//
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// Driver.swift
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// RxCocoa
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//
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// Created by Krunoslav Zaher on 9/26/16.
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// Copyright © 2016 Krunoslav Zaher. All rights reserved.
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//
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import RxSwift
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/**
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Trait that represents observable sequence with following properties:
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- it never fails
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- it delivers events on `MainScheduler.instance`
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- `share(replay: 1, scope: .whileConnected)` sharing strategy
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Additional explanation:
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- all observers share sequence computation resources
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- it's stateful, upon subscription (calling subscribe) last element is immediately replayed if it was produced
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- computation of elements is reference counted with respect to the number of observers
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- if there are no subscribers, it will release sequence computation resources
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In case trait that models event bus is required, please check `Signal`.
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`Driver<Element>` can be considered a builder pattern for observable sequences that drive the application.
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If observable sequence has produced at least one element, after new subscription is made last produced element will be
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immediately replayed on the same thread on which the subscription was made.
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When using `drive*`, `subscribe*` and `bind*` family of methods, they should always be called from main thread.
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If `drive*`, `subscribe*` and `bind*` are called from background thread, it is possible that initial replay
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will happen on background thread, and subsequent events will arrive on main thread.
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To find out more about traits and how to use them, please visit `Documentation/Traits.md`.
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*/
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public typealias Driver<Element> = SharedSequence<DriverSharingStrategy, Element>
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public struct DriverSharingStrategy: SharingStrategyProtocol {
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public static var scheduler: SchedulerType { SharingScheduler.make() }
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public static func share<Element>(_ source: Observable<Element>) -> Observable<Element> {
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source.share(replay: 1, scope: .whileConnected)
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}
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}
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extension SharedSequenceConvertibleType where SharingStrategy == DriverSharingStrategy {
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/// Adds `asDriver` to `SharingSequence` with `DriverSharingStrategy`.
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public func asDriver() -> Driver<Element> {
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self.asSharedSequence()
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}
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}
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