list widget refactor

src/vs/base/browser/ui/list/listWidget.ts

@@ -158,17 +158,11 @@ export class List<T> implements IDisposable {
 	private controller: Controller<T>;
 
 	get onFocusChange(): Event<IFocusChangeEvent<T>> {
-		return mapEvent(this.focus.onChange, e => ({
-			elements: e.indexes.map(i => this.view.element(i)),
-			indexes: e.indexes
-		}));
+		return mapEvent(this.focus.onChange, e => this.toListEvent(e));
 	}
 
 	get onSelectionChange(): Event<ISelectionChangeEvent<T>> {
-		return mapEvent(this.selection.onChange, e => ({
-			elements: e.indexes.map(i => this.view.element(i)),
-			indexes: e.indexes
-		}));
+		return mapEvent(this.selection.onChange, e => this.toListEvent(e));
 	}
 
 	constructor(
@@ -322,6 +316,10 @@ export class List<T> implements IDisposable {
 		}
 	}
 
+	private toListEvent<T>({ indexes }: ITraitChangeEvent) {
+		return { indexes, elements: indexes.map(i => this.view.element(i)) };
+	}
+
 	dispose(): void {
 		this.view = dispose(this.view);
 		this.focus = dispose(this.focus);