Merge from vscode 79a1f5a5ca0c6c53db617aa1fa5a2396d2caebe2

src/vs/editor/common/services/modelServiceImpl.ts

@@ -113,12 +113,12 @@ interface IRawConfig {
 
 const DEFAULT_EOL = (platform.isLinux || platform.isMacintosh) ? DefaultEndOfLine.LF : DefaultEndOfLine.CRLF;
 
-interface EditStackPastFutureElements {
+export interface EditStackPastFutureElements {
 	past: EditStackElement[];
 	future: EditStackElement[];
 }
 
-function isEditStackPastFutureElements(undoElements: IPastFutureElements): undoElements is EditStackPastFutureElements {
+export function isEditStackPastFutureElements(undoElements: IPastFutureElements): undoElements is EditStackPastFutureElements {
 	return (isEditStackElements(undoElements.past) && isEditStackElements(undoElements.future));
 }
 

src/vs/editor/common/services/modelUndoRedoParticipant.ts

@@ -0,0 +1,66 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { IModelService } from 'vs/editor/common/services/modelService';
+import { ITextModelService } from 'vs/editor/common/services/resolverService';
+import { Disposable, IDisposable, dispose } from 'vs/base/common/lifecycle';
+import { IUndoRedoService, UndoRedoElementType } from 'vs/platform/undoRedo/common/undoRedo';
+import { isEditStackPastFutureElements } from 'vs/editor/common/services/modelServiceImpl';
+import { IUndoRedoDelegate, MultiModelEditStackElement } from 'vs/editor/common/model/editStack';
+
+export class ModelUndoRedoParticipant extends Disposable implements IUndoRedoDelegate {
+	constructor(
+		@IModelService private readonly _modelService: IModelService,
+		@ITextModelService private readonly _textModelService: ITextModelService,
+		@IUndoRedoService private readonly _undoRedoService: IUndoRedoService,
+	) {
+		super();
+		this._register(this._modelService.onModelRemoved((model) => {
+			// a model will get disposed, so let's check if the undo redo stack is maintained
+			const elements = this._undoRedoService.getElements(model.uri);
+			if (elements.past.length === 0 && elements.future.length === 0) {
+				return;
+			}
+			if (!isEditStackPastFutureElements(elements)) {
+				return;
+			}
+			for (const element of elements.past) {
+				if (element.type === UndoRedoElementType.Workspace) {
+					element.setDelegate(this);
+				}
+			}
+			for (const element of elements.future) {
+				if (element.type === UndoRedoElementType.Workspace) {
+					element.setDelegate(this);
+				}
+			}
+		}));
+	}
+
+	public prepareUndoRedo(element: MultiModelEditStackElement): IDisposable | Promise<IDisposable> {
+		// Load all the needed text models
+		const missingModels = element.getMissingModels();
+		if (missingModels.length === 0) {
+			// All models are available!
+			return Disposable.None;
+		}
+
+		const disposablesPromises = missingModels.map(async (uri) => {
+			try {
+				const reference = await this._textModelService.createModelReference(uri);
+				return <IDisposable>reference;
+			} catch (err) {
+				// This model could not be loaded, maybe it was deleted in the meantime?
+				return Disposable.None;
+			}
+		});
+
+		return Promise.all(disposablesPromises).then(disposables => {
+			return {
+				dispose: () => dispose(disposables)
+			};
+		});
+	}
+}

src/vs/editor/common/services/resolverService.ts

@@ -26,9 +26,9 @@ export interface ITextModelService {
 	registerTextModelContentProvider(scheme: string, provider: ITextModelContentProvider): IDisposable;
 
 	/**
-	 * Check if a provider for the given `scheme` exists
+	 * Check if the given resource can be resolved to a text model.
 	 */
-	hasTextModelContentProvider(scheme: string): boolean;
+	canHandleResource(resource: URI): boolean;
 }
 
 export interface ITextModelContentProvider {