Add OptionalView implementation (#284)

Author: Kyle-Ye

Sources/OpenSwiftUICore/View/OptionalView.swift

@@ -0,0 +1,72 @@
+//
+//  OptionalView.swift
+//  OpenSwiftUICore
+//
+//  Audited for iOS 18.0
+//  Status: Complete
+
+package import OpenGraphShims
+
+extension Optional: PrimitiveView where Wrapped: View {}
+
+extension Optional: View where Wrapped: View {
+    public typealias Body = Never
+
+    nonisolated public static func _makeView(
+        view: _GraphValue<Self>,
+        inputs: _ViewInputs
+    ) -> _ViewOutputs {
+        if _SemanticFeature_v2.isEnabled {
+            return makeImplicitRoot(view: view, inputs: inputs)
+        } else {
+            let metadata = makeConditionalMetadata(ViewDescriptor.self)
+            return makeDynamicView(metadata: metadata, view: view, inputs: inputs)
+        }
+    }
+
+    nonisolated public static func _makeViewList(
+        view: _GraphValue<Self>,
+        inputs: _ViewListInputs
+    ) -> _ViewListOutputs {
+        let metadata = makeConditionalMetadata(ViewDescriptor.self)
+        return makeDynamicViewList(metadata: metadata, view: view, inputs: inputs)
+    }
+
+    nonisolated public static func _viewListCount(inputs: _ViewListCountInputs) -> Int? {
+        Wrapped._viewListCount(inputs: inputs)
+    }
+}
+
+extension Optional: DynamicView where Wrapped: View {
+    package static var canTransition: Bool { true }
+
+    package func childInfo(metadata: ConditionalMetadata<ViewDescriptor>) -> (any Any.Type, UniqueID?) {
+        withUnsafePointer(to: self) { ptr in
+            metadata.childInfo(ptr: ptr, emptyType: EmptyView.self)
+        }
+    }
+
+    package func makeChildView(
+        metadata: ConditionalMetadata<ViewDescriptor>,
+        view: Attribute<Optional<Wrapped>>,
+        inputs: _ViewInputs
+    ) -> _ViewOutputs {
+        withUnsafePointer(to: self) { ptr in
+            metadata.makeView(ptr: ptr, view: view, inputs: inputs)
+        }
+    }
+    
+    package func makeChildViewList(
+        metadata: ConditionalMetadata<ViewDescriptor>,
+        view: Attribute<Optional<Wrapped>>,
+        inputs: _ViewListInputs
+    ) -> _ViewListOutputs {
+        withUnsafePointer(to: self) { ptr in
+            metadata.makeViewList(ptr: ptr, view: view, inputs: inputs)
+        }
+    }
+
+    package typealias ID = UniqueID
+
+    package typealias Metadata = ConditionalMetadata<ViewDescriptor>
+}