Remove unneeded queue-related protocol requirements

Author: zwaldowski

Sources/Deferred/Executor.swift

@@ -49,22 +49,13 @@ public protocol Executor: class {
 
     /// Execute the `workItem`.
     func submit(_ workItem: DispatchWorkItem)
-
-    /// If the executor is a higher-level wrapper around a dispatch queue,
-    /// may be used instead of `submit(_:)` for more efficient execution.
-    var underlyingQueue: DispatchQueue? { get }
 }
 
 extension Executor {
     /// By default, submits the closure contents of the work item.
     public func submit(_ workItem: DispatchWorkItem) {
         submit(workItem.perform)
     }
-
-    /// By default, `nil`; the executor's `submit(_:)` is used unconditionally.
-    public var underlyingQueue: DispatchQueue? {
-        return nil
-    }
 }
 
 /// Dispatch queues invoke function bodies submitted to them serially in FIFO
@@ -95,10 +86,6 @@ extension DispatchQueue: Executor {
     public func submit(_ workItem: DispatchWorkItem) {
         async(execute: workItem)
     }
-
-    public var underlyingQueue: DispatchQueue? {
-        return self
-    }
 }
 
 /// An operation queue manages a number of operation objects, making high

Sources/Deferred/Future.swift

@@ -30,9 +30,6 @@ public protocol FutureProtocol: CustomDebugStringConvertible, CustomReflectable
     /// A type that represents the result of some asynchronous operation.
     associatedtype Value
 
-    /// Calls some `body` closure once the value is determined.
-    func upon(_ executor: PreferredExecutor, execute body: @escaping(Value) -> Void)
-
     /// Call some `body` closure once the value is determined.
     ///
     /// If the value is determined, the closure should be submitted to the