jupyterlab/packages/notebook-extension/src/index.ts

// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.

import {
  ILayoutRestorer, JupyterLab, JupyterLabPlugin
} from '@jupyterlab/application';

import {
  Dialog, ICommandPalette, MainAreaWidget, showDialog
} from '@jupyterlab/apputils';

import {
  CodeCell
} from '@jupyterlab/cells';

import {
  CodeEditor, IEditorServices
} from '@jupyterlab/codeeditor';

import {
  ISettingRegistry, IStateDB, PageConfig, URLExt, uuid
} from '@jupyterlab/coreutils';

import  {
  IFileBrowserFactory
} from '@jupyterlab/filebrowser';

import {
  ILauncher
} from '@jupyterlab/launcher';

import {
  IMainMenu, IEditMenu, IFileMenu, IHelpMenu, IKernelMenu, IRunMenu, IViewMenu
} from '@jupyterlab/mainmenu';

import {
  CellTools, ICellTools, INotebookTracker, NotebookActions,
  NotebookModelFactory, NotebookPanel, NotebookTracker, NotebookWidgetFactory,
  StaticNotebook
} from '@jupyterlab/notebook';

import {
  IRenderMimeRegistry
} from '@jupyterlab/rendermime';

import {
  ServiceManager
} from '@jupyterlab/services';

import {
  ReadonlyJSONObject
} from '@phosphor/coreutils';

import {
  Message, MessageLoop
} from '@phosphor/messaging';

import {
  Menu
} from '@phosphor/widgets';


/**
 * The command IDs used by the notebook plugin.
 */
namespace CommandIDs {
  export
  const createNew = 'notebook:create-new';

  export
  const interrupt = 'notebook:interrupt-kernel';

  export
  const restart = 'notebook:restart-kernel';

  export
  const restartClear = 'notebook:restart-clear-output';

  export
  const restartRunAll = 'notebook:restart-run-all';

  export
  const reconnectToKernel = 'notebook:reconnect-to-kernel';

  export
  const changeKernel = 'notebook:change-kernel';

  export
  const createConsole = 'notebook:create-console';

  export
  const createOutputView = 'notebook:create-output-view';

  export
  const clearAllOutputs = 'notebook:clear-all-cell-outputs';

  export
  const closeAndShutdown = 'notebook:close-and-shutdown';

  export
  const trust = 'notebook:trust';

  export
  const exportToFormat = 'notebook:export-to-format';

  export
  const run = 'notebook:run-cell';

  export
  const runAndAdvance = 'notebook:run-cell-and-select-next';

  export
  const runAndInsert = 'notebook:run-cell-and-insert-below';

  export
  const runInConsole = 'notebook:run-in-console';

  export
  const runAll = 'notebook:run-all-cells';

  export
  const runAllAbove = 'notebook:run-all-above';

  export
  const runAllBelow = 'notebook:run-all-below';

  export
  const toCode = 'notebook:change-cell-to-code';

  export
  const toMarkdown = 'notebook:change-cell-to-markdown';

  export
  const toRaw = 'notebook:change-cell-to-raw';

  export
  const cut = 'notebook:cut-cell';

  export
  const copy = 'notebook:copy-cell';

  export
  const pasteAbove = 'notebook:paste-cell-above';

  export
  const pasteBelow = 'notebook:paste-cell-below';

  export
  const pasteAndReplace = 'notebook:paste-and-replace-cell';

  export
  const moveUp = 'notebook:move-cell-up';

  export
  const moveDown = 'notebook:move-cell-down';

  export
  const clearOutputs = 'notebook:clear-cell-output';

  export
  const deleteCell = 'notebook:delete-cell';

  export
  const insertAbove = 'notebook:insert-cell-above';

  export
  const insertBelow = 'notebook:insert-cell-below';

  export
  const selectAbove = 'notebook:move-cursor-up';

  export
  const selectBelow = 'notebook:move-cursor-down';

  export
  const extendAbove = 'notebook:extend-marked-cells-above';

  export
  const extendBelow = 'notebook:extend-marked-cells-below';

  export
  const selectAll = 'notebook:select-all';

  export
  const deselectAll = 'notebook:deselect-all';

  export
  const editMode = 'notebook:enter-edit-mode';

  export
  const merge = 'notebook:merge-cells';

  export
  const split = 'notebook:split-cell-at-cursor';

  export
  const commandMode = 'notebook:enter-command-mode';

  export
  const toggleAllLines = 'notebook:toggle-all-cell-line-numbers';

  export
  const undoCellAction = 'notebook:undo-cell-action';

  export
  const redoCellAction = 'notebook:redo-cell-action';

  export
  const markdown1 = 'notebook:change-cell-to-heading-1';

  export
  const markdown2 = 'notebook:change-cell-to-heading-2';

  export
  const markdown3 = 'notebook:change-cell-to-heading-3';

  export
  const markdown4 = 'notebook:change-cell-to-heading-4';

  export
  const markdown5 = 'notebook:change-cell-to-heading-5';

  export
  const markdown6 = 'notebook:change-cell-to-heading-6';

  export
  const hideCode = 'notebook:hide-cell-code';

  export
  const showCode = 'notebook:show-cell-code';

