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import time
import calendar
from datetime import datetime, date, timedelta, tzinfo
from rfc822 import parsedate_tz, mktime_tz, formatdate
__all__ = [
'UTC', 'timedelta_to_seconds',
'year', 'month', 'week', 'day', 'hour', 'minute', 'second',
'parse_date', 'serialize_date',
'parse_date_delta', 'serialize_date_delta',
]
_NOW = None # hook point for unit tests
def _now():
if _NOW is not None:
return _NOW
return datetime.now()
class _UTC(tzinfo):
def dst(self, dt):
return timedelta(0)
def utcoffset(self, dt):
return timedelta(0)
def tzname(self, dt):
return 'UTC'
def __repr__(self):
return 'UTC'
UTC = _UTC()
def timedelta_to_seconds(td):
"""
Converts a timedelta instance to seconds.
"""
return td.seconds + (td.days*24*60*60)
day = timedelta(days=1)
week = timedelta(weeks=1)
hour = timedelta(hours=1)
minute = timedelta(minutes=1)
second = timedelta(seconds=1)
# Estimate, I know; good enough for expirations
month = timedelta(days=30)
year = timedelta(days=365)
def parse_date(value):
if not value:
return None
try:
value = str(value)
except:
return None
t = parsedate_tz(value)
if t is None:
# Could not parse
return None
if t[-1] is None:
# No timezone given. None would mean local time, but we'll force UTC
t = t[:9] + (0,)
t = mktime_tz(t)
return datetime.fromtimestamp(t, UTC)
def serialize_date(dt):
if isinstance(dt, unicode):
dt = dt.encode('ascii')
if isinstance(dt, str):
return dt
if isinstance(dt, timedelta):
dt = _now() + dt
if isinstance(dt, (datetime, date)):
dt = dt.timetuple()
if isinstance(dt, (tuple, time.struct_time)):
dt = calendar.timegm(dt)
if not isinstance(dt, (float, int, long)):
raise ValueError(
"You must pass in a datetime, date, time tuple, or integer object, not %r" % dt)
return formatdate(dt)
def parse_date_delta(value):
"""
like parse_date, but also handle delta seconds
"""
if not value:
return None
try:
value = int(value)
except ValueError:
return parse_date(value)
else:
return _now() + timedelta(seconds=value)
def serialize_date_delta(value):
if isinstance(value, (float, int)):
return str(int(value))
else:
return serialize_date(value)
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