Add 'submodules/SSignalKit/' from commit '359b2ee7c9f20f99f221f78e307369ef5ad0ece2'

git-subtree-dir: submodules/SSignalKit
git-subtree-mainline: 4459dc5b47
git-subtree-split: 359b2ee7c9

submodules/SSignalKit/SwiftSignalKit/Queue.swift

@@ -0,0 +1,88 @@
+import Foundation
+
+private let QueueSpecificKey = DispatchSpecificKey<NSObject>()
+
+private let globalMainQueue = Queue(queue: DispatchQueue.main, specialIsMainQueue: true)
+private let globalDefaultQueue = Queue(queue: DispatchQueue.global(qos: .default), specialIsMainQueue: false)
+private let globalBackgroundQueue = Queue(queue: DispatchQueue.global(qos: .background), specialIsMainQueue: false)
+
+public final class Queue {
+    private let nativeQueue: DispatchQueue
+    private var specific = NSObject()
+    private let specialIsMainQueue: Bool
+    
+    public var queue: DispatchQueue {
+        get {
+            return self.nativeQueue
+        }
+    }
+    
+    public class func mainQueue() -> Queue {
+        return globalMainQueue
+    }
+    
+    public class func concurrentDefaultQueue() -> Queue {
+        return globalDefaultQueue
+    }
+    
+    public class func concurrentBackgroundQueue() -> Queue {
+        return globalBackgroundQueue
+    }
+    
+    public init(queue: DispatchQueue) {
+        self.nativeQueue = queue
+        self.specialIsMainQueue = false
+    }
+    
+    fileprivate init(queue: DispatchQueue, specialIsMainQueue: Bool) {
+        self.nativeQueue = queue
+        self.specialIsMainQueue = specialIsMainQueue
+    }
+    
+    public init(name: String? = nil, qos: DispatchQoS = .default) {
+        self.nativeQueue = DispatchQueue(label: name ?? "", qos: qos)
+        
+        self.specialIsMainQueue = false
+        
+        self.nativeQueue.setSpecific(key: QueueSpecificKey, value: self.specific)
+    }
+    
+    public func isCurrent() -> Bool {
+        if DispatchQueue.getSpecific(key: QueueSpecificKey) === self.specific {
+            return true
+        } else if self.specialIsMainQueue && Thread.isMainThread {
+            return true
+        } else {
+            return false
+        }
+    }
+    
+    public func async(_ f: @escaping () -> Void) {
+        if self.isCurrent() {
+            f()
+        } else {
+            self.nativeQueue.async(execute: f)
+        }
+    }
+    
+    public func sync(_ f: () -> Void) {
+        if self.isCurrent() {
+            f()
+        } else {
+            self.nativeQueue.sync(execute: f)
+        }
+    }
+    
+    public func justDispatch(_ f: @escaping () -> Void) {
+        self.nativeQueue.async(execute: f)
+    }
+    
+    public func justDispatchWithQoS(qos: DispatchQoS, _ f: @escaping () -> Void) {
+        self.nativeQueue.async(group: nil, qos: qos, flags: [.enforceQoS], execute: f)
+    }
+    
+    public func after(_ delay: Double, _ f: @escaping() -> Void) {
+        let time: DispatchTime = DispatchTime.now() + delay
+        self.nativeQueue.asyncAfter(deadline: time, execute: f)
+    }
+}