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 { Subject } from '../Subject';
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import { OperatorFunction } from '../types';
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/**
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* Branch out the source Observable values as a nested Observable with each
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* nested Observable emitting at most `windowSize` values.
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*
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* <span class="informal">It's like {@link bufferCount}, but emits a nested
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* Observable instead of an array.</span>
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*
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* 
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*
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* Returns an Observable that emits windows of items it collects from the source
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* Observable. The output Observable emits windows every `startWindowEvery`
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* items, each containing no more than `windowSize` items. When the source
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* Observable completes or encounters an error, the output Observable emits
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* the current window and propagates the notification from the source
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* Observable. If `startWindowEvery` is not provided, then new windows are
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* started immediately at the start of the source and when each window completes
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* with size `windowSize`.
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*
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* ## Examples
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* Ignore every 3rd click event, starting from the first one
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* ```ts
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* import { fromEvent } from 'rxjs';
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* import { windowCount, map, mergeAll, skip } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const result = clicks.pipe(
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* windowCount(3),
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* map(win => win.pipe(skip(1))), // skip first of every 3 clicks
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* mergeAll() // flatten the Observable-of-Observables
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* );
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* result.subscribe(x => console.log(x));
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* ```
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*
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* Ignore every 3rd click event, starting from the third one
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* ```ts
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* import { fromEvent } from 'rxjs';
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* import { windowCount, mergeAll } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const result = clicks.pipe(
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* windowCount(2, 3),
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* mergeAll(), // flatten the Observable-of-Observables
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* );
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* result.subscribe(x => console.log(x));
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* ```
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*
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* @see {@link window}
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* @see {@link windowTime}
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* @see {@link windowToggle}
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* @see {@link windowWhen}
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* @see {@link bufferCount}
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*
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* @param {number} windowSize The maximum number of values emitted by each
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* window.
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* @param {number} [startWindowEvery] Interval at which to start a new window.
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* For example if `startWindowEvery` is `2`, then a new window will be started
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* on every other value from the source. A new window is started at the
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* beginning of the source by default.
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* @return {Observable<Observable<T>>} An Observable of windows, which in turn
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* are Observable of values.
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* @method windowCount
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* @owner Observable
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*/
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export function windowCount<T>(windowSize: number,
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startWindowEvery: number = 0): OperatorFunction<T, Observable<T>> {
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return function windowCountOperatorFunction(source: Observable<T>) {
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return source.lift(new WindowCountOperator<T>(windowSize, startWindowEvery));
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};
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}
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class WindowCountOperator<T> implements Operator<T, Observable<T>> {
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constructor(private windowSize: number,
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private startWindowEvery: number) {
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}
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call(subscriber: Subscriber<Observable<T>>, source: any): any {
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return source.subscribe(new WindowCountSubscriber(subscriber, this.windowSize, this.startWindowEvery));
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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 WindowCountSubscriber<T> extends Subscriber<T> {
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private windows: Subject<T>[] = [ new Subject<T>() ];
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private count: number = 0;
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constructor(protected destination: Subscriber<Observable<T>>,
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private windowSize: number,
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private startWindowEvery: number) {
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super(destination);
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destination.next(this.windows[0]);
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}
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protected _next(value: T) {
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const startWindowEvery = (this.startWindowEvery > 0) ? this.startWindowEvery : this.windowSize;
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const destination = this.destination;
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const windowSize = this.windowSize;
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const windows = this.windows;
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const len = windows.length;
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for (let i = 0; i < len && !this.closed; i++) {
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windows[i].next(value);
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}
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const c = this.count - windowSize + 1;
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if (c >= 0 && c % startWindowEvery === 0 && !this.closed) {
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windows.shift().complete();
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}
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if (++this.count % startWindowEvery === 0 && !this.closed) {
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const window = new Subject<T>();
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windows.push(window);
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destination.next(window);
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}
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}
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protected _error(err: any) {
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const windows = this.windows;
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if (windows) {
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while (windows.length > 0 && !this.closed) {
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windows.shift().error(err);
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}
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}
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this.destination.error(err);
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}
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protected _complete() {
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const windows = this.windows;
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if (windows) {
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while (windows.length > 0 && !this.closed) {
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windows.shift().complete();
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}
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}
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this.destination.complete();
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}
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protected _unsubscribe() {
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this.count = 0;
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this.windows = null;
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}
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}
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