gen_an_index

# File lib/rdoc/generators/html_generator.rb, line 1318
    def gen_an_index(collection, title, template, filename)
      template = TemplatePage.new(RDoc::Page::FR_INDEX_BODY, template)
      res = []
      collection.sort.each do |f|
        if f.document_self
          res << { "href" => f.path, "name" => f.index_name }
        end
      end

      values = {
        "entries"    => res,
        'list_title' => CGI.escapeHTML(title),
        'index_url'  => main_url,
        'charset'    => @options.charset,
        'style_url'  => style_url('', @options.css),
      }

      File.open(filename, "w") do |f|
        template.write_html_on(f, values)
      end
    end