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249 lines
7.5 KiB
249 lines
7.5 KiB
"""
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Functions to parse datetime objects.
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We're using regular expressions rather than time.strptime because:
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- They provide both validation and parsing.
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- They're more flexible for datetimes.
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- The date/datetime/time constructors produce friendlier error messages.
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Stolen from https://raw.githubusercontent.com/django/django/main/django/utils/dateparse.py at
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9718fa2e8abe430c3526a9278dd976443d4ae3c6
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Changed to:
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* use standard python datetime types not django.utils.timezone
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* raise ValueError when regex doesn't match rather than returning None
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* support parsing unix timestamps for dates and datetimes
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"""
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import re
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from datetime import date, datetime, time, timedelta, timezone
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from typing import Dict, Optional, Type, Union
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from . import errors
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date_expr = r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
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time_expr = (
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r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
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r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
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r'(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$'
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)
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date_re = re.compile(f'{date_expr}$')
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time_re = re.compile(time_expr)
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datetime_re = re.compile(f'{date_expr}[T ]{time_expr}')
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standard_duration_re = re.compile(
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r'^'
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r'(?:(?P<days>-?\d+) (days?, )?)?'
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r'((?:(?P<hours>-?\d+):)(?=\d+:\d+))?'
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r'(?:(?P<minutes>-?\d+):)?'
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r'(?P<seconds>-?\d+)'
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r'(?:\.(?P<microseconds>\d{1,6})\d{0,6})?'
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r'$'
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)
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# Support the sections of ISO 8601 date representation that are accepted by timedelta
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iso8601_duration_re = re.compile(
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r'^(?P<sign>[-+]?)'
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r'P'
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r'(?:(?P<days>\d+(.\d+)?)D)?'
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r'(?:T'
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r'(?:(?P<hours>\d+(.\d+)?)H)?'
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r'(?:(?P<minutes>\d+(.\d+)?)M)?'
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r'(?:(?P<seconds>\d+(.\d+)?)S)?'
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r')?'
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r'$'
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)
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EPOCH = datetime(1970, 1, 1)
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# if greater than this, the number is in ms, if less than or equal it's in seconds
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# (in seconds this is 11th October 2603, in ms it's 20th August 1970)
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MS_WATERSHED = int(2e10)
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# slightly more than datetime.max in ns - (datetime.max - EPOCH).total_seconds() * 1e9
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MAX_NUMBER = int(3e20)
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StrBytesIntFloat = Union[str, bytes, int, float]
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def get_numeric(value: StrBytesIntFloat, native_expected_type: str) -> Union[None, int, float]:
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if isinstance(value, (int, float)):
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return value
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try:
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return float(value)
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except ValueError:
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return None
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except TypeError:
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raise TypeError(f'invalid type; expected {native_expected_type}, string, bytes, int or float')
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def from_unix_seconds(seconds: Union[int, float]) -> datetime:
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if seconds > MAX_NUMBER:
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return datetime.max
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elif seconds < -MAX_NUMBER:
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return datetime.min
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while abs(seconds) > MS_WATERSHED:
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seconds /= 1000
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dt = EPOCH + timedelta(seconds=seconds)
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return dt.replace(tzinfo=timezone.utc)
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def _parse_timezone(value: Optional[str], error: Type[Exception]) -> Union[None, int, timezone]:
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if value == 'Z':
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return timezone.utc
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elif value is not None:
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offset_mins = int(value[-2:]) if len(value) > 3 else 0
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offset = 60 * int(value[1:3]) + offset_mins
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if value[0] == '-':
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offset = -offset
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try:
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return timezone(timedelta(minutes=offset))
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except ValueError:
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raise error()
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else:
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return None
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def parse_date(value: Union[date, StrBytesIntFloat]) -> date:
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"""
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Parse a date/int/float/string and return a datetime.date.
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Raise ValueError if the input is well formatted but not a valid date.
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Raise ValueError if the input isn't well formatted.
