# File lib/mail/parsers/content_type.rb, line 52
    def _nt_content_type
      start_index = index
      if node_cache[:content_type].has_key?(index)
        cached = node_cache[:content_type][index]
        if cached
          cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
          @index = cached.interval.end
        end
        return cached
      end

      i0, s0 = index, []
      r1 = _nt_main_type
      s0 << r1
      if r1
        if has_terminal?("/", false, index)
          r2 = instantiate_node(SyntaxNode,input, index...(index + 1))
          @index += 1
        else
          terminal_parse_failure("/")
          r2 = nil
        end
        s0 << r2
        if r2
          r3 = _nt_sub_type
          s0 << r3
          if r3
            s4, i4 = [], index
            loop do
              i5, s5 = index, []
              r6 = _nt_CFWS
              s5 << r6
              if r6
                s7, i7 = [], index
                loop do
                  if has_terminal?(";", false, index)
                    r8 = instantiate_node(SyntaxNode,input, index...(index + 1))
                    @index += 1
                  else
                    terminal_parse_failure(";")
                    r8 = nil
                  end
                  if r8
                    s7 << r8
                  else
                    break
                  end
                end
                r7 = instantiate_node(SyntaxNode,input, i7...index, s7)
                s5 << r7
                if r7
                  r9 = _nt_parameter
                  s5 << r9
                  if r9
                    r10 = _nt_CFWS
                    s5 << r10
                  end
                end
              end
              if s5.last
                r5 = instantiate_node(SyntaxNode,input, i5...index, s5)
                r5.extend(ContentType0)
              else
                @index = i5
                r5 = nil
              end
              if r5
                s4 << r5
              else
                break
              end
            end
            r4 = instantiate_node(SyntaxNode,input, i4...index, s4)
            s0 << r4
          end
        end
      end
      if s0.last
        r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
        r0.extend(ContentType1)
        r0.extend(ContentType2)
      else
        @index = i0
        r0 = nil
      end

      node_cache[:content_type][start_index] = r0

      r0
    end