13)]
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self.a_month = a_month
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self.f_month = f_month
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def __calc_am_pm(self):
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# Set self.am_pm by using time.strftime().
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# The magic date (1999,3,17,hour,44,55,2,76,0) is not really that
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# magical; just happened to have used it everywhere else where a
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# static date was needed.
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am_pm = []
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for hour in (1, 22):
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time_tuple = time.struct_time((1999,3,17,hour,44,55,2,76,0))
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am_pm.append(time.strftime("%p", time_tuple).lower())
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self.am_pm = am_pm
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def __calc_date_time(self):
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# Set self.date_time, self.date, & self.time by using
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# time.strftime().
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# Use (1999,3,17,22,44,55,2,76,0) for magic date because the amount of
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# overloaded numbers is minimized. The order in which searches for
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# values within the format string is very important; it eliminates
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# possible ambiguity for what something represents.
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time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0))
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date_time = [None, None, None]
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date_time[0] = time.strftime("%c", time_tuple).lower()
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date_time[1] = time.strftime("%x", time_tuple).lower()
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date_time[2] = time.strftime("%X", time_tuple).lower()
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replacement_pairs = [('%', '%%'), (self.f_weekday[2], '%A'),
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(self.f_month[3], '%B'), (self.a_weekday[2], '%a'),
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(self.a_month[3], '%b'), (self.am_pm[1], '%p'),
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('1999', '%Y'), ('99', '%y'), ('22', '%H'),
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('44', '%M'), ('55', '%S'), ('76', '%j'),
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('17', '%d'), ('03', '%m'), ('3', '%m'),
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# '3' needed for when no leading zero.
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('2', '%w'), ('10', '%I')]
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replacement_pairs.extend([(tz, "%Z") for tz_values in self.timezone
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for tz in tz_values])
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for offset,directive in ((0,'%c'), (1,'%x'), (2,'%X')):
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current_format = date_time[offset]
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for old, new in replacement_pairs:
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# Must deal with possible lack of locale info
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# manifesting itself as the empty string (e.g., Swedish's
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# lack of AM/PM info) or a platform returning a tuple of empty
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# strings (e.g., MacOS 9 having timezone as ('','')).
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if old:
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current_format = current_format.replace(old, new)
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# If %W is used, then Sunday, 2005-01-03 will fall on week 0 since
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# 2005-01-03 occurs before the first Monday of the year. Otherwise
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# %U is used.
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time_tuple = time.struct_time((1999,1,3,1,1,1,6,3,0))
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if '00' in time.strftime(directive, time_tuple):
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U_W = '%W'
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else:
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U_W = '%U'
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date_time[offset] = current_format.replace('11', U_W)
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self.LC_date_time = date_time[0]
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self.LC_date = date_time[1]
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self.LC_time = date_time[2]
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def __calc_timezone(self):
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# Set self.timezone by using time.tzname.
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# Do not worry about possibility of time.tzname[0] == timetzname[1]
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# and time.daylight; handle that in strptime .
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try:
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time.tzset()
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except AttributeError:
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pass
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no_saving = frozenset(["utc", "gmt", time.tzname[0].lower()])
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if time.daylight:
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has_saving = frozenset([time.tzname[1].lower()])
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else:
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has_saving = frozenset()
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self.timezone = (no_saving, has_saving)
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class TimeRE(dict):
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"""Handle conversion from format directives to regexes."""
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def __init__(self, locale_time=None):
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"""Create keys/values.
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Order of execution is important for dependency reasons.
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"""
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if locale_time:
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self.locale_time = locale_time
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else:
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self.locale_time = LocaleTime()
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base = super()
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base.__init__({
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# The " \d" part of the regex is to make %c from ANSI C work
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'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])",
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'f': r"(?P<f>[0-9]{1,6})",
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'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
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'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])",
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'j': r"(?P<j>36[0-6]|3[0-5]\d|[1-2]\d\d|0[1-9]\d|00[1-9]|[1-9]\d|0[1-9]|[1-9])",
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'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])",
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'M': r"(?P<M>[0-5]\d|\d)",
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'S': r"(?P<S>6[0-1]|[0-5]\d|\d)",
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'U': r"(?P<U>5[0-3]|[0-4]\d|\d)",
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'w': r"(?P<w>[0-6])",
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# W is set below by using 'U'
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'y': r"(?P<y>\d\d)",
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#XXX: Does 'Y' need to worry about having less or more than
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# 4 digits?
