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Pods/RxSwift/RxSwift/Observables/First.swift

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+//
+//  First.swift
+//  RxSwift
+//
+//  Created by Krunoslav Zaher on 7/31/17.
+//  Copyright © 2017 Krunoslav Zaher. All rights reserved.
+//
+
+private final class FirstSink<Element, Observer: ObserverType> : Sink<Observer>, ObserverType where Observer.Element == Element? {
+    typealias Parent = First<Element>
+
+    func on(_ event: Event<Element>) {
+        switch event {
+        case .next(let value):
+            self.forwardOn(.next(value))
+            self.forwardOn(.completed)
+            self.dispose()
+        case .error(let error):
+            self.forwardOn(.error(error))
+            self.dispose()
+        case .completed:
+            self.forwardOn(.next(nil))
+            self.forwardOn(.completed)
+            self.dispose()
+        }
+    }
+}
+
+final class First<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 = FirstSink(observer: observer, cancel: cancel)
+        let subscription = self.source.subscribe(sink)
+        return (sink: sink, subscription: subscription)
+    }
+}