Remove _AnyApp, add Renderer.AppType associated type

README.md

@@ -48,23 +48,18 @@ struct Counter: View {
     }
   }
 }
-```
-
-You can then render your view in any DOM node captured with
-[JavaScriptKit](https://github.com/kateinoigakukun/JavaScriptKit/), just
-pass it as an argument to the `DOMRenderer` initializer together with your view:
-
-```swift
-import JavaScriptKit
-import TokamakDOM
 
-let document = JSObjectRef.global.document.object!
-
-let divElement = document.createElement!("div").object!
-let renderer = DOMRenderer(Counter(count: 5, limit: 15), divElement)
+struct CounterApp: App {
+  var body: some Scene {
+    WindowGroup("Counter Demo") {
+      Counter(count: 5, limit: 15)
+    }
+  }
+}
 
-let body = document.body.object!
-_ = body.appendChild!(divElement)
+// @main attribute is not supported in SwiftPM apps.
+// See https://bugs.swift.org/browse/SR-12683 for more details.
+CounterApp.main()
 ```
 
 ### Arbitrary HTML
@@ -108,9 +103,9 @@ app.
 ## Requirements for app developers
 
 - macOS 10.15 and Xcode 11.4/11.5/11.6 for macOS. Xcode betas are currently not supported. You can have
-those installed, but please make sure you use 
-[`xcode-select`](https://developer.apple.com/library/archive/technotes/tn2339/_index.html#//apple_ref/doc/uid/DTS40014588-CH1-HOW_DO_I_SELECT_THE_DEFAULT_VERSION_OF_XCODE_TO_USE_FOR_MY_COMMAND_LINE_TOOLS_) 
-to point it to a release version of Xcode.
+  those installed, but please make sure you use
+  [`xcode-select`](https://developer.apple.com/library/archive/technotes/tn2339/_index.html#//apple_ref/doc/uid/DTS40014588-CH1-HOW_DO_I_SELECT_THE_DEFAULT_VERSION_OF_XCODE_TO_USE_FOR_MY_COMMAND_LINE_TOOLS_)
+  to point it to a release version of Xcode.
 - [Swift 5.2 or later](https://swift.org/download/) for Linux.
 
 ## Requirements for app users
@@ -128,7 +123,7 @@ Not all of these were tested though, compatibility reports are very welcome!
 
 Tokamak relies on [`carton`](https://carton.dev) as a primary build tool. As a part of these steps
 you'll install `carton` via [Homebrew](https://brew.sh/) on macOS (unfortunately you'll have to build
-it manually on Linux). Assuming you already have Homebrew installed, you can create a new Tokamak 
+it manually on Linux). Assuming you already have Homebrew installed, you can create a new Tokamak
 app by following these steps:
 
 1. Install `carton`:
@@ -156,15 +151,15 @@ carton init --template tokamak
 ```
 
 4. Build the project and start the development server, `carton dev` can be kept running
-during development:
+   during development:
 
 ```
 carton dev
 ```
 
 5. Open [http://127.0.0.1:8080/](http://127.0.0.1:8080/) in your browser to see the app
-running. You can edit the app source code in your favorite editor and save it, `carton` 
-will immediately rebuild the app and reload all browser tabs that have the app open.
+   running. You can edit the app source code in your favorite editor and save it, `carton`
+   will immediately rebuild the app and reload all browser tabs that have the app open.
 
 You can also clone this repository and run `carton dev` in its root directory. This
 will build the demo app that shows almost all of the currently implemented APIs.

Sources/TokamakCore/App/Scenes/Scene.swift

@@ -27,10 +27,6 @@ protocol TitledScene {
   var title: Text? { get }
 }
 
-protocol ViewContainingScene {
-  var anyContent: AnyView { get }
-}
-
 protocol ParentScene {
   var children: [_AnyScene] { get }
 }

Sources/TokamakCore/App/Scenes/WindowGroup.swift

@@ -15,7 +15,7 @@
 //  Created by Carson Katri on 7/16/20.
 //
 
-public struct WindowGroup<Content>: Scene, TitledScene, ViewContainingScene where Content: View {
+public struct WindowGroup<Content>: Scene, TitledScene where Content: View {
   public let id: String
   public let title: Text?
   public let content: Content

