1import { Operator } from '../Operator'; 2import { Subscriber } from '../Subscriber'; 3import { Observable } from '../Observable'; 4import { Subject } from '../Subject'; 5import { OperatorFunction } from '../types'; 6 7/** 8 * Branch out the source Observable values as a nested Observable with each 9 * nested Observable emitting at most `windowSize` values. 10 * 11 * <span class="informal">It's like {@link bufferCount}, but emits a nested 12 * Observable instead of an array.</span> 13 * 14 * ![](windowCount.png) 15 * 16 * Returns an Observable that emits windows of items it collects from the source 17 * Observable. The output Observable emits windows every `startWindowEvery` 18 * items, each containing no more than `windowSize` items. When the source 19 * Observable completes or encounters an error, the output Observable emits 20 * the current window and propagates the notification from the source 21 * Observable. If `startWindowEvery` is not provided, then new windows are 22 * started immediately at the start of the source and when each window completes 23 * with size `windowSize`. 24 * 25 * ## Examples 26 * Ignore every 3rd click event, starting from the first one 27 * ```ts 28 * import { fromEvent } from 'rxjs'; 29 * import { windowCount, map, mergeAll, skip } from 'rxjs/operators'; 30 * 31 * const clicks = fromEvent(document, 'click'); 32 * const result = clicks.pipe( 33 * windowCount(3), 34 * map(win => win.pipe(skip(1))), // skip first of every 3 clicks 35 * mergeAll() // flatten the Observable-of-Observables 36 * ); 37 * result.subscribe(x => console.log(x)); 38 * ``` 39 * 40 * Ignore every 3rd click event, starting from the third one 41 * ```ts 42 * import { fromEvent } from 'rxjs'; 43 * import { windowCount, mergeAll } from 'rxjs/operators'; 44 * 45 * const clicks = fromEvent(document, 'click'); 46 * const result = clicks.pipe( 47 * windowCount(2, 3), 48 * mergeAll(), // flatten the Observable-of-Observables 49 * ); 50 * result.subscribe(x => console.log(x)); 51 * ``` 52 * 53 * @see {@link window} 54 * @see {@link windowTime} 55 * @see {@link windowToggle} 56 * @see {@link windowWhen} 57 * @see {@link bufferCount} 58 * 59 * @param {number} windowSize The maximum number of values emitted by each 60 * window. 61 * @param {number} [startWindowEvery] Interval at which to start a new window. 62 * For example if `startWindowEvery` is `2`, then a new window will be started 63 * on every other value from the source. A new window is started at the 64 * beginning of the source by default. 65 * @return {Observable<Observable<T>>} An Observable of windows, which in turn 66 * are Observable of values. 67 * @method windowCount 68 * @owner Observable 69 */ 70export function windowCount<T>(windowSize: number, 71 startWindowEvery: number = 0): OperatorFunction<T, Observable<T>> { 72 return function windowCountOperatorFunction(source: Observable<T>) { 73 return source.lift(new WindowCountOperator<T>(windowSize, startWindowEvery)); 74 }; 75} 76 77class WindowCountOperator<T> implements Operator<T, Observable<T>> { 78 79 constructor(private windowSize: number, 80 private startWindowEvery: number) { 81 } 82 83 call(subscriber: Subscriber<Observable<T>>, source: any): any { 84 return source.subscribe(new WindowCountSubscriber(subscriber, this.windowSize, this.startWindowEvery)); 85 } 86} 87 88/** 89 * We need this JSDoc comment for affecting ESDoc. 90 * @ignore 91 * @extends {Ignored} 92 */ 93class WindowCountSubscriber<T> extends Subscriber<T> { 94 private windows: Subject<T>[] = [ new Subject<T>() ]; 95 private count: number = 0; 96 97 constructor(protected destination: Subscriber<Observable<T>>, 98 private windowSize: number, 99 private startWindowEvery: number) { 100 super(destination); 101 destination.next(this.windows[0]); 102 } 103 104 protected _next(value: T) { 105 const startWindowEvery = (this.startWindowEvery > 0) ? this.startWindowEvery : this.windowSize; 106 const destination = this.destination; 107 const windowSize = this.windowSize; 108 const windows = this.windows; 109 const len = windows.length; 110 111 for (let i = 0; i < len && !this.closed; i++) { 112 windows[i].next(value); 113 } 114 const c = this.count - windowSize + 1; 115 if (c >= 0 && c % startWindowEvery === 0 && !this.closed) { 116 windows.shift().complete(); 117 } 118 if (++this.count % startWindowEvery === 0 && !this.closed) { 119 const window = new Subject<T>(); 120 windows.push(window); 121 destination.next(window); 122 } 123 } 124 125 protected _error(err: any) { 126 const windows = this.windows; 127 if (windows) { 128 while (windows.length > 0 && !this.closed) { 129 windows.shift().error(err); 130 } 131 } 132 this.destination.error(err); 133 } 134 135 protected _complete() { 136 const windows = this.windows; 137 if (windows) { 138 while (windows.length > 0 && !this.closed) { 139 windows.shift().complete(); 140 } 141 } 142 this.destination.complete(); 143 } 144 145 protected _unsubscribe() { 146 this.count = 0; 147 this.windows = null; 148 } 149} 150