_strptime.py revision f568218e7e6211fa93d390eb327379776962867e
1"""Strptime-related classes and functions. 2 3CLASSES: 4 LocaleTime -- Discovers and stores locale-specific time information 5 TimeRE -- Creates regexes for pattern matching a string of text containing 6 time information 7 8FUNCTIONS: 9 _getlang -- Figure out what language is being used for the locale 10 strptime -- Calculates the time struct represented by the passed-in string 11 12""" 13import time 14import locale 15import calendar 16from re import compile as re_compile 17from re import IGNORECASE, ASCII 18from re import escape as re_escape 19from datetime import (date as datetime_date, 20 timedelta as datetime_timedelta, 21 timezone as datetime_timezone) 22try: 23 from _thread import allocate_lock as _thread_allocate_lock 24except: 25 from _dummy_thread import allocate_lock as _thread_allocate_lock 26 27__all__ = [] 28 29def _getlang(): 30 # Figure out what the current language is set to. 31 return locale.getlocale(locale.LC_TIME) 32 33class LocaleTime(object): 34 """Stores and handles locale-specific information related to time. 35 36 ATTRIBUTES: 37 f_weekday -- full weekday names (7-item list) 38 a_weekday -- abbreviated weekday names (7-item list) 39 f_month -- full month names (13-item list; dummy value in [0], which 40 is added by code) 41 a_month -- abbreviated month names (13-item list, dummy value in 42 [0], which is added by code) 43 am_pm -- AM/PM representation (2-item list) 44 LC_date_time -- format string for date/time representation (string) 45 LC_date -- format string for date representation (string) 46 LC_time -- format string for time representation (string) 47 timezone -- daylight- and non-daylight-savings timezone representation 48 (2-item list of sets) 49 lang -- Language used by instance (2-item tuple) 50 """ 51 52 def __init__(self): 53 """Set all attributes. 54 55 Order of methods called matters for dependency reasons. 56 57 The locale language is set at the offset and then checked again before 58 exiting. This is to make sure that the attributes were not set with a 59 mix of information from more than one locale. This would most likely 60 happen when using threads where one thread calls a locale-dependent 61 function while another thread changes the locale while the function in 62 the other thread is still running. Proper coding would call for 63 locks to prevent changing the locale while locale-dependent code is 64 running. The check here is done in case someone does not think about 65 doing this. 66 67 Only other possible issue is if someone changed the timezone and did 68 not call tz.tzset . That is an issue for the programmer, though, 69 since changing the timezone is worthless without that call. 70 71 """ 72 self.lang = _getlang() 73 self.__calc_weekday() 74 self.__calc_month() 75 self.__calc_am_pm() 76 self.__calc_timezone() 77 self.__calc_date_time() 78 if _getlang() != self.lang: 79 raise ValueError("locale changed during initialization") 80 81 def __pad(self, seq, front): 82 # Add '' to seq to either the front (is True), else the back. 83 seq = list(seq) 84 if front: 85 seq.insert(0, '') 86 else: 87 seq.append('') 88 return seq 89 90 def __calc_weekday(self): 91 # Set self.a_weekday and self.f_weekday using the calendar 92 # module. 93 a_weekday = [calendar.day_abbr[i].lower() for i in range(7)] 94 f_weekday = [calendar.day_name[i].lower() for i in range(7)] 95 self.a_weekday = a_weekday 96 self.f_weekday = f_weekday 97 98 def __calc_month(self): 99 # Set self.f_month and self.a_month using the calendar module. 100 a_month = [calendar.month_abbr[i].lower() for i in range(13)] 101 f_month = [calendar.month_name[i].lower() for i in range(13)] 102 self.a_month = a_month 103 self.f_month = f_month 104 105 def __calc_am_pm(self): 106 # Set self.am_pm by using time.strftime(). 