_strptime.py revision 2067bfdf253e134a4144d3747300dbfcc7cc6203
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 18from re import escape as re_escape 19from datetime import date as datetime_date 20try: 21 from _thread import allocate_lock as _thread_allocate_lock 22except: 23 from _dummy_thread import allocate_lock as _thread_allocate_lock 24 25__all__ = [] 26 27def _getlang(): 28 # Figure out what the current language is set to. 29 return locale.getlocale(locale.LC_TIME) 30 31class LocaleTime(object): 32 """Stores and handles locale-specific information related to time. 33 34 ATTRIBUTES: 35 f_weekday -- full weekday names (7-item list) 36 a_weekday -- abbreviated weekday names (7-item list) 37 f_month -- full month names (13-item list; dummy value in [0], which 38 is added by code) 39 a_month -- abbreviated month names (13-item list, dummy value in 40 [0], which is added by code) 41 am_pm -- AM/PM representation (2-item list) 42 LC_date_time -- format string for date/time representation (string) 43 LC_date -- format string for date representation (string) 44 LC_time -- format string for time representation (string) 45 timezone -- daylight- and non-daylight-savings timezone representation 46 (2-item list of sets) 47 lang -- Language used by instance (2-item tuple) 48 """ 49 50 def __init__(self): 51 """Set all attributes. 52 53 Order of methods called matters for dependency reasons. 54 55 The locale language is set at the offset and then checked again before 56 exiting. This is to make sure that the attributes were not set with a 57 mix of information from more than one locale. This would most likely 58 happen when using threads where one thread calls a locale-dependent 59 function while another thread changes the locale while the function in 60 the other thread is still running. Proper coding would call for 61 locks to prevent changing the locale while locale-dependent code is 62 running. The check here is done in case someone does not think about 63 doing this. 64 65 Only other possible issue is if someone changed the timezone and did 66 not call tz.tzset . That is an issue for the programmer, though, 67 since changing the timezone is worthless without that call. 68 69 """ 70 self.lang = _getlang() 71 self.__calc_weekday() 72 self.__calc_month() 73 self.__calc_am_pm() 74 self.__calc_timezone() 75 self.__calc_date_time() 76 if _getlang() != self.lang: 77 raise ValueError("locale changed during initialization") 78 79 def __pad(self, seq, front): 80 # Add '' to seq to either the front (is True), else the back. 81 seq = list(seq) 82 if front: 83 seq.insert(0, '') 84 else: 85 seq.append('') 86 return seq 87 88 def __calc_weekday(self): 89 # Set self.a_weekday and self.f_weekday using the calendar 90 # module. 91 a_weekday = [calendar.day_abbr[i].lower() for i in range(7)] 92 f_weekday = [calendar.day_name[i].lower() for i in range(7)] 93 self.a_weekday = a_weekday 94 self.f_weekday = f_weekday 95 96 def __calc_month(self): 97 # Set self.f_month and self.a_month using the calendar module. 98 a_month = [calendar.month_abbr[i].lower() for i in range(13)] 99 f_month = [calendar.month_name[i].lower() for i in range(13)] 100 self.a_month = a_month 101 self.f_month = f_month 102 103 def __calc_am_pm(self): 104 # Set self.am_pm by using time.strftime(). 105 106 # The magic date (1999,3,17,hour,44,55,2,76,0) is not really that 107 # magical; just happened to have used it everywhere else where a 108 # static date was needed. 109 am_pm = [] 110 for hour in (1, 22): 111 time_tuple = time.struct_time((1999,3,17,hour,44,55,2,76,0)) 112 am_pm.append(time.strftime("%p", time_tuple).lower()) 113 self.am_pm = am_pm 114 115 def __calc_date_time(self): 116 # Set self.date_time, self.date, & self.time by using 117 # time.strftime(). 118 119 # Use (1999,3,17,22,44,55,2,76,0) for magic date because the amount of 120 # overloaded numbers is minimized. The order in which searches for 121 # values within the format string is very important; it eliminates 122 # possible ambiguity for what something represents. 