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AsSingle.swift
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AsSingle.swift
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//
// AsSingle.swift
// RxSwift
//
// Created by Krunoslav Zaher on 3/12/17.
// Copyright © 2017 Krunoslav Zaher. All rights reserved.
//
private final class AsSingleSink<Observer: ObserverType> : Sink<Observer>, ObserverType {
typealias Element = Observer.Element
private var element: Event<Element>?
func on(_ event: Event<Element>) {
switch event {
case .next:
if self.element != nil {
self.forwardOn(.error(RxError.moreThanOneElement))
self.dispose()
}
self.element = event
case .error:
self.forwardOn(event)
self.dispose()
case .completed:
if let element = self.element {
self.forwardOn(element)
self.forwardOn(.completed)
}
else {
self.forwardOn(.error(RxError.noElements))
}
self.dispose()
}
}
}
final class AsSingle<Element>: Producer<Element> {
private let source: Observable<Element>
init(source: Observable<Element>) {
self.source = source
}
override func run<Observer: ObserverType>(_ observer: Observer, cancel: Cancelable) -> (sink: Disposable, subscription: Disposable) where Observer.Element == Element {
let sink = AsSingleSink(observer: observer, cancel: cancel)
let subscription = self.source.subscribe(sink)
return (sink: sink, subscription: subscription)
}
}