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

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

submodules/SSignalKit/SwiftSignalKit/Signal_Take.swift

@@ -0,0 +1,73 @@
+import Foundation
+
+public func take<T, E>(_ count: Int) -> (Signal<T, E>) -> Signal<T, E> {
+    return { signal in
+        return Signal { subscriber in
+            let counter = Atomic(value: 0)
+            return signal.start(next: { next in
+                var passthrough = false
+                var complete = false
+                let _ = counter.modify { value in
+                    let updatedCount = value + 1
+                    passthrough = updatedCount <= count
+                    complete = updatedCount == count
+                    return updatedCount
+                }
+                if passthrough {
+                    subscriber.putNext(next)
+                }
+                if complete {
+                    subscriber.putCompletion()
+                }
+            }, error: { error in
+                subscriber.putError(error)
+            }, completed: {
+                subscriber.putCompletion()
+            })
+        }
+    }
+}
+
+public struct SignalTakeAction {
+    public let passthrough: Bool
+    public let complete: Bool
+    
+    public init(passthrough: Bool, complete: Bool) {
+        self.passthrough = passthrough
+        self.complete = complete
+    }
+}
+
+public func take<T, E>(until: @escaping (T) -> SignalTakeAction) -> (Signal<T, E>) -> Signal<T, E> {
+    return { signal in
+        return Signal { subscriber in
+            return signal.start(next: { next in
+                let action = until(next)
+                if action.passthrough {
+                    subscriber.putNext(next)
+                }
+                if action.complete {
+                    subscriber.putCompletion()
+                }
+            }, error: { error in
+                subscriber.putError(error)
+            }, completed: {
+                subscriber.putCompletion()
+            })
+        }
+    }
+}
+
+public func last<T, E>(signal: Signal<T, E>) -> Signal<T?, E> {
+    return Signal { subscriber in
+        let value = Atomic<T?>(value: nil)
+        return signal.start(next: { next in
+            let _ = value.swap(next)
+        }, error: { error in
+            subscriber.putError(error)
+        }, completed: {
+            subscriber.putNext(value.with({ $0 }))
+            subscriber.putCompletion()
+        })
+    }
+}