107 108 # The magic date (1999,3,17,hour,44,55,2,76,0) is not really that 109 # magical; just happened to have used it everywhere else where a 110 # static date was needed. 111 am_pm = [] 112 for hour in (1, 22): 113 time_tuple = time.struct_time((1999,3,17,hour,44,55,2,76,0)) 114 am_pm.append(time.strftime("%p", time_tuple).lower()) 115 self.am_pm = am_pm 116 117 def __calc_date_time(self): 118 # Set self.date_time, self.date, & self.time by using 119 # time.strftime(). 120 121 # Use (1999,3,17,22,44,55,2,76,0) for magic date because the amount of 122 # overloaded numbers is minimized. The order in which searches for 123 # values within the format string is very important; it eliminates 124 # possible ambiguity for what something represents. 125 time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0)) 126 date_time = [None, None, None] 127 date_time[0] = time.strftime("%c", time_tuple).lower() 128 date_time[1] = time.strftime("%x", time_tuple).lower() 129 date_time[2] = time.strftime("%X", time_tuple).lower() 130 replacement_pairs = [('%', '%%'), (self.f_weekday[2], '%A'), 131 (self.f_month[3], '%B'), (self.a_weekday[2], '%a'), 132 (self.a_month[3], '%b'), (self.am_pm[1], '%p'), 133 ('1999', '%Y'), ('99', '%y'), ('22', '%H'), 134 ('44', '%M'), ('55', '%S'), ('76', '%j'), 135 ('17', '%d'), ('03', '%m'), ('3', '%m'), 136 # '3' needed for when no leading zero. 137 ('2', '%w'), ('10', '%I')] 138 replacement_pairs.extend([(tz, "%Z") for tz_values in self.timezone 139 for tz in tz_values]) 140 for offset,directive in ((0,'%c'), (1,'%x'), (2,'%X')): 141 current_format = date_time[offset] 142 for old, new in replacement_pairs: 143 # Must deal with possible lack of locale info 144 # manifesting itself as the empty string (e.g., Swedish's 145 # lack of AM/PM info) or a platform returning a tuple of empty 146 # strings (e.g., MacOS 9 having timezone as ('','')). 147 if old: 148 current_format = current_format.replace(old, new) 149 # If %W is used, then Sunday, 2005-01-03 will fall on week 0 since 150 # 2005-01-03 occurs before the first Monday of the year. Otherwise 151 # %U is used. 152 time_tuple = time.struct_time((1999,1,3,1,1,1,6,3,0)) 153 if '00' in time.strftime(directive, time_tuple): 154 U_W = '%W' 155 else: 156 U_W = '%U' 157 date_time[offset] = current_format.replace('11', U_W) 158 self.LC_date_time = date_time[0] 159 self.LC_date = date_time[1] 160 self.LC_time = date_time[2] 161 162 def __calc_timezone(self): 163 # Set self.timezone by using time.tzname. 164 # Do not worry about possibility of time.tzname[0] == timetzname[1] 165 # and time.daylight; handle that in strptime . 166 try: 167 time.tzset() 168 except AttributeError: 169 pass 170 no_saving = frozenset(["utc", "gmt", time.tzname[0].lower()]) 171 if time.daylight: 172 has_saving = frozenset([time.tzname[1].lower()]) 173 else: 174 has_saving = frozenset() 175 self.timezone = (no_saving, has_saving) 176 177 178class TimeRE(dict): 179 """Handle conversion from format directives to regexes.""" 180 181 def __init__(self, locale_time=None): 182 """Create keys/values. 183 184 Order of execution is important for dependency reasons. 185 186 """ 187 if locale_time: 188 self.locale_time = locale_time 189 else: 190 self.locale_time = LocaleTime() 191 base = super() 192 base.__init__({ 193 # The " \d" part of the regex is to make %c from ANSI C work 194 'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])", 195 'f': r"(?P<f>[0-9]{1,6})", 196 'H': r"(?P<H>2[0-3]|[0-1]\d|\d)", 197 'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])", 198 '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])", 199 'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])", 200 'M': r"(?P<M>[0-5]\d|\d)", 201 'S': r"(?P<S>6[0-1]|[0-5]\d|\d)", 202 'U': r"(?P<U>5[0-3]|[0-4]\d|\d)", 203 'w': r"(?P<w>[0-6])", 204 # W is set below by using 'U' 205 'y': r"(?P<y>\d\d)", 206 #XXX: Does 'Y' need to worry about having less or more than 207 # 4 digits? 