Define and set RefTarget in TokamakUIKit (#54)

Also add `UIView.animate` animation effect to example code. Also removes redundant `Updatable` protocol.

Resolves #49 

* Define and set RefTarget in TokamakUIKit
* Add animation example
* Rename backgroundColor to currentColor
* Add comments to Animation example

Example/Tokamak.xcodeproj/project.pbxproj

@@ -15,6 +15,7 @@
 		A6D5AF87221B131400DBF186 /* Image.swift in Sources */ = {isa = PBXBuildFile; fileRef = A6D5AF86221B131400DBF186 /* Image.swift */; };
 		C449B806DFEE55B6CEE6478C /* libPods-TokamakDemo.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 5B96B435A9D67621D318616E /* libPods-TokamakDemo.a */; };
 		D11DB6432219C03000013FC3 /* Timer.swift in Sources */ = {isa = PBXBuildFile; fileRef = D11DB6422219C03000013FC3 /* Timer.swift */; };
+		D1BB3D302223F6B400C30062 /* Animation.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1BB3D2F2223F6B400C30062 /* Animation.swift */; };
 		D1BFAF772215795900845EA0 /* Router.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1BFAF762215795900845EA0 /* Router.swift */; };
 		D1BFAF792215800A00845EA0 /* Counter.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1BFAF782215800A00845EA0 /* Counter.swift */; };
 		D1BFAF7B22158B4000845EA0 /* List.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1BFAF7A22158B4000845EA0 /* List.swift */; };
@@ -43,6 +44,7 @@
 		A9EEF813955DAEEFE1D52ED4 /* Pods-TokamakDemo.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-TokamakDemo.debug.xcconfig"; path = "Pods/Target Support Files/Pods-TokamakDemo/Pods-TokamakDemo.debug.xcconfig"; sourceTree = "<group>"; };
 		C6DA99382B6892EAB361742F /* LICENSE */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text; name = LICENSE; path = ../LICENSE; sourceTree = "<group>"; };
 		D11DB6422219C03000013FC3 /* Timer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Timer.swift; sourceTree = "<group>"; };
+		D1BB3D2F2223F6B400C30062 /* Animation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Animation.swift; sourceTree = "<group>"; };
 		D1BFAF762215795900845EA0 /* Router.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Router.swift; sourceTree = "<group>"; };
 		D1BFAF782215800A00845EA0 /* Counter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Counter.swift; sourceTree = "<group>"; };
 		D1BFAF7A22158B4000845EA0 /* List.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = List.swift; sourceTree = "<group>"; };
@@ -162,6 +164,7 @@
 				D1F2C3262214407B008358DC /* TableModal.swift */,
 				D11DB6422219C03000013FC3 /* Timer.swift */,
 				A6D5AF86221B131400DBF186 /* Image.swift */,
+				D1BB3D2F2223F6B400C30062 /* Animation.swift */,
 			);
 			path = Components;
 			sourceTree = "<group>";
@@ -283,6 +286,7 @@
 				D1F7185D2215A4A1004E5951 /* LayerProps.swift in Sources */,
 				D1BFAF792215800A00845EA0 /* Counter.swift in Sources */,
 				D1F718612215A617004E5951 /* Modals.swift in Sources */,
+				D1BB3D302223F6B400C30062 /* Animation.swift in Sources */,
 				D1F7185522159EAD004E5951 /* DatePickers.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Example/Tokamak/Components/Animation.swift

@@ -0,0 +1,67 @@
+//
+//  Animation.swift
+//  TokamakDemo
+//
+//  Created by Max Desiatov on 25/02/2019.
+//  Copyright © 2019 Tokamak. All rights reserved.
+//
+
+import Tokamak
+
+struct Animation: CompositeComponent {
+  private static let colors: [(Color, String)] = [
+    (.white, "white"),
+    (.red, "red"),
+    (.green, "green"),
+    (.blue, "blue"),
+  ]
+
+  typealias Props = Null
+  typealias Children = [AnyNode]
+
+  static func render(props: Null, children: Children, hooks: Hooks) -> AnyNode {
+    let previousColor = hooks.state(0)
+    let currentColor = hooks.state(0)
+    let ref = hooks.ref(type: UIView.self)
+
+    hooks.effect(currentColor.value) {
+      guard let view = ref.value else { return }
+
+      guard currentColor.value != previousColor.value else {
+        view.backgroundColor = UIColor(colors[currentColor.value].0)
+        return
+      }
+
+      UIView.animate(withDuration: 0.5, animations: {
+        view.backgroundColor = UIColor(colors[currentColor.value].0)
+      }, completion: { _ in
+        previousColor.set(currentColor.value)
+      })
+    }
+
+    return View.node(
+      .init(Style(
+        Edges.equal(to: .parent),
+        backgroundColor: .white
+      )),
+      StackView.node(.init(
+        Edges.equal(to: .safeArea),
+        axis: .vertical,
+        distribution: .fillEqually
+      ), [
+        View.node(ref: ref, .init(), children),
+        SegmentedControl.node(
+          .init(
+            value: currentColor.value,
+            valueHandler: Handler {
+              // sometimes UISegmentedControl allows deselecting all segments
+              guard $0 >= 0 else { return }
+              currentColor.set($0)
+            }
+          ),
+          colors.map { $0.1 }
+        ),
+      ])
+    )
+  }
+}

