expand.js
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"use strict";
var __extends = (this && this.__extends) || function (d, b) {
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var tryCatch_1 = require('../util/tryCatch');
var errorObject_1 = require('../util/errorObject');
var OuterSubscriber_1 = require('../OuterSubscriber');
var subscribeToResult_1 = require('../util/subscribeToResult');
/* tslint:disable:max-line-length */
/**
* Recursively projects each source value to an Observable which is merged in
* the output Observable.
*
* <span class="informal">It's similar to {@link mergeMap}, but applies the
* projection function to every source value as well as every output value.
* It's recursive.</span>
*
* <img src="./img/expand.png" width="100%">
*
* 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 <caption>Start emitting the powers of two on every click, at most 10 of them</caption>
* 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 Scheduler 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
*/
function expand(project, concurrent, scheduler) {
if (concurrent === void 0) { concurrent = Number.POSITIVE_INFINITY; }
if (scheduler === void 0) { scheduler = undefined; }
concurrent = (concurrent || 0) < 1 ? Number.POSITIVE_INFINITY : concurrent;
return this.lift(new ExpandOperator(project, concurrent, scheduler));
}
exports.expand = expand;
var ExpandOperator = (function () {
function ExpandOperator(project, concurrent, scheduler) {
this.project = project;
this.concurrent = concurrent;
this.scheduler = scheduler;
}
ExpandOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new ExpandSubscriber(subscriber, this.project, this.concurrent, this.scheduler));
};
return ExpandOperator;
}());
exports.ExpandOperator = ExpandOperator;
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var ExpandSubscriber = (function (_super) {
__extends(ExpandSubscriber, _super);
function ExpandSubscriber(destination, project, concurrent, scheduler) {
_super.call(this, destination);
this.project = project;
this.concurrent = concurrent;
this.scheduler = scheduler;
this.index = 0;
this.active = 0;
this.hasCompleted = false;
if (concurrent < Number.POSITIVE_INFINITY) {
this.buffer = [];
}
}
ExpandSubscriber.dispatch = function (arg) {
var subscriber = arg.subscriber, result = arg.result, value = arg.value, index = arg.index;
subscriber.subscribeToProjection(result, value, index);
};
ExpandSubscriber.prototype._next = function (value) {
var destination = this.destination;
if (destination.closed) {
this._complete();
return;
}
var index = this.index++;
if (this.active < this.concurrent) {
destination.next(value);
var result = tryCatch_1.tryCatch(this.project)(value, index);
if (result === errorObject_1.errorObject) {
destination.error(errorObject_1.errorObject.e);
}
else if (!this.scheduler) {
this.subscribeToProjection(result, value, index);
}
else {
var state = { subscriber: this, result: result, value: value, index: index };
this.add(this.scheduler.schedule(ExpandSubscriber.dispatch, 0, state));
}
}
else {
this.buffer.push(value);
}
};
ExpandSubscriber.prototype.subscribeToProjection = function (result, value, index) {
this.active++;
this.add(subscribeToResult_1.subscribeToResult(this, result, value, index));
};
ExpandSubscriber.prototype._complete = function () {
this.hasCompleted = true;
if (this.hasCompleted && this.active === 0) {
this.destination.complete();
}
};
ExpandSubscriber.prototype.notifyNext = function (outerValue, innerValue, outerIndex, innerIndex, innerSub) {
this._next(innerValue);
};
ExpandSubscriber.prototype.notifyComplete = function (innerSub) {
var buffer = this.buffer;
this.remove(innerSub);
this.active--;
if (buffer && buffer.length > 0) {
this._next(buffer.shift());
}
if (this.hasCompleted && this.active === 0) {
this.destination.complete();
}
};
return ExpandSubscriber;
}(OuterSubscriber_1.OuterSubscriber));
exports.ExpandSubscriber = ExpandSubscriber;
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