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| // | |
| // EmitWhile.swift | |
| // | |
| // Created by Daniel Tartaglia on 09/06/2018. | |
| // Copyright © 2021 Daniel Tartaglia. MIT License. | |
| // | |
| import Foundation | |
| import RxSwift | |
| /** | |
| Calls `producer` with `seed` then emits result and also passes it to `pred`. Will continue to call | |
| `producer` with new values as long as `pred` returns values. | |
| - parameter seed: The starting value needed for the first producer call. | |
| - parameter pred: A closure that determines the next value pass into the producer or returns nil if no | |
| more calls are necessary. | |
| - parameter producer: A closure that returns a Single. | |
| - returns: An observable that emits each producer's value. | |
| */ | |
| func emitWhile<T, U>(seed: U, pred: @escaping (T) -> U?, producer: @escaping (U) -> Single<T>) -> Observable<T> { | |
| producer(seed) | |
| .asObservable() | |
| .flatMap { (result) -> Observable<T> in | |
| guard let value = pred(result) else { return .just(result) } | |
| return emitWhile(seed: value, pred: pred, producer: producer) | |
| .startWith(result) | |
| } | |
| } |
Many thanks to @cjspradling on the RxSwift slack for ideas on refinement!
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cool！