Replace ViewDeferredToRenderer, fix renderer tests

Package.swift

@@ -172,14 +172,9 @@ let package = Package(
       name: "TokamakTests",
       dependencies: ["TokamakTestRenderer"]
     ),
-    // FIXME: re-enable when `ViewDeferredToRenderer` conformance conflicts issue is resolved
-    // Currently, when multiple modules that have conflicting `ViewDeferredToRenderer`
-    // implementations are linked in the same binary, only a single one is used with no defined
-    // behavior for that. We need to replace `ViewDeferredToRenderer` with a different solution
-    // that isn't prone to these hard to debug errors.
-    // .testTarget(
-    //   name: "TokamakStaticHTMLTests",
-    //   dependencies: ["TokamakStaticHTML"]
-    // ),
+    .testTarget(
+      name: "TokamakStaticHTMLTests",
+      dependencies: ["TokamakStaticHTML"]
+    ),
   ]
 )

Sources/TokamakCore/MountedViews/MountedApp.swift

@@ -30,7 +30,7 @@ final class MountedApp<R: Renderer>: MountedCompositeElement<R> {
     // They also have no parents, so the `parent` argument is discarded as well.
     let childBody = reconciler.render(mountedApp: self)
 
-    let child: MountedElement<R> = mountChild(childBody)
+    let child: MountedElement<R> = mountChild(reconciler.renderer, childBody)
     mountedChildren = [child]
     child.mount(before: nil, on: self, with: reconciler)
   }
@@ -39,9 +39,14 @@ final class MountedApp<R: Renderer>: MountedCompositeElement<R> {
     mountedChildren.forEach { $0.unmount(with: reconciler) }
   }
 
-  private func mountChild(_ childBody: _AnyScene) -> MountedElement<R> {
+  /// Mounts a child scene within the app.
+  /// - Parameters:
+  ///   - renderer: A instance conforming to the `Renderer` protocol to render the mounted scene with.
+  ///   - childBody: The body of the child scene to mount for this app.
+  /// - Returns: Returns an instance of the `MountedScene` class that's already mounted in this app.
+  private func mountChild(_ renderer: R, _ childBody: _AnyScene) -> MountedScene<R> {
     let mountedScene: MountedScene<R> = childBody
-      .makeMountedScene(parentTarget, environmentValues, self)
+      .makeMountedScene(renderer, parentTarget, environmentValues, self)
     if let title = mountedScene.title {
       // swiftlint:disable force_cast
       (app.type as! _TitledApp.Type)._setTitle(title)
@@ -59,7 +64,7 @@ final class MountedApp<R: Renderer>: MountedCompositeElement<R> {
         $0.environmentValues = environmentValues
         $0.scene = _AnyScene(element)
       },
-      mountChild: { mountChild($0) }
+      mountChild: { mountChild(reconciler.renderer, $0) }
     )
   }
 }

Sources/TokamakCore/MountedViews/MountedCompositeView.swift

@@ -26,14 +26,16 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
     let childBody = reconciler.render(compositeView: self)
 
     let child: MountedElement<R> = childBody.makeMountedView(
+      reconciler.renderer,
       parentTarget,
       environmentValues,
       self
     )
     mountedChildren = [child]
     child.mount(before: sibling, on: self, with: reconciler)
 
-    // `_TargetRef` is a composite view, so it's enough to check for it only here
+    // `_TargetRef` (and `TargetRefType` generic eraser protocol it conforms to) is a composite view, so it's enough
+    // to check for it only here.
     if var targetRef = view.view as? TargetRefType {
       // `_TargetRef` body is not always a host view that has a target, need to traverse
       // all descendants to find a `MountedHostView<R>` instance.
@@ -51,7 +53,7 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
     reconciler.afterCurrentRender(perform: { [weak self] in
       guard let self = self else { return }
 
-      // FIXME: this has to be implemented in a render-specific way, otherwise it's equivalent to
+      // FIXME: this has to be implemented in a renderer-specific way, otherwise it's equivalent to
       // `_onMount` and `_onUnmount` at the moment,
       // see https://github.com/swiftwasm/Tokamak/issues/175 for more details
       if let appearanceAction = self.view.view as? AppearanceActionType {
@@ -89,7 +91,9 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
         $0.environmentValues = environmentValues
         $0.view = AnyView(element)
       },
-      mountChild: { $0.makeMountedView(parentTarget, environmentValues, self) }
+      mountChild: {
+        $0.makeMountedView(reconciler.renderer, parentTarget, environmentValues, self)
+      }
     )
   }
 }

