Merge branch 'master' into replace-codemirror-with-monaco

src/Explorer/Notebook/MonacoEditor/MonacoEditor.tsx

@@ -0,0 +1,464 @@
+import { Channels } from "@nteract/messaging";
+import * as monaco from "./monaco";
+import * as React from "react";
+import { completionProvider } from "./completions/completionItemProvider";
+import { AppState, ContentRef } from "@nteract/core";
+import { connect } from "react-redux";
+import "./styles.css";
+import { LightThemeName, HCLightThemeName, DarkThemeName } from "./theme";
+// import { logger } from "src/common/localLogger";
+import { getCellMonacoLanguage } from "./selectors";
+// import { DocumentUri } from "./documentUri";
+
+export type IModelContentChangedEvent = monaco.editor.IModelContentChangedEvent;
+
+/**
+ * Initial props for Monaco received from agnostic component
+ */
+export interface IMonacoProps {
+  id: string;
+  contentRef: ContentRef;
+  modelUri?: monaco.Uri;
+  theme: monaco.editor.IStandaloneThemeData | monaco.editor.BuiltinTheme | string;
+  cellLanguageOverride?: string;
+  notebookLanguageOverride?: string;
+  readOnly?: boolean;
+  channels: Channels | undefined;
+  enableCompletion: boolean;
+  shouldRegisterDefaultCompletion?: boolean;
+  onChange: (value: string, event?: unknown) => void;
+  onFocusChange: (focus: boolean) => void;
+  onCursorPositionChange?: (selection: monaco.ISelection | null) => void;
+  onRegisterCompletionProvider?: (languageId: string) => void;
+  value: string;
+  editorFocused: boolean;
+  lineNumbers: boolean;
+
+  /** set height of editor to fit the specified number of lines in display */
+  numberOfLines?: number;
+
+  options?: monaco.editor.IEditorOptions;
+}
+
+/**
+ * Monaco specific props derived from State
+ */
+interface IMonacoStateProps {
+  language: string;
+}
+
+// Cache the custom theme data to avoid repeatly defining the custom theme
+let customThemeData: monaco.editor.IStandaloneThemeData;
+
+function getMonacoTheme(theme: monaco.editor.IStandaloneThemeData | monaco.editor.BuiltinTheme | string) {
+  if (typeof theme === "string") {
+    switch (theme) {
+      case "vs-dark":
+        return DarkThemeName;
+      case "hc-black":
+        return "hc-black";
+      case "vs":
+        return LightThemeName;
+      case "hc-light":
+        return HCLightThemeName;
+      default:
+        return LightThemeName;
+    }
+  } else if (theme === undefined || typeof theme === "undefined") {
+    return LightThemeName;
+  } else {
+    const themeName = "custom-vs";
+
+    // Skip redefining the same custom theme if it is the same theme data.
+    if (customThemeData !== theme) {
+      monaco.editor.defineTheme(themeName, theme);
+      customThemeData = theme;
+    }
+
+    return themeName;
+  }
+}
+
+const makeMapStateToProps = (initialState: AppState, initialProps: IMonacoProps) => {
+  const { id, contentRef } = initialProps;
+  const mapStateToProps = (state: AppState, ownProps: IMonacoProps & IMonacoStateProps) => {
+    return {
+      language: getCellMonacoLanguage(
+        state,
+        contentRef,
+        id,
+        ownProps.cellLanguageOverride,
+        ownProps.notebookLanguageOverride
+      )
+    };
+  };
+  return mapStateToProps;
+};
+
+/**
+ * Creates a MonacoEditor instance within the MonacoContainer div
+ */
+export class MonacoEditor extends React.Component<IMonacoProps & IMonacoStateProps> {
+  editor?: monaco.editor.IStandaloneCodeEditor;
+  editorContainerRef = React.createRef<HTMLDivElement>();
+  contentHeight?: number;
+  private cursorPositionListener?: monaco.IDisposable;
+
+  constructor(props: IMonacoProps & IMonacoStateProps) {
+    super(props);
+    this.onFocus = this.onFocus.bind(this);
+    this.onBlur = this.onBlur.bind(this);
+    this.calculateHeight = this.calculateHeight.bind(this);
+  }
+
+  onDidChangeModelContent(e: monaco.editor.IModelContentChangedEvent): void {
+    if (this.editor) {
+      if (this.props.onChange) {
+        this.props.onChange(this.editor.getValue(), e);
+      }
+
+      this.calculateHeight();
+    }
+  }
+
+  /**
+   * Adjust the height of editor
+   *
+   * @remarks
+   * The way to determine how many lines we should display in editor:
+   * If numberOfLines is not set or set to 0, we adjust the height to fit the content
+   * If numberOfLines is specified we respect that setting
+   */
+  calculateHeight(): void {
+    // Make sure we have an editor
+    if (!this.editor) {
+      return;
+    }
+
+    // Make sure we have a model
+    const model = this.editor.getModel();
+    if (!model) {
+      return;
+    }
+
+    if (this.editorContainerRef && this.editorContainerRef.current) {
+      const expectedLines = this.props.numberOfLines || model.getLineCount();
+      // The find & replace menu takes up 2 lines, that is why 2 line is set as the minimum number of lines
+      // TODO: we should either disable the find/replace menu or auto expand the editor when find/replace is triggerred.
+      const finalizedLines = Math.max(expectedLines, 1) + 1;
+      const lineHeight = this.editor.getConfiguration().lineHeight;
+
+      const contentHeight = finalizedLines * lineHeight;
+      if (this.contentHeight !== contentHeight) {
+        this.editorContainerRef.current.style.height = contentHeight + "px";
+        this.editor.layout();
+        this.contentHeight = contentHeight;
+      }
+    }
+  }
+
+  componentDidMount(): void {
+    if (this.editorContainerRef && this.editorContainerRef.current) {
