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

src/operator/shareReplay.ts

@@ -1,26 +1,12 @@
 import { Observable } from '../Observable';
-import { multicast } from './multicast';
-import { ReplaySubject } from '../ReplaySubject';
-import { ConnectableObservable } from '../observable/ConnectableObservable';
 import { IScheduler } from '../Scheduler';
+import { shareReplay as higherOrder } from '../operators/shareReplay';
 
 /**
  * @method shareReplay
  * @owner Observable
  */
-export function shareReplay<T>(
-  this: Observable<T>,
-  bufferSize?: number,
-  windowTime?: number,
-  scheduler?: IScheduler
-): Observable<T> {
-  let subject: ReplaySubject<T>;
-  const connectable = multicast.call(this, function shareReplaySubjectFactory(this: ConnectableObservable<T>) {
-    if (this._isComplete) {
-      return subject;
-    } else {
-      return (subject = new ReplaySubject<T>(bufferSize, windowTime, scheduler));
-    }
-  });
-  return connectable.refCount();
+export function shareReplay<T>(this: Observable<T>, bufferSize?: number, windowTime?: number, scheduler?: IScheduler):
+  Observable<T> {
+  return higherOrder(bufferSize, windowTime, scheduler)(this);
 };

src/operators/index.ts

@@ -63,6 +63,7 @@ export { sampleTime } from './sampleTime';
 export { scan } from './scan';
 export { sequenceEqual } from './sequenceEqual';
 export { share } from './share';
+export { shareReplay } from './shareReplay';
 export { subscribeOn } from './subscribeOn';
 export { switchAll } from './switchAll';
 export { switchMap } from './switchMap';

src/operators/shareReplay.ts

@@ -0,0 +1,25 @@
+import { Observable } from '../Observable';
+import { multicast } from './multicast';
+import { refCount } from './refCount';
+import { ReplaySubject } from '../ReplaySubject';
+import { ConnectableObservable } from '../observable/ConnectableObservable';
+import { IScheduler } from '../Scheduler';
+
+import { MonoTypeOperatorFunction } from '../interfaces';
+
+/**
+ * @method shareReplay
+ * @owner Observable
+ */
+export function shareReplay<T>(bufferSize?: number, windowTime?: number, scheduler?: IScheduler ): MonoTypeOperatorFunction<T> {
+  let subject: ReplaySubject<T>;
+
+  const connectable = multicast(function shareReplaySubjectFactory(this: ConnectableObservable<T>) {
+    if (this._isComplete) {
+      return subject;
+    } else {
+      return (subject = new ReplaySubject<T>(bufferSize, windowTime, scheduler));
+    }
+  });
+  return (source: Observable<T>) => refCount()(connectable(source));
+};