Add `DefaultApp` type to simplify `DOMRenderer.init` (#217)

This means that the `View` initializer of `DOMRenderer` now can delegate to the `App` initializer by creating a wrapping `DefaultApp`. It would simplify https://github.com/swiftwasm/Tokamak/pull/136 for me, where I no longer need to implement color scheme observation for these two different codepaths separately.

Sources/TokamakCore/App/App.swift

@@ -29,8 +29,8 @@ public protocol App: _TitledApp {
   var body: Body { get }
 
   /// Implemented by the renderer to mount the `App`
-  static func _launch(_ app: Self,
-                      _ rootEnvironment: EnvironmentValues)
+  static func _launch(_ app: Self, _ rootEnvironment: EnvironmentValues)
+
   /// Implemented by the renderer to update the `App` on `ScenePhase` changes
   var _phasePublisher: CurrentValueSubject<ScenePhase, Never> { get }
 

Sources/TokamakCore/StackReconciler.swift

@@ -58,8 +58,8 @@ public final class StackReconciler<R: Renderer> {
     rootElement.mount(with: self)
     if let mountedApp = rootElement as? MountedApp<R> {
       app._phasePublisher.sink { [weak self] phase in
-        if mountedApp.environmentValues[keyPath: \.scenePhase] != phase {
-          mountedApp.environmentValues[keyPath: \.scenePhase] = phase
+        if mountedApp.environmentValues.scenePhase != phase {
+          mountedApp.environmentValues.scenePhase = phase
           self?.queueUpdate(for: mountedApp)
         }
       }.store(in: &mountedApp.subscriptions)

Sources/TokamakDOM/App.swift

@@ -23,7 +23,6 @@ private enum ScenePhaseObserver {
   static var publisher = CurrentValueSubject<ScenePhase, Never>(.active)
 
   static func observe() {
-    let document = JSObjectRef.global.document.object!
     _ = document.addEventListener!("visibilitychange", JSClosure { _ in
       let visibilityState = document.visibilityState.string
       if visibilityState == "visible" {
@@ -44,12 +43,11 @@ extension App {
   /// The body is styled with `margin: 0;` to match the `SwiftUI` layout
   /// system as closely as possible
   ///
-  public static func _launch(_ app: Self,
-                             _ rootEnvironment: EnvironmentValues) {
-    let document = JSObjectRef.global.document.object!
-    let body = document.body.object!
-    let head = document.head.object!
-    body.style = "margin: 0;"
+  public static func _launch(_ app: Self, _ rootEnvironment: EnvironmentValues) {
+    let body = TokamakDOM.body
+    if body.style == .undefined {
+      body.style = "margin: 0;"
+    }
     let rootStyle = document.createElement!("style").object!
     rootStyle.id = "_tokamak-app-style"
     rootStyle.innerHTML = .string(tokamakStyles)
@@ -74,3 +72,13 @@ extension App {
     ScenePhaseObserver.publisher
   }
 }
+
+struct DefaultApp<V: View>: App {
+  var content: V?
+
+  var body: some Scene {
+    WindowGroup {
+      content
+    }
+  }
+}

Sources/TokamakDOM/DOMRenderer.swift

@@ -23,7 +23,7 @@ extension EnvironmentValues {
   static var defaultEnvironment: Self {
     var environment = EnvironmentValues()
     environment[_ToggleStyleKey] = _AnyToggleStyle(DefaultToggleStyle())
-    environment[keyPath: \._defaultAppStorage] = LocalStorage.standard
+    environment._defaultAppStorage = LocalStorage.standard
     _DefaultSceneStorageProvider.default = SessionStorage.standard
 
     return environment
@@ -55,6 +55,7 @@ private extension AnyView {
 
 let log = JSObjectRef.global.console.object!.log.function!
 let document = JSObjectRef.global.document.object!
+let body = document.body.object!
 let head = document.head.object!
 
 let timeoutScheduler = { (closure: @escaping () -> ()) in
@@ -77,28 +78,15 @@ public final class DOMRenderer: Renderer {
 
   private let rootRef: JSObjectRef
 
-  public init<V: View>(
+  public convenience init<V: View>(
     _ view: V,
     _ ref: JSObjectRef,
     _ rootEnvironment: EnvironmentValues? = nil
   ) {
-    rootRef = ref
-    appendRootStyle(ref)
-
-    reconciler = StackReconciler(
-      view: view,
-      target: DOMNode(view, ref),
-      environment: .defaultEnvironment,
-      renderer: self,
-      scheduler: timeoutScheduler
-    )
+    self.init(DefaultApp(content: view), ref, rootEnvironment)
   }
 
-  init<A: App>(
-    _ app: A,
-    _ ref: JSObjectRef,
-    _ rootEnvironment: EnvironmentValues? = nil
-  ) {
+  init<A: App>(_ app: A, _ ref: JSObjectRef, _ rootEnvironment: EnvironmentValues? = nil) {
     rootRef = ref
     appendRootStyle(ref)
 

Sources/TokamakDOM/Views/HTML.swift

@@ -45,7 +45,7 @@ extension AnyHTML {
     // then use the standard lib to get the difference?
 
     for (attribute, value) in attributes {
-      _ = dom.ref[dynamicMember: attribute] = JSValue(stringLiteral: value)
+      _ = dom.ref[dynamicMember: attribute] = .string(value)
     }
 
     dom.reinstall(listeners)