+      // Register Jupyter completion provider if needed
+      this.registerCompletionProvider();
+
+      // Use Monaco model uri if provided. Otherwise, create a new model uri using editor id.
+      const uri = this.props.modelUri ? this.props.modelUri : monaco.Uri.file(this.props.id);
+
+      // Only create a new model if it does not exist. For example, when we double click on a markdown cell,
+      // an editor model is created for it. Once we go back to markdown preview mode that doesn't use the editor,
+      // double clicking on the markdown cell will again instantiate a monaco editor. In that case, we should
+      // rebind the previously created editor model for the markdown instead of recreating one. Monaco does not
+      // allow models to be recreated with the same uri.
+      let model = monaco.editor.getModel(uri);
+      if (!model) {
+        model = monaco.editor.createModel(this.props.value, this.props.language, uri);
+      }
+
+      // Create Monaco editor backed by a Monaco model.
+      this.editor = monaco.editor.create(this.editorContainerRef.current, {
+        // Following are the default settings
+        minimap: {
+          enabled: false
+        },
+        autoIndent: true,
+        overviewRulerLanes: 1,
+        scrollbar: {
+          useShadows: false,
+          verticalHasArrows: false,
+          horizontalHasArrows: false,
+          vertical: "hidden",
+          horizontal: "hidden",
+          verticalScrollbarSize: 0,
+          horizontalScrollbarSize: 0,
+          arrowSize: 30
+        },
+        scrollBeyondLastLine: false,
+        find: {
+          // TODO Need this?
+          // addExtraSpaceOnTop: false, // pops the editor out of alignment if turned on
+          seedSearchStringFromSelection: true, // default is true
+          autoFindInSelection: false // default is false
+        },
+        // Disable highlight current line, too much visual noise with it on.
+        // VS Code also has it disabled for their notebook experience.
+        renderLineHighlight: "none",
+
+        // Allow editor pop up widgets such as context menus, signature help, hover tips to be able to be
+        // displayed outside of the editor. Without this, the pop up widgets can be clipped.
+        fixedOverflowWidgets: true,
+
+        // Apply custom settings from configuration
+        ...this.props.options,
+
+        // Apply specific settings passed-in as direct props
+        model,
+        value: this.props.value,
+        language: this.props.language,
+        readOnly: this.props.readOnly,
+        lineNumbers: this.props.lineNumbers ? "on" : "off",
+        theme: getMonacoTheme(this.props.theme)
+      });
+
+      this.addEditorTopMargin();
+
+      // Ignore Ctrl + Enter
+      // tslint:disable-next-line no-bitwise
+      this.editor.addCommand(
+        monaco.KeyMod.CtrlCmd | monaco.KeyCode.Enter,
+        () => {
+          // Do nothing. This is handled elsewhere, we just don't want the editor to put the newline.
+        },
+        undefined
+      );
+      // TODO Add right context
+
+      this.toggleEditorOptions(this.props.editorFocused);
+
+      if (this.props.editorFocused) {
+        if (!this.editor.hasTextFocus()) {
+          // Bring browser focus to the editor if text not already in focus
+          this.editor.focus();
+        }
+        this.registerCursorListener();
+      }
+
+      // TODO: Need to remove the event listener when the editor is disposed, or we have a memory leak here.
+      //       The same applies to the other event listeners below
+      // Adds listener under the resize window event which calls the resize method
+      window.addEventListener("resize", this.resize.bind(this));
+
+      // Adds listeners for undo and redo actions emitted from the toolbar
+      this.editorContainerRef.current.addEventListener("undo", () => {
+        if (this.editor) {
+          this.editor.trigger("undo-event", "undo", {});
+        }
+      });
+      this.editorContainerRef.current.addEventListener("redo", () => {
+        if (this.editor) {
+          this.editor.trigger("redo-event", "redo", {});
+        }
+      });
+
+      this.editor.onDidChangeModelContent(this.onDidChangeModelContent.bind(this));
+      this.editor.onDidFocusEditorText(this.onFocus);
+      this.editor.onDidBlurEditorText(this.onBlur);
+      this.calculateHeight();
+
+      // FIXME: This might need further investigation as the props value should be respected in construction
+      // The following is a mitigation measure till that time
+      // Ensures that the source contents of the editor (value) is consistent with the state of the editor
+      this.editor.setValue(this.props.value);
+    }
+  }
+
+  addEditorTopMargin(): void {
+    if (this.editor) {
+      // Monaco editor doesn't have margins
+      // https://github.com/notable/notable/issues/551
+      // This is a workaround to add an editor area 12px padding at the top
+      // so that cursors rendered by collab decorators could be visible without being cut.
+      this.editor.changeViewZones(changeAccessor => {
+        const domNode = document.createElement("div");
+        changeAccessor.addZone({
+          afterLineNumber: 0,
+          heightInPx: 12,
+          domNode
+        });
+      });
+    }
+  }
+
+  /**
+   * Tells editor to check the surrounding container size and resize itself appropriately
+   */
+  resize(): void {
+    if (this.editor && this.props.editorFocused) {
