feat: add subview and section extraction APIs

Sources/OpenSwiftUI/View/Subview/Subview.swift

@@ -0,0 +1,16 @@
+//
+//  Subview.swift
+//  OpenSwiftUI
+//
+//  Audited for 6.5.4
+//  Status: Complete
+
+@_spi(ForOpenSwiftUIOnly) public import OpenSwiftUICore
+
+@_spi(DoNotImportVariadicView)
+extension Subview {
+    @available(*, deprecated, renamed: "containerValues")
+    public var traits: TraitValues {
+        TraitValues(base: base.traits)
+    }
+}

Sources/OpenSwiftUI/View/Subview/SubviewCollection.swift

@@ -0,0 +1,90 @@
+//
+//  SubviewCollection.swift
+//  OpenSwiftUI
+//
+//  Audited for 6.5.4
+//  Status: Complete
+
+@_spi(ForOpenSwiftUIOnly) public import OpenSwiftUICore
+
+// MARK: - Group + SubviewCollection
+
+@_spi(DoNotImportVariadicView)
+extension Group {
+    @available(*, deprecated, message: "Use the public API instead.")
+    @_disfavoredOverload
+    public init<Base, Result>(
+        elementsOf view: Base,
+        @ViewBuilder transform: @escaping (SubviewCollection) -> Result
+    ) where Content == GroupElementsOfContent<Base, Result>, Base: View, Result: View {
+        self.init {
+            GroupElementsOfContent(subviews: view) { subviews in
+                transform(SubviewCollection(subviews))
+            }
+        }
+    }
+}
+
+// MARK: - SubviewCollection
+
+@_spi(DoNotImportVariadicView)
+@available(*, deprecated, renamed: "SubviewsCollection")
+public struct SubviewCollection: RandomAccessCollection {
+    package var base: _VariadicView.Children
+
+    @usableFromInline
+    init(_ subviews: SubviewsCollection) {
+        base = subviews.base
+    }
+
+    public subscript(index: Int) -> Subview {
+        Subview(base[index])
+    }
+
+    public subscript(bounds: Range<Int>) -> Slice<SubviewCollection> {
+        Slice(base: self, bounds: bounds)
+    }
+
+    public var startIndex: Int { base.startIndex }
+
+    public var endIndex: Int { base.endIndex }
+
+    public func selectedSubview<V>(selection: V) -> Subview? where V: Hashable {
+        var start = 0
+        var index = 0
+        var selectedIndex: Int?
+        base.list.applySublists(from: &start, list: nil) { sublist in
+            if sublist.traits.tag(for: V.self) == selection,
+               !sublist.traits.isAuxiliaryContent {
+                selectedIndex = index
+                return false
+            }
+            index &+= sublist.count
+            return true
+        }
+        return selectedIndex.map { Subview(base[$0]) }
+    }
+}
+
+@_spi(DoNotImportVariadicView)
+@available(*, unavailable)
+extension SubviewCollection: Sendable {}
+
+@_spi(DoNotImportVariadicView)
+@available(OpenSwiftUI_v6_0, *)
+extension SubviewCollection: View, MultiView, PrimitiveView {
+    public var body: some View {
+        base
+    }
+
+    nonisolated public static func _makeViewList(
+        view: _GraphValue<Self>,
+        inputs: _ViewListInputs
+    ) -> _ViewListOutputs {
+        _VariadicView.Children._makeViewList(view: view[\.base], inputs: inputs)
+    }
+
+    nonisolated public static func _viewListCount(inputs: _ViewListCountInputs) -> Int? {
+        _VariadicView.Children._viewListCount(inputs: inputs)
+    }
+}

Sources/OpenSwiftUICore/View/DynamicViewContent/ForEach.swift

@@ -3,7 +3,7 @@
 //  OpenSwiftUICore
 //
 //  Audited for 6.5.4
-//  Status: Blocked by Subview
+//  Status: Complete
 //  ID: 1A3DD35AB7F6976908CD7AF959F34D1F (SwiftUICore)
 
 import Foundation
@@ -148,7 +148,7 @@ public struct ForEach<Data, ID, Content> where Data: RandomAccessCollection, ID:
 @available(*, unavailable)
 extension ForEach: Sendable {}
 
-// MARK: - ForEach + View [Blocked by Subview]
+// MARK: - ForEach + View
 
 @available(OpenSwiftUI_v1_0, *)
 extension ForEach: View, PrimitiveView where Content: View {
@@ -169,8 +169,19 @@ extension ForEach: View, PrimitiveView where Content: View {
         view: _GraphValue<Self>,
         inputs: _ViewInputs
     ) -> _ViewOutputs? {
-        // TODO: Subview stuff
-        return nil
+        if let view = view as? _GraphValue<ForEach<ForEachSubviewCollection<Content>, Subview.ID, Content>> {
+            return AnyView._makeView(
+                view: view[offset: { .of(&$0.data.substituteView) }],
+                inputs: inputs
+            )
+        } else if let view = view as? _GraphValue<ForEach<ForEachSectionCollection<Content>, SectionConfiguration.ID, Content>> {
+            return AnyView._makeView(
+                view: view[offset: { .of(&$0.data.substituteView) }],
+                inputs: inputs
+            )
+        } else {
+            return nil
+        }
     }
 
     nonisolated public static func _makeViewList(
@@ -217,8 +228,19 @@ extension ForEach: View, PrimitiveView where Content: View {
         view: _GraphValue<Self>,
         inputs: _ViewListInputs
     ) -> _ViewListOutputs? {
-        // TODO: Subview stuff
-        return nil
+        if let view = view as? _GraphValue<ForEach<ForEachSubviewCollection<Content>, Subview.ID, Content>> {
+            return AnyView._makeViewList(
+                view: view[offset: { .of(&$0.data.substituteView) }],
+                inputs: inputs
+            )
+        } else if let view = view as? _GraphValue<ForEach<ForEachSectionCollection<Content>, SectionConfiguration.ID, Content>> {
+            return AnyView._makeViewList(
+                view: view[offset: { .of(&$0.data.substituteView) }],
+                inputs: inputs
+            )
+        } else {
+            return nil
+        }
     }
 }