look_for_directives_in

# File lib/rdoc/parser/ruby.rb, line 1724
  def look_for_directives_in(context, comment)
    preprocess = RDoc::Markup::PreProcess.new(@file_name,
                                              @options.rdoc_include)

    preprocess.handle(comment) do |directive, param|
      case directive
      when 'enddoc' then
        throw :enddoc
      when 'main' then
        @options.main_page = param
        ''
      when 'method', 'singleton-method' then
        false # ignore
      when 'section' then
        context.set_current_section(param, comment)
        comment.replace ''
        break
      when 'startdoc' then
        context.start_doc
        context.force_documentation = true
        ''
      when 'stopdoc' then
        context.stop_doc
        ''
      when 'title' then
        @options.title = param
        ''
      else
        warn "Unrecognized directive '#{directive}'"
        false
      end
    end

    remove_private_comments(comment)
  end