mercurial/utils/dateutil.py

wireprotov2: define and use stream encoders

Now that we have basic support for defining stream encoding, it is
time to start doing something with it.

We define various classes implementing stream encoders/decoders for
the defined encoding profiles. This is relatively straightforward.

We teach the inputstream and outputstream classes how to encode,
decode, and flush data.

We then teach the clientreactor how to filter received data through
the inputstream decoder.

One of the features of the framing format is that streams can span
requests. This is a differentiating feature from say HTTP/2, which
associates streams with requests. By allowing streams to span requests,
we can reuse compression context data across requests/responses. But
in order to do this, we need a mechanism to "flush" the encoder at
logical boundaries so that receivers receive all data where it is
expected. And a "flush" event is distinct from a "finish" event from
the perspective of certain compressors because a "flush" will retain
compression context state whereas a "finish" operation will not. This
is why encoders have both a flush() and a finish() and each uses
specific flushing semantics on the underlying compressor.

The added tests verify various behavior of decoders via clientreactor.
These tests do test some compression behavior via use of outputstream.
But for all intents and purposes, server reactor support for encoding
is not yet implemented.

Differential Revision: https://phab.mercurial-scm.org/D4921

# util.py - Mercurial utility functions relative to dates
#
#  Copyright 2018 Boris Feld <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import, print_function

import calendar
import datetime
import time

from ..i18n import _
from .. import (
    encoding,
    error,
    pycompat,
)

# used by parsedate
defaultdateformats = (
    '%Y-%m-%dT%H:%M:%S', # the 'real' ISO8601
    '%Y-%m-%dT%H:%M',    #   without seconds
    '%Y-%m-%dT%H%M%S',   # another awful but legal variant without :
    '%Y-%m-%dT%H%M',     #   without seconds
    '%Y-%m-%d %H:%M:%S', # our common legal variant
    '%Y-%m-%d %H:%M',    #   without seconds
    '%Y-%m-%d %H%M%S',   # without :
    '%Y-%m-%d %H%M',     #   without seconds
    '%Y-%m-%d %I:%M:%S%p',
    '%Y-%m-%d %H:%M',
    '%Y-%m-%d %I:%M%p',
    '%Y-%m-%d',
    '%m-%d',
    '%m/%d',
    '%m/%d/%y',
    '%m/%d/%Y',
    '%a %b %d %H:%M:%S %Y',
    '%a %b %d %I:%M:%S%p %Y',
    '%a, %d %b %Y %H:%M:%S',        #  GNU coreutils "/bin/date --rfc-2822"
    '%b %d %H:%M:%S %Y',
    '%b %d %I:%M:%S%p %Y',
    '%b %d %H:%M:%S',
    '%b %d %I:%M:%S%p',
    '%b %d %H:%M',
    '%b %d %I:%M%p',
    '%b %d %Y',
    '%b %d',
    '%H:%M:%S',
    '%I:%M:%S%p',
    '%H:%M',
    '%I:%M%p',
)

extendeddateformats = defaultdateformats + (
    "%Y",
    "%Y-%m",
    "%b",
    "%b %Y",
)

def makedate(timestamp=None):
    '''Return a unix timestamp (or the current time) as a (unixtime,
    offset) tuple based off the local timezone.'''
    if timestamp is None:
        timestamp = time.time()
    if timestamp < 0:
        hint = _("check your clock")
        raise error.Abort(_("negative timestamp: %d") % timestamp, hint=hint)
    delta = (datetime.datetime.utcfromtimestamp(timestamp) -
             datetime.datetime.fromtimestamp(timestamp))
    tz = delta.days * 86400 + delta.seconds
    return timestamp, tz

def datestr(date=None, format='%a %b %d %H:%M:%S %Y %1%2'):
    """represent a (unixtime, offset) tuple as a localized time.
    unixtime is seconds since the epoch, and offset is the time zone's
    number of seconds away from UTC.