Example/Tokamak/Components/Modals.swift

@@ -29,42 +29,18 @@ struct NavigationModal: PureLeafComponent {
   }
 }
 
-struct SimpleModal: LeafComponent {
+struct SimpleModal: PureLeafComponent {
   struct Props: Equatable {
     let isPresented: State<Bool>
   }
 
-  private static let colors: [(Color, String)] = [
-    (.white, "white"),
-    (.red, "red"),
-    (.green, "green"),
-    (.blue, "blue"),
-  ]
-
-  static func render(props: Props, hooks: Hooks) -> AnyNode {
-    let backgroundColor = hooks.state(0)
-
+  static func render(props: Props) -> AnyNode {
     return props.isPresented.value ? ModalPresenter.node(
-      View.node(
-        .init(Style(
-          Edges.equal(to: .parent),
-          backgroundColor: colors[backgroundColor.value].0
-        )),
-        StackView.node(.init(
-          Edges.equal(to: .parent),
-          axis: .vertical,
-          distribution: .fillEqually
-        ), [
-          Button.node(.init(
-            onPress: Handler { props.isPresented.set(false) }
-          ), "Close Modal"),
-          SegmentedControl.node(
-            .init(value: backgroundColor.value,
-                  valueHandler: Handler(backgroundColor.set)),
-            colors.map { $0.1 }
-          ),
-        ])
-      )
+      Animation.node(Null(),
+                     Button.node(.init(
+                       Style(Center.equal(to: .parent)),
+                       onPress: Handler { props.isPresented.set(false) }
+      ), "Close Modal"))
     ) : Null.node()
   }
 }

Example/Tokamak/Components/Timer.swift

@@ -17,7 +17,7 @@ struct TimerCounter: LeafComponent {
     let timer = hooks.ref(type: Timer.self)
     let interval = hooks.state(1.0)
 
-    hooks.effect(interval.value) { () -> () -> () in
+    hooks.finalizedEffect(interval.value) {
       timer.value = Timer.scheduledTimer(
         withTimeInterval: interval.value,
         repeats: true

Example/Tokamak/Router.swift

@@ -18,6 +18,7 @@ enum AppRoute: String, CaseIterable {
   case layerProps = "Layer Props"
   case timer
   case image
+  case animation
 }
 
 extension AppRoute: CustomStringConvertible {
@@ -59,6 +60,8 @@ struct Router: NavigationRouter {
       result = TimerCounter.node()
     case .image:
       result = ImageExample.node()
+    case .animation:
+      result = Animation.node()
     }
 
     return NavigationItem.node(

Sources/Tokamak/AnyNode.swift

@@ -77,6 +77,12 @@ extension Component where Children == [AnyNode] {
   }
 }
 
+extension Component where Props == Null, Children == [AnyNode] {
+  public static func node() -> AnyNode {
+    return node(Null(), [])
+  }
+}
+
 extension Component where Props: Default, Props.DefaultValue == Props,
   Children == [AnyNode] {
   public static func node(_ child: AnyNode) -> AnyNode {
@@ -127,3 +133,23 @@ extension RefComponent {
     )
   }
 }
+
+extension RefComponent where Children == [AnyNode] {
+  public static func node(
+    ref: Ref<RefTarget?>,
+    _ props: Props,
+    _ child: AnyNode
+  ) -> AnyNode {
+    return node(ref: ref, props, [child])
+  }
+
+  public static func node(ref: Ref<RefTarget?>, _ props: Props) -> AnyNode {
+    return node(ref: ref, props, [])
+  }
+}
+
+extension RefComponent where Children == Null {
+  public static func node(ref: Ref<RefTarget?>, _ props: Props) -> AnyNode {
+    return node(ref: ref, props, Null())
+  }
+}