Sources/TokamakCore/MountedViews/MountedElement.swift

@@ -222,13 +222,14 @@ extension TypeInfo {
 
 extension AnyView {
   func makeMountedView<R: Renderer>(
+    _ renderer: R,
     _ parentTarget: R.TargetType,
     _ environmentValues: EnvironmentValues,
     _ parent: MountedElement<R>?
   ) -> MountedElement<R> {
     if type == EmptyView.self {
       return MountedEmptyView(self, environmentValues, parent)
-    } else if bodyType == Never.self && !(type is ViewDeferredToRenderer.Type) {
+    } else if bodyType == Never.self && !renderer.isPrimitiveView(type) {
       return MountedHostView(self, parentTarget, environmentValues, parent)
     } else {
       return MountedCompositeView(self, parentTarget, environmentValues, parent)

Sources/TokamakCore/MountedViews/MountedHostView.swift

@@ -45,7 +45,7 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
     on parent: MountedElement<R>? = nil,
     with reconciler: StackReconciler<R>
   ) {
-    guard let target = reconciler.renderer?.mountTarget(
+    guard let target = reconciler.renderer.mountTarget(
       before: sibling,
       to: parentTarget,
       with: self
@@ -57,7 +57,7 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
     guard !view.children.isEmpty else { return }
 
     mountedChildren = view.children.map {
-      $0.makeMountedView(target, environmentValues, self)
+      $0.makeMountedView(reconciler.renderer, target, environmentValues, self)
     }
 
     /* Remember that `GroupView`s are always "flattened", their `target` instances are targets of
@@ -74,7 +74,7 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
   override func unmount(with reconciler: StackReconciler<R>) {
     guard let target = target else { return }
 
-    reconciler.renderer?.unmount(
+    reconciler.renderer.unmount(
       target: target,
       from: parentTarget,
       with: self
@@ -88,7 +88,7 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
 
     updateEnvironment()
     target.view = view
-    reconciler.renderer?.update(target: target, with: self)
+    reconciler.renderer.update(target: target, with: self)
 
     var childrenViews = view.children
 
@@ -101,7 +101,9 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
 
     // if no existing children then mount all new children
     case (true, false):
-      mountedChildren = childrenViews.map { $0.makeMountedView(target, environmentValues, self) }
+      mountedChildren = childrenViews.map {
+        $0.makeMountedView(reconciler.renderer, target, environmentValues, self)
+      }
       mountedChildren.forEach { $0.mount(on: self, with: reconciler) }
 
     // if both arrays have items then reconcile by types and keys
@@ -124,7 +126,12 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
             as a "cursor" sibling when mounting. Only then we can dispose of the old mounted child
             by unmounting it.
            */
-          newChild = childView.makeMountedView(target, environmentValues, self)
+          newChild = childView.makeMountedView(
+            reconciler.renderer,
+            target,
+            environmentValues,
+            self
+          )
           newChild.mount(before: mountedChild.firstDescendantTarget, on: self, with: reconciler)
           mountedChild.unmount(with: reconciler)
         }
@@ -144,7 +151,7 @@ public final class MountedHostView<R: Renderer>: MountedElement<R> {
         // mount remaining views
         for firstChild in childrenViews {
           let newChild: MountedElement<R> =
-            firstChild.makeMountedView(target, environmentValues, self)
+            firstChild.makeMountedView(reconciler.renderer, target, environmentValues, self)
           newChild.mount(on: self, with: reconciler)
           newChildren.append(newChild)
         }

Sources/TokamakCore/MountedViews/MountedScene.swift

@@ -36,7 +36,7 @@ final class MountedScene<R: Renderer>: MountedCompositeElement<R> {
     let childBody = reconciler.render(mountedScene: self)
 
     let child: MountedElement<R> = childBody
-      .makeMountedElement(parentTarget, environmentValues, self)
+      .makeMountedElement(reconciler.renderer, parentTarget, environmentValues, self)
     mountedChildren = [child]
     child.mount(before: sibling, on: self, with: reconciler)
   }
@@ -60,7 +60,9 @@ final class MountedScene<R: Renderer>: MountedCompositeElement<R> {
           $0.view = AnyView(view)
         }
       },
-      mountChild: { $0.makeMountedElement(parentTarget, environmentValues, self) }
+      mountChild: {
+        $0.makeMountedElement(reconciler.renderer, parentTarget, environmentValues, self)
+      }
     )
   }
 }
@@ -76,21 +78,23 @@ extension _AnyScene.BodyResult {
   }
 