Sources/TokamakCore/App/_AnyScene.swift

@@ -15,13 +15,62 @@
 //  Created by Carson Katri on 7/19/20.
 //
 
+import Runtime
+
 public struct _AnyScene: Scene {
-  let scene: Any
+  /** The result type of `bodyClosure` allowing to disambiguate between scenes that
+   produce other scenes or scenes that only produce containing views.
+   */
+  enum BodyResult {
+    case scene(_AnyScene)
+    case view(AnyView)
+  }
+
+  /** The name of the unapplied generic type of the underlying `view`. `Button<Text>` and
+   `Button<Image>` types are different, but when reconciling the tree of mounted views
+   they are treated the same, thus the `Button` part of the type (the type constructor)
+   is stored in this property.
+   */
+  let typeConstructorName: String
+
+  /// The actual `Scene` value wrapped within this `_AnyScene`.
+  var scene: Any
+
+  /// The type of the underlying `scene`
   let type: Any.Type
 
+  /** Type-erased `body` of the underlying `scene`. Needs to take a fresh version of `scene` as an
+   argument, otherwise it captures an old value of the `body` property.
+   */
+  let bodyClosure: (Any) -> BodyResult
+
+  /** The type of the `body` of the underlying `scene`. Used to cast the result of the applied
+   `bodyClosure` property.
+   */
+  let bodyType: Any.Type
+
   init<S: Scene>(_ scene: S) {
-    self.scene = scene
-    type = S.self
+    if let anyScene = scene as? _AnyScene {
+      self = anyScene
+    } else {
+      self.scene = scene
+      type = S.self
+      bodyType = S.Body.self
+      if scene is SceneDeferredToRenderer {
+        // swiftlint:disable:next force_cast
+        bodyClosure = { .view(($0 as! SceneDeferredToRenderer).deferredBody) }
+      } else {
+        // swiftlint:disable:next force_cast
+        bodyClosure = { .scene(_AnyScene(($0 as! S).body)) }
+      }
+      // FIXME: no idea if using `mangledName` is reliable, but seems to be the only way to get
+      // a name of a type constructor in runtime. Should definitely check if these are different
+      // across modules, otherwise can cause problems with scenes with same names in different
+      // modules.
+
+      // swiftlint:disable:next force_try
+      typeConstructorName = try! typeInfo(of: type).mangledName
+    }
   }
 
   public var body: Never {

Sources/TokamakCore/DynamicProperty.swift

@@ -29,9 +29,11 @@ extension TypeInfo {
   /// Extract all `DynamicProperty` from a type, recursively.
   /// This is necessary as a `DynamicProperty` can be nested.
   /// `EnvironmentValues` can also be injected at this point.
-  func dynamicProperties(_ environment: EnvironmentValues,
-                         source: inout Any,
-                         shouldUpdate: Bool) -> [PropertyInfo] {
+  func dynamicProperties<T>(
+    _ environment: EnvironmentValues,
+    source: inout T,
+    shouldUpdate: Bool
+  ) -> [PropertyInfo] {
     var dynamicProps = [PropertyInfo]()
     for prop in properties where prop.type is DynamicProperty.Type {
       dynamicProps.append(prop)
@@ -40,9 +42,11 @@ extension TypeInfo {
       propInfo.injectEnvironment(from: environment, into: &source)
       var extracted = try! prop.get(from: source)
       dynamicProps.append(
-        contentsOf: propInfo.dynamicProperties(environment,
-                                               source: &extracted,
-                                               shouldUpdate: shouldUpdate)
+        contentsOf: propInfo.dynamicProperties(
+          environment,
+          source: &extracted,
+          shouldUpdate: shouldUpdate
+        )
       )
       // swiftlint:disable:next force_cast
       var extractedDynamicProp = extracted as! DynamicProperty

Sources/TokamakCore/MountedViews/MountedApp.swift

@@ -34,49 +34,40 @@ final class MountedApp<R: Renderer>: MountedCompositeElement<R> {
     mountedChildren.forEach { $0.unmount(with: reconciler) }
   }
 