Sources/Tokamak/Hooks/Effect.swift

@@ -15,7 +15,7 @@ extension Hooks {
    closure should return a cleanup closure to be executed before the next
    call to `render` or when a component is unmounted.
    */
-  public func effect(closure: @escaping () -> () -> ()) {
+  public func finalizedEffect(closure: @escaping () -> () -> ()) {
     scheduleEffect(nil, closure)
   }
 
@@ -55,7 +55,10 @@ extension Hooks {
    trigger effect execution (unsubscribing from updates on old user ID and
    subscribing for new user ID) when the ID has changed.
    */
-  public func effect<T>(_ observed: T, closure: @escaping () -> () -> ())
+  public func finalizedEffect<T>(
+    _ observed: T,
+    closure: @escaping () -> () -> ()
+  )
     where T: Equatable {
     scheduleEffect(AnyEquatable(observed), closure)
   }

Sources/Tokamak/Hooks/State.swift

@@ -5,16 +5,6 @@
 //  Created by Max Desiatov on 09/02/2019.
 //
 
-/// Formalizes an update to a value with a given action. Note that `update`
-/// function is mutating here to allow efficient in-place updates. As long as
-/// `Updatable` is implemented on a value type, this still allows freezing it
-/// into an immutable value when needed.
-public protocol Updatable {
-  associatedtype Action
-
-  mutating func update(_ action: Action)
-}
-
 typealias Updater<T> = (inout T) -> ()
 
 /** Note that `set` functions are not `mutating`, they never update the
@@ -54,14 +44,6 @@ public struct State<T> {
 
 extension State: Equatable where T: Equatable {}
 
-extension State where T: Updatable {
-  /// For any `Reduceable` state you can dispatch an `Action` to reduce that
-  /// state to a different value.
-  public func set(_ action: T.Action) {
-    updateHandler.value { $0.update(action) }
-  }
-}
-
 extension Hooks {
   /** Allows a component to have its own state and to be updated when the state
    changes. Returns a very simple state container, which on initial call of

Sources/Tokamak/MountedComponents/MountedHostComponent.swift

@@ -42,6 +42,8 @@ public final class MountedHostComponent<R: Renderer>: MountedComponent<R> {
 
     self.target = target
 
+    reconciler.renderer?.update(target: target, with: self)
+
     switch node.children.value {
     case let nodes as [AnyNode]:
       mountedChildren = nodes.map { $0.makeMountedComponent(target) }

Sources/TokamakTestRenderer/TestRenderer.swift

@@ -28,8 +28,6 @@ public final class TestRenderer: Renderer {
     let result = TestView(component.node)
     parent.add(subview: result)
 
-    update(target: result, with: component)
-
     return result
   }
 

Sources/TokamakUIKit/Boxes/ViewBox.swift

@@ -19,4 +19,8 @@ class ViewBox<T: UIView>: ViewControllerBox<UIViewController> {
 
     super.init(viewController, node)
   }
+
+  override var refTarget: Any {
+    return view
+  }
 }

Sources/TokamakUIKit/Boxes/ViewControllerBox.swift

@@ -19,4 +19,8 @@ class ViewControllerBox<T: UIViewController>: UITarget {
   override var viewController: UIViewController {
     return containerViewController
   }
+
+  override var refTarget: Any {
+    return containerViewController
+  }
 }

Sources/TokamakUIKit/Components/Host/Button.swift

@@ -19,6 +19,7 @@ final class TokamakButton: UIButton, Default {
 
 extension Button: UIControlComponent {
   typealias Target = TokamakButton
+  public typealias RefTarget = UIButton
 
   static func update(control box: ControlBox<TokamakButton>,
                      _ props: Button.Props,

Sources/TokamakUIKit/Components/Host/DatePicker.swift

@@ -27,6 +27,7 @@ final class TokamakDatePicker: UIDatePicker, Default, ValueStorage {
 
 extension DatePicker: UIValueComponent {
   typealias Target = TokamakDatePicker
+  public typealias RefTarget = UIDatePicker
 
   static func update(valueBox: ValueControlBox<TokamakDatePicker>,
                      _ props: DatePicker.Props,

