very first proposed API for multiple roots, #28526

src/vs/vscode.proposed.d.ts

@@ -7,6 +7,13 @@
 
 declare module 'vscode' {
 
+	export namespace workspace {
+
+		export const onDidChangeWorkspaceFolders: Event<Uri[] | undefined>;
+
+		export let workspaceFolders: Uri[] | undefined;
+	}
+
 	/**
 	 * Controls the behaviour of the terminal's visibility.
 	 */

src/vs/workbench/api/node/extHost.api.impl.ts

@@ -54,6 +54,12 @@ export interface IExtensionApiFactory {
 	(extension: IExtensionDescription): typeof vscode;
 }
 
+function assertProposedApi(extension: IExtensionDescription): void {
+	if (!extension.enableProposedApi) {
+		throw new Error(`[${extension.id}]: Proposed API is only available when running out of dev or with the following command line switch: --enable-proposed-api ${extension.id}`);
+	}
+}
+
 function proposedApiFunction<T>(extension: IExtensionDescription, fn: T): T {
 	if (extension.enableProposedApi) {
 		return fn;
@@ -348,6 +354,13 @@ export function createApiFactory(
 			set rootPath(value) {
 				throw errors.readonly();
 			},
+			get workspaceFolders() {
+				assertProposedApi(extension);
+				return extHostWorkspace.getRoots();
+			},
+			onDidChangeWorkspaceFolders: proposedApiFunction(extension, (listener, thisArgs?, disposables?) => {
+				return extHostWorkspace.onDidChangeWorkspace(listener, thisArgs, disposables);
+			}),
 			asRelativePath: (pathOrUri) => {
 				return extHostWorkspace.getRelativePath(pathOrUri);
 			},

src/vs/workbench/api/node/extHostWorkspace.ts

@@ -21,11 +21,11 @@ export class ExtHostWorkspace extends ExtHostWorkspaceShape {
 
 	private static _requestIdPool = 0;
 
-	private readonly _onDidChangeWorkspace = new Emitter<this>();
+	private readonly _onDidChangeWorkspace = new Emitter<URI[]>();
 	private readonly _proxy: MainThreadWorkspaceShape;
 	private _workspace: Workspace;
 
-	readonly onDidChangeWorkspace: Event<this> = this._onDidChangeWorkspace.event;
+	readonly onDidChangeWorkspace: Event<URI[]> = this._onDidChangeWorkspace.event;
 
 	constructor(threadService: IThreadService, data: IWorkspaceData) {
 		super();
@@ -35,8 +35,12 @@ export class ExtHostWorkspace extends ExtHostWorkspaceShape {
 
 	// --- workspace ---
 
-	get workspace(): Workspace {
-		return this._workspace;
+	getRoots(): URI[] {
+		if (!this._workspace) {
+			return undefined;
+		} else {
+			return this._workspace.roots.slice(0);
+		}
 	}
 
 	getPath(): string {
@@ -85,7 +89,7 @@ export class ExtHostWorkspace extends ExtHostWorkspaceShape {
 
 	$acceptWorkspaceData(data: IWorkspaceData): void {
 		this._workspace = data ? new Workspace(data.id, data.name, data.roots) : null;
-		this._onDidChangeWorkspace.fire(this);
+		this._onDidChangeWorkspace.fire(this.getRoots());
 	}
 
 	// --- search ---