123 time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0)) 124 date_time = [None, None, None] 125 date_time[0] = time.strftime("%c", time_tuple).lower() 126 date_time[1] = time.strftime("%x", time_tuple).lower() 127 date_time[2] = time.strftime("%X", time_tuple).lower() 128 replacement_pairs = [('%', '%%'), (self.f_weekday[2], '%A'), 129 (self.f_month[3], '%B'), (self.a_weekday[2], '%a'), 130 (self.a_month[3], '%b'), (self.am_pm[1], '%p'), 131 ('1999', '%Y'), ('99', '%y'), ('22', '%H'), 132 ('44', '%M'), ('55', '%S'), ('76', '%j'), 133 ('17', '%d'), ('03', '%m'), ('3', '%m'), 134 # '3' needed for when no leading zero. 135 ('2', '%w'), ('10', '%I')] 136 replacement_pairs.extend([(tz, "%Z") for tz_values in self.timezone 137 for tz in tz_values]) 138 for offset,directive in ((0,'%c'), (1,'%x'), (2,'%X')): 139 current_format = date_time[offset] 140 for old, new in replacement_pairs: 141 # Must deal with possible lack of locale info 142 # manifesting itself as the empty string (e.g., Swedish's 143 # lack of AM/PM info) or a platform returning a tuple of empty 144 # strings (e.g., MacOS 9 having timezone as ('','')). 145 if old: 146 current_format = current_format.replace(old, new) 147 # If %W is used, then Sunday, 2005-01-03 will fall on week 0 since 148 # 2005-01-03 occurs before the first Monday of the year. Otherwise 149 # %U is used. 150 time_tuple = time.struct_time((1999,1,3,1,1,1,6,3,0)) 151 if '00' in time.strftime(directive, time_tuple): 152 U_W = '%W' 153 else: 154 U_W = '%U' 155 date_time[offset] = current_format.replace('11', U_W) 156 self.LC_date_time = date_time[0] 157 self.LC_date = date_time[1] 158 self.LC_time = date_time[2] 159 160 def __calc_timezone(self): 161 # Set self.timezone by using time.tzname. 162 # Do not worry about possibility of time.tzname[0] == timetzname[1] 163 # and time.daylight; handle that in strptime . 164 try: 165 time.tzset() 166 except AttributeError: 167 pass 168 no_saving = frozenset(["utc", "gmt", time.tzname[0].lower()]) 169 if time.daylight: 170 has_saving = frozenset([time.tzname[1].lower()]) 171 else: 172 has_saving = frozenset() 173 self.timezone = (no_saving, has_saving) 174 175 176class TimeRE(dict): 177 """Handle conversion from format directives to regexes.""" 178 179 def __init__(self, locale_time=None): 180 """Create keys/values. 181 182 Order of execution is important for dependency reasons. 183 184 """ 185 if locale_time: 186 self.locale_time = locale_time 187 else: 188 self.locale_time = LocaleTime() 189 base = super() 190 base.__init__({ 191 # The " \d" part of the regex is to make %c from ANSI C work 192 'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])", 193 'f': r"(?P<f>[0-9]{1,6})", 194 'H': r"(?P<H>2[0-3]|[0-1]\d|\d)", 195 'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])", 196 '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])", 197 'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])", 198 'M': r"(?P<M>[0-5]\d|\d)", 199 'S': r"(?P<S>6[0-1]|[0-5]\d|\d)", 200 'U': r"(?P<U>5[0-3]|[0-4]\d|\d)", 201 'w': r"(?P<w>[0-6])", 202 # W is set below by using 'U' 203 'y': r"(?P<y>\d\d)", 204 #XXX: Does 'Y' need to worry about having less or more than 205 # 4 digits? 206 'Y': r"(?P<Y>\d\d\d\d)", 207 'A': self.__seqToRE(self.locale_time.f_weekday, 'A'), 208 'a': self.__seqToRE(self.locale_time.a_weekday, 'a'), 209 'B': self.__seqToRE(self.locale_time.f_month[1:], 'B'), 210 'b': self.__seqToRE(self.locale_time.a_month[1:], 'b'), 211 'p': self.__seqToRE(self.locale_time.am_pm, 'p'), 212 'Z': self.__seqToRE((tz for tz_names in self.locale_time.timezone 213 for tz in tz_names), 214 'Z'), 215 '%': '%'}) 216 base.__setitem__('W', base.__getitem__('U').replace('U', 'W')) 217 base.__setitem__('c', self.pattern(self.locale_time.LC_date_time)) 218 base.__setitem__('x', self.pattern(self.locale_time.LC_date)) 219 base.__setitem__('X', self.pattern(self.locale_time.LC_time)) 220 221 def __seqToRE(self, to_convert, directive): 222 """Convert a list to a regex string for matching a directive. 223 224 Want possible matching values to be from longest to shortest. This 225 prevents the possibility of a match occuring for a value that also 226 a substring of a larger value that should have matched (e.g., 'abc' 227 matching when 'abcdef' should have been the match). 