class ActiveSupport::TimeZone

Time.zone.parse('22:30:00') # => Fri, 31 Dec 1999 22:30:00 HST -10:00
Time.zone.now # => Fri, 31 Dec 1999 14:00:00 HST -10:00

TimeZone#now:
If upper components are missing from the string, they are supplied from

Time.zone.parse('1999-12-31 14:00:00') # => Fri, 31 Dec 1999 14:00:00 HST -10:00
Time.zone = 'Hawaii' # => "Hawaii"

of +self+ from parsed string.
Method for creating new ActiveSupport::TimeWithZone instance in time zone

def parse(str, now=now())
  parts = Date._parse(str, false)
  return if parts.empty?
  time = Time.new(
    parts.fetch(:year, now.year),
    parts.fetch(:mon, now.month),
    parts.fetch(:mday, now.day),
    parts.fetch(:hour, 0),
    parts.fetch(:min, 0),
    parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
    parts.fetch(:offset, 0)
  )
  if parts[:offset]
    TimeWithZone.new(time.utc, self)
  else
    TimeWithZone.new(nil, self, time)
  end
end