  export
  const hideAllCode = 'notebook:hide-all-cell-code';

  export
  const showAllCode = 'notebook:show-all-cell-code';

  export
  const hideOutput = 'notebook:hide-cell-outputs';

  export
  const showOutput = 'notebook:show-cell-outputs';

  export
  const hideAllOutputs = 'notebook:hide-all-cell-outputs';

  export
  const showAllOutputs = 'notebook:show-all-cell-outputs';

  export
  const enableOutputScrolling = 'notebook:enable-output-scrolling';

  export
  const disableOutputScrolling = 'notebook:disable-output-scrolling';

  export
  const saveWithView = 'notebook:save-with-view';
}


/**
 * The class name for the notebook icon from the default theme.
 */
const NOTEBOOK_ICON_CLASS = 'jp-NotebookIcon';

/**
 * The name of the factory that creates notebooks.
 */
const FACTORY = 'Notebook';

/**
 * The allowed Export To ... formats and their human readable labels.
 */
const EXPORT_TO_FORMATS = [
  { 'format': 'html', 'label': 'HTML' },
  { 'format': 'latex', 'label': 'LaTeX' },
  { 'format': 'markdown', 'label': 'Markdown' },
  { 'format': 'pdf', 'label': 'PDF' },
  { 'format': 'rst', 'label': 'ReStructured Text' },
  { 'format': 'script', 'label': 'Executable Script' },
  { 'format': 'slides', 'label': 'Reveal.js Slides' }
];


/**
 * The notebook widget tracker provider.
 */
const trackerPlugin: JupyterLabPlugin<INotebookTracker> = {
  id: '@jupyterlab/notebook-extension:tracker',
  provides: INotebookTracker,
  requires: [
    IMainMenu,
    ICommandPalette,
    NotebookPanel.IContentFactory,
    IEditorServices,
    ILayoutRestorer,
    IRenderMimeRegistry,
    ISettingRegistry
  ],
  optional: [IFileBrowserFactory, ILauncher],
  activate: activateNotebookHandler,
  autoStart: true
};


/**
 * The notebook cell factory provider.
 */
const factory: JupyterLabPlugin<NotebookPanel.IContentFactory> = {
  id: '@jupyterlab/notebook-extension:factory',
  provides: NotebookPanel.IContentFactory,
  requires: [IEditorServices],
  autoStart: true,
  activate: (app: JupyterLab, editorServices: IEditorServices) => {
    let editorFactory = editorServices.factoryService.newInlineEditor;
    return new NotebookPanel.ContentFactory({ editorFactory });
  }
};

/**
 * The cell tools extension.
 */
const tools: JupyterLabPlugin<ICellTools> = {
  activate: activateCellTools,
  provides: ICellTools,
  id: '@jupyterlab/notebook-extension:tools',
  autoStart: true,
  requires: [INotebookTracker, IEditorServices, IStateDB]
};


/**
 * Export the plugins as default.
 */
const plugins: JupyterLabPlugin<any>[] = [factory, trackerPlugin, tools];
export default plugins;


/**
 * Activate the cell tools extension.
 */
function activateCellTools(app: JupyterLab, tracker: INotebookTracker, editorServices: IEditorServices, state: IStateDB): Promise<ICellTools> {
  const id = 'cell-tools';
  const celltools = new CellTools({ tracker });
  const activeCellTool = new CellTools.ActiveCellTool();
  const slideShow = CellTools.createSlideShowSelector();
  const nbConvert = CellTools.createNBConvertSelector();
  const editorFactory = editorServices.factoryService.newInlineEditor;
  const metadataEditor = new CellTools.MetadataEditorTool({ editorFactory });

  // Create message hook for triggers to save to the database.
  const hook = (sender: any, message: Message): boolean => {
    switch (message.type) {
      case 'activate-request':
        state.save(id, { open: true });
        break;
      case 'after-hide':
      case 'close-request':
        state.remove(id);
        break;
      default:
        break;
    }
    return true;
  };

  celltools.title.label = 'Cell Tools';
  celltools.id = id;
  celltools.addItem({ tool: activeCellTool, rank: 1 });
  celltools.addItem({ tool: slideShow, rank: 2 });
  celltools.addItem({ tool: nbConvert, rank: 3 });
  celltools.addItem({ tool: metadataEditor, rank: 4 });
  MessageLoop.installMessageHook(celltools, hook);

  // Wait until the application has finished restoring before rendering.
  Promise.all([state.fetch(id), app.restored]).then(([args]) => {
    const open = !!(args && (args as ReadonlyJSONObject)['open'] as boolean);

    // After initial restoration, check if the cell tools should render.
    if (tracker.size) {
      app.shell.addToLeftArea(celltools);
      if (open) {
        app.shell.activateById(celltools.id);
      }
    }

