//
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// Sample.swift
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// RxSwift
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//
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// Created by Krunoslav Zaher on 5/1/15.
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// Copyright © 2015 Krunoslav Zaher. All rights reserved.
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//
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extension ObservableType {
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/**
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Samples the source observable sequence using a sampler observable sequence producing sampling ticks.
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Upon each sampling tick, the latest element (if any) in the source sequence during the last sampling interval is sent to the resulting sequence.
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**In case there were no new elements between sampler ticks, no element is sent to the resulting sequence.**
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- seealso: [sample operator on reactivex.io](http://reactivex.io/documentation/operators/sample.html)
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- parameter sampler: Sampling tick sequence.
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- returns: Sampled observable sequence.
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*/
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public func sample<Source: ObservableType>(_ sampler: Source)
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-> Observable<Element> {
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return Sample(source: self.asObservable(), sampler: sampler.asObservable())
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}
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}
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final private class SamplerSink<Observer: ObserverType, SampleType>
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: ObserverType
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, LockOwnerType
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, SynchronizedOnType {
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typealias Element = SampleType
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typealias Parent = SampleSequenceSink<Observer, SampleType>
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private let _parent: Parent
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var _lock: RecursiveLock {
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return self._parent._lock
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}
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init(parent: Parent) {
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self._parent = parent
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}
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func on(_ event: Event<Element>) {
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self.synchronizedOn(event)
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}
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func _synchronized_on(_ event: Event<Element>) {
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switch event {
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case .next, .completed:
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if let element = _parent._element {
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self._parent._element = nil
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self._parent.forwardOn(.next(element))
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}
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if self._parent._atEnd {
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self._parent.forwardOn(.completed)
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self._parent.dispose()
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}
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case .error(let e):
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self._parent.forwardOn(.error(e))
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self._parent.dispose()
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}
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}
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}
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final private class SampleSequenceSink<Observer: ObserverType, SampleType>
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: Sink<Observer>
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, ObserverType
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, LockOwnerType
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, SynchronizedOnType {
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typealias Element = Observer.Element
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typealias Parent = Sample<Element, SampleType>
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private let _parent: Parent
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let _lock = RecursiveLock()
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// state
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fileprivate var _element = nil as Element?
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fileprivate var _atEnd = false
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private let _sourceSubscription = SingleAssignmentDisposable()
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init(parent: Parent, observer: Observer, cancel: Cancelable) {
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self._parent = parent
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super.init(observer: observer, cancel: cancel)
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}
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func run() -> Disposable {
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self._sourceSubscription.setDisposable(self._parent._source.subscribe(self))
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let samplerSubscription = self._parent._sampler.subscribe(SamplerSink(parent: self))
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return Disposables.create(_sourceSubscription, samplerSubscription)
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}
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func on(_ event: Event<Element>) {
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self.synchronizedOn(event)
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}
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func _synchronized_on(_ event: Event<Element>) {
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switch event {
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case .next(let element):
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self._element = element
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case .error:
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self.forwardOn(event)
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self.dispose()
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case .completed:
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self._atEnd = true
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self._sourceSubscription.dispose()
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}
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}
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}
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final private class Sample<Element, SampleType>: Producer<Element> {
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fileprivate let _source: Observable<Element>
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fileprivate let _sampler: Observable<SampleType>
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init(source: Observable<Element>, sampler: Observable<SampleType>) {
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self._source = source
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self._sampler = sampler
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}
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override func run<Observer: ObserverType>(_ observer: Observer, cancel: Cancelable) -> (sink: Disposable, subscription: Disposable) where Observer.Element == Element {
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let sink = SampleSequenceSink(parent: self, observer: observer, cancel: cancel)
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let subscription = sink.run()
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return (sink: sink, subscription: subscription)
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}
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}
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