208 'Y': r"(?P<Y>\d\d\d\d)", 209 'z': r"(?P<z>[+-]\d\d[0-5]\d)", 210 'A': self.__seqToRE(self.locale_time.f_weekday, 'A'), 211 'a': self.__seqToRE(self.locale_time.a_weekday, 'a'), 212 'B': self.__seqToRE(self.locale_time.f_month[1:], 'B'), 213 'b': self.__seqToRE(self.locale_time.a_month[1:], 'b'), 214 'p': self.__seqToRE(self.locale_time.am_pm, 'p'), 215 'Z': self.__seqToRE((tz for tz_names in self.locale_time.timezone 216 for tz in tz_names), 217 'Z'), 218 '%': '%'}) 219 base.__setitem__('W', base.__getitem__('U').replace('U', 'W')) 220 base.__setitem__('c', self.pattern(self.locale_time.LC_date_time)) 221 base.__setitem__('x', self.pattern(self.locale_time.LC_date)) 222 base.__setitem__('X', self.pattern(self.locale_time.LC_time)) 223 224 def __seqToRE(self, to_convert, directive): 225 """Convert a list to a regex string for matching a directive. 226 227 Want possible matching values to be from longest to shortest. This 228 prevents the possibility of a match occuring for a value that also 229 a substring of a larger value that should have matched (e.g., 'abc' 230 matching when 'abcdef' should have been the match). 231 232 """ 233 to_convert = sorted(to_convert, key=len, reverse=True) 234 for value in to_convert: 235 if value != '': 236 break 237 else: 238 return '' 239 regex = '|'.join(re_escape(stuff) for stuff in to_convert) 240 regex = '(?P<%s>%s' % (directive, regex) 241 return '%s)' % regex 242 243 def pattern(self, format): 244 """Return regex pattern for the format string. 245 246 Need to make sure that any characters that might be interpreted as 247 regex syntax are escaped. 248 249 """ 250 processed_format = '' 251 # The sub() call escapes all characters that might be misconstrued 252 # as regex syntax. Cannot use re.escape since we have to deal with 253 # format directives (%m, etc.). 254 regex_chars = re_compile(r"([\\.^$*+?\(\){}\[\]|])") 255 format = regex_chars.sub(r"\\\1", format) 256 whitespace_replacement = re_compile('\s+') 257 format = whitespace_replacement.sub('\s+', format) 258 while '%' in format: 259 directive_index = format.index('%')+1 260 processed_format = "%s%s%s" % (processed_format, 261 format[:directive_index-1], 262 self[format[directive_index]]) 263 format = format[directive_index+1:] 264 return "%s%s" % (processed_format, format) 265 266 def compile(self, format): 267 """Return a compiled re object for the format string.""" 268 return re_compile(self.pattern(format), IGNORECASE) 269 270_cache_lock = _thread_allocate_lock() 271# DO NOT modify _TimeRE_cache or _regex_cache without acquiring the cache lock 272# first! 273_TimeRE_cache = TimeRE() 274_CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache 275_regex_cache = {} 276 277def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon): 278 """Calculate the Julian day based on the year, week of the year, and day of 279 the week, with week_start_day representing whether the week of the year 280 assumes the week starts on Sunday or Monday (6 or 0).""" 281 first_weekday = datetime_date(year, 1, 1).weekday() 282 # If we are dealing with the %U directive (week starts on Sunday), it's 283 # easier to just shift the view to Sunday being the first day of the 284 # week. 285 if not week_starts_Mon: 286 first_weekday = (first_weekday + 1) % 7 287 day_of_week = (day_of_week + 1) % 7 288 # Need to watch out for a week 0 (when the first day of the year is not 289 # the same as that specified by %U or %W). 