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92 lines
3.4 KiB
92 lines
3.4 KiB
"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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