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datetime_parse.py
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datetime_parse.py
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"""
Functions to parse datetime objects.
We're using regular expressions rather than time.strptime because:
- They provide both validation and parsing.
- They're more flexible for datetimes.
- The date/datetime/time constructors produce friendlier error messages.
Stolen from https://raw.githubusercontent.com/django/django/master/django/utils/dateparse.py at
9718fa2e8abe430c3526a9278dd976443d4ae3c6
Changed to:
* use standard python datetime types not django.utils.timezone
* raise ValueError when regex doesn't match rather than returning None
* support parsing unix timestamps for dates and datetimes
"""
import re
from datetime import date, datetime, time, timedelta, timezone
from typing import Dict, Union
from . import errors
date_re = re.compile(r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$')
time_re = re.compile(
r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
)
datetime_re = re.compile(
r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
r'(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$'
)
standard_duration_re = re.compile(
r'^'
r'(?:(?P<days>-?\d+) (days?, )?)?'
r'((?:(?P<hours>-?\d+):)(?=\d+:\d+))?'
r'(?:(?P<minutes>-?\d+):)?'
r'(?P<seconds>-?\d+)'
r'(?:\.(?P<microseconds>\d{1,6})\d{0,6})?'
r'$'
)
# Support the sections of ISO 8601 date representation that are accepted by timedelta
iso8601_duration_re = re.compile(
r'^(?P<sign>[-+]?)'
r'P'
r'(?:(?P<days>\d+(.\d+)?)D)?'
r'(?:T'
r'(?:(?P<hours>\d+(.\d+)?)H)?'
r'(?:(?P<minutes>\d+(.\d+)?)M)?'
r'(?:(?P<seconds>\d+(.\d+)?)S)?'
r')?'
r'$'
)
EPOCH = datetime(1970, 1, 1)
# if greater than this, the number is in ms, if less than or equal it's in seconds
# (in seconds this is 11th October 2603, in ms it's 20th August 1970)
MS_WATERSHED = int(2e10)
StrBytesIntFloat = Union[str, bytes, int, float]
def get_numeric(value: StrBytesIntFloat, native_expected_type: str) -> Union[None, int, float]:
if isinstance(value, (int, float)):
return value
try:
return float(value)
except ValueError:
return None
except TypeError:
raise TypeError(f'invalid type; expected {native_expected_type}, string, bytes, int or float')
def from_unix_seconds(seconds: Union[int, float]) -> datetime:
while abs(seconds) > MS_WATERSHED:
seconds /= 1000
dt = EPOCH + timedelta(seconds=seconds)
return dt.replace(tzinfo=timezone.utc)
def parse_date(value: Union[date, StrBytesIntFloat]) -> date:
"""
Parse a date/int/float/string and return a datetime.date.
Raise ValueError if the input is well formatted but not a valid date.
Raise ValueError if the input isn't well formatted.
"""
if isinstance(value, date):
if isinstance(value, datetime):
return value.date()
else:
return value
number = get_numeric(value, 'date')
if number is not None:
return from_unix_seconds(number).date()
if isinstance(value, bytes):
value = value.decode()
match = date_re.match(value) # type: ignore
if match is None:
raise errors.DateError()
kw = {k: int(v) for k, v in match.groupdict().items()}
try:
return date(**kw)
except ValueError:
raise errors.DateError()
def parse_time(value: Union[time, StrBytesIntFloat]) -> time:
"""
Parse a time/string and return a datetime.time.
This function doesn't support time zone offsets.
Raise ValueError if the input is well formatted but not a valid time.
Raise ValueError if the input isn't well formatted, in particular if it contains an offset.
"""
if isinstance(value, time):
return value
number = get_numeric(value, 'time')
if number is not None:
if number >= 86400:
# doesn't make sense since the time time loop back around to 0
raise errors.TimeError()
return (datetime.min + timedelta(seconds=number)).time()
if isinstance(value, bytes):
value = value.decode()
match = time_re.match(value) # type: ignore
if match is None:
raise errors.TimeError()
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
kw_ = {k: int(v) for k, v in kw.items() if v is not None}
try:
return time(**kw_) # type: ignore
except ValueError:
raise errors.TimeError()
def parse_datetime(value: Union[datetime, StrBytesIntFloat]) -> datetime:
"""
Parse a datetime/int/float/string and return a datetime.datetime.
This function supports time zone offsets. When the input contains one,
the output uses a timezone with a fixed offset from UTC.
Raise ValueError if the input is well formatted but not a valid datetime.
Raise ValueError if the input isn't well formatted.
"""
if isinstance(value, datetime):
return value
number = get_numeric(value, 'datetime')
if number is not None:
return from_unix_seconds(number)
if isinstance(value, bytes):
value = value.decode()
match = datetime_re.match(value) # type: ignore
if match is None:
raise errors.DateTimeError()
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
tzinfo_str = kw.pop('tzinfo')
if tzinfo_str == 'Z':
tzinfo = timezone.utc
elif tzinfo_str is not None:
offset_mins = int(tzinfo_str[-2:]) if len(tzinfo_str) > 3 else 0
offset = 60 * int(tzinfo_str[1:3]) + offset_mins
if tzinfo_str[0] == '-':
offset = -offset
tzinfo = timezone(timedelta(minutes=offset))
else:
tzinfo = None
kw_: Dict[str, Union[int, timezone]] = {k: int(v) for k, v in kw.items() if v is not None}
kw_['tzinfo'] = tzinfo
try:
return datetime(**kw_) # type: ignore
except ValueError:
raise errors.DateTimeError()
def parse_duration(value: StrBytesIntFloat) -> timedelta:
"""
Parse a duration int/float/string and return a datetime.timedelta.
The preferred format for durations in Django is '%d %H:%M:%S.%f'.
Also supports ISO 8601 representation.
"""
if isinstance(value, timedelta):
return value
if isinstance(value, (int, float)):
# bellow code requires a string
value = str(value)
elif isinstance(value, bytes):
value = value.decode()
try:
match = standard_duration_re.match(value) or iso8601_duration_re.match(value)
except TypeError:
raise TypeError('invalid type; expected timedelta, string, bytes, int or float')
if not match:
raise errors.DurationError()
kw = match.groupdict()
sign = -1 if kw.pop('sign', '+') == '-' else 1
if kw.get('microseconds'):
kw['microseconds'] = kw['microseconds'].ljust(6, '0')
if kw.get('seconds') and kw.get('microseconds') and kw['seconds'].startswith('-'):
kw['microseconds'] = '-' + kw['microseconds']
kw_ = {k: float(v) for k, v in kw.items() if v is not None}
return sign * timedelta(**kw_) # type: ignore