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//
// ActivityIndicator.swift
// RxExample
//
// Created by Krunoslav Zaher on 10/18/15.
// Copyright © 2015 Krunoslav Zaher. All rights reserved.
//
import RxSwift
import RxCocoa
private struct ActivityToken<E> : ObservableConvertibleType, Disposable {
private let _source: Observable<E>
private let _dispose: Cancelable
init(source: Observable<E>, disposeAction: @escaping () -> ()) {
_source = source
_dispose = Disposables.create(with: disposeAction)
}
func dispose() {
_dispose.dispose()
}
func asObservable() -> Observable<E> {
return _source
}
}
/**
Enables monitoring of sequence computation.
If there is at least one sequence computation in progress, `true` will be sent.
When all activities complete `false` will be sent.
*/
public class ActivityIndicator : SharedSequenceConvertibleType {
public typealias E = Bool
public typealias SharingStrategy = DriverSharingStrategy
private let _lock = NSRecursiveLock()
private let _relay = BehaviorRelay(value: 0)
private let _loading: SharedSequence<SharingStrategy, Bool>
public init() {
_loading = _relay.asDriver()
.map { $0 > 0 }
.distinctUntilChanged()
}
fileprivate func trackActivityOfObservable<O: ObservableConvertibleType>(_ source: O) -> Observable<O.E> {
return Observable.using({ () -> ActivityToken<O.E> in
self.increment()
return ActivityToken(source: source.asObservable(), disposeAction: self.decrement)
}) { t in
return t.asObservable()
}
}
private func increment() {
_lock.lock()
_relay.accept(_relay.value + 1)
_lock.unlock()
}
private func decrement() {
_lock.lock()
_relay.accept(_relay.value - 1)
_lock.unlock()
}
public func asSharedSequence() -> SharedSequence<SharingStrategy, E> {
return _loading
}
}
extension ObservableConvertibleType {
public func trackActivity(_ activityIndicator: ActivityIndicator) -> Observable<E> {
return activityIndicator.trackActivityOfObservable(self)
}
}