    >>> datestr((0, 0))
    'Thu Jan 01 00:00:00 1970 +0000'
    >>> datestr((42, 0))
    'Thu Jan 01 00:00:42 1970 +0000'
    >>> datestr((-42, 0))
    'Wed Dec 31 23:59:18 1969 +0000'
    >>> datestr((0x7fffffff, 0))
    'Tue Jan 19 03:14:07 2038 +0000'
    >>> datestr((-0x80000000, 0))
    'Fri Dec 13 20:45:52 1901 +0000'
    """
    t, tz = date or makedate()
    if "%1" in format or "%2" in format or "%z" in format:
        sign = (tz > 0) and "-" or "+"
        minutes = abs(tz) // 60
        q, r = divmod(minutes, 60)
        format = format.replace("%z", "%1%2")
        format = format.replace("%1", "%c%02d" % (sign, q))
        format = format.replace("%2", "%02d" % r)
    d = t - tz
    if d > 0x7fffffff:
        d = 0x7fffffff
    elif d < -0x80000000:
        d = -0x80000000
    # Never use time.gmtime() and datetime.datetime.fromtimestamp()
    # because they use the gmtime() system call which is buggy on Windows
    # for negative values.
    t = datetime.datetime(1970, 1, 1) + datetime.timedelta(seconds=d)
    s = encoding.strtolocal(t.strftime(encoding.strfromlocal(format)))
    return s

def shortdate(date=None):
    """turn (timestamp, tzoff) tuple into iso 8631 date."""
    return datestr(date, format='%Y-%m-%d')

def parsetimezone(s):
    """find a trailing timezone, if any, in string, and return a
       (offset, remainder) pair"""
    s = pycompat.bytestr(s)

    if s.endswith("GMT") or s.endswith("UTC"):
        return 0, s[:-3].rstrip()

    # Unix-style timezones [+-]hhmm
    if len(s) >= 5 and s[-5] in "+-" and s[-4:].isdigit():
        sign = (s[-5] == "+") and 1 or -1
        hours = int(s[-4:-2])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-5].rstrip()

    # ISO8601 trailing Z
    if s.endswith("Z") and s[-2:-1].isdigit():
        return 0, s[:-1]

    # ISO8601-style [+-]hh:mm
    if (len(s) >= 6 and s[-6] in "+-" and s[-3] == ":" and
        s[-5:-3].isdigit() and s[-2:].isdigit()):
        sign = (s[-6] == "+") and 1 or -1
        hours = int(s[-5:-3])
        minutes = int(s[-2:])
        return -sign * (hours * 60 + minutes) * 60, s[:-6]

    return None, s

def strdate(string, format, defaults=None):
    """parse a localized time string and return a (unixtime, offset) tuple.
    if the string cannot be parsed, ValueError is raised."""
    if defaults is None:
        defaults = {}

    # NOTE: unixtime = localunixtime + offset
    offset, date = parsetimezone(string)

    # add missing elements from defaults
    usenow = False # default to using biased defaults
    for part in ("S", "M", "HI", "d", "mb", "yY"): # decreasing specificity
        part = pycompat.bytestr(part)
        found = [True for p in part if ("%"+p) in format]
        if not found:
            date += "@" + defaults[part][usenow]
            format += "@%" + part[0]
        else:
            # We've found a specific time element, less specific time
            # elements are relative to today
            usenow = True

    timetuple = time.strptime(encoding.strfromlocal(date),
                              encoding.strfromlocal(format))
    localunixtime = int(calendar.timegm(timetuple))
    if offset is None:
        # local timezone
        unixtime = int(time.mktime(timetuple))
        offset = unixtime - localunixtime
    else:
        unixtime = localunixtime + offset
    return unixtime, offset

def parsedate(date, formats=None, bias=None):
    """parse a localized date/time and return a (unixtime, offset) tuple.

    The date may be a "unixtime offset" string or in one of the specified
    formats. If the date already is a (unixtime, offset) tuple, it is returned.

