tz.py

Python的一个ORM,现在很火

class _tzicalvtz(datetime.tzinfo):
    def __init__(self, tzid, comps=[]):
        self._tzid = tzid
        self._comps = comps
        self._cachedate = []
        self._cachecomp = []

    def _find_comp(self, dt):
        if len(self._comps) == 1:
            return self._comps[0]
        dt = dt.replace(tzinfo=None)
        try:
            return self._cachecomp[self._cachedate.index(dt)]
        except ValueError:
            pass
        lastcomp = None
        lastcompdt = None
        for comp in self._comps:
            if not comp.isdst:
                # Handle the extra hour in DST -> STD
                compdt = comp.rrule.before(dt-comp.tzoffsetdiff, inc=True)
            else:
                compdt = comp.rrule.before(dt, inc=True)
            if compdt and (not lastcompdt or lastcompdt < compdt):
                lastcompdt = compdt
                lastcomp = comp
        if not lastcomp:
            # RFC says nothing about what to do when a given
            # time is before the first onset date. We'll look for the
            # first standard component, or the first component, if
            # none is found.
            for comp in self._comps:
                if not comp.isdst:
                    lastcomp = comp
                    break
            else:
                lastcomp = comp[0]
        self._cachedate.insert(0, dt)
        self._cachecomp.insert(0, lastcomp)
        if len(self._cachedate) > 10:
            self._cachedate.pop()
            self._cachecomp.pop()
        return lastcomp

    def utcoffset(self, dt):
        return self._find_comp(dt).tzoffsetto

    def dst(self, dt):
        comp = self._find_comp(dt)
        if comp.isdst:
            return comp.tzoffsetdiff
        else:
            return ZERO

    def tzname(self, dt):
        return self._find_comp(dt).tzname

    def __repr__(self):
        return "<tzicalvtz %s>" % `self._tzid`

    __reduce__ = object.__reduce__

class tzical:
    def __init__(self, fileobj):
        global rrule
        if not rrule:
            from dateutil import rrule

        if isinstance(fileobj, basestring):
            self._s = fileobj
            fileobj = open(fileobj)
        elif hasattr(fileobj, "name"):
            self._s = fileobj.name
        else:
            self._s = `fileobj`

        self._vtz = {}

        self._parse_rfc(fileobj.read())

    def keys(self):
        return self._vtz.keys()

    def get(self, tzid=None):
        if tzid is None:
            keys = self._vtz.keys()
            if len(keys) == 0:
                raise "no timezones defined"
            elif len(keys) > 1:
                raise "more than one timezone available"
            tzid = keys[0]
        return self._vtz.get(tzid)

    def _parse_offset(self, s):
        s = s.strip()
        if not s:
            raise ValueError, "empty offset"
        if s[0] in ('+', '-'):
            signal = (-1,+1)[s[0]=='+']
            s = s[1:]
        else:
            signal = +1
        if len(s) == 4:
            return (int(s[:2])*3600+int(s[2:])*60)*signal
        elif len(s) == 6:
            return (int(s[:2])*3600+int(s[2:4])*60+int(s[4:]))*signal
        else:
            raise ValueError, "invalid offset: "+s

    def _parse_rfc(self, s):
        lines = s.splitlines()
        if not lines:
            raise ValueError, "empty string"

        # Unfold
        i = 0
        while i < len(lines):
            line = lines[i].rstrip()
            if not line:
                del lines[i]
            elif i > 0 and line[0] == " ":
                lines[i-1] += line[1:]
                del lines[i]
            else:
                i += 1

