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

src/operator/bufferCount.ts

@@ -1,7 +1,6 @@
-import { Operator } from '../Operator';
-import { Subscriber } from '../Subscriber';
+
 import { Observable } from '../Observable';
-import { TeardownLogic } from '../Subscription';
+import { bufferCount as higherOrder } from '../operators';
 
 /**
  * Buffers the source Observable values until the size hits the maximum
@@ -45,98 +44,5 @@ import { TeardownLogic } from '../Subscription';
  * @owner Observable
  */
 export function bufferCount<T>(this: Observable<T>, bufferSize: number, startBufferEvery: number = null): Observable<T[]> {
- return this.lift(new BufferCountOperator<T>(bufferSize, startBufferEvery));
-}
-
-class BufferCountOperator<T> implements Operator<T, T[]> {
- private subscriberClass: any;
-
- constructor(private bufferSize: number, private startBufferEvery: number) {
- if (!startBufferEvery || bufferSize === startBufferEvery) {
- this.subscriberClass = BufferCountSubscriber;
- } else {
- this.subscriberClass = BufferSkipCountSubscriber;
- }
- }
-
- call(subscriber: Subscriber<T[]>, source: any): TeardownLogic {
- return source.subscribe(new this.subscriberClass(subscriber, this.bufferSize, this.startBufferEvery));
- }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class BufferCountSubscriber<T> extends Subscriber<T> {
- private buffer: T[] = [];
-
- constructor(destination: Subscriber<T[]>, private bufferSize: number) {
- super(destination);
- }
-
- protected _next(value: T): void {
- const buffer = this.buffer;
-
- buffer.push(value);
-
- if (buffer.length == this.bufferSize) {
- this.destination.next(buffer);
- this.buffer = [];
- }
- }
-
- protected _complete(): void {
- const buffer = this.buffer;
- if (buffer.length > 0) {
- this.destination.next(buffer);
- }
- super._complete();
- }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class BufferSkipCountSubscriber<T> extends Subscriber<T> {
- private buffers: Array<T[]> = [];
- private count: number = 0;
-
- constructor(destination: Subscriber<T[]>, private bufferSize: number, private startBufferEvery: number) {
- super(destination);
- }
-
- protected _next(value: T): void {
- const { bufferSize, startBufferEvery, buffers, count } = this;
-
- this.count++;
- if (count % startBufferEvery === 0) {
- buffers.push([]);
- }
-
- for (let i = buffers.length; i--; ) {
- const buffer = buffers[i];
- buffer.push(value);
- if (buffer.length === bufferSize) {
- buffers.splice(i, 1);
- this.destination.next(buffer);
- }
- }
- }
-
- protected _complete(): void {
- const { buffers, destination } = this;
-
- while (buffers.length > 0) {
- let buffer = buffers.shift();
- if (buffer.length > 0) {
- destination.next(buffer);
- }
- }
- super._complete();
- }
-
+ return higherOrder(bufferSize, startBufferEvery)(this);
 }