    >>> parsedate(b' today ') == parsedate(
    ...     datetime.date.today().strftime('%b %d').encode('ascii'))
    True
    >>> parsedate(b'yesterday ') == parsedate(
    ...     (datetime.date.today() - datetime.timedelta(days=1)
    ...      ).strftime('%b %d').encode('ascii'))
    True
    >>> now, tz = makedate()
    >>> strnow, strtz = parsedate(b'now')
    >>> (strnow - now) < 1
    True
    >>> tz == strtz
    True
    """
    if bias is None:
        bias = {}
    if not date:
        return 0, 0
    if isinstance(date, tuple) and len(date) == 2:
        return date
    if not formats:
        formats = defaultdateformats
    date = date.strip()

    if date == 'now' or date == _('now'):
        return makedate()
    if date == 'today' or date == _('today'):
        date = datetime.date.today().strftime(r'%b %d')
        date = encoding.strtolocal(date)
    elif date == 'yesterday' or date == _('yesterday'):
        date = (datetime.date.today() -
                datetime.timedelta(days=1)).strftime(r'%b %d')
        date = encoding.strtolocal(date)

    try:
        when, offset = map(int, date.split(' '))
    except ValueError:
        # fill out defaults
        now = makedate()
        defaults = {}
        for part in ("d", "mb", "yY", "HI", "M", "S"):
            # this piece is for rounding the specific end of unknowns
            b = bias.get(part)
            if b is None:
                if part[0:1] in "HMS":
                    b = "00"
                else:
                    b = "0"

            # this piece is for matching the generic end to today's date
            n = datestr(now, "%" + part[0:1])

            defaults[part] = (b, n)

        for format in formats:
            try:
                when, offset = strdate(date, format, defaults)
            except (ValueError, OverflowError):
                pass
            else:
                break
        else:
            raise error.ParseError(
                _('invalid date: %r') % pycompat.bytestr(date))
    # validate explicit (probably user-specified) date and
    # time zone offset. values must fit in signed 32 bits for
    # current 32-bit linux runtimes. timezones go from UTC-12
    # to UTC+14
    if when < -0x80000000 or when > 0x7fffffff:
        raise error.ParseError(_('date exceeds 32 bits: %d') % when)
    if offset < -50400 or offset > 43200:
        raise error.ParseError(_('impossible time zone offset: %d') % offset)
    return when, offset

def matchdate(date):
    """Return a function that matches a given date match specifier

    Formats include:

    '{date}' match a given date to the accuracy provided

    '<{date}' on or before a given date

    '>{date}' on or after a given date

    >>> p1 = parsedate(b"10:29:59")
    >>> p2 = parsedate(b"10:30:00")
    >>> p3 = parsedate(b"10:30:59")
    >>> p4 = parsedate(b"10:31:00")
    >>> p5 = parsedate(b"Sep 15 10:30:00 1999")
    >>> f = matchdate(b"10:30")
    >>> f(p1[0])
    False
    >>> f(p2[0])
    True
    >>> f(p3[0])
    True
    >>> f(p4[0])
    False
    >>> f(p5[0])
    False
    """

    def lower(date):
        d = {'mb': "1", 'd': "1"}
        return parsedate(date, extendeddateformats, d)[0]

    def upper(date):
        d = {'mb': "12", 'HI': "23", 'M': "59", 'S': "59"}
        for days in ("31", "30", "29"):
            try:
                d["d"] = days
                return parsedate(date, extendeddateformats, d)[0]
            except error.ParseError:
                pass
        d["d"] = "28"
        return parsedate(date, extendeddateformats, d)[0]

    date = date.strip()

    if not date:
        raise error.Abort(_("dates cannot consist entirely of whitespace"))
    elif date[0] == "<":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '<DATE'"))
        when = upper(date[1:])
        return lambda x: x <= when
    elif date[0] == ">":
        if not date[1:]:
            raise error.Abort(_("invalid day spec, use '>DATE'"))
        when = lower(date[1:])
        return lambda x: x >= when
    elif date[0] == "-":
        try:
            days = int(date[1:])
        except ValueError:
            raise error.Abort(_("invalid day spec: %s") % date[1:])
        if days < 0:
            raise error.Abort(_("%s must be nonnegative (see 'hg help dates')")
                % date[1:])
        when = makedate()[0] - days * 3600 * 24
        return lambda x: x >= when
    elif " to " in date:
        a, b = date.split(" to ")
        start, stop = lower(a), upper(b)
        return lambda x: x >= start and x <= stop
    else:
        start, stop = lower(date), upper(date)
        return lambda x: x >= start and x <= stop