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