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

src/operator/timeInterval.ts

@@ -1,8 +1,8 @@
-import { Operator } from '../Operator';
 import { Observable } from '../Observable';
-import { Subscriber } from '../Subscriber';
 import { IScheduler } from '../Scheduler';
 import { async } from '../scheduler/async';
+import { timeInterval as higherOrder, TimeInterval } from '../operators/timeInterval';
+export {TimeInterval};
 
 /**
  * @param scheduler
@@ -11,44 +11,5 @@ import { async } from '../scheduler/async';
  * @owner Observable
  */
 export function timeInterval<T>(this: Observable<T>, scheduler: IScheduler = async): Observable<TimeInterval<T>> {
-  return this.lift(new TimeIntervalOperator(scheduler));
-}
-
-export class TimeInterval<T> {
-  constructor(public value: T, public interval: number) {
-
-  }
-};
-
-class TimeIntervalOperator<T> implements Operator<T, TimeInterval<T>> {
-  constructor(private scheduler: IScheduler) {
-
-  }
-
-  call(observer: Subscriber<TimeInterval<T>>, source: any): any {
-    return source.subscribe(new TimeIntervalSubscriber(observer, this.scheduler));
-  }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class TimeIntervalSubscriber<T> extends Subscriber<T> {
-  private lastTime: number = 0;
-
-  constructor(destination: Subscriber<TimeInterval<T>>, private scheduler: IScheduler) {
-    super(destination);
-
-    this.lastTime = scheduler.now();
-  }
-
-  protected _next(value: T) {
-    let now = this.scheduler.now();
-    let span = now - this.lastTime;
-    this.lastTime = now;
-
-    this.destination.next(new TimeInterval(value, span));
-  }
+  return higherOrder(scheduler)(this);
 }

src/operators/index.ts

@@ -67,6 +67,7 @@ export { takeLast } from './takeLast';
 export { tap } from './tap';
 export { throttle } from './throttle';
 export { throttleTime } from './throttleTime';
+export { timeInterval } from './timeInterval';
 export { timestamp } from './timestamp';
 export { toArray } from './toArray';
 export { window } from './window';

src/operators/timeInterval.ts

@@ -0,0 +1,49 @@
+import { Operator } from '../Operator';
+import { Observable } from '../Observable';
+import { Subscriber } from '../Subscriber';
+import { IScheduler } from '../Scheduler';
+import { async } from '../scheduler/async';
+import { OperatorFunction } from '../interfaces';
+
+export function timeInterval<T>(scheduler: IScheduler = async): OperatorFunction<T, TimeInterval<T>> {
+  return (source: Observable<T>) => source.lift(new TimeIntervalOperator(scheduler));
+}
+
+export class TimeInterval<T> {
+  constructor(public value: T, public interval: number) {
+
+  }
+};
+
+class TimeIntervalOperator<T> implements Operator<T, TimeInterval<T>> {
+  constructor(private scheduler: IScheduler) {
+
+  }
+
+  call(observer: Subscriber<TimeInterval<T>>, source: any): any {
+    return source.subscribe(new TimeIntervalSubscriber(observer, this.scheduler));
+  }
+}
+
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+class TimeIntervalSubscriber<T> extends Subscriber<T> {
+  private lastTime: number = 0;
+
+  constructor(destination: Subscriber<TimeInterval<T>>, private scheduler: IScheduler) {
+    super(destination);
+
+    this.lastTime = scheduler.now();
+  }
+
+  protected _next(value: T) {
+    let now = this.scheduler.now();
+    let span = now - this.lastTime;
+    this.lastTime = now;
+
+    this.destination.next(new TimeInterval(value, span));
+  }
+}