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cpython/Lib/_strptime.py

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"""Strptime-related classes and functions.
CLASSES:
LocaleTime -- Discovers and/or stores locale-specific time information
TimeRE -- Creates regexes for pattern matching a string of text containing
time information as is returned by time.strftime()
FUNCTIONS:
_getlang -- Figure out what language is being used for the locale
strptime -- Calculates the time struct represented by the passed-in string
Requires Python 2.2.1 or higher (mainly because of the use of property()).
Can be used in Python 2.2 if the following line is added:
True = 1; False = 0
"""
import time
import locale
import calendar
from re import compile as re_compile
from re import IGNORECASE
from datetime import date as datetime_date
__author__ = "Brett Cannon"
__email__ = "brett@python.org"
__all__ = ['strptime']
def _getlang():
# Figure out what the current language is set to.
current_lang = locale.getlocale(locale.LC_TIME)[0]
if current_lang:
return current_lang
else:
current_lang = locale.getdefaultlocale()[0]
if current_lang:
return current_lang
else:
return ''
class LocaleTime(object):
"""Stores and handles locale-specific information related to time.
ATTRIBUTES (all read-only after instance creation! Instance variables that
store the values have mangled names):
f_weekday -- full weekday names (7-item list)
a_weekday -- abbreviated weekday names (7-item list)
f_month -- full weekday names (14-item list; dummy value in [0], which
is added by code)
a_month -- abbreviated weekday names (13-item list, dummy value in
[0], which is added by code)
am_pm -- AM/PM representation (2-item list)
LC_date_time -- format string for date/time representation (string)
LC_date -- format string for date representation (string)
LC_time -- format string for time representation (string)
timezone -- daylight- and non-daylight-savings timezone representation
(3-item list; code tacks on blank item at end for
possible lack of timezone such as UTC)
lang -- Language used by instance (string)
"""
def __init__(self, f_weekday=None, a_weekday=None, f_month=None,
a_month=None, am_pm=None, LC_date_time=None, LC_time=None,
LC_date=None, timezone=None, lang=None):
"""Optionally set attributes with passed-in values."""
if f_weekday is None:
self.__f_weekday = None
elif len(f_weekday) == 7:
self.__f_weekday = list(f_weekday)
else:
raise TypeError("full weekday names must be a 7-item sequence")
if a_weekday is None:
self.__a_weekday = None
elif len(a_weekday) == 7:
self.__a_weekday = list(a_weekday)
else:
raise TypeError(
"abbreviated weekday names must be a 7-item sequence")
if f_month is None:
self.__f_month = None
elif len(f_month) == 12:
self.__f_month = self.__pad(f_month, True)
else:
raise TypeError("full month names must be a 12-item sequence")
if a_month is None:
self.__a_month = None
elif len(a_month) == 12:
self.__a_month = self.__pad(a_month, True)
else:
raise TypeError(
"abbreviated month names must be a 12-item sequence")
if am_pm is None:
self.__am_pm = None
elif len(am_pm) == 2:
self.__am_pm = am_pm
else:
raise TypeError("AM/PM representation must be a 2-item sequence")
self.__LC_date_time = LC_date_time
self.__LC_time = LC_time
self.__LC_date = LC_date
self.__timezone = timezone
if timezone:
if len(timezone) != 2:
raise TypeError("timezone names must contain 2 items")
else:
self.__timezone = self.__pad(timezone, False)
self.__lang = lang
def __pad(self, seq, front):
# Add '' to seq to either front (is True), else the back.
seq = list(seq)
if front:
seq.insert(0, '')
else:
seq.append('')
return seq
def __set_nothing(self, stuff):
# Raise TypeError when trying to set an attribute.
raise TypeError("attribute does not support assignment")
def __get_f_weekday(self):
# Fetch self.f_weekday.
if not self.__f_weekday:
self.__calc_weekday()
return self.__f_weekday
def __get_a_weekday(self):
# Fetch self.a_weekday.
if not self.__a_weekday:
self.__calc_weekday()
return self.__a_weekday
f_weekday = property(__get_f_weekday, __set_nothing,
doc="Full weekday names")
a_weekday = property(__get_a_weekday, __set_nothing,
doc="Abbreviated weekday names")
def __get_f_month(self):