+      this.editor.layout();
+    }
+  }
+
+  componentDidUpdate(): void {
+    if (!this.editor) {
+      return;
+    }
+
+    const { value, channels, /* language, contentRef, id,*/ editorFocused, theme } = this.props;
+
+    // Ensures that the source contents of the editor (value) is consistent with the state of the editor
+    if (this.editor.getValue() !== value) {
+      this.editor.setValue(value);
+    }
+
+    completionProvider.setChannels(channels);
+
+    // Register Jupyter completion provider if needed
+    this.registerCompletionProvider();
+
+    /*
+    // Apply new model to the editor when the language is changed.
+    const model = this.editor.getModel();
+    if (model && language && model.getModeId() !== language) {
+      const newUri = DocumentUri.createCellUri(contentRef, id, language);
+      if (!monaco.editor.getModel(newUri)) {
+        // Save the cursor position before we set new model.
+        const position = this.editor.getPosition();
+
+        // Set new model targeting the changed language.
+        this.editor.setModel(monaco.editor.createModel(value, language, newUri));
+        this.addEditorTopMargin();
+
+        // Restore cursor position to new model.
+        if (position) {
+          this.editor.setPosition(position);
+        }
+
+        // Dispose of the old model in a seperate event. We cannot dispose of the model within the
+        // componentDidUpdate method or else the editor will throw an exception. Zero in the timeout field
+        // means execute immediately but in a seperate next event.
+        setTimeout(() => model.dispose(), 0);
+      }
+    }
+    */
+
+    if (theme) {
+      monaco.editor.setTheme(getMonacoTheme(theme));
+    }
+
+    // In the multi-tabs scenario, when the notebook is hidden by setting "display:none",
+    // Any state update propagated here would cause a UI re-layout, monaco-editor will then recalculate
+    // and set its height to 5px.
+    // To work around that issue, we skip updating the UI when parent element's offsetParent is null (which
+    // indicate an ancient element is hidden by display set to none)
+    // We may revisit this when we get to refactor for multi-notebooks.
+    if (!this.editorContainerRef.current?.offsetParent) {
+      return;
+    }
+
+    // Set focus
+    if (editorFocused && !this.editor.hasTextFocus()) {
+      this.editor.focus();
+    }
+
+    // Tells the editor pane to check if its container has changed size and fill appropriately
+    this.editor.layout();
+  }
+
+  componentWillUnmount(): void {
+    if (this.editor) {
+      try {
+        const model = this.editor.getModel();
+        if (model) {
+          model.dispose();
+        }
+
+        this.editor.dispose();
+      } catch (err) {
+        console.error(`Error occurs in disposing editor: ${JSON.stringify(err)}`);
+      }
+    }
+  }
+
+  render(): JSX.Element {
+    return (
+      <div className="monaco-container">
+        <div ref={this.editorContainerRef} id={`editor-${this.props.id}`} />
+      </div>
+    );
+  }
+
+  /**
+   * Register default kernel-based completion provider.
+   * @param language Language
+   */
+  registerDefaultCompletionProvider(language: string): void {
+    // onLanguage event is emitted only once per language when language is first time needed.
+    monaco.languages.onLanguage(language, () => {
+      monaco.languages.registerCompletionItemProvider(language, completionProvider);
+    });
+  }
+
+  private onFocus() {
+    this.props.onFocusChange(true);
+    this.toggleEditorOptions(true);
+    this.registerCursorListener();
+  }
+
+  private onBlur() {
+    this.props.onFocusChange(false);
+    this.toggleEditorOptions(false);
+    this.unregisterCursorListener();
+  }
+
+  private registerCursorListener() {
+    if (this.editor && this.props.onCursorPositionChange) {
+      const selection = this.editor.getSelection();
+      this.props.onCursorPositionChange(selection);
+
+      if (!this.cursorPositionListener) {
+        this.cursorPositionListener = this.editor.onDidChangeCursorSelection(event =>
+          this.props.onCursorPositionChange!(event.selection)
+        );
+      }
+    }
+  }
+
+  private unregisterCursorListener() {
+    if (this.cursorPositionListener) {
+      this.cursorPositionListener.dispose();
+      this.cursorPositionListener = undefined;
+    }
+  }
+
+  /**
+   * Toggle editor options based on if the editor is in active state (i.e. focused).
+   * When the editor is not active, we want to deactivate some of the visual noise.
+   * @param isActive Whether editor is active.
+   */
+  private toggleEditorOptions(isActive: boolean) {
+    if (this.editor) {
+      this.editor.updateOptions({
+        matchBrackets: isActive,
+        occurrencesHighlight: isActive,
+        renderIndentGuides: isActive
+      });
+    }
+  }
+
+  /**
+   * Register language features for target language. Call before setting language type to model.
+   */
+  private registerCompletionProvider() {
+    const { enableCompletion, language, onRegisterCompletionProvider, shouldRegisterDefaultCompletion } = this.props;
+
+    if (enableCompletion && language) {
+      if (onRegisterCompletionProvider) {
+        onRegisterCompletionProvider(language);
+      } else if (shouldRegisterDefaultCompletion) {
+        this.registerDefaultCompletionProvider(language);
+      }
+    }
+  }
+}
+
+export default connect<IMonacoStateProps, void, IMonacoProps, AppState>(makeMapStateToProps)(MonacoEditor);

