Folding Ribbon: Collapsed Indicators, Masking, Bracket Emphasis

Sources/CodeEditSourceEditor/Controller/TextViewController+TextFormation.swift

@@ -11,23 +11,6 @@ import TextFormation
 import TextStory
 
 extension TextViewController {
-
-    internal enum BracketPairs {
-        static let allValues: [(String, String)] = [
-            ("{", "}"),
-            ("[", "]"),
-            ("(", ")"),
-            ("\"", "\""),
-            ("'", "'")
-        ]
-
-        static let emphasisValues: [(String, String)] = [
-            ("{", "}"),
-            ("[", "]"),
-            ("(", ")")
-        ]
-    }
-
     // MARK: - Filter Configuration
 
     /// Initializes any filters for text editing.

Sources/CodeEditSourceEditor/Enums/BracketPairs.swift

@@ -0,0 +1,29 @@
+//
+//  BracketPairs.swift
+//  CodeEditSourceEditor
+//
+//  Created by Khan Winter on 6/5/25.
+//
+
+enum BracketPairs {
+    static let allValues: [(String, String)] = [
+        ("{", "}"),
+        ("[", "]"),
+        ("(", ")"),
+        ("\"", "\""),
+        ("'", "'")
+    ]
+
+    static let emphasisValues: [(String, String)] = [
+        ("{", "}"),
+        ("[", "]"),
+        ("(", ")")
+    ]
+
+    /// Checks if the given string is a matchable emphasis string.
+    /// - Parameter potentialMatch: The string to check for matches.
+    /// - Returns: True if a match was found with either start or end bracket pairs.
+    static func matches(_ potentialMatch: String) -> Bool {
+        allValues.contains(where: { $0.0 == potentialMatch || $0.1 == potentialMatch })
+    }
+}

Sources/CodeEditSourceEditor/Extensions/NSBezierPath+RoundedCorners.swift

@@ -22,6 +22,7 @@ extension NSBezierPath {
         public static let bottomLeft = Corners(rawValue: 1 << 1)
         public static let topRight = Corners(rawValue: 1 << 2)
         public static let bottomRight = Corners(rawValue: 1 << 3)
+        public static let all: Corners = Corners(rawValue: 0b1111)
     }
 
     // swiftlint:disable:next function_body_length

Sources/CodeEditSourceEditor/Extensions/NSColor+LightDark.swift

@@ -0,0 +1,23 @@
+//
+//  NSColor+LightDark.swift
+//  CodeEditSourceEditor
+//
+//  Created by Khan Winter on 6/4/25.
+//
+
+import AppKit
+
+extension NSColor {
+    convenience init(light: NSColor, dark: NSColor) {
+        self.init(name: nil) { appearance in
+            return switch appearance.name {
+            case .aqua:
+                light
+            case .darkAqua:
+                dark
+            default:
+                NSColor()
+            }
+        }
+    }
+}

Sources/CodeEditSourceEditor/Extensions/NSRect+Transform.swift

@@ -0,0 +1,19 @@
+//
+//  NSRect+Transform.swift
+//  CodeEditSourceEditor
+//
+//  Created by Khan Winter on 6/4/25.
+//
+
+import AppKit
+
+extension NSRect {
+    func transform(x xVal: CGFloat = 0, y yVal: CGFloat = 0, width: CGFloat = 0, height: CGFloat = 0) -> NSRect {
+        NSRect(
+            x: self.origin.x + xVal,
+            y: self.origin.y + yVal,
+            width: self.width + width,
+            height: self.height + height
+        )
+    }
+}

Sources/CodeEditSourceEditor/LineFolding/Model/LineFoldCalculator.swift

@@ -19,7 +19,7 @@ actor LineFoldCalculator {
 
     private var valueStreamContinuation: AsyncStream<LineFoldStorage>.Continuation
     private var textChangedTask: Task<Void, Never>?
-    
+
     /// Create a new calculator object that listens to a given stream for text changes.
     /// - Parameters:
     ///   - foldProvider: The object to use to calculate fold regions.
@@ -39,7 +39,7 @@ actor LineFoldCalculator {
     deinit {
         textChangedTask?.cancel()
     }
-    
+
     /// Sets up an attached task to listen to values on a stream of text changes.
     /// - Parameter textChangedStream: A stream of text changes.
     private func listenToTextChanges(textChangedStream: AsyncStream<(NSRange, Int)>) {
@@ -105,7 +105,7 @@ actor LineFoldCalculator {
 
         await yieldNewStorage(newFolds: foldCache, controller: controller, documentRange: documentRange)
     }
-    
+
     /// Yield a new storage value on the value stream using a new set of folds.
     /// - Parameters:
     ///   - newFolds: The new folds to yield with the storage value.