290 week_0_length = (7 - first_weekday) % 7 291 if week_of_year == 0: 292 return 1 + day_of_week - first_weekday 293 else: 294 days_to_week = week_0_length + (7 * (week_of_year - 1)) 295 return 1 + days_to_week + day_of_week 296 297 298def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"): 299 """Return a 2-tuple consisting of a time struct and an int containing 300 the number of microseconds based on the input string and the 301 format string.""" 302 303 for index, arg in enumerate([data_string, format]): 304 if not isinstance(arg, str): 305 msg = "strptime() argument {} must be str, not {}" 306 raise TypeError(msg.format(index, type(arg))) 307 308 global _TimeRE_cache, _regex_cache 309 with _cache_lock: 310 311 if _getlang() != _TimeRE_cache.locale_time.lang: 312 _TimeRE_cache = TimeRE() 313 _regex_cache.clear() 314 if len(_regex_cache) > _CACHE_MAX_SIZE: 315 _regex_cache.clear() 316 locale_time = _TimeRE_cache.locale_time 317 format_regex = _regex_cache.get(format) 318 if not format_regex: 319 try: 320 format_regex = _TimeRE_cache.compile(format) 321 # KeyError raised when a bad format is found; can be specified as 322 # \\, in which case it was a stray % but with a space after it 323 except KeyError as err: 324 bad_directive = err.args[0] 325 if bad_directive == "\\": 326 bad_directive = "%" 327 del err 328 raise ValueError("'%s' is a bad directive in format '%s'" % 329 (bad_directive, format)) 330 # IndexError only occurs when the format string is "%" 331 except IndexError: 332 raise ValueError("stray %% in format '%s'" % format) 333 _regex_cache[format] = format_regex 334 found = format_regex.match(data_string) 335 if not found: 336 raise ValueError("time data %r does not match format %r" % 337 (data_string, format)) 338 if len(data_string) != found.end(): 339 raise ValueError("unconverted data remains: %s" % 340 data_string[found.end():]) 341 342 year = 1900 343 month = day = 1 344 hour = minute = second = fraction = 0 345 tz = -1 346 tzoffset = None 347 # Default to -1 to signify that values not known; not critical to have, 348 # though 349 week_of_year = -1 350 week_of_year_start = -1 351 # weekday and julian defaulted to -1 so as to signal need to calculate 352 # values 353 weekday = julian = -1 354 found_dict = found.groupdict() 355 for group_key in found_dict.keys(): 356 # Directives not explicitly handled below: 357 # c, x, X 358 # handled by making out of other directives 359 # U, W 360 # worthless without day of the week 361 if group_key == 'y': 362 year = int(found_dict['y']) 363 # Open Group specification for strptime() states that a %y 364 #value in the range of [00, 68] is in the century 2000, while 365 #[69,99] is in the century 1900 366 if year <= 68: 367 year += 2000 368 else: 369 year += 1900 370 elif group_key == 'Y': 371 year = int(found_dict['Y']) 372 elif group_key == 'm': 373 month = int(found_dict['m']) 374 elif group_key == 'B': 375 month = locale_time.f_month.index(found_dict['B'].lower()) 376 elif group_key == 'b': 377 month = locale_time.a_month.index(found_dict['b'].lower()) 378 elif group_key == 'd': 379 day = int(found_dict['d']) 380 elif group_key == 'H': 381 hour = int(found_dict['H']) 382 elif group_key == 'I': 383 hour = int(found_dict['I']) 384 ampm = found_dict.get('p', '').lower() 385 # If there was no AM/PM indicator, we'll treat this like AM 386 if ampm in ('', locale_time.am_pm[0]): 387 # We're in AM so the hour is correct unless we're 388 # looking at 12 midnight. 