0001    //
0002    //  OperationQueueScheduler.swift
0003    //  Rx
0004    //
0005    //  Created by Krunoslav Zaher on 4/4/15.
0006    //  Copyright © 2015 Krunoslav Zaher. All rights reserved.
0007    //
0008    
0009    import Foundation
0010    
0011    /**
0012    Abstracts the work that needs to be performed on a specific `NSOperationQueue`.
0013    
0014    This scheduler is suitable for cases when there is some bigger chunk of work that needs to be performed in background and you want to fine tune concurrent processing using `maxConcurrentOperationCount`.
0015    */
0016    public class OperationQueueScheduler: ImmediateSchedulerType {
0017        public let operationQueue
OperationQueueScheduler.swift:25
        self.operationQueue = operationQueue
OperationQueueScheduler.swift:50
        self.operationQueue.addOperation(operation): NSOperationQueue
0018        
0019        /**
0020        Constructs new instance of `OperationQueueScheduler` that performs work on `operationQueue`.
0021        
0022        - parameter operationQueue: Operation queue targeted to perform work on.
0023        */
0024        public init(operationQueue: NSOperationQueue) {
0025            self.operationQueue = operationQueue
0026        }
0027        
0028        /**
0029        Schedules an action to be executed recursively.
0030        
0031        - parameter state: State passed to the action to be executed.
0032        - parameter action: Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in recursive invocation state.
0033        - returns: The disposable object used to cancel the scheduled action (best effort).
0034        */
0035        public func schedule<StateType>(state: StateType, action: (StateType) -> Disposable) -> Disposable {
0036            
0037            let compositeDisposable = CompositeDisposable()
0038            
0039            weak var compositeDisposableWeak = compositeDisposable
0040            
0041            let operation = NSBlockOperation {
0042                if compositeDisposableWeak?.disposed ?? false {
0043                    return
0044                }
0045                
0046                let disposable = action(state)
0047                compositeDisposableWeak?.addDisposable(disposable)
0048            }
0049    
0050            self.operationQueue.addOperation(operation)
0051            
0052            compositeDisposable.addDisposable(AnonymousDisposable {
0053                operation.cancel()
0054            })
0055    
0056            return compositeDisposable
0057        }
0058    
0059    }