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417 lines
13 KiB
Python
417 lines
13 KiB
Python
# -*- coding: utf-8 -*-
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"""
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This module offers a parser for ISO-8601 strings
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It is intended to support all valid date, time and datetime formats per the
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ISO-8601 specification.
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..versionadded:: 2.7.0
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"""
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from datetime import datetime, timedelta, time, date
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import calendar
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from dateutil import tz
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from functools import wraps
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import re
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import six
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__all__ = ["isoparse", "isoparser"]
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def _takes_ascii(f):
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@wraps(f)
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def func(self, str_in, *args, **kwargs):
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# If it's a stream, read the whole thing
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str_in = getattr(str_in, 'read', lambda: str_in)()
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# If it's unicode, turn it into bytes, since ISO-8601 only covers ASCII
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if isinstance(str_in, six.text_type):
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# ASCII is the same in UTF-8
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try:
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str_in = str_in.encode('ascii')
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except UnicodeEncodeError as e:
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msg = 'ISO-8601 strings should contain only ASCII characters'
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six.raise_from(ValueError(msg), e)
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return f(self, str_in, *args, **kwargs)
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return func
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class isoparser(object):
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def __init__(self, sep=None):
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"""
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:param sep:
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A single character that separates date and time portions. If
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``None``, the parser will accept any single character.
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For strict ISO-8601 adherence, pass ``'T'``.
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"""
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if sep is not None:
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if (len(sep) != 1 or ord(sep) >= 128 or sep in '0123456789'):
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raise ValueError('Separator must be a single, non-numeric ' +
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'ASCII character')
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sep = sep.encode('ascii')
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self._sep = sep
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@_takes_ascii
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def isoparse(self, dt_str):
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"""
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Parse an ISO-8601 datetime string into a :class:`datetime.datetime`.
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An ISO-8601 datetime string consists of a date portion, followed
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optionally by a time portion - the date and time portions are separated
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by a single character separator, which is ``T`` in the official
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standard. Incomplete date formats (such as ``YYYY-MM``) may *not* be
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combined with a time portion.
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Supported date formats are:
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Common:
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- ``YYYY``
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- ``YYYY-MM``
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- ``YYYY-MM-DD`` or ``YYYYMMDD``
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Uncommon:
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- ``YYYY-Www`` or ``YYYYWww`` - ISO week (day defaults to 0)
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- ``YYYY-Www-D`` or ``YYYYWwwD`` - ISO week and day
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The ISO week and day numbering follows the same logic as
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:func:`datetime.date.isocalendar`.
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Supported time formats are:
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- ``hh``
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- ``hh:mm`` or ``hhmm``
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- ``hh:mm:ss`` or ``hhmmss``
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- ``hh:mm:ss.ssssss`` (Up to 6 sub-second digits)
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Midnight is a special case for `hh`, as the standard supports both
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00:00 and 24:00 as a representation. The decimal separator can be
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either a dot or a comma.
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.. caution::
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Support for fractional components other than seconds is part of the
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ISO-8601 standard, but is not currently implemented in this parser.
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Supported time zone offset formats are:
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- `Z` (UTC)
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- `±HH:MM`
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- `±HHMM`
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- `±HH`
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Offsets will be represented as :class:`dateutil.tz.tzoffset` objects,
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with the exception of UTC, which will be represented as
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:class:`dateutil.tz.tzutc`. Time zone offsets equivalent to UTC (such
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as `+00:00`) will also be represented as :class:`dateutil.tz.tzutc`.
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:param dt_str:
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A string or stream containing only an ISO-8601 datetime string
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:return:
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Returns a :class:`datetime.datetime` representing the string.
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Unspecified components default to their lowest value.
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.. warning::
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As of version 2.7.0, the strictness of the parser should not be
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considered a stable part of the contract. Any valid ISO-8601 string
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that parses correctly with the default settings will continue to
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parse correctly in future versions, but invalid strings that
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currently fail (e.g. ``2017-01-01T00:00+00:00:00``) are not
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guaranteed to continue failing in future versions if they encode
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a valid date.
