Keep view model in sync with model (#44805)

src/vs/editor/common/model/textModel.ts

@@ -1018,12 +1018,12 @@ export class TextModel extends Disposable implements model.ITextModel {
 
 	public pushEditOperations(beforeCursorState: Selection[], editOperations: model.IIdentifiedSingleEditOperation[], cursorStateComputer: model.ICursorStateComputer): Selection[] {
 		try {
-			this._eventEmitter.beginDeferredEmit();
 			this._onDidChangeDecorations.beginDeferredEmit();
+			this._eventEmitter.beginDeferredEmit();
 			return this._pushEditOperations(beforeCursorState, editOperations, cursorStateComputer);
 		} finally {
-			this._onDidChangeDecorations.endDeferredEmit();
 			this._eventEmitter.endDeferredEmit();
+			this._onDidChangeDecorations.endDeferredEmit();
 		}
 	}
 
@@ -1108,12 +1108,12 @@ export class TextModel extends Disposable implements model.ITextModel {
 
 	public applyEdits(rawOperations: model.IIdentifiedSingleEditOperation[]): model.IIdentifiedSingleEditOperation[] {
 		try {
-			this._eventEmitter.beginDeferredEmit();
 			this._onDidChangeDecorations.beginDeferredEmit();
+			this._eventEmitter.beginDeferredEmit();
 			return this._applyEdits(rawOperations);
 		} finally {
-			this._onDidChangeDecorations.endDeferredEmit();
 			this._eventEmitter.endDeferredEmit();
+			this._onDidChangeDecorations.endDeferredEmit();
 		}
 	}
 
@@ -1250,12 +1250,12 @@ export class TextModel extends Disposable implements model.ITextModel {
 
 	public undo(): Selection[] {
 		try {
-			this._eventEmitter.beginDeferredEmit();
 			this._onDidChangeDecorations.beginDeferredEmit();
+			this._eventEmitter.beginDeferredEmit();
 			return this._undo();
 		} finally {
-			this._onDidChangeDecorations.endDeferredEmit();
 			this._eventEmitter.endDeferredEmit();
+			this._onDidChangeDecorations.endDeferredEmit();
 		}
 	}
 
@@ -1275,12 +1275,12 @@ export class TextModel extends Disposable implements model.ITextModel {
 
 	public redo(): Selection[] {
 		try {
-			this._eventEmitter.beginDeferredEmit();
 			this._onDidChangeDecorations.beginDeferredEmit();
+			this._eventEmitter.beginDeferredEmit();
 			return this._redo();
 		} finally {
-			this._onDidChangeDecorations.endDeferredEmit();
 			this._eventEmitter.endDeferredEmit();
+			this._onDidChangeDecorations.endDeferredEmit();
 		}
 	}
 
@@ -2469,12 +2469,12 @@ export class DidChangeContentEmitter extends Disposable {
 	public readonly event: Event<InternalModelContentChangeEvent> = this._actual.event;
 
 	private _deferredCnt: number;
-	private _deferredEvents: InternalModelContentChangeEvent[];
+	private _deferredEvent: InternalModelContentChangeEvent;
 
 	constructor() {
 		super();
 		this._deferredCnt = 0;
-		this._deferredEvents = [];
+		this._deferredEvent = null;
 	}
 
 	public beginDeferredEmit(): void {
@@ -2484,15 +2484,21 @@ export class DidChangeContentEmitter extends Disposable {
 	public endDeferredEmit(): void {
 		this._deferredCnt--;
 		if (this._deferredCnt === 0) {
-			while (this._deferredEvents.length > 0) {
-				this._actual.fire(this._deferredEvents.shift());
+			if (this._deferredEvent !== null) {
+				const e = this._deferredEvent;
+				this._deferredEvent = null;
+				this._actual.fire(e);
 			}
 		}
 	}
 
 	public fire(e: InternalModelContentChangeEvent): void {
 		if (this._deferredCnt > 0) {
-			this._deferredEvents.push(e);
+			if (this._deferredEvent) {
+				this._deferredEvent = this._deferredEvent.merge(e);
+			} else {
+				this._deferredEvent = e;
+			}
 			return;
 		}
 		this._actual.fire(e);