# Fetch self.f_month.
if not self.__f_month:
self.__calc_month()
return self.__f_month
def __get_a_month(self):
# Fetch self.a_month.
if not self.__a_month:
self.__calc_month()
return self.__a_month
f_month = property(__get_f_month, __set_nothing,
doc="Full month names (dummy value at index 0)")
a_month = property(__get_a_month, __set_nothing,
doc="Abbreviated month names (dummy value at index 0)")
def __get_am_pm(self):
# Fetch self.am_pm.
if not self.__am_pm:
self.__calc_am_pm()
return self.__am_pm
am_pm = property(__get_am_pm, __set_nothing, doc="AM/PM representation")
def __get_timezone(self):
# Fetch self.timezone.
if not self.__timezone:
self.__calc_timezone()
return self.__timezone
timezone = property(__get_timezone, __set_nothing,
doc="Timezone representation (dummy value at index 2)")
def __get_LC_date_time(self):
# Fetch self.LC_date_time.
if not self.__LC_date_time:
self.__calc_date_time()
return self.__LC_date_time
def __get_LC_date(self):
# Fetch self.LC_date.
if not self.__LC_date:
self.__calc_date_time()
return self.__LC_date
def __get_LC_time(self):
# Fetch self.LC_time.
if not self.__LC_time:
self.__calc_date_time()
return self.__LC_time
LC_date_time = property(
__get_LC_date_time, __set_nothing,
doc=
"Format string for locale's date/time representation ('%c' format)")
LC_date = property(__get_LC_date, __set_nothing,
doc="Format string for locale's date representation ('%x' format)")
LC_time = property(__get_LC_time, __set_nothing,
doc="Format string for locale's time representation ('%X' format)")
def __get_lang(self):
# Fetch self.lang.
if not self.__lang:
self.__calc_lang()
return self.__lang
lang = property(__get_lang, __set_nothing,
doc="Language used for instance")
def __calc_weekday(self):
# Set self.__a_weekday and self.__f_weekday using the calendar
# module.
a_weekday = [calendar.day_abbr[i] for i in range(7)]
f_weekday = [calendar.day_name[i] for i in range(7)]
if not self.__a_weekday:
self.__a_weekday = a_weekday
if not self.__f_weekday:
self.__f_weekday = f_weekday
def __calc_month(self):
# Set self.__f_month and self.__a_month using the calendar module.
a_month = [calendar.month_abbr[i] for i in range(13)]
f_month = [calendar.month_name[i] for i in range(13)]
if not self.__a_month:
self.__a_month = a_month
if not self.__f_month:
self.__f_month = f_month
def __calc_am_pm(self):
# Set self.__am_pm by using time.strftime().
# The magic date (1999,3,17,hour,44,55,2,76,0) is not really that
# magical; just happened to have used it everywhere else where a
# static date was needed.
am_pm = []
for hour in (01,22):
time_tuple = time.struct_time((1999,3,17,hour,44,55,2,76,0))
am_pm.append(time.strftime("%p", time_tuple))
self.__am_pm = am_pm
def __calc_date_time(self):
# Set self.__date_time, self.__date, & self.__time by using
# time.strftime().
# Use (1999,3,17,22,44,55,2,76,0) for magic date because the amount of
# overloaded numbers is minimized. The order in which searches for
# values within the format string is very important; it eliminates
# possible ambiguity for what something represents.
time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0))
date_time = [None, None, None]
date_time[0] = time.strftime("%c", time_tuple)
date_time[1] = time.strftime("%x", time_tuple)
date_time[2] = time.strftime("%X", time_tuple)
for offset,directive in ((0,'%c'), (1,'%x'), (2,'%X')):
current_format = date_time[offset]