src/Explorer/Notebook/MonacoEditor/completions/completionItemProvider.ts

@@ -0,0 +1,239 @@
+import * as monaco from "monaco-editor/esm/vs/editor/editor.api";
+// import * as monaco from "../monaco";
+import { Observable, Observer } from "rxjs";
+import { first, map } from "rxjs/operators";
+import { childOf, JupyterMessage, ofMessageType, Channels } from "@nteract/messaging";
+
+/**
+ * TODO: import from nteract when the changes under editor-base.ts are ported to nteract.
+ */
+import { CompletionResults, CompletionMatch, completionRequest, js_idx_to_char_idx } from "../editor-base";
+
+/**
+ * Jupyter to Monaco completion item kinds.
+ */
+const unknownJupyterKind = "<unknown>";
+const jupyterToMonacoCompletionItemKind = {
+  [unknownJupyterKind]: monaco.languages.CompletionItemKind.Field,
+  class: monaco.languages.CompletionItemKind.Class,
+  function: monaco.languages.CompletionItemKind.Function,
+  keyword: monaco.languages.CompletionItemKind.Keyword,
+  instance: monaco.languages.CompletionItemKind.Variable,
+  statement: monaco.languages.CompletionItemKind.Variable
+};
+
+/**
+ * Completion item provider.
+ */
+class CompletionItemProvider implements monaco.languages.CompletionItemProvider {
+  private channels: Channels | undefined;
+
+  /**
+   * Set Channels of Jupyter kernel.
+   * @param channels Channels of Jupyter kernel.
+   */
+  setChannels(channels: Channels | undefined) {
+    this.channels = channels;
+  }
+
+  /**
+   * Whether provider is connected to Jupyter kernel.
+   */
+  get isConnectedToKernel() {
+    return !!this.channels;
+  }
+
+  /**
+   * Additional characters to trigger completion other than Ctrl+Space.
+   */
+  get triggerCharacters() {
+    return [" ", "<", "/", ".", "="];
+  }
+
+  /**
+   * Get list of completion items at position of cursor.
+   * @param model Monaco editor text model.
+   * @param position Position of cursor.
+   */
+  async provideCompletionItems(model: monaco.editor.ITextModel, position: monaco.Position) {
+    // Convert to zero-based index
+    let cursorPos = model.getOffsetAt(position);
+    const code = model.getValue();
+    cursorPos = js_idx_to_char_idx(cursorPos, code);
+
+    // Get completions from Jupyter kernel if its Channels is connected
+    let items = [];
+    if (this.channels) {
+      try {
+        const message = completionRequest(code, cursorPos);
+        items = await this.codeCompleteObservable(this.channels, message, model).toPromise();
+      } catch (error) {
+        // Temporary log error to console until we settle on how we log in V3
+        // tslint:disable-next-line
+        console.error(error);
+      }
+    }
+
+    return Promise.resolve<monaco.languages.CompletionList>({
+      suggestions: items,
+      incomplete: false
+    });
+  }
+
+  /**
+   * Get list of completion items from Jupyter kernel.
+   * @param channels Channels of Jupyter kernel.
+   * @param message Jupyter message for completion request.
+   * @param model Text model.
+   */
+  private codeCompleteObservable(channels: Channels, message: JupyterMessage, model: monaco.editor.ITextModel) {
+    // Process completion response
+    const completion$ = channels.pipe(
+      childOf(message),
+      ofMessageType("complete_reply"),
+      map(entry => entry.content),
+      first(),
+      map(results => this.adaptToMonacoCompletions(results, model))
+    );
+
+    // Subscribe and send completion request message
+    return Observable.create((observer: Observer<unknown>) => {
+      const subscription = completion$.subscribe(observer);
+      channels.next(message);
+      return subscription;
+    });
+  }
+
+  /**
+   * Converts Jupyter completion result to list of Monaco completion items.
+   */
+  private adaptToMonacoCompletions(results: CompletionResults, model: monaco.editor.ITextModel) {
+    let range: monaco.IRange;
+    let percentCount = 0;
+    let matches = results ? results.matches : [];
+    if (results.metadata && results.metadata._jupyter_types_experimental) {
+      matches = results.metadata._jupyter_types_experimental as CompletionMatch[];
+    }
+    return matches.map((match: CompletionMatch, index: number) => {
+      if (typeof match === "string") {
+        const text = this.sanitizeText(match);
+        const filtered = this.getFilterText(text);
+        return {
+          kind: this.adaptToMonacoCompletionItemKind(unknownJupyterKind),
+          label: text,
+          insertText: text,
+          filterText: filtered,
+          sortText: this.getSortText(index)
+        } as monaco.languages.CompletionItem;
+      } else {