Sources/CodeEditSourceEditor/LineFolding/Model/LineFoldingModel.swift

@@ -19,6 +19,9 @@ import Combine
 /// - Loop through the list, creating nested folds as indents go up and down.
 ///
 class LineFoldingModel: NSObject, NSTextStorageDelegate, ObservableObject {
+    static let emphasisId = "lineFolding"
+
+
     /// An ordered tree of fold ranges in a document. Can be traversed using ``FoldRange/parent``
     /// and ``FoldRange/subFolds``.
     @Published var foldCache: LineFoldStorage = LineFoldStorage(documentLength: 0)
@@ -92,4 +95,35 @@ class LineFoldingModel: NSObject, NSTextStorageDelegate, ObservableObject {
         }
         return deepestFold
     }
+
+    func emphasizeBracketsForFold(_ fold: FoldRange) {
+        clearEmphasis()
+
+        // Find the text object, make sure there's available characters around the fold.
+        guard let text = controller?.textView.textStorage.string as? NSString,
+              fold.range.lowerBound > 0 && fold.range.upperBound < text.length - 1 else {
+            return
+        }
+
+        let firstRange = NSRange(location: fold.range.lowerBound - 1, length: 1)
+        let secondRange = NSRange(location: fold.range.upperBound, length: 1)
+
+        // Check if these are emphasizable bracket pairs.
+        guard BracketPairs.matches(text.substring(from: firstRange) ?? "")
+                && BracketPairs.matches(text.substring(from: secondRange) ?? "") else {
+            return
+        }
+
+        controller?.textView.emphasisManager?.addEmphases(
+            [
+                Emphasis(range: firstRange, style: .standard, flash: false, inactive: false, selectInDocument: false),
+                Emphasis(range: secondRange, style: .standard, flash: false, inactive: false, selectInDocument: false),
+            ],
+            for: Self.emphasisId
+        )
+    }
+
+    func clearEmphasis() {
+        controller?.textView.emphasisManager?.removeEmphases(for: Self.emphasisId)
+    }
 }

Sources/CodeEditSourceEditor/LineFolding/Placeholder/LineFoldPlaceholder.swift

@@ -10,22 +10,40 @@ import CodeEditTextView
 
 class LineFoldPlaceholder: TextAttachment {
     let fold: FoldRange
+    let charWidth: CGFloat
+    var isSelected: Bool = false
 
-    init(fold: FoldRange) {
+    init(fold: FoldRange, charWidth: CGFloat) {
         self.fold = fold
+        self.charWidth = charWidth
     }
 
-    var width: CGFloat { 17 }
+    var width: CGFloat {
+        charWidth * 5
+    }
 
     func draw(in context: CGContext, rect: NSRect) {
         context.saveGState()
 
         let centerY = rect.midY - 1.5
 
+        if isSelected {
+            context.setFillColor(NSColor.controlAccentColor.cgColor)
+            context.addPath(
+                NSBezierPath(
+                    rect: rect.transform(x: 2.0, y: 3.0, width: -4.0, height: -6.0 ),
+                    roundedCorners: .all,
+                    cornerRadius: 2
+                ).cgPathFallback
+            )
+            context.fillPath()
+        }
+
         context.setFillColor(NSColor.secondaryLabelColor.cgColor)
-        context.addEllipse(in: CGRect(x: rect.minX + 2, y: centerY, width: 3, height: 3))
-        context.addEllipse(in: CGRect(x: rect.minX + 7, y: centerY, width: 3, height: 3))
-        context.addEllipse(in: CGRect(x: rect.minX + 12, y: centerY, width: 3, height: 3))
+        let size = charWidth / 2
+        context.addEllipse(in: CGRect(x: rect.minX + charWidth * 1.25, y: centerY, width: size, height: size))
+        context.addEllipse(in: CGRect(x: rect.minX + (charWidth * 2.25), y: centerY, width: size, height: size))
+        context.addEllipse(in: CGRect(x: rect.minX + (charWidth * 3.25), y: centerY, width: size, height: size))
         context.fillPath()
 
         context.restoreGState()