Assert When Layout Is Recursively Called

Author: thecoolwinter

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager+Public.swift

@@ -191,6 +191,7 @@ extension TextLayoutManager {
         for fragmentPosition in line.data.lineFragments.linesInRange(relativeRange) {
             guard let intersectingRange = fragmentPosition.range.intersection(relativeRange) else { continue }
             let fragmentRect = fragmentPosition.data.rectFor(range: intersectingRange)
+            guard fragmentRect.width > 0 else { continue }
             rects.append(
                 CGRect(
                     x: fragmentRect.minX + edgeInsets.left,

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager.swift

@@ -199,15 +199,33 @@ public class TextLayoutManager: NSObject {
     /// ``TextLayoutManager/estimateLineHeight()`` is called.
     private var _estimateLineHeight: CGFloat?
 
+    /// Asserts that the caller is not in an active layout pass.
+    /// See docs on ``isInLayout`` for more details.
+    private func assertNotInLayout() {
+        #if DEBUG // This is redundant, but it keeps the flag debug-only too which helps prevent misuse.
+        assert(!isInLayout, "layoutLines called while already in a layout pass. This is a programmer error.")
+        #endif
+    }
+
     // MARK: - Layout
 
     /// Lays out all visible lines
     func layoutLines(in rect: NSRect? = nil) { // swiftlint:disable:this function_body_length
+        assertNotInLayout()
         guard let visibleRect = rect ?? delegate?.visibleRect,
               !isInTransaction,
               let textStorage else {
             return
         }
+
+        // The macOS may call `layout` on the textView while we're laying out fragment views. This ensures the view
+        // tree modifications caused by this method are atomic, so macOS won't call `layout` while we're already doing
+        // that
+        CATransaction.begin()
+        #if DEBUG
+        isInLayout = true
+        #endif
+
         let minY = max(visibleRect.minY - verticalLayoutPadding, 0)
         let maxY = max(visibleRect.maxY + verticalLayoutPadding, 0)
         let originalHeight = lineStorage.height
@@ -253,6 +271,11 @@ public class TextLayoutManager: NSObject {
             newVisibleLines.insert(linePosition.data.id)
         }
 
+        #if DEBUG
+        isInLayout = false
+        #endif
+        CATransaction.commit()
+
         // Enqueue any lines not used in this layout pass.
         viewReuseQueue.enqueueViews(notInSet: usedFragmentIDs)
 

Sources/CodeEditTextView/TextSelectionManager/TextSelectionManager.swift

@@ -86,6 +86,8 @@ public class TextSelectionManager: NSObject {
     /// Set the selected ranges to new ranges. Overrides any existing selections.
     /// - Parameter range: The selected ranges to set.
     public func setSelectedRanges(_ ranges: [NSRange]) {
+        let oldRanges = textSelections.map(\.range)
+
         textSelections.forEach { $0.view?.removeFromSuperview() }
         // Remove duplicates, invalid ranges, update suggested X position.
         textSelections = Set(ranges)
@@ -99,8 +101,11 @@ public class TextSelectionManager: NSObject {
                 return selection
             }
         updateSelectionViews()
-        NotificationCenter.default.post(Notification(name: Self.selectionChangedNotification, object: self))
         delegate?.setNeedsDisplay()
+
+        if oldRanges != textSelections.map(\.range) {
+            NotificationCenter.default.post(Notification(name: Self.selectionChangedNotification, object: self))
+        }
     }
 
     /// Append a new selected range to the existing ones.