    // For all subsequent widget changes, check if the cell tools should render.
    app.shell.currentChanged.connect((sender, args) => {
      // If there are any open notebooks, add cell tools to the side panel if
      // it is not already there.
      if (tracker.size) {
        if (!celltools.isAttached) {
          app.shell.addToLeftArea(celltools);
        }
        return;
      }
      // If there are no notebooks, close cell tools.
      celltools.close();
    });
  });

  return Promise.resolve(celltools);
}


/**
 * Activate the notebook handler extension.
 */
function activateNotebookHandler(app: JupyterLab, mainMenu: IMainMenu, palette: ICommandPalette, contentFactory: NotebookPanel.IContentFactory, editorServices: IEditorServices, restorer: ILayoutRestorer, rendermime: IRenderMimeRegistry, settingRegistry: ISettingRegistry, browserFactory: IFileBrowserFactory | null, launcher: ILauncher | null): INotebookTracker {
  const services = app.serviceManager;
  // An object for tracking the current notebook settings.
  let editorConfig = StaticNotebook.defaultEditorConfig;
  const factory = new NotebookWidgetFactory({
    name: FACTORY,
    fileTypes: ['notebook'],
    modelName: 'notebook',
    defaultFor: ['notebook'],
    preferKernel: true,
    canStartKernel: true,
    rendermime: rendermime,
    contentFactory,
    editorConfig,
    mimeTypeService: editorServices.mimeTypeService
  });
  const { commands, restored } = app;
  const tracker = new NotebookTracker({ namespace: 'notebook' });

  // Handle state restoration.
  restorer.restore(tracker, {
    command: 'docmanager:open',
    args: panel => ({ path: panel.context.path, factory: FACTORY }),
    name: panel => panel.context.path,
    when: services.ready
  });

  let registry = app.docRegistry;
  registry.addModelFactory(new NotebookModelFactory({}));
  registry.addWidgetFactory(factory);

  addCommands(app, services, tracker);
  populatePalette(palette);

  let id = 0; // The ID counter for notebook panels.

  factory.widgetCreated.connect((sender, widget) => {
    // If the notebook panel does not have an ID, assign it one.
    widget.id = widget.id || `notebook-${++id}`;
    widget.title.icon = NOTEBOOK_ICON_CLASS;
    // Notify the instance tracker if restore data needs to update.
    widget.context.pathChanged.connect(() => { tracker.save(widget); });
    // Add the notebook panel to the tracker.
    tracker.add(widget);
  });

  /**
   * Update the setting values.
   */
  function updateConfig(settings: ISettingRegistry.ISettings): void {
    let cached =
      settings.get('codeCellConfig').composite as Partial<CodeEditor.IConfig>;
    let code = { ...StaticNotebook.defaultEditorConfig.code };
    Object.keys(code).forEach((key: keyof CodeEditor.IConfig) => {
      code[key] = (cached[key] === null || cached[key] === undefined)
                  ? code[key]
                  : cached[key];
    });
    cached =
      settings.get('markdownCellConfig').composite as Partial<CodeEditor.IConfig>;
    let markdown = { ...StaticNotebook.defaultEditorConfig.markdown };
    Object.keys(markdown).forEach((key: keyof CodeEditor.IConfig) => {
      markdown[key] = (cached[key] === null || cached[key] === undefined)
                      ? markdown[key]
                      : cached[key];
    });
    cached =
      settings.get('rawCellConfig').composite as Partial<CodeEditor.IConfig>;
    let raw = { ...StaticNotebook.defaultEditorConfig.raw };
    Object.keys(raw).forEach((key: keyof CodeEditor.IConfig) => {
      raw[key] = (cached[key] === null || cached[key] === undefined)
                 ? raw[key]
                 : cached[key];
    });
    factory.editorConfig = editorConfig = { code, markdown, raw };
  }

  /**
   * Update the settings of the current tracker instances.
   */
  function updateTracker(): void {
    tracker.forEach(widget => { widget.content.editorConfig = editorConfig; });
  }

  // Fetch the initial state of the settings.
  Promise.all([settingRegistry.load(trackerPlugin.id), restored]).then(([settings]) => {
    updateConfig(settings);
    updateTracker();
    settings.changed.connect(() => {
      updateConfig(settings);
      updateTracker();
    });
  }).catch((reason: Error) => {
    console.error(reason.message);
    updateTracker();
  });

  // Add main menu notebook menu.
  populateMenus(app, mainMenu, tracker);

  // Utility function to create a new notebook.
  const createNew = (cwd: string, kernelName?: string) => {
    return commands.execute(
      'docmanager:new-untitled', { path: cwd, type: 'notebook' }
    ).then(model => {
      return commands.execute('docmanager:open', {
        path: model.path, factory: FACTORY,
        kernel: { name: kernelName }
      });
    });
  };

  // Add a command for creating a new notebook.
  commands.addCommand(CommandIDs.createNew, {
    label: args => {
      const kernelName = args['kernelName'] as string || '';
      if (args['isLauncher'] && args['kernelName']) {
        return services.specs.kernelspecs[kernelName].display_name;
      }
      return 'Notebook';
    },
    caption: 'Create a new notebook',
    iconClass: args => args['isLauncher'] ? '' : 'jp-NotebookIcon',
    execute: args => {
      const cwd = args['cwd'] || browserFactory ?
        browserFactory.defaultBrowser.model.path : '';
      const kernelName = args['kernelName'] as string || '';
      return createNew(cwd, kernelName);
    }
  });


