diff options
Diffstat (limited to 'pendulum/tz/zoneinfo/posix_timezone.py')
| -rw-r--r-- | pendulum/tz/zoneinfo/posix_timezone.py | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/pendulum/tz/zoneinfo/posix_timezone.py b/pendulum/tz/zoneinfo/posix_timezone.py new file mode 100644 index 0000000..a6a7c72 --- /dev/null +++ b/pendulum/tz/zoneinfo/posix_timezone.py @@ -0,0 +1,270 @@ +"""
+Parsing of a POSIX zone spec as described in the TZ part of section 8.3 in
+http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html.
+"""
+import re
+
+from typing import Optional
+
+from pendulum.constants import MONTHS_OFFSETS
+from pendulum.constants import SECS_PER_DAY
+
+from .exceptions import InvalidPosixSpec
+
+
+_spec = re.compile(
+ "^"
+ r"(?P<std_abbr><.*?>|[^-+,\d]{3,})"
+ r"(?P<std_offset>([+-])?(\d{1,2})(:\d{2}(:\d{2})?)?)"
+ r"(?P<dst_info>"
+ r" (?P<dst_abbr><.*?>|[^-+,\d]{3,})"
+ r" (?P<dst_offset>([+-])?(\d{1,2})(:\d{2}(:\d{2})?)?)?"
+ r")?"
+ r"(?:,(?P<rules>"
+ r" (?P<dst_start>"
+ r" (?:J\d+|\d+|M\d{1,2}.\d.[0-6])"
+ r" (?:/(?P<dst_start_offset>([+-])?(\d+)(:\d{2}(:\d{2})?)?))?"
+ " )"
+ " ,"
+ r" (?P<dst_end>"
+ r" (?:J\d+|\d+|M\d{1,2}.\d.[0-6])"
+ r" (?:/(?P<dst_end_offset>([+-])?(\d+)(:\d{2}(:\d{2})?)?))?"
+ " )"
+ "))?"
+ "$",
+ re.VERBOSE,
+)
+
+
+def posix_spec(spec): # type: (str) -> PosixTimezone
+ try:
+ return _posix_spec(spec)
+ except ValueError:
+ raise InvalidPosixSpec(spec)
+
+
+def _posix_spec(spec): # type: (str) -> PosixTimezone
+ m = _spec.match(spec)
+ if not m:
+ raise ValueError("Invalid posix spec")
+
+ std_abbr = _parse_abbr(m.group("std_abbr"))
+ std_offset = _parse_offset(m.group("std_offset"))
+
+ dst_abbr = None
+ dst_offset = None
+ if m.group("dst_info"):
+ dst_abbr = _parse_abbr(m.group("dst_abbr"))
+ if m.group("dst_offset"):
+ dst_offset = _parse_offset(m.group("dst_offset"))
+ else:
+ dst_offset = std_offset + 3600
+
+ dst_start = None
+ dst_end = None
+ if m.group("rules"):
+ dst_start = _parse_rule(m.group("dst_start"))
+ dst_end = _parse_rule(m.group("dst_end"))
+
+ return PosixTimezone(std_abbr, std_offset, dst_abbr, dst_offset, dst_start, dst_end)
+
+
+def _parse_abbr(text): # type: (str) -> str
+ return text.lstrip("<").rstrip(">")
+
+
+def _parse_offset(text, sign=-1): # type: (str, int) -> int
+ if text.startswith(("+", "-")):
+ if text.startswith("-"):
+ sign *= -1
+
+ text = text[1:]
+
+ minutes = 0
+ seconds = 0
+
+ parts = text.split(":")
+ hours = int(parts[0])
+
+ if len(parts) > 1:
+ minutes = int(parts[1])
+
+ if len(parts) > 2:
+ seconds = int(parts[2])
+
+ return sign * ((((hours * 60) + minutes) * 60) + seconds)
+
+
+def _parse_rule(rule): # type: (str) -> PosixTransition
+ klass = NPosixTransition
+ args = ()
+
+ if rule.startswith("M"):
+ rule = rule[1:]
+ parts = rule.split(".")
