class Mail::Parsers::EnvelopeFromParser

def parse(s)
  envelope_from = EnvelopeFromStruct.new
  if s.blank?
    return envelope_from
  end
  actions, error = Ragel.parse(:envelope_from, s)
  if error
    raise Mail::Field::ParseError.new(Mail::EnvelopeFromElement, s, error)
  end
  address_s = ctime_date_s = nil
  envelope_from = EnvelopeFromStruct.new
  actions.each_slice(2) do |action_id, p|
    action = Mail::Parsers::Ragel::ACTIONS[action_id]
    case action
    # Address
    when :address_s then address_s = p
    when :address_e
      envelope_from.address = s[address_s..(p-1)].rstrip
    # ctime_date
    when :ctime_date_s then ctime_date_s = p
    when :ctime_date_e
      envelope_from.ctime_date = s[ctime_date_s..(p-1)]
    # ignored actions
    when :angle_addr_s, :comment_e, :comment_s,
         :domain_e, :domain_s, :local_dot_atom_e,
         :local_dot_atom_pre_comment_e,
         :local_dot_atom_pre_comment_s,
         :local_dot_atom_s, :qstr_e, :qstr_s
      nil
    else
      raise Mail::Field::ParseError.new(Mail::EnvelopeFromElement, s, "Failed to process unknown action: #{action}")
    end
  end
  envelope_from
end