Sources/TokamakUIKit/Components/Host/Image.swift

@@ -28,6 +28,8 @@ extension UIImage.RenderingMode {
 }
 
 extension Image: UIViewComponent {
+  public typealias RefTarget = UIImageView
+
   static func update(
     view box: ViewBox<TokamakImage>,
     _ props: Image.Props,

Sources/TokamakUIKit/Components/Host/Label.swift

@@ -32,6 +32,8 @@ extension NSTextAlignment {
 }
 
 extension Label: UIViewComponent {
+  public typealias RefTarget = UILabel
+
   static func update(view box: ViewBox<TokamakLabel>,
                      _ props: Label.Props,
                      _ children: String) {

Sources/TokamakUIKit/Components/Host/ListView.swift

@@ -9,6 +9,8 @@ import Tokamak
 import UIKit
 
 extension ListView: UIViewComponent {
+  public typealias RefTarget = UITableView
+
   static func box(
     for view: TokamakTableView,
     _ viewController: UIViewController,

Sources/TokamakUIKit/Components/Host/NavigationItem.swift

@@ -41,7 +41,6 @@ extension NavigationItem: UIHostComponent {
 
     let viewController = UIViewController()
     let result = ViewControllerBox(viewController, component.node)
-    update(target: result, node: component.node)
 
     parent.containerViewController.pushViewController(
       viewController,

Sources/TokamakUIKit/Components/Host/SegmentedControl.swift

@@ -25,6 +25,7 @@ final class TokamakSegmentedControl: UISegmentedControl, Default, ValueStorage {
 
 extension SegmentedControl: UIValueComponent {
   typealias Target = TokamakSegmentedControl
+  public typealias RefTarget = UISegmentedControl
 
   static func update(valueBox: ValueControlBox<TokamakSegmentedControl>,
                      _ props: SegmentedControl.Props,

Sources/TokamakUIKit/Components/Host/Slider.swift

@@ -16,6 +16,7 @@ final class TokamakSlider: UISlider, Default, ValueStorage {
 
 extension Slider: UIValueComponent {
   typealias Target = TokamakSlider
+  public typealias RefTarget = UISlider
 
   static func update(valueBox: ValueControlBox<TokamakSlider>,
                      _ props: Slider.Props,

Sources/TokamakUIKit/Components/Host/StackView.swift

@@ -60,6 +60,8 @@ extension UIStackView.Distribution {
 }
 
 extension StackView: UIViewComponent {
+  public typealias RefTarget = UIStackView
+
   static func update(view box: ViewBox<TokamakStackView>,
                      _ props: StackView.Props,
                      _: [AnyNode]) {

Sources/TokamakUIKit/Components/Host/Stepper.swift

@@ -16,6 +16,7 @@ final class TokamakStepper: UIStepper, Default, ValueStorage {
 
 extension Stepper: UIValueComponent {
   typealias Target = TokamakStepper
+  public typealias RefTarget = UIStepper
 
   static func update(valueBox: ValueControlBox<TokamakStepper>,
                      _ props: Stepper.Props,

Sources/TokamakUIKit/Components/Host/Switch.swift

@@ -27,6 +27,7 @@ final class TokamakSwitch: UISwitch, Default, ValueStorage {
 
 extension Switch: UIValueComponent {
   typealias Target = TokamakSwitch
+  public typealias RefTarget = UISwitch
 
   static func update(valueBox: ValueControlBox<TokamakSwitch>,
                      _ props: Switch.Props,

Sources/TokamakUIKit/Components/Host/View.swift

@@ -15,6 +15,8 @@ final class TokamakView: UIView, Default {
 }
 
 extension View: UIViewComponent {
+  public typealias RefTarget = UIView
+
   static func update(view: ViewBox<TokamakView>,
                      _ props: View.Props,
                      _: [AnyNode]) {}

Sources/TokamakUIKit/Components/Props/Color.swift

@@ -9,7 +9,7 @@ import Tokamak
 import UIKit
 
 extension UIColor {
-  convenience init(_ color: Color) {
+  public convenience init(_ color: Color) {
     switch color.space {
     case .sRGB:
       self.init(red: CGFloat(color.red),

Sources/TokamakUIKit/Components/Props/Event.swift

@@ -9,7 +9,7 @@ import Tokamak
 import UIKit
 
 extension UIControl.Event {
-  init(_ value: Event) {
+  public init(_ value: Event) {
     switch value {
     case .touchDown:
       self = .touchDown

