import { scan as higherOrderScan } from '../operators/scan'; /* tslint:enable:max-line-length */ /** * Applies an accumulator function over the source Observable, and returns each * intermediate result, with an optional seed value. * * It's like {@link reduce}, but emits the current * accumulation whenever the source emits a value. * * * * 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 * var clicks = Rx.Observable.fromEvent(document, 'click'); * var ones = clicks.mapTo(1); * var seed = 0; * var count = ones.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} An observable of the accumulated values. * @method scan * @owner Observable */ export function scan(accumulator, seed) { if (arguments.length >= 2) { return higherOrderScan(accumulator, seed)(this); } return higherOrderScan(accumulator)(this); } //# sourceMappingURL=scan.js.map