clean up in array set

src/vs/base/common/paging.ts

@@ -111,7 +111,7 @@ export class PagedModel<T> implements IPagedModel<T> {
 
 			page.promiseIndexes.unset(index);
 
-			if (page.promiseIndexes.elements.length === 0) {
+			if (page.promiseIndexes.size === 0) {
 				page.promise.cancel();
 			}
 		});

src/vs/base/common/set.ts

@@ -3,8 +3,6 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-'use strict';
-
 export class ArraySet<T> {
 
 	private _elements: T[];
@@ -13,6 +11,10 @@ export class ArraySet<T> {
 		this._elements = elements.slice();
 	}
 
+	get size(): number {
+		return this._elements.length;
+	}
+
 	set(element: T): void {
 		this.unset(element);
 		this._elements.push(element);
@@ -31,6 +33,6 @@ export class ArraySet<T> {
 	}
 
 	get elements(): T[] {
-		return this._elements;
+		return this._elements.slice();
 	}
 }
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