# -*- coding: utf-8 -*-
###########################################################################
# Copyright (c), The AiiDA team. All rights reserved. #
# This file is part of the AiiDA code. #
# #
# The code is hosted on GitHub at https://github.com/aiidateam/aiida_core #
# For further information on the license, see the LICENSE.txt file #
# For further information please visit http://www.aiida.net #
###########################################################################
"""Utility functions to operate on datetime objects."""
from __future__ import division
from __future__ import print_function
from __future__ import absolute_import
from datetime import datetime
import pytz
from aiida.common import setup
UTC = pytz.utc
[docs]def get_current_timezone():
"""Return the current timezone.
:return: current timezone
"""
from tzlocal import get_localzone
return get_localzone()
[docs]def now():
"""Return the datetime object of the current time.
:return: datetime object represeting current time
"""
if getattr(setup, 'USE_TZ', None):
return datetime.utcnow().replace(tzinfo=UTC)
return datetime.now()
[docs]def is_naive(value):
"""Return whether the given datetime object is timezone naive
:return: boolean, True if naive, False otherwise
"""
return value.utcoffset() is None
[docs]def is_aware(value):
"""Return whether the given datetime object is timezone aware
:return: boolean, True if aware, False otherwise
"""
return value.utcoffset() is not None
[docs]def make_aware(value, timezone=None, is_dst=None):
"""
Make the given datetime object timezone aware
:param value: The datetime to make aware
:type value: :class:`!datetime.datetime`
:param timezone:
:param is_dst:
:return:
"""
if timezone is None:
timezone = get_current_timezone()
if hasattr(timezone, 'localize'):
return timezone.localize(value, is_dst=is_dst)
if is_aware(value):
raise ValueError("make_aware expects a naive datetime, got %s" % value)
# This may be wrong around DST changes!
return value.replace(tzinfo=timezone)
[docs]def localtime(value, timezone=None):
"""
Converts an aware datetime.datetime to local time.
Local time is defined by the current time zone, unless another time zone
is specified.
"""
if timezone is None:
timezone = get_current_timezone()
# If `value` is naive, astimezone() will raise a ValueError,
# so we don't need to perform a redundant check.
value = value.astimezone(timezone)
if hasattr(timezone, 'normalize'):
# This method is available for pytz time zones.
value = timezone.normalize(value)
return value
[docs]def delta(from_time, to_time=None):
"""Return the datetime object representing the different between two datetime objects.
:param from_time: starting datetime object
:param to_time: end datetime object
:return: the delta datetime object
"""
if to_time is None:
to_time = now()
try:
from_time_aware = make_aware(from_time)
except ValueError:
from_time_aware = from_time
try:
to_time_aware = make_aware(to_time)
except ValueError:
to_time_aware = to_time
return to_time_aware - from_time_aware