# File lib/mail/parsers/rfc2822.rb, line 1441
    def _nt_quoted_domain
      start_index = index
      if node_cache[:quoted_domain].has_key?(index)
        cached = node_cache[:quoted_domain][index]
        @index = cached.interval.end if cached
        return cached
      end

      i0 = index
      r1 = _nt_qdcontent
      if r1
        r0 = r1
      else
        i2, s2 = index, []
        if has_terminal?("\\", false, index)
          r3 = instantiate_node(SyntaxNode,input, index...(index + 1))
          @index += 1
        else
          terminal_parse_failure("\\")
          r3 = nil
        end
        s2 << r3
        if r3
          r4 = _nt_text
          s2 << r4
        end
        if s2.last
          r2 = instantiate_node(SyntaxNode,input, i2...index, s2)
          r2.extend(QuotedDomain0)
        else
          @index = i2
          r2 = nil
        end
        if r2
          r0 = r2
        else
          @index = i0
          r0 = nil
        end
      end

      node_cache[:quoted_domain][start_index] = r0

      r0
    end