Time.rfc2822

# File tmp/rubies/ruby-3.1.3/lib/time.rb, line 505
def rfc2822(date)
  if /\A\s*
      (?:(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun)\s*,\s*)?
      (\d{1,2})\s+
      (Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+
      (\d{2,})\s+
      (\d{2})\s*
      :\s*(\d{2})\s*
      (?::\s*(\d{2}))?\s+
      ([+-]\d{4}|
       UT|GMT|EST|EDT|CST|CDT|MST|MDT|PST|PDT|[A-IK-Z])/ix =~ date
    # Since RFC 2822 permit comments, the regexp has no right anchor.
    day = $1.to_i
    mon = MonthValue[$2.upcase]
    year = $3.to_i
    short_year_p = $3.length <= 3
    hour = $4.to_i
    min = $5.to_i
    sec = $6 ? $6.to_i : 0
    zone = $7

    if short_year_p
      # following year completion is compliant with RFC 2822.
      year = if year < 50
               2000 + year
             else
               1900 + year
             end
    end

    off = zone_offset(zone)
    year, mon, day, hour, min, sec =
      apply_offset(year, mon, day, hour, min, sec, off)
    t = self.utc(year, mon, day, hour, min, sec)
    force_zone!(t, zone, off)
    t
  else
    raise ArgumentError.new("not RFC 2822 compliant date: #{date.inspect}")
  end
end