   func makeMountedElement<R: Renderer>(
+    _ renderer: R,
     _ parentTarget: R.TargetType,
     _ environmentValues: EnvironmentValues,
     _ parent: MountedElement<R>?
   ) -> MountedElement<R> {
     switch self {
     case let .scene(scene):
-      return scene.makeMountedScene(parentTarget, environmentValues, parent)
+      return scene.makeMountedScene(renderer, parentTarget, environmentValues, parent)
     case let .view(view):
-      return view.makeMountedView(parentTarget, environmentValues, parent)
+      return view.makeMountedView(renderer, parentTarget, environmentValues, parent)
     }
   }
 }
 
 extension _AnyScene {
   func makeMountedScene<R: Renderer>(
+    _ renderer: R,
     _ parentTarget: R.TargetType,
     _ environmentValues: EnvironmentValues,
     _ parent: MountedElement<R>?
@@ -104,11 +108,16 @@ extension _AnyScene {
     let children: [MountedElement<R>]
     if let deferredScene = scene as? SceneDeferredToRenderer {
       children = [
-        deferredScene.deferredBody.makeMountedView(parentTarget, environmentValues, parent),
+        deferredScene.deferredBody.makeMountedView(
+          renderer,
+          parentTarget,
+          environmentValues,
+          parent
+        ),
       ]
     } else if let groupScene = scene as? GroupScene {
       children = groupScene.children.map {
-        $0.makeMountedScene(parentTarget, environmentValues, parent)
+        $0.makeMountedScene(renderer, parentTarget, environmentValues, parent)
       }
     } else {
       children = []

Sources/TokamakCore/Renderer.swift

@@ -66,4 +66,14 @@ public protocol Renderer: AnyObject {
     with host: MountedHost,
     completion: @escaping () -> ()
   )
+
+  /** Returns a body of a given pritimive view, or `nil` if `view` is not a primitive view for
+   this renderer.
+   */
+  func primitiveBody(for view: Any) -> AnyView?
+
+  /** Returns `true` if a given view type is a primitive view that should be deferred to this
+   renderer.
+   */
+  func isPrimitiveView(_ type: Any.Type) -> Bool
 }

Sources/TokamakCore/Shapes/Shape.swift

@@ -46,7 +46,7 @@ public struct FillStyle: Equatable, ShapeStyle {
   }
 }
 
-public struct _ShapeView<Content, Style>: PrimitiveView where Content: Shape, Style: ShapeStyle {
+public struct _ShapeView<Content, Style>: _PrimitiveView where Content: Shape, Style: ShapeStyle {
   @Environment(\.self) public var environment
   @Environment(\.foregroundColor) public var foregroundColor
   public var shape: Content

Sources/TokamakCore/StackReconciler.swift

@@ -18,7 +18,7 @@
 import CombineShim
 
 /** A class that reconciles a "raw" tree of element values (such as `App`, `Scene` and `View`,
- all coming from `body` or `deferredBody` properties) with a tree of mounted element instances
+ all coming from `body` or `renderedBody` properties) with a tree of mounted element instances
  ('MountedApp', `MountedScene`, `MountedCompositeView` and `MountedHostView` respectively). Any
  updates to the former tree are reflected in the latter tree, and then resulting changes are
  delegated to the renderer for it to reflect those in its viewport.
@@ -52,7 +52,7 @@ public final class StackReconciler<R: Renderer> {
   /** A renderer instance to delegate to. Usually the renderer owns the reconciler instance, thus
    the reference has to be weak to avoid a reference cycle.
    **/
-  private(set) weak var renderer: R?
+  private(set) unowned var renderer: R
 
   /** A platform-specific implementation of an event loop scheduler. Usually reconciler
    updates are scheduled in reponse to user input. To make updates non-blocking so that the app
@@ -73,7 +73,7 @@ public final class StackReconciler<R: Renderer> {
     self.scheduler = scheduler
     rootTarget = target
 