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'Y': r"(?P<Y>\d\d\d\d)",
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'A': self.__seqToRE(self.locale_time.f_weekday, 'A'),
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'a': self.__seqToRE(self.locale_time.a_weekday, 'a'),
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'B': self.__seqToRE(self.locale_time.f_month[1:], 'B'),
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'b': self.__seqToRE(self.locale_time.a_month[1:], 'b'),
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'p': self.__seqToRE(self.locale_time.am_pm, 'p'),
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'Z': self.__seqToRE((tz for tz_names in self.locale_time.timezone
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for tz in tz_names),
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'Z'),
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'%': '%'})
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base.__setitem__('W', base.__getitem__('U').replace('U', 'W'))
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base.__setitem__('c', self.pattern(self.locale_time.LC_date_time))
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base.__setitem__('x', self.pattern(self.locale_time.LC_date))
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base.__setitem__('X', self.pattern(self.locale_time.LC_time))
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def __seqToRE(self, to_convert, directive):
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"""Convert a list to a regex string for matching a directive.
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Want possible matching values to be from longest to shortest. This
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prevents the possibility of a match occuring for a value that also
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a substring of a larger value that should have matched (e.g., 'abc'
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matching when 'abcdef' should have been the match).
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"""
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to_convert = sorted(to_convert, key=len, reverse=True)
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for value in to_convert:
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if value != '':
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break
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else:
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return ''
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regex = '|'.join(re_escape(stuff) for stuff in to_convert)
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regex = '(?P<%s>%s' % (directive, regex)
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return '%s)' % regex
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def pattern(self, format):
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"""Return regex pattern for the format string.
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Need to make sure that any characters that might be interpreted as
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regex syntax are escaped.
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"""
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processed_format = ''
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# The sub() call escapes all characters that might be misconstrued
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# as regex syntax. Cannot use re.escape since we have to deal with
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# format directives (%m, etc.).
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regex_chars = re_compile(r"([\\.^$*+?\(\){}\[\]|])")
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format = regex_chars.sub(r"\\\1", format)
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whitespace_replacement = re_compile('\s+')
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format = whitespace_replacement.sub('\s+', format)
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while '%' in format:
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directive_index = format.index('%')+1
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processed_format = "%s%s%s" % (processed_format,
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format[:directive_index-1],
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self[format[directive_index]])
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format = format[directive_index+1:]
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return "%s%s" % (processed_format, format)
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def compile(self, format):
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"""Return a compiled re object for the format string."""
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return re_compile(self.pattern(format), IGNORECASE)
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_cache_lock = _thread_allocate_lock()
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# DO NOT modify _TimeRE_cache or _regex_cache without acquiring the cache lock
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# first!
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_TimeRE_cache = TimeRE()
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_CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache
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_regex_cache = {}
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def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon):
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"""Calculate the Julian day based on the year, week of the year, and day of
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the week, with week_start_day representing whether the week of the year
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assumes the week starts on Sunday or Monday (6 or 0)."""
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first_weekday = datetime_date(year, 1, 1).weekday()
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# If we are dealing with the %U directive (week starts on Sunday), it's
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# easier to just shift the view to Sunday being the first day of the
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# week.
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if not week_starts_Mon:
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first_weekday = (first_weekday + 1) % 7
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day_of_week = (day_of_week + 1) % 7
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# Need to watch out for a week 0 (when the first day of the year is not
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# the same as that specified by %U or %W).
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week_0_length = (7 - first_weekday) % 7
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if week_of_year == 0:
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return 1 + day_of_week - first_weekday
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else:
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days_to_week = week_0_length + (7 * (week_of_year - 1))
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return 1 + days_to_week + day_of_week
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def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
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"""Return a time struct based on the input string and the format string."""
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for index, arg in enumerate([data_string, format]):
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if not isinstance(arg, str):
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msg = "strptime() argument {} must be str, not {}"
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raise TypeError(msg.format(index, type(arg)))
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global _TimeRE_cache, _regex_cache
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with _cache_lock:
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if _getlang() != _TimeRE_cache.locale_time.lang:
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_TimeRE_cache = TimeRE()
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_regex_cache.clear()
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if len(_regex_cache) > _CACHE_MAX_SIZE:
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_regex_cache.clear()
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locale_time = _TimeRE_cache.locale_time
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format_regex = _regex_cache.get(format)
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if not format_regex:
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try:
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format_regex = _TimeRE_cache.compile(format)
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# KeyError raised when a bad format is found; can be specified as
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# \\, in which case it was a stray % but with a space after it
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except KeyError as err:
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bad_directive = err.args[0]
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if bad_directive == "\\":
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bad_directive = "%"
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del err
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raise ValueError("'%s' is a bad directive in format '%s'" %
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(bad_directive, format))
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# IndexError only occurs when the format string is "%"
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except IndexError:
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raise ValueError("stray %% in format '%s'" % format)
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_regex_cache[format] = format_regex