+        // We only need to get the range once as the range is the same for all completion items in the list.
+        if (!range) {
+          const start = model.getPositionAt(match.start);
+          const end = model.getPositionAt(match.end);
+          range = {
+            startLineNumber: start.lineNumber,
+            startColumn: start.column,
+            endLineNumber: end.lineNumber,
+            endColumn: end.column
+          };
+
+          // Get the range representing the text before the completion action was invoked.
+          // If the text starts with magics % indicator, we need to track how many of these indicators exist
+          // so that we ensure the insertion text only inserts the delta between what the user typed versus
+          // what is recommended by the completion. Without this, there will be extra % insertions.
+          // Example:
+          // User types %%p then suggestion list will recommend %%python, if we now commit the item then the
+          // final text in the editor becomes %%p%%python instead of %%python. This is why the tracking code
+          // below is needed. This behavior is only specific to the magics % indicators as Monaco does not
+          // handle % characters in their completion list well.
+          const rangeText = model.getValueInRange(range);
+          if (rangeText.startsWith("%%")) {
+            percentCount = 2;
+          } else if (rangeText.startsWith("%")) {
+            percentCount = 1;
+          }
+        }
+
+        const text = this.sanitizeText(match.text);
+        const filtered = this.getFilterText(text);
+        const insert = this.getInsertText(text, percentCount);
+        return {
+          kind: this.adaptToMonacoCompletionItemKind(match.type as keyof typeof jupyterToMonacoCompletionItemKind),
+          label: text,
+          insertText: percentCount > 0 ? insert : text,
+          filterText: filtered,
+          sortText: this.getSortText(index)
+        } as monaco.languages.CompletionItem;
+      }
+    });
+  }
+
+  /**
+   * Converts Jupyter completion item kind to Monaco completion item kind.
+   * @param kind Jupyter completion item kind.
+   */
+  private adaptToMonacoCompletionItemKind(kind: keyof typeof jupyterToMonacoCompletionItemKind) {
+    const result = jupyterToMonacoCompletionItemKind[kind];
+    return result ? result : jupyterToMonacoCompletionItemKind[unknownJupyterKind];
+  }
+
+  /**
+   * Remove everything before a dot. Jupyter completion results like to include all characters before
+   * the trigger character. For example, if user types "myarray.", we expect the completion results to
+   * show "append", "pop", etc. but for the actual case, it will show "myarray.append", "myarray.pop",
+   * etc. so we are going to sanitize the text.
+   * @param text Text of Jupyter completion item
+   */
+  private sanitizeText(text: string) {
+    const index = text.lastIndexOf(".");
+    return index > -1 && index < text.length - 1 ? text.substring(index + 1) : text;
+  }
+
+  /**
+   * Remove magics all % characters as Monaco doesn't like them for the filtering text.
+   * Without this, completion won't show magics match items.
+   * @param text Text of Jupyter completion item.
+   */
+  private getFilterText(text: string) {
+    return text.replace(/%/g, "");
+  }
+
+  /**
+   * Get insertion text handling what to insert for the magics case depending on what
+   * has already been typed.
+   * @param text Text of Jupyter completion item.
+   * @param percentCount Number of percent characters to remove
+   */
+  private getInsertText(text: string, percentCount: number) {
+    for (let i = 0; i < percentCount; i++) {
+      text = text.replace("%", "");
+    }
+    return text;
+  }
+
+  /**
+   * Maps numbers to strings, such that if a>b numerically, f(a)>f(b) lexicograhically.
+   * 1 -> "za", 26 -> "zz", 27 -> "zza", 28 -> "zzb", 52 -> "zzz", 53 ->"zzza"
+   * @param order Number to be converted to a sorting-string. order >= 0.
+   * @returns A string representing the order.
+   */
+  private getSortText(order: number): string {
+    order++;
+    const numCharacters = 26; // "z" - "a" + 1;
+    const div = Math.floor(order / numCharacters);
+
+    let sortText = "z";
+    for (let i = 0; i < div; i++) {
+      sortText += "z";
+    }
+
+    const remainder = order % numCharacters;
+    if (remainder > 0) {
+      sortText += String.fromCharCode(96 + remainder);
+    }
+    return sortText;
+  }
+}
+
+const completionProvider = new CompletionItemProvider();
+export { completionProvider };

