//
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// CombineLatest+Collection.swift
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// RxSwift
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//
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// Created by Krunoslav Zaher on 8/29/15.
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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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Merges the specified observable sequences into one observable sequence by using the selector function whenever any of the observable sequences produces an element.
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- seealso: [combinelatest operator on reactivex.io](http://reactivex.io/documentation/operators/combinelatest.html)
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- parameter resultSelector: Function to invoke whenever any of the sources produces an element.
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- returns: An observable sequence containing the result of combining elements of the sources using the specified result selector function.
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*/
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public static func combineLatest<Collection: Swift.Collection>(_ collection: Collection, resultSelector: @escaping ([Collection.Element.Element]) throws -> Element) -> Observable<Element>
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where Collection.Element: ObservableType {
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CombineLatestCollectionType(sources: collection, resultSelector: resultSelector)
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}
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/**
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Merges the specified observable sequences into one observable sequence whenever any of the observable sequences produces an element.
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- seealso: [combinelatest operator on reactivex.io](http://reactivex.io/documentation/operators/combinelatest.html)
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- returns: An observable sequence containing the result of combining elements of the sources.
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*/
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public static func combineLatest<Collection: Swift.Collection>(_ collection: Collection) -> Observable<[Element]>
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where Collection.Element: ObservableType, Collection.Element.Element == Element {
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CombineLatestCollectionType(sources: collection, resultSelector: { $0 })
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}
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}
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final class CombineLatestCollectionTypeSink<Collection: Swift.Collection, Observer: ObserverType>
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: Sink<Observer> where Collection.Element: ObservableConvertibleType {
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typealias Result = Observer.Element
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typealias Parent = CombineLatestCollectionType<Collection, Result>
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typealias SourceElement = Collection.Element.Element
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let parent: Parent
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let lock = RecursiveLock()
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// state
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var numberOfValues = 0
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var values: [SourceElement?]
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var isDone: [Bool]
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var numberOfDone = 0
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var subscriptions: [SingleAssignmentDisposable]
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init(parent: Parent, observer: Observer, cancel: Cancelable) {
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self.parent = parent
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self.values = [SourceElement?](repeating: nil, count: parent.count)
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self.isDone = [Bool](repeating: false, count: parent.count)
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self.subscriptions = [SingleAssignmentDisposable]()
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self.subscriptions.reserveCapacity(parent.count)
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for _ in 0 ..< parent.count {
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self.subscriptions.append(SingleAssignmentDisposable())
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}
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super.init(observer: observer, cancel: cancel)
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}
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func on(_ event: Event<SourceElement>, atIndex: Int) {
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self.lock.lock(); defer { self.lock.unlock() }
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switch event {
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case .next(let element):
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if self.values[atIndex] == nil {
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self.numberOfValues += 1
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}
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self.values[atIndex] = element
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if self.numberOfValues < self.parent.count {
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let numberOfOthersThatAreDone = self.numberOfDone - (self.isDone[atIndex] ? 1 : 0)
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if numberOfOthersThatAreDone == self.parent.count - 1 {
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self.forwardOn(.completed)
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self.dispose()
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}
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return
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}
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do {
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let result = try self.parent.resultSelector(self.values.map { $0! })
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self.forwardOn(.next(result))
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}
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catch let error {
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self.forwardOn(.error(error))
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self.dispose()
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}
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case .error(let error):
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self.forwardOn(.error(error))
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self.dispose()
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case .completed:
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if self.isDone[atIndex] {
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return
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}
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self.isDone[atIndex] = true
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self.numberOfDone += 1
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if self.numberOfDone == self.parent.count {
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self.forwardOn(.completed)
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self.dispose()
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}
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else {
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self.subscriptions[atIndex].dispose()
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}
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}
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}
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func run() -> Disposable {
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var j = 0
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for i in self.parent.sources {
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let index = j
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let source = i.asObservable()
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let disposable = source.subscribe(AnyObserver { event in
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self.on(event, atIndex: index)
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})
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self.subscriptions[j].setDisposable(disposable)
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j += 1
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}
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if self.parent.sources.isEmpty {
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do {
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let result = try self.parent.resultSelector([])
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self.forwardOn(.next(result))
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self.forwardOn(.completed)
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self.dispose()
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}
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catch let error {
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self.forwardOn(.error(error))
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self.dispose()
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}
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}
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return Disposables.create(subscriptions)
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}
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}
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final class CombineLatestCollectionType<Collection: Swift.Collection, Result>: Producer<Result> where Collection.Element: ObservableConvertibleType {
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typealias ResultSelector = ([Collection.Element.Element]) throws -> Result
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let sources: Collection
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let resultSelector: ResultSelector
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let count: Int
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init(sources: Collection, resultSelector: @escaping ResultSelector) {
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self.sources = sources
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self.resultSelector = resultSelector
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self.count = self.sources.count
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}
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override func run<Observer: ObserverType>(_ observer: Observer, cancel: Cancelable) -> (sink: Disposable, subscription: Disposable) where Observer.Element == Result {
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let sink = CombineLatestCollectionTypeSink(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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