155 lines
5.2 KiB
Python
155 lines
5.2 KiB
Python
"""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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import datetime
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from django.utils.regex_helper import _lazy_re_compile
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from django.utils.timezone import get_fixed_timezone
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date_re = _lazy_re_compile(r"(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$")
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time_re = _lazy_re_compile(
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r"(?P<hour>\d{1,2}):(?P<minute>\d{1,2})"
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r"(?::(?P<second>\d{1,2})(?:[\.,](?P<microsecond>\d{1,6})\d{0,6})?)?$"
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)
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datetime_re = _lazy_re_compile(
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r"(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})"
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r"[T ](?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"\s*(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$"
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)
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standard_duration_re = _lazy_re_compile(
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r"^"
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r"(?:(?P<days>-?\d+) (days?, )?)?"
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r"(?P<sign>-?)"
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r"((?:(?P<hours>\d+):)(?=\d+:\d+))?"
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r"(?:(?P<minutes>\d+):)?"
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r"(?P<seconds>\d+)"
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r"(?:[\.,](?P<microseconds>\d{1,6})\d{0,6})?"
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r"$"
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)
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# Support the sections of ISO 8601 date representation that are accepted by
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# timedelta
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iso8601_duration_re = _lazy_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"$"
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)
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# Support PostgreSQL's day-time interval format, e.g. "3 days 04:05:06". The
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# year-month and mixed intervals cannot be converted to a timedelta and thus
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# aren't accepted.
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postgres_interval_re = _lazy_re_compile(
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r"^"
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r"(?:(?P<days>-?\d+) (days? ?))?"
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r"(?:(?P<sign>[-+])?"
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r"(?P<hours>\d+):"
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r"(?P<minutes>\d\d):"
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r"(?P<seconds>\d\d)"
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r"(?:\.(?P<microseconds>\d{1,6}))?"
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r")?$"
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)
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def parse_date(value):
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"""Parse a 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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Return None if the input isn't well formatted.
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"""
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try:
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return datetime.date.fromisoformat(value)
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except ValueError:
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if match := date_re.match(value):
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kw = {k: int(v) for k, v in match.groupdict().items()}
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return datetime.date(**kw)
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def parse_time(value):
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"""Parse a string and return a datetime.time.
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This function doesn't support time zone offsets.
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Raise ValueError if the input is well formatted but not a valid time.
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Return None if the input isn't well formatted, in particular if it
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contains an offset.
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"""
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try:
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# The fromisoformat() method takes time zone info into account and
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# returns a time with a tzinfo component, if possible. However, there
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# are no circumstances where aware datetime.time objects make sense, so
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# remove the time zone offset.
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return datetime.time.fromisoformat(value).replace(tzinfo=None)
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except ValueError:
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if match := time_re.match(value):
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kw = match.groupdict()
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kw["microsecond"] = kw["microsecond"] and kw["microsecond"].ljust(6, "0")
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kw = {k: int(v) for k, v in kw.items() if v is not None}
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return datetime.time(**kw)
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def parse_datetime(value):
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"""Parse a 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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Return None if the input isn't well formatted.
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"""
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try:
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return datetime.datetime.fromisoformat(value)
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except ValueError:
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if match := datetime_re.match(value):
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kw = match.groupdict()
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kw["microsecond"] = kw["microsecond"] and kw["microsecond"].ljust(6, "0")
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tzinfo = kw.pop("tzinfo")
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if tzinfo == "Z":
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tzinfo = datetime.timezone.utc
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elif tzinfo is not None:
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offset_mins = int(tzinfo[-2:]) if len(tzinfo) > 3 else 0
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offset = 60 * int(tzinfo[1:3]) + offset_mins
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if tzinfo[0] == "-":
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offset = -offset
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tzinfo = get_fixed_timezone(offset)
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kw = {k: int(v) for k, v in kw.items() if v is not None}
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return datetime.datetime(**kw, tzinfo=tzinfo)
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def parse_duration(value):
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"""Parse a duration 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 and PostgreSQL's day-time interval
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format.
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"""
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match = (
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standard_duration_re.match(value)
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or iso8601_duration_re.match(value)
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or postgres_interval_re.match(value)
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)
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if match:
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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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kw = {k: float(v.replace(",", ".")) for k, v in kw.items() if v is not None}
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days = datetime.timedelta(kw.pop("days", 0.0) or 0.0)
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if match.re == iso8601_duration_re:
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days *= sign
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return days + sign * datetime.timedelta(**kw)
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