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found = format_regex.match(data_string)
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if not found:
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raise ValueError("time data %r does not match format %r" %
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(data_string, format))
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if len(data_string) != found.end():
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raise ValueError("unconverted data remains: %s" %
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data_string[found.end():])
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year = 1900
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month = day = 1
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hour = minute = second = fraction = 0
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tz = -1
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# Default to -1 to signify that values not known; not critical to have,
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# though
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week_of_year = -1
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week_of_year_start = -1
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# weekday and julian defaulted to -1 so as to signal need to calculate
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# values
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weekday = julian = -1
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found_dict = found.groupdict()
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for group_key in found_dict.keys():
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# Directives not explicitly handled below:
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# c, x, X
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# handled by making out of other directives
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# U, W
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# worthless without day of the week
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if group_key == 'y':
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year = int(found_dict['y'])
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# Open Group specification for strptime() states that a %y
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#value in the range of [00, 68] is in the century 2000, while
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#[69,99] is in the century 1900
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if year <= 68:
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year += 2000
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else:
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year += 1900
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elif group_key == 'Y':
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year = int(found_dict['Y'])
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elif group_key == 'm':
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month = int(found_dict['m'])
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elif group_key == 'B':
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month = locale_time.f_month.index(found_dict['B'].lower())
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elif group_key == 'b':
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month = locale_time.a_month.index(found_dict['b'].lower())
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elif group_key == 'd':
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day = int(found_dict['d'])
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elif group_key == 'H':
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hour = int(found_dict['H'])
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elif group_key == 'I':
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hour = int(found_dict['I'])
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ampm = found_dict.get('p', '').lower()
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# If there was no AM/PM indicator, we'll treat this like AM
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if ampm in ('', locale_time.am_pm[0]):
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# We're in AM so the hour is correct unless we're
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# looking at 12 midnight.
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# 12 midnight == 12 AM == hour 0
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if hour == 12:
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hour = 0
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elif ampm == locale_time.am_pm[1]:
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# We're in PM so we need to add 12 to the hour unless
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# we're looking at 12 noon.
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# 12 noon == 12 PM == hour 12
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if hour != 12:
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hour += 12
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elif group_key == 'M':
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minute = int(found_dict['M'])
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elif group_key == 'S':
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second = int(found_dict['S'])
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elif group_key == 'f':
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s = found_dict['f']
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# Pad to always return microseconds.
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s += "0" * (6 - len(s))
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fraction = int(s)
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elif group_key == 'A':
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weekday = locale_time.f_weekday.index(found_dict['A'].lower())
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elif group_key == 'a':
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weekday = locale_time.a_weekday.index(found_dict['a'].lower())
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elif group_key == 'w':
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weekday = int(found_dict['w'])
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if weekday == 0:
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weekday = 6
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else:
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weekday -= 1
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elif group_key == 'j':
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julian = int(found_dict['j'])
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elif group_key in ('U', 'W'):
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week_of_year = int(found_dict[group_key])
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if group_key == 'U':
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# U starts week on Sunday.
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week_of_year_start = 6
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else:
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# W starts week on Monday.
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week_of_year_start = 0
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elif group_key == 'Z':
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# Since -1 is default value only need to worry about setting tz if
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# it can be something other than -1.
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found_zone = found_dict['Z'].lower()
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for value, tz_values in enumerate(locale_time.timezone):
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if found_zone in tz_values:
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# Deal with bad locale setup where timezone names are the
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# same and yet time.daylight is true; too ambiguous to
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# be able to tell what timezone has daylight savings
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if (time.tzname[0] == time.tzname[1] and
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time.daylight and found_zone not in ("utc", "gmt")):
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break
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else:
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tz = value
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break
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# If we know the week of the year and what day of that week, we can figure
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# out the Julian day of the year.
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if julian == -1 and week_of_year != -1 and weekday != -1:
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week_starts_Mon = True if week_of_year_start == 0 else False
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julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
|
|
week_starts_Mon)
|
|
# Cannot pre-calculate datetime_date() since can change in Julian
|
|
# calculation and thus could have different value for the day of the week
|
|
# calculation.
|
|
if julian == -1:
|
|
# Need to add 1 to result since first day of the year is 1, not 0.
|
|
julian = datetime_date(year, month, day).toordinal() - \
|
|
datetime_date(year, 1, 1).toordinal() + 1
|
|
else: # Assume that if they bothered to include Julian day it will
|
|
# be accurate.
|
|
datetime_result = datetime_date.fromordinal((julian - 1) + datetime_date(year, 1, 1).toordinal())
|
|
year = datetime_result.year
|
|
month = datetime_result.month
|
|
day = datetime_result.day
|
|
if weekday == -1:
|
|
weekday = datetime_date(year, month, day).weekday()
|
|
return (time.struct_time((year, month, day,
|
|
hour, minute, second,
|
|
weekday, julian, tz)), fraction)
|
|
|
|
def _strptime_time(data_string, format="%a %b %d %H:%M:%S %Y"):
|
|
return _strptime(data_string, format)[0]
|