src/operators/bufferCount.ts

@@ -0,0 +1,145 @@
+import { Operator } from '../Operator';
+import { Subscriber } from '../Subscriber';
+import { Observable } from '../Observable';
+import { TeardownLogic } from '../Subscription';
+import { OperatorFunction } from '../interfaces';
+
+/**
+ * Buffers the source Observable values until the size hits the maximum
+ * `bufferSize` given.
+ *
+ * <span class="informal">Collects values from the past as an array, and emits
+ * that array only when its size reaches `bufferSize`.</span>
+ *
+ * <img src="./img/bufferCount.png" width="100%">
+ *
+ * Buffers a number of values from the source Observable by `bufferSize` then
+ * emits the buffer and clears it, and starts a new buffer each
+ * `startBufferEvery` values. If `startBufferEvery` is not provided or is
+ * `null`, then new buffers are started immediately at the start of the source
+ * and when each buffer closes and is emitted.
+ *
+ * @example <caption>Emit the last two click events as an array</caption>
+ * var clicks = Rx.Observable.fromEvent(document, 'click');
+ * var buffered = clicks.bufferCount(2);
+ * buffered.subscribe(x => console.log(x));
+ *
+ * @example <caption>On every click, emit the last two click events as an array</caption>
+ * var clicks = Rx.Observable.fromEvent(document, 'click');
+ * var buffered = clicks.bufferCount(2, 1);
+ * buffered.subscribe(x => console.log(x));
+ *
+ * @see {@link buffer}
+ * @see {@link bufferTime}
+ * @see {@link bufferToggle}
+ * @see {@link bufferWhen}
+ * @see {@link pairwise}
+ * @see {@link windowCount}
+ *
+ * @param {number} bufferSize The maximum size of the buffer emitted.
+ * @param {number} [startBufferEvery] Interval at which to start a new buffer.
+ * For example if `startBufferEvery` is `2`, then a new buffer will be started
+ * on every other value from the source. A new buffer is started at the
+ * beginning of the source by default.
+ * @return {Observable<T[]>} An Observable of arrays of buffered values.
+ * @method bufferCount
+ * @owner Observable
+ */
+export function bufferCount<T>(bufferSize: number, startBufferEvery: number = null): OperatorFunction<T, T[]> {
+ return function bufferCountOperatorFunction(source: Observable<T>) {
+ return source.lift(new BufferCountOperator<T>(bufferSize, startBufferEvery));
+ };
+}
+
+class BufferCountOperator<T> implements Operator<T, T[]> {
+ private subscriberClass: any;
+
+ constructor(private bufferSize: number, private startBufferEvery: number) {
+ if (!startBufferEvery || bufferSize === startBufferEvery) {
+ this.subscriberClass = BufferCountSubscriber;
+ } else {
+ this.subscriberClass = BufferSkipCountSubscriber;
+ }
+ }
+
+ call(subscriber: Subscriber<T[]>, source: any): TeardownLogic {
+ return source.subscribe(new this.subscriberClass(subscriber, this.bufferSize, this.startBufferEvery));
+ }
+}
+
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+class BufferCountSubscriber<T> extends Subscriber<T> {
+ private buffer: T[] = [];
+
+ constructor(destination: Subscriber<T[]>, private bufferSize: number) {
+ super(destination);
+ }
+
+ protected _next(value: T): void {
+ const buffer = this.buffer;
+
+ buffer.push(value);
+
+ if (buffer.length == this.bufferSize) {
+ this.destination.next(buffer);
+ this.buffer = [];
+ }
+ }
+
+ protected _complete(): void {
+ const buffer = this.buffer;
+ if (buffer.length > 0) {
+ this.destination.next(buffer);
+ }
+ super._complete();
+ }
+}
+
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+class BufferSkipCountSubscriber<T> extends Subscriber<T> {
+ private buffers: Array<T[]> = [];
+ private count: number = 0;
+
+ constructor(destination: Subscriber<T[]>, private bufferSize: number, private startBufferEvery: number) {
+ super(destination);
+ }
+
+ protected _next(value: T): void {
+ const { bufferSize, startBufferEvery, buffers, count } = this;
+
+ this.count++;
+ if (count % startBufferEvery === 0) {
+ buffers.push([]);
+ }
+
+ for (let i = buffers.length; i--; ) {
+ const buffer = buffers[i];
+ buffer.push(value);
+ if (buffer.length === bufferSize) {
+ buffers.splice(i, 1);
+ this.destination.next(buffer);
+ }
+ }
+ }
+
+ protected _complete(): void {
+ const { buffers, destination } = this;
+
+ while (buffers.length > 0) {
+ let buffer = buffers.shift();
+ if (buffer.length > 0) {
+ destination.next(buffer);
+ }
+ }
+ super._complete();
+ }
+
+}

src/operators/index.ts

@@ -1,6 +1,7 @@
 export { audit } from './audit';
 export { auditTime } from './auditTime';
 export { buffer } from './buffer';
+export { bufferCount } from './bufferCount';
 export { catchError } from './catchError';
 export { concat } from './concat';
 export { concatAll } from './concatAll';