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Diffstat (limited to 'dateutil/parser/isoparser.py')
| -rw-r--r-- | dateutil/parser/isoparser.py | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/dateutil/parser/isoparser.py b/dateutil/parser/isoparser.py new file mode 100644 index 0000000..1550c3a --- /dev/null +++ b/dateutil/parser/isoparser.py @@ -0,0 +1,383 @@ +# -*- coding: utf-8 -*- +""" +This module offers a parser for ISO-8601 strings + +It is intended to support all valid date, time and datetime formats per the +ISO-8601 specification. +""" +from datetime import datetime, timedelta, time, date +import calendar +from dateutil import tz + +from functools import wraps + +import re +import six + +__all__ = ["isoparse", "isoparser"] + + +def _takes_ascii(f): + @wraps(f) + def func(self, str_in, *args, **kwargs): + # If it's a stream, read the whole thing + str_in = getattr(str_in, 'read', lambda: str_in)() + + # If it's unicode, turn it into bytes, since ISO-8601 only covers ASCII + if isinstance(str_in, six.text_type): + # ASCII is the same in UTF-8 + try: + str_in = str_in.encode('ascii') + except UnicodeEncodeError as e: + msg = 'ISO-8601 strings should contain only ASCII characters' + six.raise_from(ValueError(msg), e) + + return f(self, str_in, *args, **kwargs) + + return func + + +class isoparser(object): + def __init__(self, sep='T'): + """ + :param sep: + A single character that separates date and time portions + """ + if (len(sep) != 1 or ord(sep) >= 128 or sep in '0123456789'): + raise ValueError('Separator must be a single, non-numeric ' + 'ASCII character') + + self._sep = sep.encode('ascii') + + @_takes_ascii + def isoparse(self, dt_str): + """ + Parse an ISO-8601 datetime string into a :class:`datetime.datetime`. + + An ISO-8601 datetime string consists of a date portion, followed + optionally by a time portion - the date and time portions are separated + by a single character separator, which is ``T`` in the official + standard. + + Supported date formats are: + + Common: + + - ``YYYY`` + - ``YYYY-MM`` or ``YYYYMM`` + - ``YYYY-MM-DD`` or ``YYYYMMDD`` + + Uncommon: + + - ``YYYY-Www`` or ``YYYYWww`` - ISO week (day defaults to 0) + - ``YYYY-Www-D`` or ``YYYYWwwD`` - ISO week and day + + The ISO week and day numbering follows the same logic as + :func:`datetime.date.isocalendar`. + + Supported time formats are: + + - ``hh`` + - ``hh:mm`` or ``hhmm`` + - ``hh:mm:ss`` or ``hhmmss`` + - ``hh:mm:ss.sss`` or ``hh:mm:ss.ssssss`` (3-6 sub-second digits) + + Midnight is a special case for `hh`, as the standard supports both + 00:00 and 24:00 as a representation. + + .. caution:: + + Support for fractional components other than seconds is part of the + ISO-8601 standard, but is not currently implemented in this parser. + + Supported time zone offset formats are: + + - `Z` (UTC) + - `±HH:MM` + - `±HHMM` + - `±HH` + + Offsets will be represented as :class:`dateutil.tz.tzoffset` objects, + with the exception of UTC, which will be represented as + :class:`dateutil.tz.tzutc`. Time zone offsets equivalent to UTC (such + as `+00:00`) will also be represented as :class:`dateutil.tz.tzutc`. + + :param dt_str: + A string or stream containing only an ISO-8601 datetime string + + :return: + Returns a :class:`datetime.datetime` representing the string. + Unspecified components default to their lowest value. + """ + components, pos = self._parse_isodate(dt_str) + + if len(dt_str) > pos: + if dt_str[pos:pos + 1] == self._sep: + components += self._parse_isotime(dt_str[pos + 1:]) + else: + raise ValueError('String contains unknown ISO components') + + return datetime(*components) + + @_takes_ascii + def parse_isodate(self, datestr): + """ + Parse the date portion of an ISO string. + + :param datestr: + The string portion of an ISO string, without a separator + + :return: + Returns a :class:`datetime.date` object + """ + components, pos = self._parse_isodate(datestr) + if pos < len(datestr): + raise ValueError('String contains unknown ISO ' + + 'components: {}'.format(datestr)) + return date(*components) + + @_takes_ascii + def parse_isotime(self, timestr): + """ + Parse the time portion of an ISO string. + + :param timestr: + The time portion of an ISO string, without a separator + + :return: + Returns a :class:`datetime.time` object + """ + return time(*self._parse_isotime(timestr)) + + @_takes_ascii + def parse_tzstr(self, tzstr, zero_as_utc=True): + """ + Parse a valid ISO time zone string. + + See :func:`isoparser.isoparse` for details on supported formats. + + :param tzstr: + A string representing an ISO time zone offset + + :param zero_as_utc: + Whether to return :class:`dateutil.tz.tzutc` for zero-offset zones + + :return: + Returns :class:`dateutil.tz.tzoffset` for offsets and + :class:`dateutil.tz.tzutc` for ``Z`` and (if ``zero_as_utc`` is + specified) offsets equivalent to UTC. + """ + return self._parse_tzstr(tzstr, zero_as_utc=zero_as_utc) + + # Constants + _MICROSECOND_END_REGEX = re.compile(b'[-+Z]+') + _DATE_SEP = b'-' + _TIME_SEP = b':' + _MICRO_SEP = b'.' + + def _parse_isodate(self, dt_str): + try: + return self._parse_isodate_common(dt_str) + except ValueError: + return self._parse_isodate_uncommon(dt_str) + + def _parse_isodate_common(self, dt_str): + len_str = len(dt_str) + components = [1, 1, 1] + + if len_str < 4: + raise ValueError('ISO string too short') + + # Year + components[0] = int(dt_str[0:4]) + pos = 4 + if pos >= len_str: + return components, pos + + has_sep = dt_str[pos:pos + 1] == self._DATE_SEP + if has_sep: + pos += 1 + + # Month + if len_str - pos < 2: + raise ValueError('Invalid common month') + + components[1] = int(dt_str[pos:pos + 2]) + pos += 2 + + if pos >= len_str: + return components, pos + + if has_sep: + if dt_str[pos:pos + 1] != self._DATE_SEP: + raise ValueError('Invalid separator in ISO string') + pos += 1 + + # Day + if len_str - pos < 2: + raise ValueError('Invalid common day') + components[2] = int(dt_str[pos:pos + 2]) + return components, pos + 2 + + def _parse_isodate_uncommon(self, dt_str): + if len(dt_str) < 4: + raise ValueError('ISO string too short') + + # All ISO formats start with the year + year = int(dt_str[0:4]) + + has_sep = dt_str[4:5] == self._DATE_SEP + + pos = 4 + has_sep # Skip '-' if it's there + if dt_str[pos:pos + 1] == b'W': + # YYYY-?Www-?D? + pos += 1 + weekno = int(dt_str[pos:pos + 2]) + pos += 2 + + dayno = 1 + if len(dt_str) > pos: + if (dt_str[pos:pos + 1] == self._DATE_SEP) != has_sep: + raise ValueError('Inconsistent use of dash separator') + + pos += has_sep + + dayno = int(dt_str[pos:pos + 1]) + pos += 1 + + base_date = self._calculate_weekdate(year, weekno, dayno) + else: + # YYYYDDD or YYYY-DDD + if len(dt_str) - pos < 3: + raise ValueError('Invalid ordinal day') + + ordinal_day = int(dt_str[pos:pos + 3]) + pos += 3 + + if ordinal_day < 1 or ordinal_day > (365 + calendar.isleap(year)): + raise ValueError('Invalid ordinal day' + + ' {} for year {}'.format(ordinal_day, year)) + + base_date = date(year, 1, 1) + timedelta(days=ordinal_day - 1) + + components = [base_date.year, base_date.month, base_date.day] + return components, pos + + def _calculate_weekdate(self, year, week, day): + """ + Calculate the day of corresponding to the ISO year-week-day calendar. + + This function is effectively the inverse of + :func:`datetime.date.isocalendar`. + + :param year: + The year in the ISO calendar + + :param week: + The week in the ISO calendar - range is [1, 53] + + :param day: + The day in the ISO calendar - range is [1 (MON), 7 (SUN)] + + :return: + Returns a :class:`datetime.date` + """ + if not 0 < week < 54: + raise ValueError('Invalid week: {}'.format(week)) + + if not 0 < day < 8: # Range is 1-7 + raise ValueError('Invalid weekday: {}'.format(day)) + + # Get week 1 for the specific year: + jan_4 = date(year, 1, 4) # Week 1 always has January 4th in it + week_1 = jan_4 - timedelta(days=jan_4.isocalendar()[2] - 1) + + # Now add the specific number of weeks and days to get what we want + week_offset = (week - 1) * 7 + (day - 1) + return week_1 + timedelta(days=week_offset) + + def _parse_isotime(self, timestr): + len_str = len(timestr) + components = [0, 0, 0, 0, None] + pos = 0 + comp = -1 + + if len(timestr) < 2: + raise ValueError('ISO time too short') + + has_sep = len_str >= 3 and timestr[2:3] == self._TIME_SEP + + while pos < len_str and comp < 5: + comp += 1 + + if timestr[pos:pos + 1] in b'-+Z': + # Detect time zone boundary + components[-1] = self._parse_tzstr(timestr[pos:]) + pos = len_str + break + + if comp < 3: + # Hour, minute, second + components[comp] = int(timestr[pos:pos + 2]) + pos += 2 + if (has_sep and pos < len_str and + timestr[pos:pos + 1] == self._TIME_SEP): + pos += 1 + + if comp == 3: + # Microsecond + if timestr[pos:pos + 1] != self._MICRO_SEP: + continue + + pos += 1 + us_str = self._MICROSECOND_END_REGEX.split(timestr[pos:pos + 6], + 1)[0] + + components[comp] = int(us_str) * 10**(6 - len(us_str)) + pos += len(us_str) + + if pos < len_str: + raise ValueError('Unused components in ISO string') + + if components[0] == 24: + # Standard supports 00:00 and 24:00 as representations of midnight + if any(component != 0 for component in components[1:4]): + raise ValueError('Hour may only be 24 at 24:00:00.000') + components[0] = 0 + + return components + + def _parse_tzstr(self, tzstr, zero_as_utc=True): + if tzstr == b'Z': + return tz.tzutc() + + if len(tzstr) not in {3, 5, 6}: + raise ValueError('Time zone offset must be 1, 3, 5 or 6 characters') + + if tzstr[0:1] == b'-': + mult = -1 + elif tzstr[0:1] == b'+': + mult = 1 + else: + raise ValueError('Time zone offset requires sign') + + hours = int(tzstr[1:3]) + if len(tzstr) == 3: + minutes = 0 + else: + minutes = int(tzstr[(4 if tzstr[3:4] == self._TIME_SEP else 3):]) + + if zero_as_utc and hours == 0 and minutes == 0: + return tz.tzutc() + else: + if minutes > 59: + raise ValueError('Invalid minutes in time zone offset') + + if hours > 23: + raise ValueError('Invalid hours in time zone offset') + + return tz.tzoffset(None, mult * (hours * 60 + minutes) * 60) + + +DEFAULT_ISOPARSER = isoparser() +isoparse = DEFAULT_ISOPARSER.isoparse |