# File lib/syntax/convertors/html.rb, line 12
      def convert( text, pre=true )
        html = ""
        html << "<pre>" if pre
        regions = []
        @tokenizer.tokenize( text ) do |tok|
          value = html_escape(tok)
          case tok.instruction
            when :region_close then
              regions.pop
              html << "</span>"
            when :region_open then
              regions.push tok.group
              html << "<span class=\"#{tok.group}\">#{value}"
            else
              if tok.group == ( regions.last || :normal )
                html << value
              else
                html << "<span class=\"#{tok.group}\">#{value}</span>"
              end
          end
        end
        html << "</span>" while regions.pop
        html << "</pre>" if pre
        html
      end