folding: provider event to signal that folding ranges have changed. Fixes #99914

src/vs/editor/common/modes.ts

@@ -1293,6 +1293,12 @@ export interface FoldingContext {
  * A provider of folding ranges for editor models.
  */
 export interface FoldingRangeProvider {
+
+	/**
+	 * An optional event to signal that the folding ranges from this provider have changed.
+	 */
+	onDidChange?: Event<this>;
+
 	/**
 	 * Provides the folding ranges for a specific model.
 	 */

src/vs/editor/contrib/folding/folding.ts

@@ -264,7 +264,7 @@ export class FoldingController extends Disposable implements IEditorContribution
 				}, 30000);
 				return rangeProvider; // keep memento in case there are still no foldingProviders on the next request.
 			} else if (foldingProviders.length > 0) {
-				this.rangeProvider = new SyntaxRangeProvider(editorModel, foldingProviders);
+				this.rangeProvider = new SyntaxRangeProvider(editorModel, foldingProviders, () => this.onModelContentChanged());
 			}
 		}
 		this.foldingStateMemento = null;

src/vs/editor/contrib/folding/syntaxRangeProvider.ts

@@ -9,6 +9,7 @@ import { ITextModel } from 'vs/editor/common/model';
 import { RangeProvider } from './folding';
 import { MAX_LINE_NUMBER, FoldingRegions } from './foldingRanges';
 import { CancellationToken } from 'vs/base/common/cancellation';
+import { DisposableStore } from 'vs/base/common/lifecycle';
 
 const MAX_FOLDING_REGIONS = 5000;
 
@@ -25,7 +26,17 @@ export class SyntaxRangeProvider implements RangeProvider {
 
 	readonly id = ID_SYNTAX_PROVIDER;
 
-	constructor(private readonly editorModel: ITextModel, private providers: FoldingRangeProvider[], private limit = MAX_FOLDING_REGIONS) {
+	readonly disposables: DisposableStore | undefined;
+
+	constructor(private readonly editorModel: ITextModel, private providers: FoldingRangeProvider[], handleFoldingRangesChange: () => void, private limit = MAX_FOLDING_REGIONS) {
+		for (const provider of providers) {
+			if (typeof provider.onDidChange === 'function') {
+				if (!this.disposables) {
+					this.disposables = new DisposableStore();
+				}
+				this.disposables.add(provider.onDidChange(handleFoldingRangesChange));
+			}
+		}
 	}
 
 	compute(cancellationToken: CancellationToken): Promise<FoldingRegions | null> {
@@ -39,8 +50,8 @@ export class SyntaxRangeProvider implements RangeProvider {
 	}
 
 	dispose() {
+		this.disposables?.dispose();
 	}
-
 }
 
 function collectSyntaxRanges(providers: FoldingRangeProvider[], model: ITextModel, cancellationToken: CancellationToken): Promise<IFoldingRangeData[] | null> {

src/vs/editor/contrib/folding/test/syntaxFold.test.ts

@@ -74,7 +74,7 @@ suite('Syntax folding', () => {
 		let providers = [new TestFoldingRangeProvider(model, ranges)];
 
 		async function assertLimit(maxEntries: number, expectedRanges: IndentRange[], message: string) {
-			let indentRanges = await new SyntaxRangeProvider(model, providers, maxEntries).compute(CancellationToken.None);
+			let indentRanges = await new SyntaxRangeProvider(model, providers, () => { }, maxEntries).compute(CancellationToken.None);
 			let actual: IndentRange[] = [];
 			if (indentRanges) {
 				for (let i = 0; i < indentRanges.length; i++) {

src/vs/monaco.d.ts

@@ -6137,6 +6137,10 @@ declare namespace monaco.languages {
 	 * A provider of folding ranges for editor models.
 	 */
 	export interface FoldingRangeProvider {
+		/**
+		 * An optional event to signal that the folding ranges from this provider have changed.
+		 */
+		onDidChange?: IEvent<this>;
 		/**
 		 * Provides the folding ranges for a specific model.
 		 */

src/vs/vscode.proposed.d.ts

@@ -2190,4 +2190,15 @@ declare module 'vscode' {
 		canReply: boolean;
 	}
 	//#endregion
+
+	//#region https://github.com/microsoft/vscode/issues/108929 FoldingRangeProvider.onDidChangeFoldingRanges @aeschli
+	export interface FoldingRangeProvider2 extends FoldingRangeProvider {
+
+		/**
+		 * An optional event to signal that the folding ranges from this provider have changed.
+		 */
+		onDidChangeFoldingRanges?: Event<void>;
+
+	}
+	//#endregion
 }

src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts

@@ -571,13 +571,27 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 
 	// --- folding
 