228 229 """ 230 to_convert = sorted(to_convert, key=len, reverse=True) 231 for value in to_convert: 232 if value != '': 233 break 234 else: 235 return '' 236 regex = '|'.join(re_escape(stuff) for stuff in to_convert) 237 regex = '(?P<%s>%s' % (directive, regex) 238 return '%s)' % regex 239 240 def pattern(self, format): 241 """Return regex pattern for the format string. 242 243 Need to make sure that any characters that might be interpreted as 244 regex syntax are escaped. 245 246 """ 247 processed_format = '' 248 # The sub() call escapes all characters that might be misconstrued 249 # as regex syntax. Cannot use re.escape since we have to deal with 250 # format directives (%m, etc.). 251 regex_chars = re_compile(r"([\\.^$*+?\(\){}\[\]|])") 252 format = regex_chars.sub(r"\\\1", format) 253 whitespace_replacement = re_compile('\s+') 254 format = whitespace_replacement.sub('\s+', format) 255 while '%' in format: 256 directive_index = format.index('%')+1 257 processed_format = "%s%s%s" % (processed_format, 258 format[:directive_index-1], 259 self[format[directive_index]]) 260 format = format[directive_index+1:] 261 return "%s%s" % (processed_format, format) 262 263 def compile(self, format): 264 """Return a compiled re object for the format string.""" 265 return re_compile(self.pattern(format), IGNORECASE) 266 267_cache_lock = _thread_allocate_lock() 268# DO NOT modify _TimeRE_cache or _regex_cache without acquiring the cache lock 269# first! 270_TimeRE_cache = TimeRE() 271_CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache 272_regex_cache = {} 273 274def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon): 275 """Calculate the Julian day based on the year, week of the year, and day of 276 the week, with week_start_day representing whether the week of the year 277 assumes the week starts on Sunday or Monday (6 or 0).""" 278 first_weekday = datetime_date(year, 1, 1).weekday() 279 # If we are dealing with the %U directive (week starts on Sunday), it's 280 # easier to just shift the view to Sunday being the first day of the 281 # week. 282 if not week_starts_Mon: 283 first_weekday = (first_weekday + 1) % 7 284 day_of_week = (day_of_week + 1) % 7 285 # Need to watch out for a week 0 (when the first day of the year is not 286 # the same as that specified by %U or %W). 287 week_0_length = (7 - first_weekday) % 7 288 if week_of_year == 0: 289 return 1 + day_of_week - first_weekday 290 else: 291 days_to_week = week_0_length + (7 * (week_of_year - 1)) 292 return 1 + days_to_week + day_of_week 293 294 295def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"): 296 """Return a time struct based on the input string and the format string.""" 297 global _TimeRE_cache, _regex_cache 298 with _cache_lock: 299 if _getlang() != _TimeRE_cache.locale_time.lang: 300 _TimeRE_cache = TimeRE() 301 _regex_cache.clear() 302 if len(_regex_cache) > _CACHE_MAX_SIZE: 303 _regex_cache.clear() 304 locale_time = _TimeRE_cache.locale_time 305 format_regex = _regex_cache.get(format) 306 if not format_regex: 307 try: 308 format_regex = _TimeRE_cache.compile(format) 309 # KeyError raised when a bad format is found; can be specified as 310 # \\, in which case it was a stray % but with a space after it 311 except KeyError as err: 312 bad_directive = err.args[0] 313 if bad_directive == "\\": 314 bad_directive = "%" 315 del err 316 raise ValueError("'%s' is a bad directive in format '%s'" % 317 (bad_directive, format)) 318 # IndexError only occurs when the format string is "%" 319 except IndexError: 320 raise ValueError("stray %% in format '%s'" % format) 321 _regex_cache[format] = format_regex 322 found = format_regex.match(data_string) 323 if not found: 324 raise ValueError("time data %r does not match format %r" % 325 (data_string, format)) 326 if len(data_string) != found.end(): 327 raise ValueError("unconverted data remains: %s" % 328 data_string[found.end():]) 329 year = 1900 330 month = day = 1 331 hour = minute = second = fraction = 0 332 tz = -1 333 # Default to -1 to signify that values not known; not critical to have, 334 # though 335 week_of_year = -1 336 week_of_year_start = -1 337 # weekday and julian defaulted to -1 so as to signal need to calculate 338 # values 339 weekday = julian = -1 340 found_dict = found.groupdict() 341 