  // Add a launcher item if the launcher is available.
  if (launcher) {
    services.ready.then(() => {
      const specs = services.specs;
      const baseUrl = PageConfig.getBaseUrl();

      for (let name in specs.kernelspecs) {
        let rank = name === specs.default ? 0 : Infinity;
        let kernelIconUrl = specs.kernelspecs[name].resources['logo-64x64'];
        if (kernelIconUrl) {
          let index = kernelIconUrl.indexOf('kernelspecs');
          kernelIconUrl = baseUrl + kernelIconUrl.slice(index);
        }
        launcher.add({
          command: CommandIDs.createNew,
          args: { isLauncher: true, kernelName: name },
          category: 'Notebook',
          rank,
          kernelIconUrl
        });
      }
    });
  }

  // Cell context menu groups
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook .jp-Cell',
    rank: 0
  });
  app.contextMenu.addItem({
    command: CommandIDs.cut,
    selector: '.jp-Notebook .jp-Cell',
    rank: 1
  });
  app.contextMenu.addItem({
    command: CommandIDs.copy,
    selector: '.jp-Notebook .jp-Cell',
    rank: 2
  });
  app.contextMenu.addItem({
    command: CommandIDs.pasteBelow,
    selector: '.jp-Notebook .jp-Cell',
    rank: 3
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook .jp-Cell',
    rank: 4
  });
  app.contextMenu.addItem({
    command: CommandIDs.deleteCell,
    selector: '.jp-Notebook .jp-Cell',
    rank: 5
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook .jp-Cell',
    rank: 6
  });
  app.contextMenu.addItem({
    command: CommandIDs.split,
    selector: '.jp-Notebook .jp-Cell',
    rank: 7
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook .jp-Cell',
    rank: 8
  });

  // CodeCell context menu groups
  app.contextMenu.addItem({
    command: CommandIDs.createOutputView,
    selector: '.jp-Notebook .jp-CodeCell',
    rank: 9
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook .jp-CodeCell',
    rank: 10
  });
  app.contextMenu.addItem({
    command: CommandIDs.clearOutputs,
    selector: '.jp-Notebook .jp-CodeCell',
    rank: 11
  });


  // Notebook context menu groups
  app.contextMenu.addItem({
    command: CommandIDs.clearAllOutputs,
    selector: '.jp-Notebook',
    rank: 0
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook',
    rank: 1
  });
  app.contextMenu.addItem({
    command: CommandIDs.enableOutputScrolling,
    selector: '.jp-Notebook',
    rank: 2
  });
  app.contextMenu.addItem({
    command: CommandIDs.disableOutputScrolling,
    selector: '.jp-Notebook',
    rank: 3
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook',
    rank: 4
  });
  app.contextMenu.addItem({
    command: CommandIDs.undoCellAction,
    selector: '.jp-Notebook',
    rank: 5
  });
  app.contextMenu.addItem({
    command: CommandIDs.redoCellAction,
    selector: '.jp-Notebook',
    rank: 6
  });
  app.contextMenu.addItem({
    command: CommandIDs.restart,
    selector: '.jp-Notebook',
    rank: 7
  });
  app.contextMenu.addItem({
    type: 'separator',
    selector: '.jp-Notebook',
    rank: 8
  });
  app.contextMenu.addItem({
    command: CommandIDs.createConsole,
    selector: '.jp-Notebook',
    rank: 9
  });

  return tracker;
}



/**
 * Add the notebook commands to the application's command registry.
 */
function addCommands(app: JupyterLab, services: ServiceManager, tracker: NotebookTracker): void {
  const { commands, shell } = app;

  // Get the current widget and activate unless the args specify otherwise.
  function getCurrent(args: ReadonlyJSONObject): NotebookPanel | null {
    const widget = tracker.currentWidget;
    const activate = args['activate'] !== false;

    if (activate && widget) {
      shell.activateById(widget.id);
    }

    return widget;
  }

  /**
   * Whether there is an active notebook.
   */
  function isEnabled(): boolean {
    return tracker.currentWidget !== null &&
           tracker.currentWidget === app.shell.currentWidget;
  }

  /**
   * Whether there is an notebook active, with a single selected cell.
   */
  function isEnabledAndSingleSelected(): boolean {
    if (!isEnabled()) { return false; }
    const { content } = tracker.currentWidget;
    const index = content.activeCellIndex;
    // If there are selections that are not the active cell,
    // this command is confusing, so disable it.
    for (let i = 0; i < content.widgets.length; ++i) {
      if (content.isSelected(content.widgets[i]) && i !== index) {
        return false;
      }
    }
    return true;
  }

  commands.addCommand(CommandIDs.runAndAdvance, {
    label: 'Run Selected Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.runAndAdvance(content, context.session);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.run, {
    label: 'Run Selected Cells and Don\'t Advance',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.run(content, context.session);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.runAndInsert, {
    label: 'Run Selected Cells and Insert Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.runAndInsert(content, context.session);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.runInConsole, {
    label: 'Run Selected Text or Current Line in Console',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        let cell = content.activeCell;
        let path = context.path;
        // ignore action in non-code cell
        if (!cell || cell.model.type !== 'code') {
            return Promise.resolve(void 0);
        }

        let code = '';
        const editor = cell.editor;
        const selection = editor.getSelection();
        const { start, end } = selection;
        let selected = start.column !== end.column || start.line !== end.line;