src/Explorer/Notebook/MonacoEditor/converter.ts

@@ -0,0 +1,44 @@
+import Immutable from "immutable";
+import * as monaco from "./monaco";
+/**
+ * Code Mirror to Monaco constants.
+ */
+export enum Mode {
+  markdown = "markdown",
+  raw = "plaintext",
+  python = "python",
+  csharp = "csharp"
+}
+
+/**
+ * Maps Code Mirror mode to a valid Monaco Editor supported langauge
+ * defaults to plaintext if map not found.
+ * @param mode Code Mirror mode
+ * @returns Monaco language
+ */
+export function mapCodeMirrorModeToMonaco(mode: string | { name: string }): string {
+  let language = "";
+
+  // Parse codemirror mode object
+  if (typeof mode === "string") {
+    language = mode;
+  }
+  // Vanilla object
+  else if (typeof mode === "object" && mode.name) {
+    language = mode.name;
+  }
+  // Immutable Map
+  else if (Immutable.Map.isMap(mode) && mode.has("name")) {
+    language = mode.get("name");
+  }
+
+  // Need to handle "ipython" as a special case since it is not a registered language
+  if (language === "ipython") {
+    return Mode.python;
+  } else if (language === "text/x-csharp") {
+    return Mode.csharp;
+  } else if (monaco.languages.getEncodedLanguageId(language) > 0) {
+    return language;
+  }
+  return Mode.raw;
+}