-  private func mountChild<S: Scene>(_ childBody: S) -> MountedElement<R> {
-    let mountedScene: MountedScene<R> = childBody.makeMountedView(parentTarget,
-                                                                  environmentValues)
+  private func mountChild<S: Scene>(_ scene: S) -> MountedElement<R> {
+    let mountedScene: MountedScene<R> = scene.makeMountedScene(parentTarget, environmentValues)
     if let title = mountedScene.title {
-      // swiftlint:disable force_cast
-      (app.type as! _TitledApp.Type)._setTitle(title)
+      R.AppType._setTitle(title)
     }
-    return mountedScene.body
+    return mountedScene
   }
 
   override func update(with reconciler: StackReconciler<R>) {
     let element = reconciler.render(mountedApp: self)
     reconciler.reconcile(
       self,
       with: element,
-      getElementType: { ($0 as? _AnyScene)?.type ?? type(of: $0) },
-      updateChild: { $0.scene = _AnyScene(element) },
+      getElementType: { type(of: $0) },
+      updateChild: {
+        $0.environmentValues = environmentValues
+        $0.scene = _AnyScene(element)
+      },
       mountChild: { mountChild($0) }
     )
   }
 }
 
 extension App {
-  func makeMountedApp<R>(_ parentTarget: R.TargetType,
-                         _ environmentValues: EnvironmentValues)
-    -> MountedApp<R> where R: Renderer {
-    // Find Environment changes
-    var injectableApp = self
-    let any = (injectableApp as? _AnyApp) ?? _AnyApp(injectableApp)
-    // swiftlint:disable force_try
+  func makeMountedApp<R>(
+    _ parentTarget: R.TargetType,
+    _ environmentValues: EnvironmentValues
+  ) -> MountedApp<R> where R: Renderer, R.AppType == Self {
+    // swiftlint:disable:next force_try
+    let info = try! typeInfo(of: Self.self)
 
-    let appInfo = try! typeInfo(of: any.type)
-    var extractedApp = any.app
+    var modified = self
+    info.injectEnvironment(from: environmentValues, into: &modified)
 
-    appInfo.injectEnvironment(from: environmentValues, into: &extractedApp)
-
-    // Set the extractedApp back on the AnyApp after modification
-    let anyAppInfo = try! typeInfo(of: _AnyApp.self)
-    try! anyAppInfo.property(named: "app").set(value: extractedApp, on: &injectableApp)
-    // swiftlint:enable force_try
-
-    // Make MountedView
-    let anyApp = injectableApp as? _AnyApp ?? _AnyApp(injectableApp)
-    return MountedApp(anyApp, parentTarget, environmentValues)
+    return MountedApp(modified, parentTarget, environmentValues)
   }
 }

Sources/TokamakCore/MountedViews/MountedCompositeElement.swift

@@ -27,28 +27,23 @@ class MountedCompositeElement<R: Renderer>: MountedElement<R>, Hashable {
     hasher.combine(ObjectIdentifier(self))
   }
 
-  var mountedChildren = [MountedElement<R>]()
   let parentTarget: R.TargetType
 
   var state = [Any]()
   var subscriptions = [AnyCancellable]()
-  var environmentValues: EnvironmentValues
 
-  init(_ app: _AnyApp, _ parentTarget: R.TargetType, _ environmentValues: EnvironmentValues) {
+  init(_ app: R.AppType, _ parentTarget: R.TargetType, _ environmentValues: EnvironmentValues) {
     self.parentTarget = parentTarget
-    self.environmentValues = environmentValues
-    super.init(app)
+    super.init(app, environmentValues)
   }
 
   init(_ scene: _AnyScene, _ parentTarget: R.TargetType, _ environmentValues: EnvironmentValues) {
     self.parentTarget = parentTarget
-    self.environmentValues = environmentValues
-    super.init(scene)
+    super.init(scene, environmentValues)
   }
 
   init(_ view: AnyView, _ parentTarget: R.TargetType, _ environmentValues: EnvironmentValues) {
     self.parentTarget = parentTarget
-    self.environmentValues = environmentValues
-    super.init(view)
+    super.init(view, environmentValues)
   }
 }

Sources/TokamakCore/MountedViews/MountedCompositeView.swift

@@ -44,8 +44,11 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
     reconciler.reconcile(
       self,
       with: element,
-      getElementType: { ($0 as? AnyView)?.type ?? type(of: $0) },
-      updateChild: { $0.view = AnyView(element) },
+      getElementType: { $0.type },
+      updateChild: {
+        $0.environmentValues = environmentValues
+        $0.view = AnyView(element)
+      },
       mountChild: { $0.makeMountedView(parentTarget, environmentValues) }
     )
   }