for old, new in (
('%', '%%'), (self.f_weekday[2], '%A'),
(self.f_month[3], '%B'), (self.a_weekday[2], '%a'),
(self.a_month[3], '%b'), (self.am_pm[1], '%p'),
(self.timezone[0], '%Z'), (self.timezone[1], '%Z'),
('1999', '%Y'), ('99', '%y'), ('22', '%H'),
('44', '%M'), ('55', '%S'), ('76', '%j'),
('17', '%d'), ('03', '%m'), ('3', '%m'),
# '3' needed for when no leading zero.
('2', '%w'), ('10', '%I')):
# Must deal with possible lack of locale info
# manifesting itself as the empty string (e.g., Swedish's
# lack of AM/PM info) or a platform returning a tuple of empty
# strings (e.g., MacOS 9 having timezone as ('','')).
if old:
current_format = current_format.replace(old, new)
time_tuple = time.struct_time((1999,1,3,1,1,1,6,3,0))
if time.strftime(directive, time_tuple).find('00'):
U_W = '%U'
else:
U_W = '%W'
date_time[offset] = current_format.replace('11', U_W)
if not self.__LC_date_time:
self.__LC_date_time = date_time[0]
if not self.__LC_date:
self.__LC_date = date_time[1]
if not self.__LC_time:
self.__LC_time = date_time[2]
def __calc_timezone(self):
# Set self.__timezone by using time.tzname.
#
# Empty string used for matching when timezone is not used/needed such
# as with UTC.
self.__timezone = self.__pad(time.tzname, 0)
def __calc_lang(self):
# Set self.__lang by using __getlang().
self.__lang = _getlang()
class TimeRE(dict):
"""Handle conversion from format directives to regexes."""
def __init__(self, locale_time=LocaleTime()):
"""Init inst with non-locale regexes and store LocaleTime object."""
#XXX: Does 'Y' need to worry about having less or more than 4 digits?
base = super(TimeRE, self)
base.__init__({
# The " \d" option is to make %c from ANSI C work
'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])",
'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])",
'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])",
'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])",
'M': r"(?P<M>[0-5]\d|\d)",
'S': r"(?P<S>6[0-1]|[0-5]\d|\d)",
'U': r"(?P<U>5[0-3]|[0-4]\d|\d)",
'w': r"(?P<w>[0-6])",
# W is set below by using 'U'
'y': r"(?P<y>\d\d)",
'Y': r"(?P<Y>\d\d\d\d)"})
base.__setitem__('W', base.__getitem__('U'))
self.locale_time = locale_time
def __getitem__(self, fetch):
"""Try to fetch regex; if it does not exist, construct it."""
try:
return super(TimeRE, self).__getitem__(fetch)
except KeyError:
constructors = {
'A': lambda: self.__seqToRE(self.locale_time.f_weekday, fetch),
'a': lambda: self.__seqToRE(self.locale_time.a_weekday, fetch),
'B': lambda: self.__seqToRE(self.locale_time.f_month[1:],
fetch),
'b': lambda: self.__seqToRE(self.locale_time.a_month[1:],
fetch),
'c': lambda: self.pattern(self.locale_time.LC_date_time),
'p': lambda: self.__seqToRE(self.locale_time.am_pm, fetch),
'x': lambda: self.pattern(self.locale_time.LC_date),
'X': lambda: self.pattern(self.locale_time.LC_time),
'Z': lambda: self.__seqToRE(self.locale_time.timezone, fetch),
'%': lambda: '%',
}
if fetch in constructors:
self[fetch] = constructors[fetch]()
return self[fetch]
else:
raise
def __seqToRE(self, to_convert, directive):
"""Convert a list to a regex string for matching a directive."""
def sorter(a, b):
"""Sort based on length.
Done in case for some strange reason that names in the locale only
differ by a suffix and thus want the name with the suffix to match
first.
"""
try:
a_length = len(a)
except TypeError:
a_length = 0
try:
b_length = len(b)
except TypeError:
b_length = 0
return cmp(b_length, a_length)
to_convert = to_convert[:] # Don't want to change value in-place.
for value in to_convert:
if value != '':
break
else:
return ''
to_convert.sort(sorter)
regex = '|'.join(to_convert)
regex = '(?P<%s>%s' % (directive, regex)
return '%s)' % regex
def pattern(self, format):
"""Return re pattern for the format string.
Need to make sure that any characters that might be interpreted as
regex syntax is escaped.
