Add initial hosting support (#26)

Sources/OpenSwiftUI/FrameworkIntegration/UIKit/UIHostingController.swift

@@ -0,0 +1,12 @@
+#if os(iOS)
+import UIKit
+
+@available(macOS, unavailable)
+@available(watchOS, unavailable)
+@MainActor(unsafe)
+open class UIHostingController<Content> : UIViewController where Content : View {
+    override open dynamic var keyCommands: [UIKeyCommand]? {
+        fatalError("Unimplemented")
+    }
+}
+#endif

Sources/OpenSwiftUI/FrameworkIntegration/UIKit/_UIHostingView.swift

@@ -0,0 +1,15 @@
+#if os(iOS)
+import UIKit
+
+@available(macOS, unavailable)
+@available(watchOS, unavailable)
+@MainActor(unsafe)
+open class _UIHostingView<Content>: UIView where Content: View {
+    @available(macOS, unavailable)
+    @available(watchOS, unavailable)
+    final public func _viewDebugData() -> [_ViewDebug.Data] {
+        // TODO
+        []
+    }
+}
+#endif

Sources/OpenSwiftUI/FrameworkIntegration/UIKit/_UIHostingViewable.swift

@@ -0,0 +1,29 @@
+#if os(iOS)
+import CoreGraphics
+
+@available(macOS, unavailable)
+public protocol _UIHostingViewable: AnyObject {
+    var rootView: AnyView { get set }
+    func _render(seconds: Swift.Double)
+    func _forEachIdentifiedView(body: (_IdentifiedViewProxy) -> Void)
+    func sizeThatFits(in size: CGSize) -> CGSize
+    var _disableSafeArea: Bool { get set }
+//    var _rendererConfiguration: _RendererConfiguration { get set }
+    var _rendererObject: AnyObject? { get }
+}
+
+//@available(macOS, unavailable)
+//extension UIHostingController : _UIHostingViewable where Content == AnyView {
+//}
+
+@available(macOS, unavailable)
+public func _makeUIHostingController(_ view: AnyView) -> NSObject & _UIHostingViewable {
+    fatalError("TODO")
+
+}
+
+@available(macOS, unavailable)
+public func _makeUIHostingController(_ view: AnyView, tracksContentSize: Swift.Bool) -> NSObject & _UIHostingViewable {
+    fatalError("TODO")
+}
+#endif

Sources/OpenSwiftUI/Views/View/ViewTransform.swift

@@ -0,0 +1,34 @@
+//  ID: CE19A3CEA6B9730579C42CE4C3071E74
+
+#if canImport(Darwin)
+import CoreGraphics
+#elseif os(Linux)
+import Foundation
+#endif
+
+struct ViewTransform {
+    private var chunks: ContiguousArray<Chunk>
+    var positionAdjustment: CGSize
+}
+
+extension ViewTransform {
+    private class Chunk {
+        var tags: [Tag]
+        var values: [CGFloat]
+        var spaces: [AnyHashable]
+        init() {
+            fatalError()
+        }
+
+        enum Tag {
+            case translation
+            case affine
+            case affine_inverse
+            case projection
+            case projection_inverse
+            case space
+            case sized_space
+            case scroll_layout
+        }
+    }
+}

Sources/OpenSwiftUI/Views/View/_IdentifiedViewProxy.swift

@@ -0,0 +1,14 @@
+#if canImport(Darwin)
+import CoreGraphics
+#elseif os(Linux)
+import Foundation
+#endif
+
+public struct _IdentifiedViewProxy {
+    var identifier: AnyHashable
+    var size: CGSize
+    var position: CGPoint
+    var transform: ViewTransform
+    var adjustment: (inout CGRect) -> ()?
+//    var accessibilityNodeStorage: AccessibilityNodeProxy?
+}