147 lines
4.6 KiB
Python
147 lines
4.6 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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import re
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from django.utils.timezone import get_fixed_timezone, utc
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date_re = re.compile(
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r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$'
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)
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time_re = re.compile(
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r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
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r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
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)
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datetime_re = re.compile(
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r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
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r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
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r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
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r'(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$'
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)
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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'$'
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)
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# Support the sections of ISO 8601 date representation that are accepted by
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# timedelta
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iso8601_duration_re = re.compile(
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r'^(?P<sign>[-+]?)'
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r'P'
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r'(?:(?P<days>\d+(.\d+)?)D)?'
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r'(?:T'
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r'(?:(?P<hours>\d+(.\d+)?)H)?'
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r'(?:(?P<minutes>\d+(.\d+)?)M)?'
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r'(?:(?P<seconds>\d+(.\d+)?)S)?'
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r')?'
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r'$'
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)
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# 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 = 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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match = date_re.match(value)
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if match:
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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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match = time_re.match(value)
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if match:
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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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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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match = datetime_re.match(value)
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if match:
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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 = kw.pop('tzinfo')
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if tzinfo == 'Z':
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tzinfo = 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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kw['tzinfo'] = tzinfo
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return datetime.datetime(**kw)
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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 = standard_duration_re.match(value)
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if not match:
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match = iso8601_duration_re.match(value) or postgres_interval_re.match(value)
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if match:
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kw = match.groupdict()
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days = datetime.timedelta(float(kw.pop('days', 0) or 0))
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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 days + sign * datetime.timedelta(**kw)
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