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Diffstat (limited to 'node_modules/rxjs/src/internal/operators/windowCount.ts')
| -rw-r--r-- | node_modules/rxjs/src/internal/operators/windowCount.ts | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/node_modules/rxjs/src/internal/operators/windowCount.ts b/node_modules/rxjs/src/internal/operators/windowCount.ts new file mode 100644 index 0000000..cf24e1b --- /dev/null +++ b/node_modules/rxjs/src/internal/operators/windowCount.ts @@ -0,0 +1,129 @@ +import { Observable } from '../Observable'; +import { Subject } from '../Subject'; +import { OperatorFunction } from '../types'; +import { operate } from '../util/lift'; +import { createOperatorSubscriber } from './OperatorSubscriber'; + +/** + * Branch out the source Observable values as a nested Observable with each + * nested Observable emitting at most `windowSize` values. + * + * <span class="informal">It's like {@link bufferCount}, but emits a nested + * Observable instead of an array.</span> + * + *  + * + * Returns an Observable that emits windows of items it collects from the source + * Observable. The output Observable emits windows every `startWindowEvery` + * items, each containing no more than `windowSize` items. When the source + * Observable completes or encounters an error, the output Observable emits + * the current window and propagates the notification from the source + * Observable. If `startWindowEvery` is not provided, then new windows are + * started immediately at the start of the source and when each window completes + * with size `windowSize`. + * + * ## Examples + * + * Ignore every 3rd click event, starting from the first one + * + * ```ts + * import { fromEvent, windowCount, map, skip, mergeAll } from 'rxjs'; + * + * const clicks = fromEvent(document, 'click'); + * const result = clicks.pipe( + * windowCount(3), + * map(win => win.pipe(skip(1))), // skip first of every 3 clicks + * mergeAll() // flatten the Observable-of-Observables + * ); + * result.subscribe(x => console.log(x)); + * ``` + * + * Ignore every 3rd click event, starting from the third one + * + * ```ts + * import { fromEvent, windowCount, mergeAll } from 'rxjs'; + * + * const clicks = fromEvent(document, 'click'); + * const result = clicks.pipe( + * windowCount(2, 3), + * mergeAll() // flatten the Observable-of-Observables + * ); + * result.subscribe(x => console.log(x)); + * ``` + * + * @see {@link window} + * @see {@link windowTime} + * @see {@link windowToggle} + * @see {@link windowWhen} + * @see {@link bufferCount} + * + * @param windowSize The maximum number of values emitted by each window. + * @param startWindowEvery Interval at which to start a new window. For example + * if `startWindowEvery` is `2`, then a new window will be started on every + * other value from the source. A new window is started at the beginning of the + * source by default. + * @return A function that returns an Observable of windows, which in turn are + * Observable of values. + */ +export function windowCount<T>(windowSize: number, startWindowEvery: number = 0): OperatorFunction<T, Observable<T>> { + const startEvery = startWindowEvery > 0 ? startWindowEvery : windowSize; + + return operate((source, subscriber) => { + let windows = [new Subject<T>()]; + let starts: number[] = []; + let count = 0; + + // Open the first window. + subscriber.next(windows[0].asObservable()); + + source.subscribe( + createOperatorSubscriber( + subscriber, + (value: T) => { + // Emit the value through all current windows. + // We don't need to create a new window yet, we + // do that as soon as we close one. + for (const window of windows) { + window.next(value); + } + // Here we're using the size of the window array to figure + // out if the oldest window has emitted enough values. We can do this + // because the size of the window array is a function of the values + // seen by the subscription. If it's time to close it, we complete + // it and remove it. + const c = count - windowSize + 1; + if (c >= 0 && c % startEvery === 0) { + windows.shift()!.complete(); + } + + // Look to see if the next count tells us it's time to open a new window. + // TODO: We need to figure out if this really makes sense. We're technically + // emitting windows *before* we have a value to emit them for. It's probably + // more expected that we should be emitting the window when the start + // count is reached -- not before. + if (++count % startEvery === 0) { + const window = new Subject<T>(); + windows.push(window); + subscriber.next(window.asObservable()); + } + }, + () => { + while (windows.length > 0) { + windows.shift()!.complete(); + } + subscriber.complete(); + }, + (err) => { + while (windows.length > 0) { + windows.shift()!.error(err); + } + subscriber.error(err); + }, + () => { + starts = null!; + windows = null!; + } + ) + ); + }); +} |
