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111 lines
3.9 KiB
111 lines
3.9 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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* Counts the number of emissions on the source and emits that number when the |
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* source completes. |
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* |
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* <span class="informal">Tells how many values were emitted, when the source |
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* completes.</span> |
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* |
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* <img src="./img/count.png" width="100%"> |
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* |
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* `count` transforms an Observable that emits values into an Observable that |
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* emits a single value that represents the number of values emitted by the |
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* source Observable. If the source Observable terminates with an error, `count` |
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* will pass this error notification along without emitting a value first. If |
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* the source Observable does not terminate at all, `count` will neither emit |
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* a value nor terminate. This operator takes an optional `predicate` function |
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* as argument, in which case the output emission will represent the number of |
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* source values that matched `true` with the `predicate`. |
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* |
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* @example <caption>Counts how many seconds have passed before the first click happened</caption> |
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* var seconds = Rx.Observable.interval(1000); |
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* var clicks = Rx.Observable.fromEvent(document, 'click'); |
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* var secondsBeforeClick = seconds.takeUntil(clicks); |
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* var result = secondsBeforeClick.count(); |
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* result.subscribe(x => console.log(x)); |
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* |
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* @example <caption>Counts how many odd numbers are there between 1 and 7</caption> |
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* var numbers = Rx.Observable.range(1, 7); |
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* var result = numbers.count(i => i % 2 === 1); |
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* result.subscribe(x => console.log(x)); |
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* |
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* // Results in: |
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* // 4 |
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* |
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* @see {@link max} |
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* @see {@link min} |
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* @see {@link reduce} |
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* |
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* @param {function(value: T, i: number, source: Observable<T>): boolean} [predicate] A |
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* boolean function to select what values are to be counted. It is provided with |
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* arguments of: |
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* - `value`: the value from the source Observable. |
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* - `index`: the (zero-based) "index" of the value from the source Observable. |
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* - `source`: the source Observable instance itself. |
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* @return {Observable} An Observable of one number that represents the count as |
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* described above. |
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* @method count |
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* @owner Observable |
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*/ |
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function count(predicate) { |
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return function (source) { return source.lift(new CountOperator(predicate, source)); }; |
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} |
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exports.count = count; |
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var CountOperator = (function () { |
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function CountOperator(predicate, source) { |
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this.predicate = predicate; |
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this.source = source; |
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} |
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CountOperator.prototype.call = function (subscriber, source) { |
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return source.subscribe(new CountSubscriber(subscriber, this.predicate, this.source)); |
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}; |
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return CountOperator; |
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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 CountSubscriber = (function (_super) { |
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__extends(CountSubscriber, _super); |
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function CountSubscriber(destination, predicate, source) { |
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_super.call(this, destination); |
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this.predicate = predicate; |
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this.source = source; |
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this.count = 0; |
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this.index = 0; |
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} |
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CountSubscriber.prototype._next = function (value) { |
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if (this.predicate) { |
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this._tryPredicate(value); |
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} |
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else { |
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this.count++; |
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} |
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}; |
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CountSubscriber.prototype._tryPredicate = function (value) { |
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var result; |
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try { |
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result = this.predicate(value, this.index++, this.source); |
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} |
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catch (err) { |
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this.destination.error(err); |
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return; |
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} |
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if (result) { |
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this.count++; |
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} |
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}; |
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CountSubscriber.prototype._complete = function () { |
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this.destination.next(this.count); |
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this.destination.complete(); |
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}; |
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return CountSubscriber; |
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}(Subscriber_1.Subscriber)); |
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//# sourceMappingURL=count.js.map
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