        if (selected) {
          // Get the selected code from the editor.
          const start = editor.getOffsetAt(selection.start);
          const end = editor.getOffsetAt(selection.end);
          code = editor.model.value.text.substring(start, end);
        } else {
          // no selection, submit whole line and advance
          code = editor.getLine(selection.start.line);
          const cursor = editor.getCursorPosition();
          if (cursor.line + 1 !== editor.lineCount) {
            editor.setCursorPosition({ line: cursor.line + 1, column: cursor.column });
          }
        }
        // open a console, create if needed
        if (code) {
          editor.focus();
          return commands.execute('console:open', {
              path,
              insertMode: 'split-bottom',
              activate: false
            }).then((panel) => {
              // TODO: If the panel was created, the editor loses focus.
              // if (!editor.hasFocus) {
              //   editor.focus();
              // }
              commands.execute('console:inject', { activate: false, code, path });
            }).catch((error) => {
              console.log(error);
              return Promise.resolve(void 0);
            });
        } else {
          return Promise.resolve(void 0);
        }
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.runAll, {
    label: 'Run All Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.runAll(content, context.session);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.runAllAbove, {
    label: 'Run All Above Selected Cell',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.runAllAbove(content, context.session);
      }
    },
    isEnabled: () => {
      // Can't run above if there are multiple cells selected,
      // or if we are at the top of the notebook.
      return isEnabledAndSingleSelected() &&
             tracker.currentWidget.content.activeCellIndex !== 0;
    }
  });
  commands.addCommand(CommandIDs.runAllBelow, {
    label: 'Run Selected Cell and All Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.runAllBelow(content, context.session);
      }
    },
    isEnabled: () => {
      // Can't run below if there are multiple cells selected,
      // or if we are at the bottom of the notebook.
      return isEnabledAndSingleSelected() &&
             tracker.currentWidget.content.activeCellIndex !==
             tracker.currentWidget.content.widgets.length - 1;
    }
  });
  commands.addCommand(CommandIDs.restart, {
    label: 'Restart Kernel…',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return current.session.restart();
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.closeAndShutdown, {
    label: 'Close and Shutdown',
    execute: args => {
      const current = getCurrent(args);

      if (!current) {
        return;
      }

      const fileName = current.title.label;

      return showDialog({
        title: 'Shutdown the notebook?',
        body: `Are you sure you want to close "${fileName}"?`,
        buttons: [Dialog.cancelButton(), Dialog.warnButton()]
      }).then(result => {
        if (result.button.accept) {
          return current.context.session.shutdown()
            .then(() => { current.dispose(); });
        }
      });
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.trust, {
    label: () => 'Trust Notebook',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content } = current;

        return NotebookActions.trust(content).then(() => context.save());
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.exportToFormat, {
    label: args => {
        const formatLabel = (args['label']) as string;

        return (args['isPalette'] ? 'Export Notebook to ' : '') + formatLabel;
    },
    execute: args => {
      const current = getCurrent(args);

      if (!current) {
        return;
      }

      const notebookPath = URLExt.encodeParts(current.context.path);
      const url = URLExt.join(
        services.serverSettings.baseUrl,
        'nbconvert',
        (args['format']) as string,
        notebookPath
      ) + '?download=true';
      const child = window.open('', '_blank');
      const { context } = current;

      if (context.model.dirty && !context.model.readOnly) {
        return context.save().then(() => { child.location.assign(url); });
      }

      return new Promise<void>((resolve) => {
        child.location.assign(url);
        resolve(undefined);
      });
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.restartClear, {
    label: 'Restart Kernel and Clear All Outputs…',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { content, session } = current;

        return session.restart()
          .then(() => { NotebookActions.clearAllOutputs(content); });
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.restartRunAll, {
    label: 'Restart Kernel and Run All Cells…',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        const { context, content, session } = current;

        return session.restart().then(restarted => {
          if (restarted) {
            NotebookActions.runAll(content, context.session);
          }
          return restarted;
        });
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.clearAllOutputs, {
    label: 'Clear All Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.clearAllOutputs(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.clearOutputs, {
    label: 'Clear Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.clearOutputs(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.interrupt, {
    label: 'Interrupt Kernel',
    execute: args => {
      const current = getCurrent(args);

      if (!current) {
        return;
      }

      const kernel = current.context.session.kernel;

