Added partition for signal and cold signal

Author: cloutiertyler

Sources/ColdSignal.swift

@@ -220,6 +220,22 @@ public extension ColdSignalType {
         }
     }
 
+    public func lift<U, F>(_ transform: @escaping (Signal<Value, ErrorType>) -> (Signal<U, F>, Signal<U, F>))
+        -> (ColdSignal<U, F>, ColdSignal<U, F>)
+    {
+        let (pipeSignal, pipeObserver) = Signal<Value, ErrorType>.pipe()
+        let (left, right) = transform(pipeSignal)
+        let coldLeft = ColdSignal<U, F> { observer in
+            left.add(observer: observer)
+            return self.coldSignal.startHandler(pipeObserver)
+        }
+        let coldRight = ColdSignal<U, F> { observer in
+            right.add(observer: observer)
+            return self.coldSignal.startHandler(pipeObserver)
+        }
+        return (coldLeft, coldRight)
+    }
+    
     /// Maps each value in the signal to a new value.
     public func map<U>(_ transform: @escaping (Value) -> U) -> ColdSignal<U, ErrorType> {
         return lift { $0.map(transform) }
@@ -235,6 +251,13 @@ public extension ColdSignalType {
         return lift { $0.filter(predicate) }
     }
 
+    /// Splits the signal into two signals. The first signal in the tuple matches the
+    /// predicate, the second signal does not match the predicate
+    public func partition(_ predicate: @escaping (Value) -> Bool)
+        -> (ColdSignal<Value, ErrorType>, ColdSignal<Value, ErrorType>) {
+        return lift { $0.partition(predicate) }
+    }
+    
     /// Aggregate values into a single combined value. Mirrors the Swift Collection
     public func reduce<T>(initial: T, _ combine: @escaping (T, Value) -> T) -> ColdSignal<T, ErrorType> {
         return lift { $0.reduce(initial: initial, combine) }

Sources/Signal.swift

@@ -284,6 +284,36 @@ public extension SignalType {
         }
     }
 
+    /// Splits the signal into two signals. The first signal in the tuple matches the
+    /// predicate, the second signal does not match the predicate
+    public func partition(_ predicate: @escaping (Value) -> Bool) -> (Signal<Value, ErrorType>, Signal<Value, ErrorType>) {
+        let left = Signal<Value, ErrorType> { observer in
+            return self.on { (event: Event<Value, ErrorType>) -> Void in
+                guard let value = event.value else {
+                    observer.sendEvent(event)
+                    return
+                }
+                
+                if predicate(value) {
+                    observer.sendNext(value)
+                }
+            }
+        }
+        let right = Signal<Value, ErrorType> { observer in
+            return self.on { (event: Event<Value, ErrorType>) -> Void in
+                guard let value = event.value else {
+                    observer.sendEvent(event)
+                    return
+                }
+                
+                if !predicate(value) {
+                    observer.sendNext(value)
+                }
+            }
+        }
+        return (left, right)
+    }
+    
     /// Aggregate values into a single combined value. Mirrors the Swift Collection
     public func reduce<T>(initial: T, _ combine: @escaping (T, Value) -> T) -> Signal<T, ErrorType> {
         return Signal { observer in