-	$registerFoldingRangeProvider(handle: number, selector: IDocumentFilterDto[]): void {
-		const proxy = this._proxy;
-		this._registrations.set(handle, modes.FoldingRangeProviderRegistry.register(selector, <modes.FoldingRangeProvider>{
+	$registerFoldingRangeProvider(handle: number, selector: IDocumentFilterDto[], eventHandle: number | undefined): void {
+		const provider = <modes.FoldingRangeProvider>{
 			provideFoldingRanges: (model, context, token) => {
-				return proxy.$provideFoldingRanges(handle, model.uri, context, token);
+				return this._proxy.$provideFoldingRanges(handle, model.uri, context, token);
 			}
-		}));
+		};
+
+		if (typeof eventHandle === 'number') {
+			const emitter = new Emitter<modes.FoldingRangeProvider>();
+			this._registrations.set(eventHandle, emitter);
+			provider.onDidChange = emitter.event;
+		}
+
+		this._registrations.set(handle, modes.FoldingRangeProviderRegistry.register(selector, provider));
+	}
+
+	$emitFoldingRangeEvent(eventHandle: number, event?: any): void {
+		const obj = this._registrations.get(eventHandle);
+		if (obj instanceof Emitter) {
+			obj.fire(event);
+		}
 	}
 
 	// -- smart select

src/vs/workbench/api/common/extHost.protocol.ts

@@ -398,7 +398,8 @@ export interface MainThreadLanguageFeaturesShape extends IDisposable {
 	$registerSignatureHelpProvider(handle: number, selector: IDocumentFilterDto[], metadata: ISignatureHelpProviderMetadataDto): void;
 	$registerDocumentLinkProvider(handle: number, selector: IDocumentFilterDto[], supportsResolve: boolean): void;
 	$registerDocumentColorProvider(handle: number, selector: IDocumentFilterDto[]): void;
-	$registerFoldingRangeProvider(handle: number, selector: IDocumentFilterDto[]): void;
+	$registerFoldingRangeProvider(handle: number, selector: IDocumentFilterDto[], eventHandle: number | undefined): void;
+	$emitFoldingRangeEvent(eventHandle: number, event?: any): void;
 	$registerSelectionRangeProvider(handle: number, selector: IDocumentFilterDto[]): void;
 	$registerCallHierarchyProvider(handle: number, selector: IDocumentFilterDto[]): void;
 	$setLanguageConfiguration(handle: number, languageId: string, configuration: ILanguageConfigurationDto): void;

src/vs/workbench/api/common/extHostLanguageFeatures.ts

@@ -1810,10 +1810,20 @@ export class ExtHostLanguageFeatures implements extHostProtocol.ExtHostLanguageF
 		return this._withAdapter(handle, ColorProviderAdapter, adapter => adapter.provideColorPresentations(URI.revive(resource), colorInfo, token), undefined);
 	}
 
-	registerFoldingRangeProvider(extension: IExtensionDescription, selector: vscode.DocumentSelector, provider: vscode.FoldingRangeProvider): vscode.Disposable {
-		const handle = this._addNewAdapter(new FoldingProviderAdapter(this._documents, provider), extension);
-		this._proxy.$registerFoldingRangeProvider(handle, this._transformDocumentSelector(selector));
-		return this._createDisposable(handle);
+	registerFoldingRangeProvider(extension: IExtensionDescription, selector: vscode.DocumentSelector, provider: vscode.FoldingRangeProvider2): vscode.Disposable {
+		const handle = this._nextHandle();
+		const eventHandle = typeof provider.onDidChangeFoldingRanges === 'function' ? this._nextHandle() : undefined;
+
+		this._adapter.set(handle, new AdapterData(new FoldingProviderAdapter(this._documents, provider), extension));
+		this._proxy.$registerFoldingRangeProvider(handle, this._transformDocumentSelector(selector), eventHandle);
+		let result = this._createDisposable(handle);
+
+		if (eventHandle !== undefined) {
+			const subscription = provider.onDidChangeFoldingRanges!(_ => this._proxy.$emitFoldingRangeEvent(eventHandle));
+			result = Disposable.from(result, subscription);
+		}
+
+		return result;
 	}
 
 	$provideFoldingRanges(handle: number, resource: UriComponents, context: vscode.FoldingContext, token: CancellationToken): Promise<modes.FoldingRange[] | undefined> {