| import { Observable } from '../Observable'; |
| import { Operator } from '../Operator'; |
| import { Subscriber } from '../Subscriber'; |
| import { MonoTypeOperatorFunction, TeardownLogic } from '../types'; |
| |
| /** |
| * Returns an Observable that skips all items emitted by the source Observable as long as a specified condition holds |
| * true, but emits all further source items as soon as the condition becomes false. |
| * |
| * ![](skipWhile.png) |
| * |
| * @param {Function} predicate - A function to test each item emitted from the source Observable. |
| * @return {Observable<T>} An Observable that begins emitting items emitted by the source Observable when the |
| * specified predicate becomes false. |
| * @method skipWhile |
| * @owner Observable |
| */ |
| export function skipWhile<T>(predicate: (value: T, index: number) => boolean): MonoTypeOperatorFunction<T> { |
| return (source: Observable<T>) => source.lift(new SkipWhileOperator(predicate)); |
| } |
| |
| class SkipWhileOperator<T> implements Operator<T, T> { |
| constructor(private predicate: (value: T, index: number) => boolean) { |
| } |
| |
| call(subscriber: Subscriber<T>, source: any): TeardownLogic { |
| return source.subscribe(new SkipWhileSubscriber(subscriber, this.predicate)); |
| } |
| } |
| |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class SkipWhileSubscriber<T> extends Subscriber<T> { |
| private skipping: boolean = true; |
| private index: number = 0; |
| |
| constructor(destination: Subscriber<T>, |
| private predicate: (value: T, index: number) => boolean) { |
| super(destination); |
| } |
| |
| protected _next(value: T): void { |
| const destination = this.destination; |
| if (this.skipping) { |
| this.tryCallPredicate(value); |
| } |
| |
| if (!this.skipping) { |
| destination.next(value); |
| } |
| } |
| |
| private tryCallPredicate(value: T): void { |
| try { |
| const result = this.predicate(value, this.index++); |
| this.skipping = Boolean(result); |
| } catch (err) { |
| this.destination.error(err); |
| } |
| } |
| } |