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

Author: jasonaden

src/operator/repeat.ts

@@ -1,8 +1,6 @@
-import { Operator } from '../Operator';
-import { Subscriber } from '../Subscriber';
+
 import { Observable } from '../Observable';
-import { EmptyObservable } from '../observable/EmptyObservable';
-import { TeardownLogic } from '../Subscription';
+import { repeat as higherOrder } from '../operators/repeat';
 
 /**
  * Returns an Observable that repeats the stream of items emitted by the source Observable at most count times.
@@ -17,44 +15,5 @@ import { TeardownLogic } from '../Subscription';
  * @owner Observable
  */
 export function repeat<T>(this: Observable<T>, count: number = -1): Observable<T> {
-  if (count === 0) {
-    return new EmptyObservable<T>();
-  } else if (count < 0) {
-    return this.lift(new RepeatOperator(-1, this));
-  } else {
-    return this.lift(new RepeatOperator(count - 1, this));
-  }
-}
-
-class RepeatOperator<T> implements Operator<T, T> {
-  constructor(private count: number,
-              private source: Observable<T>) {
-  }
-  call(subscriber: Subscriber<T>, source: any): TeardownLogic {
-    return source.subscribe(new RepeatSubscriber(subscriber, this.count, this.source));
-  }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class RepeatSubscriber<T> extends Subscriber<T> {
-  constructor(destination: Subscriber<any>,
-              private count: number,
-              private source: Observable<T>) {
-    super(destination);
-  }
-  complete() {
-    if (!this.isStopped) {
-      const { source, count } = this;
-      if (count === 0) {
-        return super.complete();
-      } else if (count > -1) {
-        this.count = count - 1;
-      }
-      source.subscribe(this._unsubscribeAndRecycle());
-    }
-  }
+  return higherOrder(count)(this);
 }

src/operators/index.ts

@@ -53,6 +53,7 @@ export { publish } from './publish';
 export { publishBehavior } from './publishBehavior';
 export { race } from './race';
 export { reduce } from './reduce';
+export { repeat } from './repeat';
 export { refCount } from './refCount';
 export { scan } from './scan';
 export { subscribeOn } from './subscribeOn';

src/operators/repeat.ts

@@ -0,0 +1,63 @@
+import { Operator } from '../Operator';
+import { Subscriber } from '../Subscriber';
+import { Observable } from '../Observable';
+import { EmptyObservable } from '../observable/EmptyObservable';
+import { TeardownLogic } from '../Subscription';
+import { MonoTypeOperatorFunction } from '../interfaces';
+
+/**
+ * Returns an Observable that repeats the stream of items emitted by the source Observable at most count times.
+ *
+ * <img src="./img/repeat.png" width="100%">
+ *
+ * @param {number} [count] The number of times the source Observable items are repeated, a count of 0 will yield
+ * an empty Observable.
+ * @return {Observable} An Observable that repeats the stream of items emitted by the source Observable at most
+ * count times.
+ * @method repeat
+ * @owner Observable
+ */
+export function repeat<T>(count: number = -1): MonoTypeOperatorFunction<T> {
+  return (source: Observable<T>) => {
+    if (count === 0) {
+      return new EmptyObservable<T>();
+    } else if (count < 0) {
+      return source.lift(new RepeatOperator(-1, source));
+    } else {
+      return source.lift(new RepeatOperator(count - 1, source));
+    }
+  };
+}
+
+class RepeatOperator<T> implements Operator<T, T> {
+  constructor(private count: number,
+              private source: Observable<T>) {
+  }
+  call(subscriber: Subscriber<T>, source: any): TeardownLogic {
+    return source.subscribe(new RepeatSubscriber(subscriber, this.count, this.source));
+  }
+}
+
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+class RepeatSubscriber<T> extends Subscriber<T> {
+  constructor(destination: Subscriber<any>,
+              private count: number,
+              private source: Observable<T>) {
+    super(destination);
+  }
+  complete() {
+    if (!this.isStopped) {
+      const { source, count } = this;
+      if (count === 0) {
+        return super.complete();
+      } else if (count > -1) {
+        this.count = count - 1;
+      }
+      source.subscribe(this._unsubscribeAndRecycle());
+    }
+  }
+}