-    rootElement = AnyView(view).makeMountedView(target, environment, nil)
+    rootElement = AnyView(view).makeMountedView(renderer, target, environment, nil)
 
     performInitialMount()
   }
@@ -201,45 +201,50 @@ public final class StackReconciler<R: Renderer> {
     }.store(in: &mountedApp.persistentSubscriptions)
   }
 
-  private func render<T>(
-    compositeElement: MountedCompositeElement<R>,
-    body bodyKeypath: ReferenceWritableKeyPath<MountedCompositeElement<R>, Any>,
-    result: KeyPath<MountedCompositeElement<R>, (Any) -> T>
-  ) -> T {
+  private func body(
+    of compositeElement: MountedCompositeElement<R>,
+    keyPath: ReferenceWritableKeyPath<MountedCompositeElement<R>, Any>
+  ) -> Any {
     compositeElement.updateEnvironment()
     if let info = typeInfo(of: compositeElement.type) {
       var stateIdx = 0
       let dynamicProps = info.dynamicProperties(
         &compositeElement.environmentValues,
-        source: &compositeElement[keyPath: bodyKeypath]
+        source: &compositeElement[keyPath: keyPath]
       )
 
       compositeElement.transientSubscriptions = []
       for property in dynamicProps {
         // Setup state/subscriptions
         if property.type is ValueStorage.Type {
-          setupStorage(id: stateIdx, for: property, of: compositeElement, body: bodyKeypath)
+          setupStorage(id: stateIdx, for: property, of: compositeElement, body: keyPath)
           stateIdx += 1
         }
         if property.type is ObservedProperty.Type {
-          setupTransientSubscription(for: property, of: compositeElement, body: bodyKeypath)
+          setupTransientSubscription(for: property, of: compositeElement, body: keyPath)
         }
       }
     }
 
-    return compositeElement[keyPath: result](compositeElement[keyPath: bodyKeypath])
+    return compositeElement[keyPath: keyPath]
   }
 
   func render(compositeView: MountedCompositeView<R>) -> AnyView {
-    render(compositeElement: compositeView, body: \.view.view, result: \.view.bodyClosure)
+    let view = body(of: compositeView, keyPath: \.view.view)
+
+    guard let renderedBody = renderer.primitiveBody(for: view) else {
+      return compositeView.view.bodyClosure(view)
+    }
+
+    return renderedBody
   }
 
   func render(mountedApp: MountedApp<R>) -> _AnyScene {
-    render(compositeElement: mountedApp, body: \.app.app, result: \.app.bodyClosure)
+    mountedApp.app.bodyClosure(body(of: mountedApp, keyPath: \.app.app))
   }
 
   func render(mountedScene: MountedScene<R>) -> _AnyScene.BodyResult {
-    render(compositeElement: mountedScene, body: \.scene.scene, result: \.scene.bodyClosure)
+    mountedScene.scene.bodyClosure(body(of: mountedScene, keyPath: \.scene.scene))
   }
 
   func reconcile<Element>(

Sources/TokamakCore/State/TargetRef.swift

@@ -12,10 +12,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+/// A helper protocol for erasing generic parameters of the `_TargetRef` type.
 protocol TargetRefType {
   var target: Target? { get set }
 }
 
+/** Allows capturing target instance of aclosest descendant host view. The resulting instance
+ is written to a given `binding`. The actual assignment to this binding is done within the
+ `MountedCompositeView` implementation. */
 public struct _TargetRef<V: View, T>: View, TargetRefType {
   let binding: Binding<T?>
 
@@ -31,8 +35,9 @@ public struct _TargetRef<V: View, T>: View, TargetRefType {
 }
 
 public extension View {
-  /** Allows capturing target instance of aclosest descendant host view. The resulting instance
-   is written to a given `binding`. */
+  /** A modifier that returns a `_TargetRef` value, which captures a target instance of a
+   closest descendant host view.
+   The resulting instance is written to a given `binding`. */
   @_spi(TokamakCore)
   func _targetRef<T: Target>(_ binding: Binding<T?>) -> _TargetRef<Self, T> {
     .init(binding: binding, view: self)

Sources/TokamakCore/Styles/ButtonStyle.swift

@@ -15,7 +15,7 @@
 //  Created by Gene Z. Ragan on 07/22/2020.
 
 public struct ButtonStyleConfiguration {
-  public struct Label: PrimitiveView {
+  public struct Label: _PrimitiveView {
     let content: AnyView
   }