skip_optional_do_after_expression

# File lib/rdoc/parser/ruby.rb, line 1520
  def skip_optional_do_after_expression
    skip_tkspace false
    tk = get_tk
    case tk
    when TkLPAREN, TkfLPAREN then
      end_token = TkRPAREN
    else
      end_token = TkNL
    end

    b_nest = 0
    nest = 0
    @scanner.instance_eval { @continue = false }

    loop do
      case tk
      when TkSEMICOLON then
        break if b_nest.zero?
      when TkLPAREN, TkfLPAREN then
        nest += 1
      when TkBEGIN then
        b_nest += 1
      when TkEND then
        b_nest -= 1
      when TkDO
        break if nest.zero?
      when end_token then
        if end_token == TkRPAREN
          nest -= 1
          break if @scanner.lex_state == EXPR_END and nest.zero?
        else
          break unless @scanner.continue
        end
      when nil then
        break
      end
      tk = get_tk
    end

    skip_tkspace false

    get_tk if TkDO === peek_tk
  end