| import { Operator } from '../Operator'; |
| import { Subscriber } from '../Subscriber'; |
| import { Observable } from '../Observable'; |
| import { OperatorFunction, TeardownLogic } from '../types'; |
| |
| /** |
| * 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> |
| * |
| * ![](bufferCount.png) |
| * |
| * 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. |
| * |
| * ## Examples |
| * |
| * Emit the last two click events as an array |
| * |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { bufferCount } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const buffered = clicks.pipe(bufferCount(2)); |
| * buffered.subscribe(x => console.log(x)); |
| * ``` |
| * |
| * On every click, emit the last two click events as an array |
| * |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { bufferCount } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const buffered = clicks.pipe(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(); |
| } |
| |
| } |