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