for group_key in found_dict.keys(): 342 # Directives not explicitly handled below: 343 # c, x, X 344 # handled by making out of other directives 345 # U, W 346 # worthless without day of the week 347 if group_key == 'y': 348 year = int(found_dict['y']) 349 # Open Group specification for strptime() states that a %y 350 #value in the range of [00, 68] is in the century 2000, while 351 #[69,99] is in the century 1900 352 if year <= 68: 353 year += 2000 354 else: 355 year += 1900 356 elif group_key == 'Y': 357 year = int(found_dict['Y']) 358 elif group_key == 'm': 359 month = int(found_dict['m']) 360 elif group_key == 'B': 361 month = locale_time.f_month.index(found_dict['B'].lower()) 362 elif group_key == 'b': 363 month = locale_time.a_month.index(found_dict['b'].lower()) 364 elif group_key == 'd': 365 day = int(found_dict['d']) 366 elif group_key == 'H': 367 hour = int(found_dict['H']) 368 elif group_key == 'I': 369 hour = int(found_dict['I']) 370 ampm = found_dict.get('p', '').lower() 371 # If there was no AM/PM indicator, we'll treat this like AM 372 if ampm in ('', locale_time.am_pm[0]): 373 # We're in AM so the hour is correct unless we're 374 # looking at 12 midnight. 375 # 12 midnight == 12 AM == hour 0 376 if hour == 12: 377 hour = 0 378 elif ampm == locale_time.am_pm[1]: 379 # We're in PM so we need to add 12 to the hour unless 380 # we're looking at 12 noon. 381 # 12 noon == 12 PM == hour 12 382 if hour != 12: 383 hour += 12 384 elif group_key == 'M': 385 minute = int(found_dict['M']) 386 elif group_key == 'S': 387 second = int(found_dict['S']) 388 elif group_key == 'f': 389 s = found_dict['f'] 390 # Pad to always return microseconds. 391 s += "0" * (6 - len(s)) 392 fraction = int(s) 393 elif group_key == 'A': 394 weekday = locale_time.f_weekday.index(found_dict['A'].lower()) 395 elif group_key == 'a': 396 weekday = locale_time.a_weekday.index(found_dict['a'].lower()) 397 elif group_key == 'w': 398 weekday = int(found_dict['w']) 399 if weekday == 0: 400 weekday = 6 401 else: 402 weekday -= 1 403 elif group_key == 'j': 404 julian = int(found_dict['j']) 405 elif group_key in ('U', 'W'): 406 week_of_year = int(found_dict[group_key]) 407 if group_key == 'U': 408 # U starts week on Sunday. 409 week_of_year_start = 6 410 else: 411 # W starts week on Monday. 412 week_of_year_start = 0 413 elif group_key == 'Z': 414 # Since -1 is default value only need to worry about setting tz if 415 # it can be something other than -1. 416 found_zone = found_dict['Z'].lower() 417 for value, tz_values in enumerate(locale_time.timezone): 418 if found_zone in tz_values: 419 # Deal with bad locale setup where timezone names are the 420 # same and yet time.daylight is true; too ambiguous to 421 # be able to tell what timezone has daylight savings 422 if (time.tzname[0] == time.tzname[1] and 423 time.daylight and found_zone not in ("utc", "gmt")): 424 break 425 else: 426 tz = value 427 break 428 # If we know the week of the year and what day of that week, we can figure 429 # out the Julian day of the year. 430 if julian == -1 and week_of_year != -1 and weekday != -1: 431 week_starts_Mon = True if week_of_year_start == 0 else False 432 julian = _calc_julian_from_U_or_W(year, week_of_year, weekday, 433 week_starts_Mon) 434 # Cannot pre-calculate datetime_date() since can change in Julian 435 # calculation and thus could have different value for the day of the week 436 # calculation. 437 if julian == -1: 438 # Need to add 1 to result since first day of the year is 1, not 0. 439 julian = datetime_date(year, month, day).toordinal() - \ 440 datetime_date(year, 1, 1).toordinal() + 1 441 else: # Assume that if they bothered to include Julian day it will 442 # be accurate. 443 datetime_result = datetime_date.fromordinal((julian - 1) + datetime_date(year, 1, 1).toordinal()) 444 year = datetime_result.year 445 month = datetime_result.month 446 day = datetime_result.day 447 if weekday == -1: 448 weekday = datetime_date(year, month, day).weekday() 449 return (time.struct_time((year, month, day, 450 hour, minute, second, 451 weekday, julian, tz)), fraction) 452 453def _strptime_time(data_string, format="%a %b %d %H:%M:%S %Y"): 454 return _strptime(data_string, format)[0] 455