src/vs/editor/common/model/textModelEvents.ts

@@ -234,6 +234,14 @@ export class ModelRawContentChangedEvent {
 		}
 		return false;
 	}
+
+	public static merge(a: ModelRawContentChangedEvent, b: ModelRawContentChangedEvent): ModelRawContentChangedEvent {
+		const changes = [].concat(a.changes).concat(b.changes);
+		const versionId = b.versionId;
+		const isUndoing = (a.isUndoing || b.isUndoing);
+		const isRedoing = (a.isRedoing || b.isRedoing);
+		return new ModelRawContentChangedEvent(changes, versionId, isUndoing, isRedoing);
+	}
 }
 
 /**
@@ -244,4 +252,27 @@ export class InternalModelContentChangeEvent {
 		public readonly rawContentChangedEvent: ModelRawContentChangedEvent,
 		public readonly contentChangedEvent: IModelContentChangedEvent,
 	) { }
+
+	public merge(other: InternalModelContentChangeEvent): InternalModelContentChangeEvent {
+		const rawContentChangedEvent = ModelRawContentChangedEvent.merge(this.rawContentChangedEvent, other.rawContentChangedEvent);
+		const contentChangedEvent = InternalModelContentChangeEvent._mergeChangeEvents(this.contentChangedEvent, other.contentChangedEvent);
+		return new InternalModelContentChangeEvent(rawContentChangedEvent, contentChangedEvent);
+	}
+
+	private static _mergeChangeEvents(a: IModelContentChangedEvent, b: IModelContentChangedEvent): IModelContentChangedEvent {
+		const changes = [].concat(a.changes).concat(b.changes);
+		const eol = b.eol;
+		const versionId = b.versionId;
+		const isUndoing = (a.isUndoing || b.isUndoing);
+		const isRedoing = (a.isRedoing || b.isRedoing);
+		const isFlush = (a.isFlush || b.isFlush);
+		return {
+			changes: changes,
+			eol: eol,
+			versionId: versionId,
+			isUndoing: isUndoing,
+			isRedoing: isRedoing,
+			isFlush: isFlush
+		};
+	}
 }

src/vs/editor/common/viewModel/splitLinesCollection.ts

@@ -180,7 +180,7 @@ export class SplitLinesCollection implements IViewModelLinesCollection {
 		let modelVersion = this.model.getVersionId();
 		if (modelVersion !== this._validModelVersionId) {
 			// This is pretty bad, it means we lost track of the model...
-			this._constructLines(false);
+			throw new Error(`ViewModel is out of sync with Model!`);
 		}
 	}
 

src/vs/editor/test/common/viewModel/viewModelImpl.test.ts

@@ -40,6 +40,40 @@ suite('ViewModel', () => {
 		});
 	});
 
+	test('issue #44805: SplitLinesCollection: attempt to access a \'newer\' model', () => {
+		const text = [''];
+		testViewModel(text, {}, (viewModel, model) => {
+			assert.equal(viewModel.getLineCount(), 1);
+
+			model.pushEditOperations([], [{
+				range: new Range(1, 1, 1, 1),
+				text: '\ninsert1'
+			}], () => ([]));
+
+			model.pushEditOperations([], [{
+				range: new Range(1, 1, 1, 1),
+				text: '\ninsert2'
+			}], () => ([]));
+
+			model.pushEditOperations([], [{
+				range: new Range(1, 1, 1, 1),
+				text: '\ninsert3'
+			}], () => ([]));
+
+			let viewLineCount: number[] = [];
+
+			viewLineCount.push(viewModel.getLineCount());
+			viewModel.addEventListener((events) => {
+				// Access the view model
+				viewLineCount.push(viewModel.getLineCount());
+			});
+			model.undo();
+			viewLineCount.push(viewModel.getLineCount());
+
+			assert.deepEqual(viewLineCount, [4, 1, 1, 1]);
+		});
+	});
+
 	function assertGetPlainTextToCopy(text: string[], ranges: Range[], emptySelectionClipboard: boolean, expected: string | string[]): void {
 		testViewModel(text, {}, (viewModel, model) => {
 			let actual = viewModel.getPlainTextToCopy(ranges, emptySelectionClipboard);