# File lib/mail/parsers/rfc2822.rb, line 588
    def _nt_ctext
      start_index = index
      if node_cache[:ctext].has_key?(index)
        cached = node_cache[:ctext][index]
        if cached
          cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
          @index = cached.interval.end
        end
        return cached
      end

      i0 = index
      r1 = _nt_NO_WS_CTL
      if r1
        r0 = r1
      else
        if has_terminal?('\G[\\x21-\\x27]', true, index)
          r2 = true
          @index += 1
        else
          r2 = nil
        end
        if r2
          r0 = r2
        else
          if has_terminal?('\G[\\x2a-\\x5b]', true, index)
            r3 = true
            @index += 1
          else
            r3 = nil
          end
          if r3
            r0 = r3
          else
            if has_terminal?('\G[\\x5d-\\x7e]', true, index)
              r4 = true
              @index += 1
            else
              r4 = nil
            end
            if r4
              r0 = r4
            else
              @index = i0
              r0 = nil
            end
          end
        end
      end

      node_cache[:ctext][start_index] = r0

      r0
    end