        invtz = False
        comptype = None
        for line in lines:
            if not line:
                continue
            name, value = line.split(':', 1)
            parms = name.split(';')
            if not parms:
                raise ValueError, "empty property name"
            name = parms[0].upper()
            parms = parms[1:]
            if invtz:
                if name == "BEGIN":
                    if value in ("STANDARD", "DAYLIGHT"):
                        # Process component
                        pass
                    else:
                        raise ValueError, "unknown component: "+value
                    comptype = value
                    founddtstart = False
                    tzoffsetfrom = None
                    tzoffsetto = None
                    rrulelines = []
                    tzname = None
                elif name == "END":
                    if value == "VTIMEZONE":
                        if comptype:
                            raise ValueError, \
                                  "component not closed: "+comptype
                        if not tzid:
                            raise ValueError, \
                                  "mandatory TZID not found"
                        if not comps:
                            raise ValueError, \
                                  "at least one component is needed"
                        # Process vtimezone
                        self._vtz[tzid] = _tzicalvtz(tzid, comps)
                        invtz = False
                    elif value == comptype:
                        if not founddtstart:
                            raise ValueError, \
                                  "mandatory DTSTART not found"
                        if tzoffsetfrom is None:
                            raise ValueError, \
                                  "mandatory TZOFFSETFROM not found"
                        if tzoffsetto is None:
                            raise ValueError, \
                                  "mandatory TZOFFSETFROM not found"
                        # Process component
                        rr = None
                        if rrulelines:
                            rr = rrule.rrulestr("\n".join(rrulelines),
                                                compatible=True,
                                                ignoretz=True,
                                                cache=True)
                        comp = _tzicalvtzcomp(tzoffsetfrom, tzoffsetto,
                                              (comptype == "DAYLIGHT"),
                                              tzname, rr)
                        comps.append(comp)
                        comptype = None
                    else:
                        raise ValueError, \
                              "invalid component end: "+value
                elif comptype:
                    if name == "DTSTART":
                        rrulelines.append(line)
                        founddtstart = True
                    elif name in ("RRULE", "RDATE", "EXRULE", "EXDATE"):
                        rrulelines.append(line)
                    elif name == "TZOFFSETFROM":
                        if parms:
                            raise ValueError, \
                                  "unsupported %s parm: %s "%(name, parms[0])
                        tzoffsetfrom = self._parse_offset(value)
                    elif name == "TZOFFSETTO":
                        if parms:
                            raise ValueError, \
                                  "unsupported TZOFFSETTO parm: "+parms[0]
                        tzoffsetto = self._parse_offset(value)
                    elif name == "TZNAME":
                        if parms:
                            raise ValueError, \
                                  "unsupported TZNAME parm: "+parms[0]
                        tzname = value
                    elif name == "COMMENT":
                        pass
                    else:
                        raise ValueError, "unsupported property: "+name
                else:
                    if name == "TZID":
                        if parms:
                            raise ValueError, \
                                  "unsupported TZID parm: "+parms[0]
                        tzid = value
                    elif name in ("TZURL", "LAST-MODIFIED", "COMMENT"):
                        pass
                    else:
                        raise ValueError, "unsupported property: "+name
            elif name == "BEGIN" and value == "VTIMEZONE":
                tzid = None
                comps = []
                invtz = True

    def __repr__(self):
        return "%s(%s)" % (self.__class__.__name__, `self._s`)

if sys.platform != "win32":
    TZFILES = ["/etc/localtime", "localtime"]
    TZPATHS = ["/usr/share/zoneinfo", "/usr/lib/zoneinfo", "/etc/zoneinfo"]
else:
    TZFILES = []
    TZPATHS = []

def gettz(name=None):
    tz = None
    if not name:
        try:
            name = os.environ["TZ"]
        except KeyError:
            pass
    if name is None or name == ":":
        for filepath in TZFILES:
            if not os.path.isabs(filepath):
                filename = filepath
                for path in TZPATHS:
                    filepath = os.path.join(path, filename)
                    if os.path.isfile(filepath):
                        break
                else:
                    continue
            if os.path.isfile(filepath):
                try:
                    tz = tzfile(filepath)
                    break
                except (IOError, OSError, ValueError):
                    pass
        else:
            tz = tzlocal()
    else:
        if name.startswith(":"):
            name = name[:-1]
        if os.path.isabs(name):
            if os.path.isfile(name):
                tz = tzfile(name)
            else:
                tz = None
        else:
            for path in TZPATHS:
                filepath = os.path.join(path, name)
                if not os.path.isfile(filepath):
                    filepath = filepath.replace(' ','_')
                    if not os.path.isfile(filepath):
                        continue
                try:
                    tz = tzfile(filepath)
                    break
                except (IOError, OSError, ValueError):
                    pass
            else:
                tz = None
                if tzwin:
                    try:
                        tz = tzwin(name)
                    except OSError:
                        pass
                if not tz:
                    from dateutil.zoneinfo import gettz
                    tz = gettz(name)
                if not tz:
                    for c in name:
                        # name must have at least one offset to be a tzstr
                        if c in "0123456789":
                            try:
                                tz = tzstr(name)
                            except ValueError:
                                pass
                            break
                    else:
                        if name in ("GMT", "UTC"):
                            tz = tzutc()
                        elif name in time.tzname:
                            tz = tzlocal()
    return tz

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