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import re
from datetime import datetime
import pytz
from pyrfc3339.utils import FixedOffset
def parse(timestamp, utc=False, produce_naive=False):
'''
Parse an :RFC:`3339`-formatted timestamp and return a
`datetime.datetime`.
If the timestamp is presented in UTC, then the `tzinfo` parameter of the
returned `datetime` will be set to `pytz.utc`.
>>> parse('2009-01-01T10:01:02Z')
datetime.datetime(2009, 1, 1, 10, 1, 2, tzinfo=<UTC>)
Otherwise, a `tzinfo` instance is created with the appropriate offset, and
the `tzinfo` parameter of the returned `datetime` is set to that value.
>>> parse('2009-01-01T14:01:02-04:00')
datetime.datetime(2009, 1, 1, 14, 1, 2, tzinfo=<UTC-04:00>)
However, if `parse()` is called with `utc=True`, then the returned
`datetime` will be normalized to UTC (and its tzinfo parameter set to
`pytz.utc`), regardless of the input timezone.
>>> parse('2009-01-01T06:01:02-04:00', utc=True)
datetime.datetime(2009, 1, 1, 10, 1, 2, tzinfo=<UTC>)
The input is strictly required to conform to :RFC:`3339`, and appropriate
exceptions are thrown for invalid input.
>>> parse('2009-01-01T06:01:02')
Traceback (most recent call last):
...
ValueError: timestamp does not conform to RFC 3339
>>> parse('2009-01-01T25:01:02Z')
Traceback (most recent call last):
...
ValueError: hour must be in 0..23
'''
parse_re = re.compile(r'''^(?:(?:(?P<date_fullyear>[0-9]{4})\-(?P<date_month>[0-9]{2})\-(?P<date_mday>[0-9]{2}))T(?:(?:(?P<time_hour>[0-9]{2})\:(?P<time_minute>[0-9]{2})\:(?P<time_second>[0-9]{2})(?P<time_secfrac>(?:\.[0-9]{1,}))?)(?P<time_offset>(?:Z|(?P<time_numoffset>(?P<time_houroffset>(?:\+|\-)[0-9]{2})\:(?P<time_minuteoffset>[0-9]{2}))))))$''',
re.I | re.X)
match = parse_re.match(timestamp)
if match is not None:
if match.group('time_offset') in ["Z", "z", "+00:00", "-00:00"]:
if produce_naive is True:
tzinfo = None
else:
tzinfo = pytz.utc
else:
if produce_naive is True:
raise ValueError("cannot produce a naive datetime from " +
"a local timestamp")
else:
tzinfo = FixedOffset(int(match.group('time_houroffset')),
int(match.group('time_minuteoffset')))
secfrac = match.group('time_secfrac')
if secfrac is None:
microsecond = 0
else:
microsecond = int(round(float(secfrac) * 1000000))
dt_out = datetime(year=int(match.group('date_fullyear')),
month=int(match.group('date_month')),
day=int(match.group('date_mday')),
hour=int(match.group('time_hour')),
minute=int(match.group('time_minute')),
second=int(match.group('time_second')),
microsecond=microsecond,
tzinfo=tzinfo)
if utc:
dt_out = dt_out.astimezone(pytz.utc)
return dt_out
else:
raise ValueError("timestamp does not conform to RFC 3339")
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