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.. versionadded:: 2.7.0
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"""
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components, pos = self._parse_isodate(dt_str)
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if len(dt_str) > pos:
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if self._sep is None or dt_str[pos:pos + 1] == self._sep:
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components += self._parse_isotime(dt_str[pos + 1:])
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else:
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raise ValueError('String contains unknown ISO components')
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if len(components) > 3 and components[3] == 24:
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components[3] = 0
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return datetime(*components) + timedelta(days=1)
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return datetime(*components)
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@_takes_ascii
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def parse_isodate(self, datestr):
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"""
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Parse the date portion of an ISO string.
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:param datestr:
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The string portion of an ISO string, without a separator
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:return:
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Returns a :class:`datetime.date` object
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"""
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components, pos = self._parse_isodate(datestr)
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if pos < len(datestr):
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raise ValueError('String contains unknown ISO ' +
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'components: {!r}'.format(datestr.decode('ascii')))
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return date(*components)
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@_takes_ascii
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def parse_isotime(self, timestr):
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"""
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Parse the time portion of an ISO string.
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:param timestr:
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The time portion of an ISO string, without a separator
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:return:
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Returns a :class:`datetime.time` object
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"""
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components = self._parse_isotime(timestr)
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if components[0] == 24:
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components[0] = 0
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return time(*components)
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@_takes_ascii
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def parse_tzstr(self, tzstr, zero_as_utc=True):
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"""
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Parse a valid ISO time zone string.
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See :func:`isoparser.isoparse` for details on supported formats.
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:param tzstr:
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A string representing an ISO time zone offset
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:param zero_as_utc:
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Whether to return :class:`dateutil.tz.tzutc` for zero-offset zones
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:return:
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Returns :class:`dateutil.tz.tzoffset` for offsets and
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:class:`dateutil.tz.tzutc` for ``Z`` and (if ``zero_as_utc`` is
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specified) offsets equivalent to UTC.
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"""
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return self._parse_tzstr(tzstr, zero_as_utc=zero_as_utc)
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# Constants
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_DATE_SEP = b'-'
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_TIME_SEP = b':'
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_FRACTION_REGEX = re.compile(b'[\\.,]([0-9]+)')
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def _parse_isodate(self, dt_str):
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try:
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return self._parse_isodate_common(dt_str)
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except ValueError:
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return self._parse_isodate_uncommon(dt_str)
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def _parse_isodate_common(self, dt_str):
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len_str = len(dt_str)
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components = [1, 1, 1]
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if len_str < 4:
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raise ValueError('ISO string too short')
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# Year
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components[0] = int(dt_str[0:4])
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pos = 4
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if pos >= len_str:
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return components, pos
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has_sep = dt_str[pos:pos + 1] == self._DATE_SEP
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if has_sep:
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pos += 1
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# Month
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if len_str - pos < 2:
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raise ValueError('Invalid common month')
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components[1] = int(dt_str[pos:pos + 2])
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pos += 2
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if pos >= len_str:
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if has_sep:
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return components, pos
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else:
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raise ValueError('Invalid ISO format')
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if has_sep:
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if dt_str[pos:pos + 1] != self._DATE_SEP:
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raise ValueError('Invalid separator in ISO string')
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pos += 1
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# Day
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if len_str - pos < 2:
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raise ValueError('Invalid common day')
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components[2] = int(dt_str[pos:pos + 2])
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return components, pos + 2
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def _parse_isodate_uncommon(self, dt_str):
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if len(dt_str) < 4:
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raise ValueError('ISO string too short')
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# All ISO formats start with the year
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year = int(dt_str[0:4])
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has_sep = dt_str[4:5] == self._DATE_SEP
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pos = 4 + has_sep # Skip '-' if it's there
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if dt_str[pos:pos + 1] == b'W':
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# YYYY-?Www-?D?
