Add _AlignmentLayout

Sources/OpenSwiftUICore/Layout/Alignment/AlignmentLayout.swift

@@ -0,0 +1,103 @@
+//
+//  AlignmentLayout.swift
+//  OpenSwiftUICore
+//
+//  Status: Complete
+
+package import Foundation
+
+// MARK: - VAlignment [6.4.41]
+
+/// An alignment in the vertical axis.
+@frozen
+public enum _VAlignment {
+    case top
+    case center
+    case bottom
+
+    package var value: CGFloat {
+        switch self {
+            case .top: 0.0
+            case .center: 0.5
+            case .bottom: 1.0
+        }
+    }
+}
+
+// MARK: - AlignmentLayout [6.4.41]
+
+@frozen
+public struct _AlignmentLayout: UnaryLayout {
+    public var horizontal: TextAlignment?
+
+    public var vertical: _VAlignment?
+
+    @inlinable
+    public init(
+        horizontal: TextAlignment? = nil,
+        vertical: _VAlignment? = nil
+    ) {
+        self.horizontal = horizontal
+        self.vertical = vertical
+    }
+
+    package func placement(
+        of child: LayoutProxy,
+        in context: PlacementContext
+    ) -> _Placement {
+        _Placement(
+            proposedSize: context.proposedSize,
+            aligning: UnitPoint(x: (horizontal ?? .center).value, y: (vertical ?? .center).value),
+            in: context.size
+        )
+    }
+
+    package func sizeThatFits(
+        in proposedSize: _ProposedSize,
+        context: SizeAndSpacingContext,
+        child: LayoutProxy
+    ) -> CGSize {
+        guard horizontal != nil,
+              vertical != nil,
+              let width = proposedSize.width,
+              let height = proposedSize.height else {
+            let childSize = child.size(in: proposedSize)
+            let width = if horizontal != nil, let width = proposedSize.width {
+                width
+            } else {
+                childSize.width
+            }
+            let height = if vertical != nil, let height = proposedSize.height {
+                height
+            } else {
+                childSize.height
+            }
+            return CGSize(width: width, height: height)
+        }
+        return CGSize(width: width, height: height)
+    }
+
+    package func spacing(
+        in context: SizeAndSpacingContext,
+        child: LayoutProxy
+    ) -> Spacing {
+        if _SemanticFeature_v3.isEnabled {
+            var spacing = child.layoutComputer.spacing()
+            spacing.reset(
+                AbsoluteEdge.Set(
+                    [horizontal == nil ? [] : .horizontal, vertical == nil ? [] : .vertical],
+                    layoutDirection: context.layoutDirection
+                )
+            )
+            return spacing
+        } else {
+            return child.layoutComputer.spacing()
+        }
+    }
+
+    public typealias AnimatableData = EmptyAnimatableData
+
+    public typealias Body = Never
+
+    package typealias PlacementContextType = PlacementContext
+}

Sources/OpenSwiftUICore/Layout/Alignment/TextAlignment.swift

@@ -2,11 +2,12 @@
 //  TextAlignment.swift
 //  OpenSwiftUICore
 //
-//  Audited for iOS 18.0
 //  Status: Complete
 
 package import Foundation
 
+// MARK: - TextAlignment [6.0.87]
+
 /// An alignment position for text along the horizontal axis.
 @frozen
 public enum TextAlignment: Hashable, CaseIterable {

Sources/OpenSwiftUICore/Layout/Edge/Edge.swift

@@ -23,16 +23,24 @@ public enum Edge: Int8, CaseIterable {
             self.rawValue = rawValue
         }
 
-        public static let top = Set(.top)
-        public static let leading = Set(.leading)
-        public static let bottom = Set(.bottom)
-        public static let trailing = Set(.trailing)
+        public static let top: Set = .init(.top)  // 1
+
+        public static let leading: Set = .init(.leading) // 2
+
+        public static let bottom: Set = .init(.bottom) // 4
+
+        public static let trailing: Set = .init(.trailing) // 8
+
         public static let all: Set = [.top, .leading, .bottom, .trailing]
-        public static let horizontal: Set = [.leading, .trailing]
-        public static let vertical: Set = [.top, .bottom]
+
+        public static let horizontal: Set = [.leading, .trailing] // 0xa
+
+        public static let vertical: Set = [.top, .bottom] // 0x5
 
         /// Creates an instance containing just e
-        public init(_ e: Edge) { self.init(rawValue: 1 << e.rawValue) }
+        public init(_ e: Edge) {
+            rawValue = 1 << e.rawValue
+        }
 
         package func contains(_ edge: Edge) -> Bool {
             contains(.init(edge))

Sources/OpenSwiftUICore/Layout/GeometryReader.swift

@@ -0,0 +1,25 @@
+//
+//  GeometryReader.swift
+//  OpenSwiftUICore
+//
+//  Status: WIP
+
+extension UnaryLayout where Self.PlacementContextType == _PositionAwarePlacementContext {
+    package static func makeViewImpl(
+        modifier: _GraphValue<Self>,
+        inputs: _ViewInputs,
+        body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
+    ) -> _ViewOutputs {
+        preconditionFailure("TODO")
+    }
+}
+
+extension UnaryLayout where Self.PlacementContextType == PlacementContext {
+    package static func makeViewImpl(
+        modifier: _GraphValue<Self>,
+        inputs: _ViewInputs,
+        body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
+    ) -> _ViewOutputs {
+        preconditionFailure("TODO")
+    }
+}

Sources/OpenSwiftUICore/Layout/PlacementContext.swift

@@ -4,7 +4,7 @@
 //
 //  Audited for iOS 18.0
 //  Status: Complete
-//  ID: BA60BF7120E939C5C25B2A488163D4AC
+//  ID: BA60BF7120E939C5C25B2A488163D4AC (SwiftUICore)
 
 package import Foundation
 package import OpenGraphShims