+ month = int(parts[0])
+ week = int(parts[1])
+ day = int(parts[2].split("/")[0])
+
+ args += (month, week, day)
+ klass = MPosixTransition
+ elif rule.startswith("J"):
+ rule = rule[1:]
+ args += (int(rule.split("/")[0]),)
+ klass = JPosixTransition
+ else:
+ args += (int(rule.split("/")[0]),)
+
+ # Checking offset
+ parts = rule.split("/")
+ if len(parts) > 1:
+ offset = _parse_offset(parts[-1], sign=1)
+ else:
+ offset = 7200
+
+ args += (offset,)
+
+ return klass(*args)
+
+
+class PosixTransition(object):
+ def __init__(self, offset): # type: (int) -> None
+ self._offset = offset
+
+ @property
+ def offset(self): # type: () -> int
+ return self._offset
+
+ def trans_offset(self, is_leap, jan1_weekday): # type: (bool, int) -> int
+ raise NotImplementedError()
+
+
+class JPosixTransition(PosixTransition):
+ def __init__(self, day, offset): # type: (int, int) -> None
+ self._day = day
+
+ super(JPosixTransition, self).__init__(offset)
+
+ @property
+ def day(self): # type: () -> int
+ """
+ day of non-leap year [1:365]
+ """
+ return self._day
+
+ def trans_offset(self, is_leap, jan1_weekday): # type: (bool, int) -> int
+ days = self._day
+ if not is_leap or days < MONTHS_OFFSETS[1][3]:
+ days -= 1
+
+ return (days * SECS_PER_DAY) + self._offset
+
+
+class NPosixTransition(PosixTransition):
+ def __init__(self, day, offset): # type: (int, int) -> None
+ self._day = day
+
+ super(NPosixTransition, self).__init__(offset)
+
+ @property
+ def day(self): # type: () -> int
+ """
+ day of year [0:365]
+ """
+ return self._day
+
+ def trans_offset(self, is_leap, jan1_weekday): # type: (bool, int) -> int
+ days = self._day
+
+ return (days * SECS_PER_DAY) + self._offset
+
+
+class MPosixTransition(PosixTransition):
+ def __init__(self, month, week, weekday, offset):
+ # type: (int, int, int, int) -> None
+ self._month = month
+ self._week = week
+ self._weekday = weekday
+
+ super(MPosixTransition, self).__init__(offset)
+
+ @property
+ def month(self): # type: () -> int
+ """
+ month of year [1:12]
+ """
+ return self._month
+
+ @property
+ def week(self): # type: () -> int
+ """
+ week of month [1:5] (5==last)
+ """
+ return self._week
+
+ @property
+ def weekday(self): # type: () -> int
+ """
+ 0==Sun, ..., 6=Sat
+ """
+ return self._weekday
+
+ def trans_offset(self, is_leap, jan1_weekday): # type: (bool, int) -> int
+ last_week = self._week == 5
+ days = MONTHS_OFFSETS[is_leap][self._month + int(last_week)]
+ weekday = (jan1_weekday + days) % 7
+ if last_week:
+ days -= (weekday + 7 - 1 - self._weekday) % 7 + 1
+ else:
+ days += (self._weekday + 7 - weekday) % 7
+ days += (self._week - 1) * 7
+
+ return (days * SECS_PER_DAY) + self._offset
+
+
+class PosixTimezone:
+ """
+ The entirety of a POSIX-string specified time-zone rule.
+
+ The standard abbreviation and offset are always given.
+ """
+
+ def __init__(
+ self,
+ std_abbr, # type: str
+ std_offset, # type: int
+ dst_abbr, # type: Optional[str]
+ dst_offset, # type: Optional[int]
+ dst_start=None, # type: Optional[PosixTransition]
+ dst_end=None, # type: Optional[PosixTransition]
+ ):
+ self._std_abbr = std_abbr
+ self._std_offset = std_offset
+ self._dst_abbr = dst_abbr
+ self._dst_offset = dst_offset
+ self._dst_start = dst_start
+ self._dst_end = dst_end
+
+ @property
+ def std_abbr(self): # type: () -> str
+ return self._std_abbr
+
+ @property
+ def std_offset(self): # type: () -> int
+ return self._std_offset
+
+ @property
+ def dst_abbr(self): # type: () -> Optional[str]
+ return self._dst_abbr
+
+ @property
+ def dst_offset(self): # type: () -> Optional[int]
+ return self._dst_offset
+
+ @property
+ def dst_start(self): # type: () -> Optional[PosixTransition]
+ return self._dst_start
+
+ @property
+ def dst_end(self): # type: () -> Optional[PosixTransition]
+ return self._dst_end
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