389 # 12 midnight == 12 AM == hour 0 390 if hour == 12: 391 hour = 0 392 elif ampm == locale_time.am_pm[1]: 393 # We're in PM so we need to add 12 to the hour unless 394 # we're looking at 12 noon. 395 # 12 noon == 12 PM == hour 12 396 if hour != 12: 397 hour += 12 398 elif group_key == 'M': 399 minute = int(found_dict['M']) 400 elif group_key == 'S': 401 second = int(found_dict['S']) 402 elif group_key == 'f': 403 s = found_dict['f'] 404 # Pad to always return microseconds. 405 s += "0" * (6 - len(s)) 406 fraction = int(s) 407 elif group_key == 'A': 408 weekday = locale_time.f_weekday.index(found_dict['A'].lower()) 409 elif group_key == 'a': 410 weekday = locale_time.a_weekday.index(found_dict['a'].lower()) 411 elif group_key == 'w': 412 weekday = int(found_dict['w']) 413 if weekday == 0: 414 weekday = 6 415 else: 416 weekday -= 1 417 elif group_key == 'j': 418 julian = int(found_dict['j']) 419 elif group_key in ('U', 'W'): 420 week_of_year = int(found_dict[group_key]) 421 if group_key == 'U': 422 # U starts week on Sunday. 423 week_of_year_start = 6 424 else: 425 # W starts week on Monday. 426 week_of_year_start = 0 427 elif group_key == 'z': 428 z = found_dict['z'] 429 tzoffset = int(z[1:3]) * 60 + int(z[3:5]) 430 if z.startswith("-"): 431 tzoffset = -tzoffset 432 elif group_key == 'Z': 433 # Since -1 is default value only need to worry about setting tz if 434 # it can be something other than -1. 435 found_zone = found_dict['Z'].lower() 436 for value, tz_values in enumerate(locale_time.timezone): 437 if found_zone in tz_values: 438 # Deal with bad locale setup where timezone names are the 439 # same and yet time.daylight is true; too ambiguous to 440 # be able to tell what timezone has daylight savings 441 if (time.tzname[0] == time.tzname[1] and 442 time.daylight and found_zone not in ("utc", "gmt")): 443 break 444 else: 445 tz = value 446 break 447 # If we know the week of the year and what day of that week, we can figure 448 # out the Julian day of the year. 449 if julian == -1 and week_of_year != -1 and weekday != -1: 450 week_starts_Mon = True if week_of_year_start == 0 else False 451 julian = _calc_julian_from_U_or_W(year, week_of_year, weekday, 452 week_starts_Mon) 453 # Cannot pre-calculate datetime_date() since can change in Julian 454 # calculation and thus could have different value for the day of the week 455 # calculation. 456 if julian == -1: 457 # Need to add 1 to result since first day of the year is 1, not 0. 458 julian = datetime_date(year, month, day).toordinal() - \ 459 datetime_date(year, 1, 1).toordinal() + 1 460 else: # Assume that if they bothered to include Julian day it will 461 # be accurate. 462 datetime_result = datetime_date.fromordinal((julian - 1) + datetime_date(year, 1, 1).toordinal()) 463 year = datetime_result.year 464 month = datetime_result.month 465 day = datetime_result.day 466 if weekday == -1: 467 weekday = datetime_date(year, month, day).weekday() 468 # Add timezone info 469 tzname = found_dict.get("Z") 470 if tzoffset is not None: 471 gmtoff = tzoffset * 60 472 else: 473 gmtoff = None 474 475 return (year, month, day, 476 hour, minute, second, 477 weekday, julian, tz, gmtoff, tzname), fraction 478 479def _strptime_time(data_string, format="%a %b %d %H:%M:%S %Y"): 480 """Return a time struct based on the input string and the 481 format string.""" 482 tt = _strptime(data_string, format)[0] 483 return time.struct_time(tt[:9]) 484 485def _strptime_datetime(class_, data_string, format="%a %b %d %H:%M:%S %Y"): 486 """Return a class_ instance based on the input string and the 487 format string.""" 488 tt, fraction = _strptime(data_string, format) 489 gmtoff, tzname = tt[-2:] 490 args = tt[:6] + (fraction,) 491 if gmtoff is not None: 492 tzdelta = datetime_timedelta(seconds=gmtoff) 493 if tzname: 494 tz = datetime_timezone(tzdelta, tzname) 495 else: 496 tz = datetime_timezone(tzdelta) 497 args += (tz,) 498 499 return class_(*args) 500