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"""
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if isinstance(value, date):
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if isinstance(value, datetime):
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return value.date()
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else:
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return value
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number = get_numeric(value, 'date')
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if number is not None:
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return from_unix_seconds(number).date()
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if isinstance(value, bytes):
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value = value.decode()
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match = date_re.match(value) # type: ignore
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if match is None:
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raise errors.DateError()
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kw = {k: int(v) for k, v in match.groupdict().items()}
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try:
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return date(**kw)
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except ValueError:
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raise errors.DateError()
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def parse_time(value: Union[time, StrBytesIntFloat]) -> time:
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"""
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Parse a time/string and return a datetime.time.
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Raise ValueError if the input is well formatted but not a valid time.
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Raise ValueError if the input isn't well formatted, in particular if it contains an offset.
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"""
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if isinstance(value, time):
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return value
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number = get_numeric(value, 'time')
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if number is not None:
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if number >= 86400:
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# doesn't make sense since the time time loop back around to 0
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raise errors.TimeError()
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return (datetime.min + timedelta(seconds=number)).time()
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if isinstance(value, bytes):
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value = value.decode()
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match = time_re.match(value) # type: ignore
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if match is None:
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raise errors.TimeError()
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kw = match.groupdict()
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if kw['microsecond']:
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kw['microsecond'] = kw['microsecond'].ljust(6, '0')
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tzinfo = _parse_timezone(kw.pop('tzinfo'), errors.TimeError)
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kw_: Dict[str, Union[None, int, timezone]] = {k: int(v) for k, v in kw.items() if v is not None}
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kw_['tzinfo'] = tzinfo
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try:
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return time(**kw_) # type: ignore
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except ValueError:
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raise errors.TimeError()
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def parse_datetime(value: Union[datetime, StrBytesIntFloat]) -> datetime:
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"""
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Parse a datetime/int/float/string and return a datetime.datetime.
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This function supports time zone offsets. When the input contains one,
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the output uses a timezone with a fixed offset from UTC.
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Raise ValueError if the input is well formatted but not a valid datetime.
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Raise ValueError if the input isn't well formatted.
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"""
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if isinstance(value, datetime):
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return value
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number = get_numeric(value, 'datetime')
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if number is not None:
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return from_unix_seconds(number)
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if isinstance(value, bytes):
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value = value.decode()
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match = datetime_re.match(value) # type: ignore
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if match is None:
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raise errors.DateTimeError()
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kw = match.groupdict()
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if kw['microsecond']:
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kw['microsecond'] = kw['microsecond'].ljust(6, '0')
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tzinfo = _parse_timezone(kw.pop('tzinfo'), errors.DateTimeError)
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kw_: Dict[str, Union[None, int, timezone]] = {k: int(v) for k, v in kw.items() if v is not None}
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kw_['tzinfo'] = tzinfo
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try:
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return datetime(**kw_) # type: ignore
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except ValueError:
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raise errors.DateTimeError()
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def parse_duration(value: StrBytesIntFloat) -> timedelta:
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"""
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Parse a duration int/float/string and return a datetime.timedelta.
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The preferred format for durations in Django is '%d %H:%M:%S.%f'.
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Also supports ISO 8601 representation.
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"""
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if isinstance(value, timedelta):
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return value
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if isinstance(value, (int, float)):
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# below code requires a string
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value = f'{value:f}'
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elif isinstance(value, bytes):
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value = value.decode()
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try:
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match = standard_duration_re.match(value) or iso8601_duration_re.match(value)
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except TypeError:
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raise TypeError('invalid type; expected timedelta, string, bytes, int or float')
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if not match:
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raise errors.DurationError()
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kw = match.groupdict()
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sign = -1 if kw.pop('sign', '+') == '-' else 1
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if kw.get('microseconds'):
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kw['microseconds'] = kw['microseconds'].ljust(6, '0')
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if kw.get('seconds') and kw.get('microseconds') and kw['seconds'].startswith('-'):
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kw['microseconds'] = '-' + kw['microseconds']
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kw_ = {k: float(v) for k, v in kw.items() if v is not None}
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return sign * timedelta(**kw_)
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