feat(toArray): add higher-order lettable version of toArray

src/operator/toArray.ts

@@ -1,41 +1,12 @@
-import { Operator } from '../Operator';
-import { Subscriber } from '../Subscriber';
+
 import { Observable } from '../Observable';
+import { toArray as higherOrder } from '../operators';
 
 /**
  * @return {Observable<any[]>|WebSocketSubject<T>|Observable<T>}
  * @method toArray
  * @owner Observable
  */
 export function toArray<T>(this: Observable<T>): Observable<T[]> {
-  return this.lift(new ToArrayOperator());
-}
-
-class ToArrayOperator<T> implements Operator<T, T[]> {
-  call(subscriber: Subscriber<T[]>, source: any): any {
-    return source.subscribe(new ToArraySubscriber(subscriber));
-  }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class ToArraySubscriber<T> extends Subscriber<T> {
-
-  private array: T[] = [];
-
-  constructor(destination: Subscriber<T[]>) {
-    super(destination);
-  }
-
-  protected _next(x: T) {
-    this.array.push(x);
-  }
-
-  protected _complete() {
-    this.destination.next(this.array);
-    this.destination.complete();
-  }
+  return higherOrder()(this);
 }

src/operators/index.ts

@@ -22,6 +22,7 @@ export { switchAll } from './switchAll';
 export { switchMap } from './switchMap';
 export { takeLast } from './takeLast';
 export { tap } from './tap';
+export { toArray } from './toArray';
 export { window } from './window';
 export { windowCount } from './windowCount';
 export { windowTime } from './windowTime';

src/operators/toArray.ts

@@ -0,0 +1,11 @@
+import { reduce } from './reduce';
+import { OperatorFunction } from '../interfaces';
+
+function toArrayReducer<T>(arr: T[], item: T, index: number) {
+  arr.push(item);
+  return arr;
+}
+
+export function toArray<T>(): OperatorFunction<T, T[]> {
+  return reduce(toArrayReducer, []);
+}