# File lib/mail/parsers/content_disposition.rb, line 122
    def _nt_disposition_type
      start_index = index
      if node_cache[:disposition_type].has_key?(index)
        cached = node_cache[:disposition_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[iI]', true, index)
        r2 = true
        @index += 1
      else
        r2 = nil
      end
      s1 << r2
      if r2
        if has_terminal?('\G[nN]', true, index)
          r3 = true
          @index += 1
        else
          r3 = nil
        end
        s1 << r3
        if r3
          if has_terminal?('\G[lL]', true, index)
            r4 = true
            @index += 1
          else
            r4 = nil
          end
          s1 << r4
          if r4
            if has_terminal?('\G[iI]', true, index)
              r5 = true
              @index += 1
            else
              r5 = nil
            end
            s1 << r5
            if r5
              if has_terminal?('\G[nN]', true, index)
                r6 = true
                @index += 1
              else
                r6 = nil
              end
              s1 << r6
              if r6
                if has_terminal?('\G[eE]', true, index)
                  r7 = true
                  @index += 1
                else
                  r7 = nil
                end
                s1 << r7
              end
            end
          end
        end
      end
      if s1.last
        r1 = instantiate_node(SyntaxNode,input, i1...index, s1)
        r1.extend(DispositionType0)
      else
        @index = i1
        r1 = nil
      end
      if r1
        r0 = r1
      else
        i8, s8 = index, []
        if has_terminal?('\G[aA]', true, index)
          r9 = true
          @index += 1
        else
          r9 = nil
        end
        s8 << r9
        if r9
          if has_terminal?('\G[tT]', true, index)
            r10 = true
            @index += 1
          else
            r10 = nil
          end
          s8 << r10
          if r10
            if has_terminal?('\G[tT]', true, index)
              r11 = true
              @index += 1
            else
              r11 = nil
            end
            s8 << r11
            if r11
              if has_terminal?('\G[aA]', true, index)
                r12 = true
                @index += 1
              else
                r12 = nil
              end
              s8 << r12
              if r12
                if has_terminal?('\G[cC]', true, index)
                  r13 = true
                  @index += 1
                else
                  r13 = nil
                end
                s8 << r13
                if r13
                  if has_terminal?('\G[hH]', true, index)
                    r14 = true
                    @index += 1
                  else
                    r14 = nil
                  end
                  s8 << r14
                  if r14
                    if has_terminal?('\G[mM]', true, index)
                      r15 = true
                      @index += 1
                    else
                      r15 = nil
                    end
                    s8 << r15
                    if r15
                      if has_terminal?('\G[eE]', true, index)
                        r16 = true
                        @index += 1
                      else
                        r16 = nil
                      end
                      s8 << r16
                      if r16
                        if has_terminal?('\G[nN]', true, index)
                          r17 = true
                          @index += 1
                        else
                          r17 = nil
                        end
                        s8 << r17
                        if r17
                          if has_terminal?('\G[tT]', true, index)
                            r18 = true
                            @index += 1
                          else
                            r18 = nil
                          end
                          s8 << r18
                        end
                      end
                    end
                  end
                end
              end
            end
          end
        end
        if s8.last
          r8 = instantiate_node(SyntaxNode,input, i8...index, s8)
          r8.extend(DispositionType1)
        else
          @index = i8
          r8 = nil
        end
        if r8
          r0 = r8
        else
          r19 = _nt_extension_token
          if r19
            r0 = r19
          else
            if has_terminal?('', false, index)
              r20 = instantiate_node(SyntaxNode,input, index...(index + 0))
              @index += 0
            else
              terminal_parse_failure('')
              r20 = nil
            end
            if r20
              r0 = r20
            else
              @index = i0
              r0 = nil
            end
          end
        end
      end

      node_cache[:disposition_type][start_index] = r0

      r0
    end