Add AbsoluteEdge

Sources/OpenSwiftUICore/Layout/LayoutAdjustments/Edge/AbsoluteEdge.swift

@@ -0,0 +1,79 @@
+//
+//  AbsoluteEdge.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2024
+//  Status: Complete
+
+// MARK: - AbsoluteEdge
+
+@frozen
+public enum AbsoluteEdge: Int8, CaseIterable {
+    case top
+    case left
+    case bottom
+    case right
+
+    var horizontal: Bool {
+        self == .left || self == .right
+    }
+
+    var opposite: AbsoluteEdge {
+        switch self {
+        case .top: return .bottom
+        case .left: return .right
+        case .bottom: return .top
+        case .right: return .left
+        }
+    }
+
+    /// An efficient set of AbsoluteEdges.
+    @frozen
+    public struct Set: OptionSet {
+
+        public let rawValue: Int8
+
+        public init(rawValue: Int8) {
+            self.rawValue = rawValue
+        }
+
+        public static let top = Set(.top)
+        public static let left = Set(.left)
+        public static let bottom = Set(.bottom)
+        public static let right = Set(.right)
+        public static let all: Set = [.top, .left, .bottom, .right]
+        public static let horizontal: Set = [.left, .right]
+        public static let vertical: Set = [.top, .bottom]
+
+        public init(_ edge: AbsoluteEdge) { self.init(rawValue: 1 << edge.rawValue) }
+
+        func contains(_ edge: AbsoluteEdge) -> Bool {
+            contains(.init(edge))
+        }
+
+        init(_ edgeSet: Edge.Set, layoutDirection: LayoutDirection) {
+            var set: Set = []
+            if edgeSet.contains(.leading) {
+                if layoutDirection == .leftToRight {
+                    set.insert(.left)
+                } else {
+                    set.insert(.right)
+                }
+            }
+            if edgeSet.contains(.trailing) {
+                if layoutDirection == .leftToRight {
+                    set.insert(.right)
+                } else {
+                    set.insert(.left)
+                }
+            }
+            if edgeSet.contains(.top) {
+                set.insert(.top)
+            }
+            if edgeSet.contains(.bottom) {
+                set.insert(.bottom)
+            }
+            self = set
+        }
+    }
+}