Allow empty selections -> index.

Author: rebornix

src/vs/workbench/contrib/notebook/browser/controller/chat/notebookChatController.ts

@@ -354,6 +354,7 @@ export class NotebookChatController extends Disposable implements INotebookEdito
 		}
 
 		this._notebookEditor.focusContainer(true);
+		this._notebookEditor.setFocus({ start: this._widget.afterModelPosition, end: this._widget.afterModelPosition });
 		this._notebookEditor.setSelections([{
 			start: this._widget.afterModelPosition,
 			end: this._widget.afterModelPosition

src/vs/workbench/contrib/notebook/browser/viewModel/notebookViewModelImpl.ts

@@ -361,9 +361,6 @@ export class NotebookViewModel extends Disposable implements EditorFoldingStateD
 		this._focused = focused;
 	}
 
-	/**
-	 * Empty selection will be turned to `null`
-	 */
 	validateRange(cellRange: ICellRange | null | undefined): ICellRange | null {
 		if (!cellRange) {
 			return null;
@@ -372,11 +369,7 @@ export class NotebookViewModel extends Disposable implements EditorFoldingStateD
 		const start = clamp(cellRange.start, 0, this.length);
 		const end = clamp(cellRange.end, 0, this.length);
 
-		if (start === end) {
-			return null;
-		}
-
-		if (start < end) {
+		if (start <= end) {
 			return { start, end };
 		} else {
 			return { start: end, end: start };

src/vs/workbench/contrib/notebook/common/notebookRange.ts

@@ -65,7 +65,7 @@ export function reduceCellRanges(ranges: ICellRange[]): ICellRange[] {
 		return [];
 	}
 
-	return sorted.reduce((prev: ICellRange[], curr) => {
+	const reduced = sorted.reduce((prev: ICellRange[], curr) => {
 		const last = prev[prev.length - 1];
 		if (last.end >= curr.start) {
 			last.end = Math.max(last.end, curr.end);
@@ -74,6 +74,13 @@ export function reduceCellRanges(ranges: ICellRange[]): ICellRange[] {
 		}
 		return prev;
 	}, [first] as ICellRange[]);
+
+	if (reduced.length > 1) {
+		// remove the (0, 0) range
+		return reduced.filter(range => !(range.start === range.end && range.start === 0));
+	}
+
+	return reduced;
 }
 
 export function cellRangesEqual(a: ICellRange[], b: ICellRange[]) {

src/vs/workbench/contrib/notebook/test/browser/notebookCommon.test.ts

@@ -399,6 +399,12 @@ suite('CellRange', function () {
 			{ start: 0, end: 4 }
 		]);
 	});
+
+	test('Reduce ranges 2, empty ranges', function () {
+		assert.deepStrictEqual(reduceCellRanges([{ start: 0, end: 0 }, { start: 0, end: 0 }]), [{ start: 0, end: 0 }]);
+		assert.deepStrictEqual(reduceCellRanges([{ start: 0, end: 0 }, { start: 1, end: 2 }]), [{ start: 1, end: 2 }]);
+		assert.deepStrictEqual(reduceCellRanges([{ start: 2, end: 2 }]), [{ start: 2, end: 2 }]);
+	});
 });
 
 suite('NotebookWorkingCopyTypeIdentifier', function () {

src/vs/workbench/contrib/notebook/test/browser/notebookSelection.test.ts

@@ -278,7 +278,7 @@ suite('NotebookCellList focus/selection', () => {
 			(editor, viewModel) => {
 				assert.deepStrictEqual(viewModel.validateRange(null), null);
 				assert.deepStrictEqual(viewModel.validateRange(undefined), null);
-				assert.deepStrictEqual(viewModel.validateRange({ start: 0, end: 0 }), null);
+				assert.deepStrictEqual(viewModel.validateRange({ start: 0, end: 0 }), { start: 0, end: 0 });
 				assert.deepStrictEqual(viewModel.validateRange({ start: 0, end: 2 }), { start: 0, end: 2 });
 				assert.deepStrictEqual(viewModel.validateRange({ start: 0, end: 3 }), { start: 0, end: 2 });
 				assert.deepStrictEqual(viewModel.validateRange({ start: -1, end: 3 }), { start: 0, end: 2 });