      if (kernel) {
        return kernel.interrupt();
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.toCode, {
    label: 'Change to Code Cell Type',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.changeCellType(current.content, 'code');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.toMarkdown, {
    label: 'Change to Markdown Cell Type',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.changeCellType(current.content, 'markdown');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.toRaw, {
    label: 'Change to Raw Cell Type',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.changeCellType(current.content, 'raw');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.cut, {
    label: 'Cut Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.cut(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.copy, {
    label: 'Copy Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.copy(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.pasteBelow, {
    label: 'Paste Cells Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.paste(current.content, 'below');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.pasteAbove, {
    label: 'Paste Cells Above',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.paste(current.content, 'above');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.pasteAndReplace, {
    label: 'Paste Cells and Replace',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.paste(current.content, 'replace');
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.deleteCell, {
    label: 'Delete Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.deleteCells(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.split, {
    label: 'Split Cell',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.splitCell(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.merge, {
    label: 'Merge Selected Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.mergeCells(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.insertAbove, {
    label: 'Insert Cell Above',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.insertAbove(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.insertBelow, {
    label: 'Insert Cell Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.insertBelow(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.selectAbove, {
    label: 'Select Cell Above',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.selectAbove(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.selectBelow, {
    label: 'Select Cell Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.selectBelow(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.extendAbove, {
    label: 'Extend Selection Above',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.extendSelectionAbove(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.extendBelow, {
    label: 'Extend Selection Below',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.extendSelectionBelow(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.selectAll, {
    label: 'Select All Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.selectAll(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.deselectAll, {
    label: 'Deselect All Cells',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.deselectAll(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.moveUp, {
    label: 'Move Cells Up',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.moveUp(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.moveDown, {
    label: 'Move Cells Down',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.moveDown(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.toggleAllLines, {
    label: 'Toggle All Line Numbers',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.toggleAllLineNumbers(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.commandMode, {
    label: 'Enter Command Mode',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        current.content.mode = 'command';
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.editMode, {
    label: 'Enter Edit Mode',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        current.content.mode = 'edit';
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.undoCellAction, {
    label: 'Undo Cell Operation',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.undo(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.redoCellAction, {
    label: 'Redo Cell Operation',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.redo(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.changeKernel, {
    label: 'Change Kernel…',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return current.context.session.selectKernel();
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.reconnectToKernel, {
    label: 'Reconnect To Kernel',
    execute: args => {
      const current = getCurrent(args);

      if (!current) {
        return;
      }

      const kernel = current.context.session.kernel;

      if (kernel) {
        return kernel.reconnect();
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.createOutputView, {
    label: 'Create New View for Output',
    execute: args => {
      // Clone the OutputArea
      const current = getCurrent({ ...args, activate: false });
      const nb = current.content;
      const content = (nb.activeCell as CodeCell).cloneOutputArea();
      // Create a MainAreaWidget
      const widget = new MainAreaWidget({ content });
      widget.id = `LinkedOutputView-${uuid()}`;
      widget.title.label = 'Output View';
      widget.title.icon = NOTEBOOK_ICON_CLASS;
      widget.title.caption = current.title.label ? `For Notebook: ${current.title.label}` : 'For Notebook:';
      widget.addClass('jp-LinkedOutputView');
      current.context.addSibling(
        widget, { ref: current.id, mode: 'split-bottom' }
      );

      // Remove the output view if the parent notebook is closed.
      nb.disposed.connect(widget.dispose);
    },
    isEnabled: isEnabledAndSingleSelected
  });
  commands.addCommand(CommandIDs.createConsole, {
    label: 'New Console for Notebook',
    execute: args => {
      const current = getCurrent({ ...args, activate: false });
      const widget = tracker.currentWidget;

      if (!current || !widget) {
        return;
      }

      const options: ReadonlyJSONObject = {
        path: widget.context.path,
        preferredLanguage: widget.context.model.defaultKernelLanguage,
        activate: args['activate'],
        ref: current.id,
        insertMode: 'split-bottom'
      };

      return commands.execute('console:create', options);
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown1, {
    label: 'Change to Heading 1',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 1);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown2, {
    label: 'Change to Heading 2',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 2);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown3, {
    label: 'Change to Heading 3',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 3);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown4, {
    label: 'Change to Heading 4',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 4);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown5, {
    label: 'Change to Heading 5',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 5);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.markdown6, {
    label: 'Change to Heading 6',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.setMarkdownHeader(current.content, 6);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.hideCode, {
    label: 'Collapse Selected Code',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.hideCode(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.showCode, {
    label: 'Expand Selected Code',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.showCode(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.hideAllCode, {
    label: 'Collapse All Code',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.hideAllCode(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.showAllCode, {
    label: 'Expand All Code',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.showAllCode(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.hideOutput, {
    label: 'Collapse Selected Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.hideOutput(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.showOutput, {
    label: 'Expand Selected Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.showOutput(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.hideAllOutputs, {
    label: 'Collapse All Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.hideAllOutputs(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.showAllOutputs, {
    label: 'Expand All Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.showAllOutputs(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.enableOutputScrolling, {
    label: 'Enable Scrolling for Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.enableOutputScrolling(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.disableOutputScrolling, {
    label: 'Disable Scrolling for Outputs',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        return NotebookActions.disableOutputScrolling(current.content);
      }
    },
    isEnabled
  });
  commands.addCommand(CommandIDs.saveWithView, {
    label: 'Save Notebook with View State',
    execute: args => {
      const current = getCurrent(args);

      if (current) {
        NotebookActions.persistViewState(current.content);
        app.commands.execute('docmanager:save');
      }
    },
    isEnabled
  });
}