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pos += 1
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weekno = int(dt_str[pos:pos + 2])
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pos += 2
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dayno = 1
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if len(dt_str) > pos:
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if (dt_str[pos:pos + 1] == self._DATE_SEP) != has_sep:
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raise ValueError('Inconsistent use of dash separator')
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pos += has_sep
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dayno = int(dt_str[pos:pos + 1])
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pos += 1
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base_date = self._calculate_weekdate(year, weekno, dayno)
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else:
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# YYYYDDD or YYYY-DDD
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if len(dt_str) - pos < 3:
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raise ValueError('Invalid ordinal day')
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ordinal_day = int(dt_str[pos:pos + 3])
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pos += 3
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if ordinal_day < 1 or ordinal_day > (365 + calendar.isleap(year)):
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raise ValueError('Invalid ordinal day' +
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' {} for year {}'.format(ordinal_day, year))
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base_date = date(year, 1, 1) + timedelta(days=ordinal_day - 1)
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components = [base_date.year, base_date.month, base_date.day]
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return components, pos
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def _calculate_weekdate(self, year, week, day):
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"""
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Calculate the day of corresponding to the ISO year-week-day calendar.
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This function is effectively the inverse of
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:func:`datetime.date.isocalendar`.
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:param year:
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The year in the ISO calendar
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:param week:
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The week in the ISO calendar - range is [1, 53]
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:param day:
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The day in the ISO calendar - range is [1 (MON), 7 (SUN)]
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:return:
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Returns a :class:`datetime.date`
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"""
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if not 0 < week < 54:
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raise ValueError('Invalid week: {}'.format(week))
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if not 0 < day < 8: # Range is 1-7
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raise ValueError('Invalid weekday: {}'.format(day))
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# Get week 1 for the specific year:
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jan_4 = date(year, 1, 4) # Week 1 always has January 4th in it
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week_1 = jan_4 - timedelta(days=jan_4.isocalendar()[2] - 1)
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# Now add the specific number of weeks and days to get what we want
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week_offset = (week - 1) * 7 + (day - 1)
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return week_1 + timedelta(days=week_offset)
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def _parse_isotime(self, timestr):
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len_str = len(timestr)
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components = [0, 0, 0, 0, None]
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pos = 0
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comp = -1
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if len_str < 2:
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raise ValueError('ISO time too short')
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has_sep = False
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while pos < len_str and comp < 5:
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comp += 1
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if timestr[pos:pos + 1] in b'-+Zz':
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# Detect time zone boundary
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components[-1] = self._parse_tzstr(timestr[pos:])
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pos = len_str
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break
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if comp == 1 and timestr[pos:pos+1] == self._TIME_SEP:
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has_sep = True
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pos += 1
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elif comp == 2 and has_sep:
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if timestr[pos:pos+1] != self._TIME_SEP:
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raise ValueError('Inconsistent use of colon separator')
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pos += 1
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if comp < 3:
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# Hour, minute, second
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components[comp] = int(timestr[pos:pos + 2])
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pos += 2
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if comp == 3:
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# Fraction of a second
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frac = self._FRACTION_REGEX.match(timestr[pos:])
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if not frac:
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continue
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us_str = frac.group(1)[:6] # Truncate to microseconds
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components[comp] = int(us_str) * 10**(6 - len(us_str))
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pos += len(frac.group())
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if pos < len_str:
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raise ValueError('Unused components in ISO string')
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if components[0] == 24:
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# Standard supports 00:00 and 24:00 as representations of midnight
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if any(component != 0 for component in components[1:4]):
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raise ValueError('Hour may only be 24 at 24:00:00.000')
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return components
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def _parse_tzstr(self, tzstr, zero_as_utc=True):
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if tzstr == b'Z' or tzstr == b'z':
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return tz.UTC
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if len(tzstr) not in {3, 5, 6}:
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raise ValueError('Time zone offset must be 1, 3, 5 or 6 characters')
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if tzstr[0:1] == b'-':
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mult = -1
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elif tzstr[0:1] == b'+':
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mult = 1
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else:
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raise ValueError('Time zone offset requires sign')
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hours = int(tzstr[1:3])
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if len(tzstr) == 3:
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minutes = 0
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else:
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minutes = int(tzstr[(4 if tzstr[3:4] == self._TIME_SEP else 3):])
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if zero_as_utc and hours == 0 and minutes == 0:
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return tz.UTC
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else:
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if minutes > 59:
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raise ValueError('Invalid minutes in time zone offset')
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if hours > 23:
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raise ValueError('Invalid hours in time zone offset')
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return tz.tzoffset(None, mult * (hours * 60 + minutes) * 60)
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DEFAULT_ISOPARSER = isoparser()
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isoparse = DEFAULT_ISOPARSER.isoparse
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