Updates to offset operator to work with axis-specific Edge types

Author: jayrhynas

Cartography/Edge+OffsetOperator.swift

@@ -22,18 +22,16 @@ precedencegroup OffsetPrecedence {
 infix operator |-|: OffsetPrecedence
 
 @available(iOS 10.0, macOS 10.12, tvOS 10.0, *)
-extension Edge {
-    public static func |-|(lhs: Edge, rhs: Edge) -> Dimension {
-        if let first = lhs.xAnchor, let second = rhs.xAnchor {
-            return Dimension(lhs.context, first.anchorWithOffset(to: second))
-        } else if let first = lhs.yAnchor, let second = rhs.yAnchor {
+extension EdgeXAxis {
+    public static func |-|(lhs: EdgeXAxis, rhs: EdgeXAxis) -> Dimension {
+        if let first = lhs.anchor, let second = rhs.anchor {
             return Dimension(lhs.context, first.anchorWithOffset(to: second))
         } else {
             return Dimension(lhs.context, lhs.item, .notAnAttribute)
         }
     }
 
-    internal var xAnchor: NSLayoutXAxisAnchor? {
+    internal var anchor: NSLayoutXAxisAnchor? {
         if attribute == .left, let item = item as? SupportsLeftAnchor {
             return item.leftAnchor
         }
@@ -53,8 +51,19 @@ extension Edge {
             return nil
         }
     }
-    
-    internal var yAnchor: NSLayoutYAxisAnchor? {
+}
+
+@available(iOS 10.0, macOS 10.12, tvOS 10.0, *)
+extension EdgeYAxis {
+    public static func |-|(lhs: EdgeYAxis, rhs: EdgeYAxis) -> Dimension {
+        if let first = lhs.anchor, let second = rhs.anchor {
+            return Dimension(lhs.context, first.anchorWithOffset(to: second))
+        } else {
+            return Dimension(lhs.context, lhs.item, .notAnAttribute)
+        }
+    }
+
+    internal var anchor: NSLayoutYAxisAnchor? {
         if attribute == .top, let item = item as? SupportsTopAnchor {
             return item.topAnchor
         }