/**
 * Populate the application's command palette with notebook commands.
 */
function populatePalette(palette: ICommandPalette): void {
  let category = 'Notebook Operations';
  [
    CommandIDs.createNew,
    CommandIDs.interrupt,
    CommandIDs.restart,
    CommandIDs.restartClear,
    CommandIDs.restartRunAll,
    CommandIDs.runAll,
    CommandIDs.runAllAbove,
    CommandIDs.runAllBelow,
    CommandIDs.selectAll,
    CommandIDs.deselectAll,
    CommandIDs.clearAllOutputs,
    CommandIDs.toggleAllLines,
    CommandIDs.editMode,
    CommandIDs.commandMode,
    CommandIDs.changeKernel,
    CommandIDs.reconnectToKernel,
    CommandIDs.createConsole,
    CommandIDs.closeAndShutdown,
    CommandIDs.trust,
    CommandIDs.saveWithView
  ].forEach(command => { palette.addItem({ command, category }); });

  EXPORT_TO_FORMATS.forEach(exportToFormat => {
    let args = {
      'format': exportToFormat['format'],
      'label': exportToFormat['label'],
      'isPalette': true
    };
    palette.addItem({ command: CommandIDs.exportToFormat, category, args });
  });

  category = 'Notebook Cell Operations';
  [
    CommandIDs.run,
    CommandIDs.runAndAdvance,
    CommandIDs.runAndInsert,
    CommandIDs.runInConsole,
    CommandIDs.clearOutputs,
    CommandIDs.toCode,
    CommandIDs.toMarkdown,
    CommandIDs.toRaw,
    CommandIDs.cut,
    CommandIDs.copy,
    CommandIDs.pasteBelow,
    CommandIDs.pasteAbove,
    CommandIDs.pasteAndReplace,
    CommandIDs.deleteCell,
    CommandIDs.split,
    CommandIDs.merge,
    CommandIDs.insertAbove,
    CommandIDs.insertBelow,
    CommandIDs.selectAbove,
    CommandIDs.selectBelow,
    CommandIDs.extendAbove,
    CommandIDs.extendBelow,
    CommandIDs.moveDown,
    CommandIDs.moveUp,
    CommandIDs.undoCellAction,
    CommandIDs.redoCellAction,
    CommandIDs.markdown1,
    CommandIDs.markdown2,
    CommandIDs.markdown3,
    CommandIDs.markdown4,
    CommandIDs.markdown5,
    CommandIDs.markdown6,
    CommandIDs.hideCode,
    CommandIDs.showCode,
    CommandIDs.hideAllCode,
    CommandIDs.showAllCode,
    CommandIDs.hideOutput,
    CommandIDs.showOutput,
    CommandIDs.hideAllOutputs,
    CommandIDs.showAllOutputs,
    CommandIDs.enableOutputScrolling,
    CommandIDs.disableOutputScrolling
  ].forEach(command => { palette.addItem({ command, category }); });
}


/**
 * Populates the application menus for the notebook.
 */
function populateMenus(app: JupyterLab, mainMenu: IMainMenu, tracker: INotebookTracker): void {
  let { commands } = app;

  // Add undo/redo hooks to the edit menu.
  mainMenu.editMenu.undoers.add({
    tracker,
    undo: widget => { widget.content.activeCell.editor.undo(); },
    redo: widget => { widget.content.activeCell.editor.redo(); }
  } as IEditMenu.IUndoer<NotebookPanel>);

  // Add a clearer to the edit menu
  mainMenu.editMenu.clearers.add({
    tracker,
    noun: 'Outputs',
    pluralNoun: 'Outputs',
    clearCurrent: (current: NotebookPanel) => {
      return NotebookActions.clearOutputs(current.content);
    },
    clearAll: (current: NotebookPanel) => {
      return NotebookActions.clearAllOutputs(current.content);
    }
  } as IEditMenu.IClearer<NotebookPanel>);

  // Add new notebook creation to the file menu.
  mainMenu.fileMenu.newMenu.addGroup([{ command: CommandIDs.createNew }], 10);

  // Add a close and shutdown command to the file menu.
  mainMenu.fileMenu.closeAndCleaners.add({
    tracker,
    action: 'Shutdown',
    name: 'Notebook',
    closeAndCleanup: (current: NotebookPanel) => {
      const fileName = current.title.label;
      return showDialog({
        title: 'Shutdown the notebook?',
        body: `Are you sure you want to close "${fileName}"?`,
        buttons: [Dialog.cancelButton(), Dialog.warnButton()]
      }).then(result => {
        if (result.button.accept) {
          return current.context.session.shutdown()
            .then(() => { current.dispose(); });
        }
      });
    }
  } as IFileMenu.ICloseAndCleaner<NotebookPanel>);

  // Add a save with view command to the file menu.
  mainMenu.fileMenu.persistAndSavers.add({
    tracker,
    action: 'with View State',
    name: 'Notebook',
    persistAndSave: (current: NotebookPanel) => {
      NotebookActions.persistViewState(current.content);
      return app.commands.execute('docmanager:save');
    }
  } as IFileMenu.IPersistAndSave<NotebookPanel>);

  // Add a notebook group to the File menu.
  let exportTo = new Menu({ commands } );
  exportTo.title.label = 'Export Notebook As…';
  EXPORT_TO_FORMATS.forEach(exportToFormat => {
    exportTo.addItem({ command: CommandIDs.exportToFormat, args: exportToFormat });
  });
  const fileGroup = [
    { command: CommandIDs.trust },
    { type: 'submenu', submenu: exportTo } as Menu.IItemOptions
  ];
  mainMenu.fileMenu.addGroup(fileGroup, 10);