Sources/TokamakUIKit/Components/Protocols/UIViewComponent.swift

@@ -8,7 +8,7 @@
 import Tokamak
 import UIKit
 
-protocol UIViewComponent: UIHostComponent, HostComponent {
+protocol UIViewComponent: UIHostComponent, RefComponent {
   associatedtype Target: UIView & Default
 
   static func update(view box: ViewBox<Target>,
@@ -94,16 +94,6 @@ extension UIViewComponent where Target == Target.DefaultValue,
     component: UIKitRenderer.MountedHost,
     _ renderer: UIKitRenderer
   ) -> UITarget? {
-    guard let children = component.node.children.value as? Children else {
-      childrenAssertionFailure()
-      return nil
-    }
-
-    guard let props = component.node.props.value as? Props else {
-      propsAssertionFailure()
-      return nil
-    }
-
     let target = Target.defaultValue
     let result: ViewBox<Target>
 
@@ -167,9 +157,6 @@ extension UIViewComponent where Target == Target.DefaultValue,
       parentAssertionFailure()
     }
 
-    applyStyle(result, props)
-    update(view: result, props, children)
-
     return result
   }
 

Sources/TokamakUIKit/UIKitRenderer.swift

@@ -30,7 +30,11 @@ struct HackyProvider: SimpleCellProvider {
 
 class UITarget: Target {
   var viewController: UIViewController {
-    fatalError("viewController should be overriden in UITarget subclass")
+    fatalError("\(#function) should be overriden in UITarget subclass")
+  }
+
+  var refTarget: Any {
+    fatalError("\(#function) should be overriden in UITarget subclass")
   }
 }
 
@@ -79,6 +83,12 @@ final class UIKitRenderer: Renderer {
 
     rendererComponent.update(target: target,
                              node: component.node)
+
+    guard
+      let componentType = component.type as? AnyRefComponent.Type,
+      let anyRef = component.node.ref else { return }
+
+    componentType.update(ref: anyRef, with: target.refTarget)
   }
 
   func unmount(

Tests/TokamakTests/HooksTests.swift

@@ -14,22 +14,6 @@ extension Button: RefComponent {
   public typealias RefTarget = TestView
 }
 
-extension Int: Updatable {
-  public enum Action {
-    case increment
-    case decrement
-  }
-
-  public mutating func update(_ action: Int.Action) {
-    switch action {
-    case .decrement:
-      self -= 1
-    case .increment:
-      self += 1
-    }
-  }
-}
-
 private extension Hooks {
   func custom() -> State<Int> {
     return state(42)
@@ -42,7 +26,6 @@ struct Test: LeafComponent {
   static func render(props: Null, hooks: Hooks) -> AnyNode {
     let state1 = hooks.custom()
     let state2 = hooks.custom()
-    let state3 = hooks.custom()
     let ref = hooks.ref(type: TestView.self)
 
     return StackView.node([
@@ -55,9 +38,6 @@ struct Test: LeafComponent {
       Button.node(.init(onPress: Handler { state2.set { $0 + 1 } }),
                   "Increment"),
       Label.node("\(state2.value)"),
-      Button.node(.init(onPress: Handler { state3.set(.increment) }),
-                  "Increment"),
-      Label.node("\(state3.value)"),
     ])
   }
 }
@@ -74,8 +54,6 @@ final class HooksTests: XCTestCase {
       let button1Handler = button1Props.handlers[.touchUpInside]?.value,
       let button2Props = stack.subviews[2].props(Button.Props.self),
       let button2Handler = button2Props.handlers[.touchUpInside]?.value,
-      let button3Props = stack.subviews[4].props(Button.Props.self),
-      let button3Handler = button3Props.handlers[.touchUpInside]?.value,
       let button1Ref = stack.subviews[0].node.ref as? Ref<TestView?>
     else {
       XCTAssert(false, "components have no handlers")
@@ -89,16 +67,11 @@ final class HooksTests: XCTestCase {
     button2Handler(())
     button2Handler(())
 
-    button3Handler(())
-    button3Handler(())
-    button3Handler(())
-
     let e = expectation(description: "rerender")
 
     DispatchQueue.main.async {
       XCTAssertEqual(stack.subviews[1].node.children, AnyEquatable("43"))
       XCTAssertEqual(stack.subviews[3].node.children, AnyEquatable("44"))
-      XCTAssertEqual(stack.subviews[5].node.children, AnyEquatable("45"))
 
       e.fulfill()
     }