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103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
"""ISO 8601 date time string parsing
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Basic usage:
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>>> import iso8601
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>>> iso8601.parse_date("2007-01-25T12:00:00Z")
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datetime.datetime(2007, 1, 25, 12, 0, tzinfo=<iso8601.iso8601.Utc ...>)
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>>>
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"""
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from datetime import datetime, timedelta, tzinfo
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import re
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__all__ = ["parse_date", "ParseError"]
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# Adapted from http://delete.me.uk/2005/03/iso8601.html
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ISO8601_REGEX = re.compile(r"(?P<year>[0-9]{4})(-(?P<month>[0-9]{1,2})(-(?P<day>[0-9]{1,2})"
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r"((?P<separator>.)(?P<hour>[0-9]{2}):(?P<minute>[0-9]{2})(:(?P<second>[0-9]{2})(\.(?P<fraction>[0-9]+))?)?"
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r"(?P<timezone>Z|(([-+])([0-9]{2}):([0-9]{2})))?)?)?)?"
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)
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TIMEZONE_REGEX = re.compile("(?P<prefix>[+-])(?P<hours>[0-9]{2}).(?P<minutes>[0-9]{2})")
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class ParseError(Exception):
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"""Raised when there is a problem parsing a date string"""
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# Yoinked from python docs
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ZERO = timedelta(0)
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class Utc(tzinfo):
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"""UTC
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"""
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def utcoffset(self, dt):
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return ZERO
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def tzname(self, dt):
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return "UTC"
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def dst(self, dt):
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return ZERO
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UTC = Utc()
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class FixedOffset(tzinfo):
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"""Fixed offset in hours and minutes from UTC
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"""
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def __init__(self, offset_hours, offset_minutes, name):
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self.__offset = timedelta(hours=offset_hours, minutes=offset_minutes)
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self.__name = name
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def utcoffset(self, dt):
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return self.__offset
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def tzname(self, dt):
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return self.__name
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def dst(self, dt):
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return ZERO
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def __repr__(self):
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return "<FixedOffset %r>" % self.__name
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def parse_timezone(tzstring, default_timezone=UTC):
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"""Parses ISO 8601 time zone specs into tzinfo offsets
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"""
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if tzstring == "Z":
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return default_timezone
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# This isn't strictly correct, but it's common to encounter dates without
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# timezones so I'll assume the default (which defaults to UTC).
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# Addresses issue 4.
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if tzstring is None:
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return default_timezone
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m = TIMEZONE_REGEX.match(tzstring)
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prefix, hours, minutes = m.groups()
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hours, minutes = int(hours), int(minutes)
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if prefix == "-":
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hours = -hours
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minutes = -minutes
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return FixedOffset(hours, minutes, tzstring)
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def parse_date(datestring, default_timezone=UTC):
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"""Parses ISO 8601 dates into datetime objects
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The timezone is parsed from the date string. However it is quite common to
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have dates without a timezone (not strictly correct). In this case the
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default timezone specified in default_timezone is used. This is UTC by
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default.
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"""
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if not isinstance(datestring, basestring):
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raise ParseError("Expecting a string %r" % datestring)
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m = ISO8601_REGEX.match(datestring)
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if not m:
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raise ParseError("Unable to parse date string %r" % datestring)
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groups = m.groupdict()
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tz = parse_timezone(groups["timezone"], default_timezone=default_timezone)
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if groups["fraction"] is None:
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groups["fraction"] = 0
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else:
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groups["fraction"] = int(float("0.%s" % groups["fraction"]) * 1e6)
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return datetime(int(groups["year"]), int(groups["month"]), int(groups["day"]),
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int(groups["hour"]), int(groups["minute"]), int(groups["second"]),
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int(groups["fraction"]), tz)
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