92 lines
3.4 KiB
JavaScript
92 lines
3.4 KiB
JavaScript
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"use strict";
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var __extends = (this && this.__extends) || function (d, b) {
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for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
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function __() { this.constructor = d; }
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d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
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};
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var Subscriber_1 = require('../Subscriber');
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/**
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* Emits values emitted by the source Observable so long as each value satisfies
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* the given `predicate`, and then completes as soon as this `predicate` is not
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* satisfied.
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*
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* <span class="informal">Takes values from the source only while they pass the
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* condition given. When the first value does not satisfy, it completes.</span>
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*
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* <img src="./img/takeWhile.png" width="100%">
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*
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* `takeWhile` subscribes and begins mirroring the source Observable. Each value
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* emitted on the source is given to the `predicate` function which returns a
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* boolean, representing a condition to be satisfied by the source values. The
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* output Observable emits the source values until such time as the `predicate`
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* returns false, at which point `takeWhile` stops mirroring the source
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* Observable and completes the output Observable.
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*
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* @example <caption>Emit click events only while the clientX property is greater than 200</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks.takeWhile(ev => ev.clientX > 200);
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* result.subscribe(x => console.log(x));
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*
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* @see {@link take}
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* @see {@link takeLast}
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* @see {@link takeUntil}
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* @see {@link skip}
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*
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* @param {function(value: T, index: number): boolean} predicate A function that
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* evaluates a value emitted by the source Observable and returns a boolean.
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* Also takes the (zero-based) index as the second argument.
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* @return {Observable<T>} An Observable that emits the values from the source
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* Observable so long as each value satisfies the condition defined by the
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* `predicate`, then completes.
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* @method takeWhile
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* @owner Observable
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*/
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function takeWhile(predicate) {
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return function (source) { return source.lift(new TakeWhileOperator(predicate)); };
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}
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exports.takeWhile = takeWhile;
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var TakeWhileOperator = (function () {
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function TakeWhileOperator(predicate) {
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this.predicate = predicate;
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}
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TakeWhileOperator.prototype.call = function (subscriber, source) {
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return source.subscribe(new TakeWhileSubscriber(subscriber, this.predicate));
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};
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return TakeWhileOperator;
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}());
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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var TakeWhileSubscriber = (function (_super) {
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__extends(TakeWhileSubscriber, _super);
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function TakeWhileSubscriber(destination, predicate) {
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_super.call(this, destination);
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this.predicate = predicate;
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this.index = 0;
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}
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TakeWhileSubscriber.prototype._next = function (value) {
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var destination = this.destination;
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var result;
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try {
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result = this.predicate(value, this.index++);
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}
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catch (err) {
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destination.error(err);
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return;
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}
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this.nextOrComplete(value, result);
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};
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TakeWhileSubscriber.prototype.nextOrComplete = function (value, predicateResult) {
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var destination = this.destination;
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if (Boolean(predicateResult)) {
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destination.next(value);
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}
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else {
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destination.complete();
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}
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};
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return TakeWhileSubscriber;
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}(Subscriber_1.Subscriber));
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//# sourceMappingURL=takeWhile.js.map
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