  // Add a kernel user to the Kernel menu
  mainMenu.kernelMenu.kernelUsers.add({
    tracker,
    interruptKernel: current => {
      let kernel = current.session.kernel;
      if (kernel) {
        return kernel.interrupt();
      }
      return Promise.resolve(void 0);
    },
    noun: 'All Outputs',
    restartKernel: current => current.session.restart(),
    restartKernelAndClear: current => {
      return current.session.restart().then(restarted => {
        if (restarted) {
          NotebookActions.clearAllOutputs(current.content);
        }
        return restarted;
      });
    },
    changeKernel: current => current.session.selectKernel(),
    shutdownKernel: current => current.session.shutdown(),
  } as IKernelMenu.IKernelUser<NotebookPanel>);

  // Add a console creator the the Kernel menu
  mainMenu.fileMenu.consoleCreators.add({
    tracker,
    name: 'Notebook',
    createConsole: current => {
      const options: ReadonlyJSONObject = {
        path: current.context.path,
        preferredLanguage: current.context.model.defaultKernelLanguage,
        activate: true,
        ref: current.id,
        insertMode: 'split-bottom'
      };
      return commands.execute('console:create', options);
    }
  } as IFileMenu.IConsoleCreator<NotebookPanel>);

  // Add some commands to the application view menu.
  const collapseGroup = [
    CommandIDs.hideCode,
    CommandIDs.hideOutput,
    CommandIDs.hideAllCode,
    CommandIDs.hideAllOutputs
  ].map(command => { return { command }; });
  mainMenu.viewMenu.addGroup(collapseGroup, 10);

  const expandGroup = [
    CommandIDs.showCode,
    CommandIDs.showOutput,
    CommandIDs.showAllCode,
    CommandIDs.showAllOutputs
  ].map(command => { return { command }; });
  mainMenu.viewMenu.addGroup(expandGroup, 11);

  // Add an IEditorViewer to the application view menu
  mainMenu.viewMenu.editorViewers.add({
    tracker,
    toggleLineNumbers: widget => {
      NotebookActions.toggleAllLineNumbers(widget.content);
    },
    lineNumbersToggled: widget => {
      const config = widget.content.editorConfig;
      return !!(config.code.lineNumbers && config.markdown.lineNumbers &&
        config.raw.lineNumbers);
    }
  } as IViewMenu.IEditorViewer<NotebookPanel>);

  // Add an ICodeRunner to the application run menu
  mainMenu.runMenu.codeRunners.add({
    tracker,
    noun: 'Cells',
    run: current => {
      const { context, content } = current;
      return NotebookActions.runAndAdvance(content, context.session)
      .then(() => void 0);
    },
    runAll: current => {
      const { context, content } = current;
      return NotebookActions.runAll(content, context.session)
      .then(() => void 0);
    },
    restartAndRunAll: current => {
      const { context, content } = current;
      return context.session.restart()
      .then(restarted => {
        if (restarted) {
          NotebookActions.runAll(content, context.session);
        }
        return restarted;
      });
    }
  } as IRunMenu.ICodeRunner<NotebookPanel>);

  // Add a run+insert and run+don't advance group to the run menu.
  const runExtras = [
    CommandIDs.runAndInsert,
    CommandIDs.run,
    CommandIDs.runInConsole,
  ].map(command => { return { command }; });

  // Add a run all above/below group to the run menu.
  const runAboveBelowGroup = [
    CommandIDs.runAllAbove,
    CommandIDs.runAllBelow
  ].map(command => { return { command }; });

  // Add commands to the application edit menu.
  const undoCellActionGroup = [
    CommandIDs.undoCellAction,
    CommandIDs.redoCellAction
  ].map(command => { return { command }; });

  const copyGroup = [
    CommandIDs.cut,
    CommandIDs.copy,
    CommandIDs.pasteBelow,
    CommandIDs.pasteAbove,
    CommandIDs.pasteAndReplace,
  ].map(command => { return { command }; });

  const selectGroup = [
    CommandIDs.selectAll,
    CommandIDs.deselectAll,
  ].map(command => { return { command }; });

  const splitMergeGroup = [
    CommandIDs.split,
    CommandIDs.merge
  ].map(command => { return { command }; });

  const moveCellsGroup = [
    CommandIDs.moveUp,
    CommandIDs.moveDown
  ].map(command => { return { command }; });


  mainMenu.editMenu.addGroup(undoCellActionGroup, 4);
  mainMenu.editMenu.addGroup(copyGroup, 5);
  mainMenu.editMenu.addGroup([{ command: CommandIDs.deleteCell }], 6);
  mainMenu.editMenu.addGroup(selectGroup, 7);
  mainMenu.editMenu.addGroup(moveCellsGroup, 8);
  mainMenu.editMenu.addGroup(splitMergeGroup, 9);
  mainMenu.runMenu.addGroup(runExtras, 10);
  mainMenu.runMenu.addGroup(runAboveBelowGroup, 11);

  // Add kernel information to the application help menu.
  mainMenu.helpMenu.kernelUsers.add({
    tracker,
    getKernel: current => current.session.kernel
  } as IHelpMenu.IKernelUser<NotebookPanel>);
}