import { expand as higherOrder } from '../operators/expand'; /* tslint:enable:max-line-length */ /** * Recursively projects each source value to an Observable which is merged in * the output Observable. * * It's similar to {@link mergeMap}, but applies the * projection function to every source value as well as every output value. * It's recursive. * * * * Returns an Observable that emits items based on applying a function that you * supply to each item emitted by the source Observable, where that function * returns an Observable, and then merging those resulting Observables and * emitting the results of this merger. *Expand* will re-emit on the output * Observable every source value. Then, each output value is given to the * `project` function which returns an inner Observable to be merged on the * output Observable. Those output values resulting from the projection are also * given to the `project` function to produce new output values. This is how * *expand* behaves recursively. * * @example Start emitting the powers of two on every click, at most 10 of them * var clicks = Rx.Observable.fromEvent(document, 'click'); * var powersOfTwo = clicks * .mapTo(1) * .expand(x => Rx.Observable.of(2 * x).delay(1000)) * .take(10); * powersOfTwo.subscribe(x => console.log(x)); * * @see {@link mergeMap} * @see {@link mergeScan} * * @param {function(value: T, index: number) => Observable} project A function * that, when applied to an item emitted by the source or the output Observable, * returns an Observable. * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input * Observables being subscribed to concurrently. * @param {Scheduler} [scheduler=null] The IScheduler to use for subscribing to * each projected inner Observable. * @return {Observable} An Observable that emits the source values and also * result of applying the projection function to each value emitted on the * output Observable and and merging the results of the Observables obtained * from this transformation. * @method expand * @owner Observable */ export function expand(project, concurrent = Number.POSITIVE_INFINITY, scheduler = undefined) { concurrent = (concurrent || 0) < 1 ? Number.POSITIVE_INFINITY : concurrent; return higherOrder(project, concurrent, scheduler)(this); } //# sourceMappingURL=expand.js.map