src/Explorer/Notebook/MonacoEditor/editor-base.ts

@@ -0,0 +1,76 @@
+// Disable linting on file since we will be moving the code below to nteract which have different rules configured.
+// tslint:disable:variable-name
+// tslint:disable:interface-name
+
+/**
+ * TODO: Create new editor-base package in nteract repo and move all code below to new package.
+ */
+
+import { createMessage } from "@nteract/messaging";
+
+/**
+ * Jupyter messaging protocol's _jupyter_types_experimental completion result.
+ */
+interface CompletionResult {
+  end: number;
+  start: number;
+  type: string;
+  text: string;
+  displayText?: string;
+}
+
+/**
+ * Juptyer completion match item.
+ */
+export type CompletionMatch = string | CompletionResult;
+
+/**
+ * Jupyter messaging protocol's complete_reply response.
+ */
+export interface CompletionResults {
+  status: string;
+  cursor_start: number;
+  cursor_end: number;
+  matches: CompletionMatch[];
+  metadata?: {
+    _jupyter_types_experimental?: unknown;
+  };
+}
+
+/**
+ * Create Jupyter messaging protocol's complete_request message.
+ * @param code Code of editor.
+ * @param cursorPos cursor position represented in the Jupyter messaging protocol (character position)
+ */
+export const completionRequest = (code: string, cursorPos: number) =>
+  createMessage("complete_request", {
+    content: {
+      code,
+      cursor_pos: cursorPos
+    }
+  });
+
+/**
+ * JavaScript stores text as utf16 and string indices use "code units",
+ * which stores high-codepoint characters as "surrogate pairs",
+ * which occupy two indices in the JavaScript string.
+ * We need to translate cursor_pos in the protocol (in characters)
+ * to js offset (with surrogate pairs taking two spots).
+ * @param js_idx JavaScript index
+ * @param text Text
+ */
+export const js_idx_to_char_idx: (js_idx: number, text: string) => number = (js_idx: number, text: string): number => {
+  let char_idx: number = js_idx;
+  for (let i = 0; i + 1 < text.length && i < js_idx; i++) {
+    const char_code: number = text.charCodeAt(i);
+    // check for surrogate pair
+    if (char_code >= 0xd800 && char_code <= 0xdbff) {
+      const next_char_code: number = text.charCodeAt(i + 1);
+      if (next_char_code >= 0xdc00 && next_char_code <= 0xdfff) {
+        char_idx--;
+        i++;
+      }
+    }
+  }
+  return char_idx;
+};

src/Explorer/Notebook/MonacoEditor/monaco.ts

@@ -0,0 +1,10 @@
+export * from "monaco-editor/esm/vs/editor/editor.api";
+
+// /**
+//  * Set the custom worker url to workaround the cross-domain issue with creating web worker
+//  * See https://github.com/microsoft/monaco-editor/blob/master/docs/integrate-amd-cross.md for more details
+//  * This step has to be executed after a importing of monaco-editor once per chunk to make sure
+//  * the custom worker url overwrites the one from monaco-editor module itself.
+//  */
+// import { setMonacoWorkerUrl } from "./workerUrl";
+// setMonacoWorkerUrl();

src/Explorer/Notebook/MonacoEditor/selectors.ts

@@ -0,0 +1,67 @@
+import { AppState, ContentRef, selectors as nteractSelectors } from "@nteract/core";
+import { CellId } from "@nteract/commutable";
+import { Mode, mapCodeMirrorModeToMonaco } from "./converter";
+
+/**
+ * Returns the language to use for syntax highlighting and autocompletion in the Monaco Editor for a given cell, falling back to the notebook language if one for the cell is not defined.
+ */
+export const getCellMonacoLanguage = (
+  state: AppState,
+  contentRef: ContentRef,
+  cellId: CellId,
+  cellLanguageOverride?: string,
+  notebookLanguageOverride?: string
+): string => {
+  const model = nteractSelectors.model(state, { contentRef });
+  if (!model || model.type !== "notebook") {
+    throw new Error("Connected Editor components should not be used with non-notebook models");
+  }
+
+  const cell = nteractSelectors.notebook.cellById(model, { id: cellId });
+  if (!cell) {
+    throw new Error("Invalid cell id");
+  }
+
+  switch (cell.cell_type) {
+    case "markdown":
+      return Mode.markdown;
+    case "raw":
+      return Mode.raw;
+    case "code":
+      if (cellLanguageOverride) {
+        return mapCodeMirrorModeToMonaco(cellLanguageOverride);
+      } else {
+        // Fall back to notebook language if cell language isn't present.
+        return getNotebookMonacoLanguage(state, contentRef, notebookLanguageOverride);
+      }
+  }
+};
+
+/**
+ * Returns the language to use for syntax highlighting and autocompletion in the Monaco Editor for a given notebook.
+ */
+export const getNotebookMonacoLanguage = (
+  state: AppState,
+  contentRef: ContentRef,
+  notebookLanguageOverride?: string
+): string => {
+  const model = nteractSelectors.model(state, { contentRef });
+  if (!model || model.type !== "notebook") {
+    throw new Error("Connected Editor components should not be used with non-notebook models");
+  }
+
+  if (notebookLanguageOverride) {
+    return mapCodeMirrorModeToMonaco(notebookLanguageOverride);
+  }
+
+  const kernelRef = model.kernelRef;
+  let codeMirrorMode;
+  // Try to get the CodeMirror mode from the kernel.
+  if (kernelRef) {
+    codeMirrorMode = nteractSelectors.kernel(state, { kernelRef })?.info?.codemirrorMode;
+  }
+  // As a fallback, get the CodeMirror mode from the notebook itself.
+  codeMirrorMode = codeMirrorMode ?? nteractSelectors.notebook.codeMirrorMode(model);
+
+  return mapCodeMirrorModeToMonaco(codeMirrorMode);
+};