"""
processed_format = ''
# The sub() call escapes all characters that might be misconstrued
# as regex syntax.
regex_chars = re_compile(r"([\\.^$*+?{}\[\]|])")
format = regex_chars.sub(r"\\\1", format)
whitespace_replacement = re_compile('\s+')
format = whitespace_replacement.sub('\s*', format)
while format.find('%') != -1:
directive_index = format.index('%')+1
processed_format = "%s%s%s" % (processed_format,
format[:directive_index-1],
self[format[directive_index]])
format = format[directive_index+1:]
return "%s%s" % (processed_format, format)
def compile(self, format):
"""Return a compiled re object for the format string."""
return re_compile(self.pattern(format), IGNORECASE)
# Cached TimeRE; probably only need one instance ever so cache it for performance
_locale_cache = TimeRE()
# Cached regex objects; same reason as for TimeRE cache
_regex_cache = dict()
def strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
"""Return a time struct based on the input data and the format string."""
global _locale_cache
global _regex_cache
locale_time = _locale_cache.locale_time
# If the language changes, caches are invalidated, so clear them
if locale_time.lang != _getlang():
_locale_cache = TimeRE()
_regex_cache.clear()
format_regex = _regex_cache.get(format)
if not format_regex:
# Limit regex cache size to prevent major bloating of the module;
# The value 5 is arbitrary
if len(_regex_cache) > 5:
_regex_cache.clear()
format_regex = _locale_cache.compile(format)
_regex_cache[format] = format_regex
found = format_regex.match(data_string)
if not found:
raise ValueError("time data did not match format")
if len(data_string) != found.end():
raise ValueError("unconverted data remains: %s" %
data_string[found.end():])
year = 1900
month = day = 1
hour = minute = second = 0
tz = -1
# weekday and julian defaulted to -1 so as to signal need to calculate values
weekday = julian = -1
found_dict = found.groupdict()
for group_key in found_dict.iterkeys():
if group_key == 'y':
year = int(found_dict['y'])
# Open Group specification for strptime() states that a %y
#value in the range of [00, 68] is in the century 2000, while
#[69,99] is in the century 1900
if year <= 68:
year += 2000
else:
year += 1900
elif group_key == 'Y':
year = int(found_dict['Y'])
elif group_key == 'm':
month = int(found_dict['m'])
elif group_key == 'B':
month = _insensitiveindex(locale_time.f_month, found_dict['B'])
elif group_key == 'b':
month = _insensitiveindex(locale_time.a_month, found_dict['b'])
elif group_key == 'd':
day = int(found_dict['d'])
elif group_key is 'H':
hour = int(found_dict['H'])
elif group_key == 'I':
hour = int(found_dict['I'])
ampm = found_dict.get('p', '').lower()
# If there was no AM/PM indicator, we'll treat this like AM
if ampm in ('', locale_time.am_pm[0].lower()):
# We're in AM so the hour is correct unless we're
# looking at 12 midnight.
# 12 midnight == 12 AM == hour 0
if hour == 12:
hour = 0
elif ampm == locale_time.am_pm[1].lower():
# We're in PM so we need to add 12 to the hour unless
# we're looking at 12 noon.
# 12 noon == 12 PM == hour 12
if hour != 12:
hour += 12
elif group_key == 'M':
minute = int(found_dict['M'])
elif group_key == 'S':
second = int(found_dict['S'])
elif group_key == 'A':
weekday = _insensitiveindex(locale_time.f_weekday,
found_dict['A'])
elif group_key == 'a':
weekday = _insensitiveindex(locale_time.a_weekday,
found_dict['a'])
elif group_key == 'w':
weekday = int(found_dict['w'])
if weekday == 0:
weekday = 6
else:
weekday -= 1
elif group_key == 'j':
julian = int(found_dict['j'])
elif group_key == 'Z':
found_zone = found_dict['Z'].lower()
if locale_time.timezone[0] == locale_time.timezone[1]:
pass #Deals with bad locale setup where timezone info is
# the same; first found on FreeBSD 4.4.
elif locale_time.timezone[0].lower() == found_zone:
tz = 0
elif locale_time.timezone[1].lower() == found_zone:
tz = 1
elif locale_time.timezone[2].lower() == found_zone:
tz = -1
# 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))
def _insensitiveindex(lst, findme):
# Perform a case-insensitive index search.
#XXX <bc>: If LocaleTime is not exposed, then consider removing this and
# just lowercase when LocaleTime sets its vars and lowercasing
# search values.
findme = findme.lower()
for key,item in enumerate(lst):
if item.lower() == findme:
return key
else:
raise ValueError("value not in list")
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