# File lib/mail/parsers/rfc2822.rb, line 1014
    def _nt_atom
      start_index = index
      if node_cache[:atom].has_key?(index)
        cached = node_cache[:atom][index]
        @index = cached.interval.end if cached
        return cached
      end

      i0, s0 = index, []
      r2 = _nt_CFWS
      if r2
        r1 = r2
      else
        r1 = instantiate_node(SyntaxNode,input, index...index)
      end
      s0 << r1
      if r1
        s3, i3 = [], index
        loop do
          r4 = _nt_atext
          if r4
            s3 << r4
          else
            break
          end
        end
        if s3.empty?
          @index = i3
          r3 = nil
        else
          r3 = instantiate_node(SyntaxNode,input, i3...index, s3)
        end
        s0 << r3
        if r3
          r6 = _nt_CFWS
          if r6
            r5 = r6
          else
            r5 = instantiate_node(SyntaxNode,input, index...index)
          end
          s0 << r5
        end
      end
      if s0.last
        r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
        r0.extend(Atom0)
      else
        @index = i0
        r0 = nil
      end

      node_cache[:atom][start_index] = r0

      r0
    end