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import datetime
import re
import string
from typing import Optional
def datetime_now() -> datetime.datetime:
"""
Return the current local date and time.
:return: Returns an aware datetime object of the current date
and time.
"""
return datetime.datetime.now(tz=datetime.timezone.utc)
def datetime_to_str(dt: datetime.datetime) -> str:
"""
Convert a datetime object into a ISO 8601 string, e.g.
'2019-04-24T17:06:53.039991Z'.
:param dt: The datetime object to process.
:return: Return a string representing the date in
ISO 8601 (timezone=UTC).
"""
return dt.astimezone(tz=datetime.timezone.utc).strftime(
'%Y-%m-%dT%H:%M:%S.%fZ')
def str_to_datetime(string: str) -> datetime.datetime:
"""
Convert an ISO 8601 string into a datetime object.
The following formats are supported:
- 2020-03-03T09:21:43.636153304Z
- 2020-03-03T15:52:30.136257504-0600
- 2020-03-03T15:52:30.136257504
:param string: The string to parse.
:return: Returns an aware datetime object of the given date
and time string.
:raises: :exc:`~exceptions.ValueError` for an unknown
datetime string.
"""
fmts = [
'%Y-%m-%dT%H:%M:%S.%f',
'%Y-%m-%dT%H:%M:%S.%f%z'
]
# In *all* cases, the 9 digit second precision is too much for
# Python's strptime. Shorten it to 6 digits.
p = re.compile(r'(\.[\d]{6})[\d]*')
string = p.sub(r'\1', string)
# Replace trailing Z with -0000, since (on Python 3.6.8) it
# won't parse.
if string and string[-1] == 'Z':
string = string[:-1] + '-0000'
for fmt in fmts:
try:
dt = datetime.datetime.strptime(string, fmt)
# Make sure the datetime object is aware (timezone is set).
# If not, then assume the time is in UTC.
if dt.tzinfo is None:
dt = dt.replace(tzinfo=datetime.timezone.utc)
return dt
except ValueError:
pass
raise ValueError("Time data {} does not match one of the formats {}".format(
string, str(fmts)))
def parse_timedelta(delta: str) -> Optional[datetime.timedelta]:
"""
Returns a timedelta object represents a duration, the difference
between two dates or times.
>>> parse_timedelta('foo')
>>> parse_timedelta('2d') == datetime.timedelta(days=2)
True
>>> parse_timedelta("4w") == datetime.timedelta(days=28)
True
>>> parse_timedelta("5s") == datetime.timedelta(seconds=5)
True
>>> parse_timedelta("-5s") == datetime.timedelta(days=-1, seconds=86395)
True
:param delta: The string to process, e.g. '2h', '10d', '30s'.
:return: The `datetime.timedelta` object or `None` in case of
a parsing error.
"""
parts = re.match(r'(?P<seconds>-?\d+)s|'
r'(?P<minutes>-?\d+)m|'
r'(?P<hours>-?\d+)h|'
r'(?P<days>-?\d+)d|'
r'(?P<weeks>-?\d+)w$',
delta,
re.IGNORECASE)
if not parts:
return None
parts = parts.groupdict()
args = {name: int(param) for name, param in parts.items() if param}
return datetime.timedelta(**args)
def is_hex(s: str, strict: bool = True) -> bool:
"""Simple check that a string contains only hex chars"""
try:
int(s, 16)
except ValueError:
return False
# s is multiple chars, but we should catch a '+/-' prefix too.
if strict:
if s[0] not in string.hexdigits:
return False
return True
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