src/Explorer/Notebook/MonacoEditor/styles.css

@@ -0,0 +1,22 @@
+/*
+For the following components, we use the inherited width values from monaco-container.
+On resizing the browser, the width of monaco-container will be calculated
+and we just use the calculated width for the following components
+So we don't need to use Monaco editor's layout() function which is expensive operation and causes performance issues on resizing.
+*/
+/*
+TODO: These styles below are added for resizing perf improvement.
+Once the virtualization is implemented, we will revisit this later.
+ */
+.monaco-container .monaco-editor {
+  width: inherit !important;
+}
+
+.monaco-container .monaco-editor .overflow-guard {
+  width: inherit !important;
+}
+
+/* 26px is the left margin for .monaco-scrollable-element  */
+.monaco-container .monaco-editor .monaco-scrollable-element.editor-scrollable.vs {
+  width: calc(100% - 26px) !important;
+}

src/Explorer/Notebook/MonacoEditor/theme.ts

@@ -0,0 +1,75 @@
+import * as monaco from "./monaco";
+
+// TODO: move defineTheme calls to an initialization function
+
+/**
+ * The default light theme with customized background
+ */
+export const LightThemeName = "vs-light";
+
+/**
+ * Default monaco theme for light theme
+ */
+export const customMonacoLightTheme: monaco.editor.IStandaloneThemeData = {
+  base: "vs", // Derive from default light theme of Monaco
+  inherit: true,
+  rules: [],
+  colors: {
+    // We want Monaco background to use the same background for our themes.
+    // Without this, the Monaco light theme has a yellowish tone.
+    // Verified with UX that white meets all the accessbility requirements for light
+    // and high contrast light theme.
+    "editor.background": "#FFFFFF"
+  }
+};
+
+monaco.editor.defineTheme(LightThemeName, customMonacoLightTheme);
+
+/**
+ * The default dark theme with customized background
+ */
+export const DarkThemeName = "aznb-dark";
+
+/**
+ * Default monaco theme for dark theme
+ */
+export const customMonacoDarkTheme: monaco.editor.IStandaloneThemeData = {
+  base: "vs-dark", // Derive from default dark theme of Monaco
+  inherit: true,
+  rules: [],
+  colors: {
+    "editor.background": "#1b1a19"
+  }
+};
+
+monaco.editor.defineTheme(DarkThemeName, customMonacoDarkTheme);
+
+/**
+ * The custom high contrast light theme with customized background
+ */
+export const HCLightThemeName = "hc-light";
+
+/**
+ * Default monaco theme for light high contrast mode
+ */
+export const customMonacoHCLightTheme: monaco.editor.IStandaloneThemeData = {
+  base: "vs", // Derive from default light theme of Monaco; change all grey colors to black to comply with highcontrast rules
+  inherit: true,
+  rules: [
+    { token: "annotation", foreground: "000000" },
+    { token: "delimiter.html", foreground: "000000" },
+    { token: "operator.scss", foreground: "000000" },
+    { token: "operator.sql", foreground: "000000" },
+    { token: "operator.swift", foreground: "000000" },
+    { token: "predefined.sql", foreground: "000000" }
+  ],
+  colors: {
+    // We want Monaco background to use the same background for our themes.
+    // Without this, the Monaco light theme has a yellowish tone.
+    // Verified with UX that white meets all the accessbility requirements for light
+    // and high contrast light theme.
+    "editor.background": "#FFFFFF"
+  }
+};
+
+monaco.editor.defineTheme(HCLightThemeName, customMonacoHCLightTheme);

src/Explorer/Notebook/NotebookRenderer/NotebookRenderer.tsx

@@ -30,6 +30,7 @@ import { CellType } from "@nteract/commutable/src";
 import "./NotebookRenderer.less";
 import HoverableCell from "./decorators/HoverableCell";
 import CellLabeler from "./decorators/CellLabeler";
+import MonacoEditor from "../MonacoEditor/MonacoEditor";
 import * as cdbActions from "../NotebookComponent/actions";
 
 export interface NotebookRendererBaseProps {
@@ -116,7 +117,12 @@ class BaseNotebookRenderer extends React.Component<NotebookRendererProps> {
                           {{
                             editor: {
                               codemirror: (props: PassedEditorProps) => (
-                                <CodeMirrorEditor {...props} lineNumbers={true} />
+                                <MonacoEditor
+                                  {...props}
+                                  lineNumbers={true}
+                                  enableCompletion={true}
+                                  shouldRegisterDefaultCompletion={true}
+                                />
                               )
                             },
                             prompt: ({ id, contentRef }: { id: CellId; contentRef: ContentRef }) => (