ꦫꦣꦺꦤ꧀ꦄꦤ꧀ꦠꦱꦺꦤ

PATH: usr / local / lib / node_modules / ghost-cli / node_modules / rxjs / src / internal / operators

import { Operator } from '../Operator';
import { Observable } from '../Observable';
import { Subscriber } from '../Subscriber';
import { OperatorFunction } from '../types';

/**
 * Groups pairs of consecutive emissions together and emits them as an array of
 * two values.
 *
 * <span class="informal">Puts the current value and previous value together as
 * an array, and emits that.</span>
 *
 * ![](pairwise.png)
 *
 * The Nth emission from the source Observable will cause the output Observable
 * to emit an array [(N-1)th, Nth] of the previous and the current value, as a
 * pair. For this reason, `pairwise` emits on the second and subsequent
 * emissions from the source Observable, but not on the first emission, because
 * there is no previous value in that case.
 *
 * ## Example
 * On every click (starting from the second), emit the relative distance to the previous click
 * ```ts
 * import { fromEvent } from 'rxjs';
 * import { pairwise, map } from 'rxjs/operators';
 *
 * const clicks = fromEvent(document, 'click');
 * const pairs = clicks.pipe(pairwise());
 * const distance = pairs.pipe(
 *   map(pair => {
 *     const x0 = pair[0].clientX;
 *     const y0 = pair[0].clientY;
 *     const x1 = pair[1].clientX;
 *     const y1 = pair[1].clientY;
 *     return Math.sqrt(Math.pow(x0 - x1, 2) + Math.pow(y0 - y1, 2));
 *   }),
 * );
 * distance.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link buffer}
 * @see {@link bufferCount}
 *
 * @return {Observable<Array<T>>} An Observable of pairs (as arrays) of
 * consecutive values from the source Observable.
 * @method pairwise
 * @owner Observable
 */
export function pairwise<T>(): OperatorFunction<T, [T, T]> {
  return (source: Observable<T>) => source.lift(new PairwiseOperator());
}

class PairwiseOperator<T> implements Operator<T, [T, T]> {
  call(subscriber: Subscriber<[T, T]>, source: any): any {
    return source.subscribe(new PairwiseSubscriber(subscriber));
  }
}

/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class PairwiseSubscriber<T> extends Subscriber<T> {
  private prev: T;
  private hasPrev: boolean = false;

constructor(destination: Subscriber<[T, T]>) {
    super(destination);
  }

_next(value: T): void {
    let pair: [T, T] | undefined;

if (this.hasPrev) {
      pair = [this.prev, value];
    } else {
      this.hasPrev = true;
    }

this.prev = value;

if (pair) {
      this.destination.next(pair);
    }
  }
}

[-] toArray.ts [edit]
[-] window.ts [edit]
[-] retry.ts [edit]
[-] mergeAll.ts [edit]
[-] windowWhen.ts [edit]
[-] every.ts [edit]
[-] timeout.ts [edit]
[-] debounceTime.ts [edit]
[-] index.ts [edit]
[-] takeWhile.ts [edit]
[-] audit.ts [edit]
[-] reduce.ts [edit]
[-] mapTo.ts [edit]
[-] count.ts [edit]
[-] debounce.ts [edit]
[-] throwIfEmpty.ts [edit]
[-] auditTime.ts [edit]
[-] scan.ts [edit]
[-] switchAll.ts [edit]
[-] map.ts [edit]
[-] bufferCount.ts [edit]
[-] mergeScan.ts [edit]
[-] publish.ts [edit]
[-] min.ts [edit]
[+] ..
[-] publishReplay.ts [edit]
[-] bufferTime.ts [edit]
[-] share.ts [edit]
[-] repeat.ts [edit]
[-] distinct.ts [edit]
[-] concatMapTo.ts [edit]
[-] buffer.ts [edit]
[-] concatMap.ts [edit]
[-] max.ts [edit]
[-] partition.ts [edit]
[-] observeOn.ts [edit]
[-] bufferWhen.ts [edit]
[-] dematerialize.ts [edit]
[-] throttle.ts [edit]
[-] groupBy.ts [edit]
[-] withLatestFrom.ts [edit]
[-] exhaust.ts [edit]
[-] exhaustMap.ts [edit]
[-] retryWhen.ts [edit]
[-] zipAll.ts [edit]
[-] find.ts [edit]
[-] mergeMap.ts [edit]
[-] single.ts [edit]
[-] last.ts [edit]
[-] combineLatest.ts [edit]
[-] publishLast.ts [edit]
[-] pluck.ts [edit]
[-] pairwise.ts [edit]
[-] distinctUntilChanged.ts [edit]
[-] timeInterval.ts [edit]
[-] shareReplay.ts [edit]
[-] skipUntil.ts [edit]
[-] findIndex.ts [edit]
[-] windowToggle.ts [edit]
[-] startWith.ts [edit]
[-] timeoutWith.ts [edit]
[-] concat.ts [edit]
[-] materialize.ts [edit]
[-] timestamp.ts [edit]
[-] onErrorResumeNext.ts [edit]
[-] subscribeOn.ts [edit]
[-] takeUntil.ts [edit]
[-] skipLast.ts [edit]
[-] throttleTime.ts [edit]
[-] mergeMapTo.ts [edit]
[-] multicast.ts [edit]
[-] merge.ts [edit]
[-] takeLast.ts [edit]
[-] delayWhen.ts [edit]
[-] sampleTime.ts [edit]
[-] tap.ts [edit]
[-] take.ts [edit]
[-] sample.ts [edit]
[-] filter.ts [edit]
[-] skip.ts [edit]
[-] expand.ts [edit]
[-] publishBehavior.ts [edit]
[-] sequenceEqual.ts [edit]
[-] ignoreElements.ts [edit]
[-] catchError.ts [edit]
[-] endWith.ts [edit]
[-] refCount.ts [edit]
[-] windowCount.ts [edit]
[-] defaultIfEmpty.ts [edit]
[-] windowTime.ts [edit]
[-] switchMapTo.ts [edit]
[-] switchMap.ts [edit]
[-] delay.ts [edit]
[-] bufferToggle.ts [edit]
[-] repeatWhen.ts [edit]
[-] concatAll.ts [edit]
[-] first.ts [edit]
[-] zip.ts [edit]
[-] elementAt.ts [edit]
[-] skipWhile.ts [edit]
[-] race.ts [edit]
[-] finalize.ts [edit]
[-] combineAll.ts [edit]
[-] distinctUntilKeyChanged.ts [edit]
[-] isEmpty.ts [edit]