add CellUri-util but don't use it yet

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

@@ -186,6 +186,34 @@ export function generateCellPath(cellKind: CellKind, cellHandle: number): string
 	return `/cell_${cellHandle}${cellKind === CellKind.Markdown ? '.md' : ''}`;
 }
 
+
+export namespace CellUri {
+
+	export const scheme = 'vscode-notebook';
+
+	export function generate(notebook: URI, handle: number): URI {
+		return notebook.with({
+			query: JSON.stringify({ cell: handle, notebook: notebook.toString() }),
+			scheme,
+		});
+	}
+
+	export function parse(cell: URI): { notebook: URI, handle: number } | undefined {
+		if (cell.scheme !== scheme) {
+			return undefined;
+		}
+		try {
+			const data = <{ cell: number, notebook: string }>JSON.parse(cell.query);
+			return {
+				handle: data.cell,
+				notebook: URI.parse(data.notebook)
+			};
+		} catch {
+			return undefined;
+		}
+	}
+}
+
 export function parseCellHandle(path: string): number | undefined {
 	const regex = new RegExp(/cell_(\d*)(\.)?/g);
 	let matches = regex.exec(path);

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

@@ -4,8 +4,9 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as assert from 'assert';
-import { NOTEBOOK_DISPLAY_ORDER, sortMimeTypes, CellKind, diff } from 'vs/workbench/contrib/notebook/common/notebookCommon';
+import { NOTEBOOK_DISPLAY_ORDER, sortMimeTypes, CellKind, diff, CellUri } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { TestCell } from 'vs/workbench/contrib/notebook/test/testNotebookEditor';
+import { URI } from 'vs/base/common/uri';
 
 suite('NotebookCommon', () => {
 	test('sortMimeTypes default orders', function () {
@@ -322,3 +323,19 @@ suite('NotebookCommon', () => {
 		);
 	});
 });
+
+
+suite('CellUri', function () {
+
+	test('parse, generate', function () {
+
+		const nb = URI.parse('foo:///bar/følder/file.nb');
+		const id = 17;
+
+		const data = CellUri.generate(nb, id);
+		const actual = CellUri.parse(data);
+		assert.ok(Boolean(actual));
+		assert.equal(actual?.handle, id);
+		assert.equal(actual?.notebook.toString(), nb.toString());
+	});
+});