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"""Module for parsing ISO 8601 format timestamps.
Only fixed offset timezones are supported.
http://en.wikipedia.org/wiki/ISO_8601
"""
import re
from datetime import datetime, timedelta, tzinfo
"""
TODO:
- support more combinations from ISO 8601 (only reasonable ones)
- cache TZ objects
- make it faster?
"""
__all__ = ['parse_iso_timestamp', 'FixedOffsetTimezone']
class FixedOffsetTimezone(tzinfo):
"""Fixed offset in minutes east from UTC."""
__slots__ = ('__offset', '__name')
def __init__(self, offset):
self.__offset = timedelta(minutes = offset)
# numeric tz name
h, m = divmod(abs(offset), 60)
if offset < 0:
h = -h
if m:
self.__name = "%+03d:%02d" % (h,m)
else:
self.__name = "%+03d" % h
def utcoffset(self, dt):
return self.__offset
def tzname(self, dt):
return self.__name
def dst(self, dt):
return ZERO
ZERO = timedelta(0)
_iso_regex = r"""
\s*
(?P<year> \d\d\d\d) [-] (?P<month> \d\d) [-] (?P<day> \d\d) [ T]
(?P<hour> \d\d) [:] (?P<min> \d\d)
(?: [:] (?P<sec> \d\d ) (?: [.,] (?P<ss> \d+))? )?
(?: \s* (?P<tzsign> [-+]) (?P<tzhr> \d\d) (?: [:]? (?P<tzmin> \d\d))? )?
\s* $
"""
_iso_rc = None
def parse_iso_timestamp(s, default_tz = None):
"""Parse ISO timestamp to datetime object.
YYYY-MM-DD[ T]HH:MM[:SS[.ss]][-+HH[:MM]]
Assumes that second fractions are zero-trimmed from the end,
so '.15' means 150000 microseconds.
If the timezone offset is not present, use default_tz as tzinfo.
By default its None, meaning the datetime object will be without tz.
>>> str(parse_iso_timestamp('2005-06-01 15:00'))
'2005-06-01 15:00:00'
>>> str(parse_iso_timestamp(' 2005-06-01T15:00 +02 '))
'2005-06-01 15:00:00+02:00'
>>> str(parse_iso_timestamp('2005-06-01 15:00:33+02:00'))
'2005-06-01 15:00:33+02:00'
>>> d = parse_iso_timestamp('2005-06-01 15:00:59.33 +02')
>>> d.strftime("%z %Z")
'+0200 +02'
>>> str(parse_iso_timestamp(str(d)))
'2005-06-01 15:00:59.330000+02:00'
>>> parse_iso_timestamp('2005-06-01 15:00-0530').strftime('%Y-%m-%d %H:%M %z %Z')
'2005-06-01 15:00 -0530 -05:30'
"""
global _iso_rc
if _iso_rc is None:
_iso_rc = re.compile(_iso_regex, re.X)
m = _iso_rc.match(s)
if not m:
raise ValueError('Date not in ISO format: %s' % repr(s))
tz = default_tz
if m.group('tzsign'):
tzofs = int(m.group('tzhr')) * 60
if m.group('tzmin'):
tzofs += int(m.group('tzmin'))
if m.group('tzsign') == '-':
tzofs = -tzofs
tz = FixedOffsetTimezone(tzofs)
return datetime(int(m.group('year')),
int(m.group('month')),
int(m.group('day')),
int(m.group('hour')),
int(m.group('min')),
m.group('sec') and int(m.group('sec')) or 0,
m.group('ss') and int(m.group('ss').ljust(6, '0')) or 0,
tz)
if __name__ == '__main__':
import doctest
doctest.testmod()
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