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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, MonoTypeOperatorFunction } from '../types';

/* tslint:disable:max-line-length */
export function scan<T, R>(accumulator: (acc: R, value: T, index: number) => R, seed: R): OperatorFunction<T, R>;
export function scan<T>(accumulator: (acc: T, value: T, index: number) => T, seed?: T): MonoTypeOperatorFunction<T>;
export function scan<T, R>(accumulator: (acc: R, value: T, index: number) => R): OperatorFunction<T, R>;
/* tslint:enable:max-line-length */

/**
 * Applies an accumulator function over the source Observable, and returns each
 * intermediate result, with an optional seed value.
 *
 * <span class="informal">It's like {@link reduce}, but emits the current
 * accumulation whenever the source emits a value.</span>
 *
 * ![](scan.png)
 *
 * Combines together all values emitted on the source, using an accumulator
 * function that knows how to join a new source value into the accumulation from
 * the past. Is similar to {@link reduce}, but emits the intermediate
 * accumulations.
 *
 * Returns an Observable that applies a specified `accumulator` function to each
 * item emitted by the source Observable. If a `seed` value is specified, then
 * that value will be used as the initial value for the accumulator. If no seed
 * value is specified, the first item of the source is used as the seed.
 *
 * ## Example
 * Count the number of click events
 * ```ts
 * import { fromEvent } from 'rxjs';
 * import { scan, mapTo } from 'rxjs/operators';
 *
 * const clicks = fromEvent(document, 'click');
 * const ones = clicks.pipe(mapTo(1));
 * const seed = 0;
 * const count = ones.pipe(scan((acc, one) => acc + one, seed));
 * count.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link expand}
 * @see {@link mergeScan}
 * @see {@link reduce}
 *
 * @param {function(acc: R, value: T, index: number): R} accumulator
 * The accumulator function called on each source value.
 * @param {T|R} [seed] The initial accumulation value.
 * @return {Observable<R>} An observable of the accumulated values.
 * @method scan
 * @owner Observable
 */
export function scan<T, R>(accumulator: (acc: R, value: T, index: number) => R, seed?: T | R): OperatorFunction<T, R> {
  let hasSeed = false;
  // providing a seed of `undefined` *should* be valid and trigger
  // hasSeed! so don't use `seed !== undefined` checks!
  // For this reason, we have to check it here at the original call site
  // otherwise inside Operator/Subscriber we won't know if `undefined`
  // means they didn't provide anything or if they literally provided `undefined`
  if (arguments.length >= 2) {
    hasSeed = true;
  }

return function scanOperatorFunction(source: Observable<T>): Observable<R> {
    return source.lift(new ScanOperator(accumulator, seed, hasSeed));
  };
}

class ScanOperator<T, R> implements Operator<T, R> {
  constructor(private accumulator: (acc: R, value: T, index: number) => R, private seed?: T | R, private hasSeed: boolean = false) {}

call(subscriber: Subscriber<R>, source: any): any {
    return source.subscribe(new ScanSubscriber(subscriber, this.accumulator, this.seed, this.hasSeed));
  }
}

/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class ScanSubscriber<T, R> extends Subscriber<T> {
  private index: number = 0;

get seed(): T | R {
    return this._seed;
  }

set seed(value: T | R) {
    this.hasSeed = true;
    this._seed = value;
  }

constructor(destination: Subscriber<R>, private accumulator: (acc: R, value: T, index: number) => R, private _seed: T | R,
              private hasSeed: boolean) {
    super(destination);
  }

protected _next(value: T): void {
    if (!this.hasSeed) {
      this.seed = value;
      this.destination.next(value);
    } else {
      return this._tryNext(value);
    }
  }

private _tryNext(value: T): void {
    const index = this.index++;
    let result: any;
    try {
      result = this.accumulator(<R>this.seed, value, index);
    } catch (err) {
      this.destination.error(err);
    }
    this.seed = result;
    this.destination.next(result);
  }
}

[-] 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]