# File lib/mail/parsers/content_type.rb, line 188
    def _nt_discrete_type
      start_index = index
      if node_cache[:discrete_type].has_key?(index)
        cached = node_cache[:discrete_type][index]
        if cached
          cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
          @index = cached.interval.end
        end
        return cached
      end

      i0 = index
      i1, s1 = index, []
      if has_terminal?('\G[tT]', true, index)
        r2 = true
        @index += 1
      else
        r2 = nil
      end
      s1 << r2
      if r2
        if has_terminal?('\G[eE]', true, index)
          r3 = true
          @index += 1
        else
          r3 = nil
        end
        s1 << r3
        if r3
          if has_terminal?('\G[xX]', true, index)
            r4 = true
            @index += 1
          else
            r4 = nil
          end
          s1 << r4
          if r4
            if has_terminal?('\G[tT]', true, index)
              r5 = true
              @index += 1
            else
              r5 = nil
            end
            s1 << r5
          end
        end
      end
      if s1.last
        r1 = instantiate_node(SyntaxNode,input, i1...index, s1)
        r1.extend(DiscreteType0)
      else
        @index = i1
        r1 = nil
      end
      if r1
        r0 = r1
      else
        i6, s6 = index, []
        if has_terminal?('\G[iI]', true, index)
          r7 = true
          @index += 1
        else
          r7 = nil
        end
        s6 << r7
        if r7
          if has_terminal?('\G[mM]', true, index)
            r8 = true
            @index += 1
          else
            r8 = nil
          end
          s6 << r8
          if r8
            if has_terminal?('\G[aA]', true, index)
              r9 = true
              @index += 1
            else
              r9 = nil
            end
            s6 << r9
            if r9
              if has_terminal?('\G[gG]', true, index)
                r10 = true
                @index += 1
              else
                r10 = nil
              end
              s6 << r10
              if r10
                if has_terminal?('\G[eE]', true, index)
                  r11 = true
                  @index += 1
                else
                  r11 = nil
                end
                s6 << r11
              end
            end
          end
        end
        if s6.last
          r6 = instantiate_node(SyntaxNode,input, i6...index, s6)
          r6.extend(DiscreteType1)
        else
          @index = i6
          r6 = nil
        end
        if r6
          r0 = r6
        else
          i12, s12 = index, []
          if has_terminal?('\G[aA]', true, index)
            r13 = true
            @index += 1
          else
            r13 = nil
          end
          s12 << r13
          if r13
            if has_terminal?('\G[uU]', true, index)
              r14 = true
              @index += 1
            else
              r14 = nil
            end
            s12 << r14
            if r14
              if has_terminal?('\G[dD]', true, index)
                r15 = true
                @index += 1
              else
                r15 = nil
              end
              s12 << r15
              if r15
                if has_terminal?('\G[iI]', true, index)
                  r16 = true
                  @index += 1
                else
                  r16 = nil
                end
                s12 << r16
                if r16
                  if has_terminal?('\G[oO]', true, index)
                    r17 = true
                    @index += 1
                  else
                    r17 = nil
                  end
                  s12 << r17
                end
              end
            end
          end
          if s12.last
            r12 = instantiate_node(SyntaxNode,input, i12...index, s12)
            r12.extend(DiscreteType2)
          else
            @index = i12
            r12 = nil
          end
          if r12
            r0 = r12
          else
            i18, s18 = index, []
            if has_terminal?('\G[vV]', true, index)
              r19 = true
              @index += 1
            else
              r19 = nil
            end
            s18 << r19
            if r19
              if has_terminal?('\G[iI]', true, index)
                r20 = true
                @index += 1
              else
                r20 = nil
              end
              s18 << r20
              if r20
                if has_terminal?('\G[dD]', true, index)
                  r21 = true
                  @index += 1
                else
                  r21 = nil
                end
                s18 << r21
                if r21
                  if has_terminal?('\G[eE]', true, index)
                    r22 = true
                    @index += 1
                  else
                    r22 = nil
                  end
                  s18 << r22
                  if r22
                    if has_terminal?('\G[oO]', true, index)
                      r23 = true
                      @index += 1
                    else
                      r23 = nil
                    end
                    s18 << r23
                  end
                end
              end
            end
            if s18.last
              r18 = instantiate_node(SyntaxNode,input, i18...index, s18)
              r18.extend(DiscreteType3)
            else
              @index = i18
              r18 = nil
            end
            if r18
              r0 = r18
            else
              i24, s24 = index, []
              if has_terminal?('\G[aA]', true, index)
                r25 = true
                @index += 1
              else
                r25 = nil
              end
              s24 << r25
              if r25
                if has_terminal?('\G[pP]', true, index)
                  r26 = true
                  @index += 1
                else
                  r26 = nil
                end
                s24 << r26
                if r26
                  if has_terminal?('\G[pP]', true, index)
                    r27 = true
                    @index += 1
                  else
                    r27 = nil
                  end
                  s24 << r27
                  if r27
                    if has_terminal?('\G[lL]', true, index)
                      r28 = true
                      @index += 1
                    else
                      r28 = nil
                    end
                    s24 << r28
                    if r28
                      if has_terminal?('\G[iI]', true, index)
                        r29 = true
                        @index += 1
                      else
                        r29 = nil
                      end
                      s24 << r29
                      if r29
                        if has_terminal?('\G[cC]', true, index)
                          r30 = true
                          @index += 1
                        else
                          r30 = nil
                        end
                        s24 << r30
                        if r30
                          if has_terminal?('\G[aA]', true, index)
                            r31 = true
                            @index += 1
                          else
                            r31 = nil
                          end
                          s24 << r31
                          if r31
                            if has_terminal?('\G[tT]', true, index)
                              r32 = true
                              @index += 1
                            else
                              r32 = nil
                            end
                            s24 << r32
                            if r32
                              if has_terminal?('\G[iI]', true, index)
                                r33 = true
                                @index += 1
                              else
                                r33 = nil
                              end
                              s24 << r33
                              if r33
                                if has_terminal?('\G[oO]', true, index)
                                  r34 = true
                                  @index += 1
                                else
                                  r34 = nil
                                end
                                s24 << r34
                                if r34
                                  if has_terminal?('\G[nN]', true, index)
                                    r35 = true
                                    @index += 1
                                  else
                                    r35 = nil
                                  end
                                  s24 << r35
                                end
                              end
                            end
                          end
                        end
                      end
                    end
                  end
                end
              end
              if s24.last
                r24 = instantiate_node(SyntaxNode,input, i24...index, s24)
                r24.extend(DiscreteType4)
              else
                @index = i24
                r24 = nil
              end
              if r24
                r0 = r24
              else
                r36 = _nt_extension_token
                if r36
                  r0 = r36
                else
                  @index = i0
                  r0 = nil
                end
              end
            end
          end
        end
      end

      node_cache[:discrete_type][start_index] = r0

      r0
    end