feat(groupBy): Adds subjectSelector argument to groupBy (#2023)

Adds subjectSelector argument to groupBy to allow consumers to customize the behavior of the hot

GroupedObservable.

spec/operators/groupBy-spec.ts

@@ -5,6 +5,7 @@ declare const {hot, cold, asDiagram, expectObservable, expectSubscriptions};
 
 declare const rxTestScheduler: Rx.TestScheduler;
 const Observable = Rx.Observable;
+const ReplaySubject = Rx.ReplaySubject;
 
 /** @test {groupBy} */
 describe('Observable.prototype.groupBy', () => {
@@ -98,6 +99,27 @@ describe('Observable.prototype.groupBy', () => {
  expect(resultingGroups).to.deep.equal(expectedGroups);
  });
 
+ it('should group values with a subject selector', (done: MochaDone) => {
+ const expectedGroups = [
+ { key: 1, values: [3] },
+ { key: 0, values: [2] }
+ ];
+
+ Observable.of(1, 2, 3)
+ .groupBy((x: number) => x % 2, null, null, () => new ReplaySubject(1))
+ // Ensure each inner group reaches the destination after the first event
+ // has been next'd to the group
+ .delay(5)
+ .subscribe((g: any) => {
+ const expectedGroup = expectedGroups.shift();
+ expect(g.key).to.equal(expectedGroup.key);
+
+ g.subscribe((x: any) => {
+ expect(x).to.deep.equal(expectedGroup.values.shift());
+ });
+ }, null, done);
+ });
+
  it('should handle an empty Observable', () => {
  const e1 = cold('|');
  const e1subs = '(^!)';

src/operator/groupBy.ts

@@ -31,11 +31,13 @@ import { FastMap } from '../util/FastMap';
 export function groupBy<T, K>(this: Observable<T>, keySelector: (value: T) => K): Observable<GroupedObservable<K, T>>;
 export function groupBy<T, K>(this: Observable<T>, keySelector: (value: T) => K, elementSelector: void, durationSelector: (grouped: GroupedObservable<K, T>) => Observable<any>): Observable<GroupedObservable<K, T>>;
 export function groupBy<T, K, R>(this: Observable<T>, keySelector: (value: T) => K, elementSelector?: (value: T) => R, durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>): Observable<GroupedObservable<K, R>>;
+export function groupBy<T, K, R>(this: Observable<T>, keySelector: (value: T) => K, elementSelector?: (value: T) => R, durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>, subjectSelector?: () => Subject<R>): Observable<GroupedObservable<K, R>>;
 /* tslint:disable:max-line-length */
 export function groupBy<T, K, R>(this: Observable<T>, keySelector: (value: T) => K,
  elementSelector?: ((value: T) => R) | void,
- durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>): Observable<GroupedObservable<K, R>> {
- return this.lift(new GroupByOperator(this, keySelector, elementSelector, durationSelector));
+ durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>,
+ subjectSelector?: () => Subject<R>): Observable<GroupedObservable<K, R>> {
+ return this.lift(new GroupByOperator(keySelector, elementSelector, durationSelector, subjectSelector));
 }
 
 export interface RefCountSubscription {
@@ -46,15 +48,15 @@ export interface RefCountSubscription {
 }
 
 class GroupByOperator<T, K, R> implements Operator<T, GroupedObservable<K, R>> {
- constructor(public source: Observable<T>,
- private keySelector: (value: T) => K,
+ constructor(private keySelector: (value: T) => K,
  private elementSelector?: ((value: T) => R) | void,
- private durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>) {
+ private durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>,
+ private subjectSelector?: () => Subject<R>) {
  }
 
  call(subscriber: Subscriber<GroupedObservable<K, R>>, source: any): any {
  return source._subscribe(new GroupBySubscriber(
- subscriber, this.keySelector, this.elementSelector, this.durationSelector
+ subscriber, this.keySelector, this.elementSelector, this.durationSelector, this.subjectSelector
  ));
  }
 }
@@ -72,7 +74,8 @@ class GroupBySubscriber<T, K, R> extends Subscriber<T> implements RefCountSubscr
  constructor(destination: Subscriber<GroupedObservable<K, R>>,
  private keySelector: (value: T) => K,
  private elementSelector?: ((value: T) => R) | void,
- private durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>) {
+ private durationSelector?: (grouped: GroupedObservable<K, R>) => Observable<any>,
+ private subjectSelector?: () => Subject<R>) {
  super(destination);
  }
 
@@ -109,7 +112,8 @@ class GroupBySubscriber<T, K, R> extends Subscriber<T> implements RefCountSubscr
  }
 
  if (!group) {
- groups.set(key, group = new Subject<R>());
+ group = this.subjectSelector ? this.subjectSelector() : new Subject<R>();
+ groups.set(key, group);
  const groupedObservable = new GroupedObservable(key, group, this);
  this.destination.next(groupedObservable);
  if (this.durationSelector) {