Ensure tab is handled as expected

Author: tom-ludwig

Sources/CodeEditSourceEditor/Controller/TextViewController+IndentLines.swift

@@ -38,6 +38,21 @@ extension TextViewController {
         textView.undoManager?.endUndoGrouping()
     }
 
+    /// This method is used to handle tabs appropriately when multiple lines are selected,
+    /// allowing normal use of tabs.
+    ///
+    /// - Returns: A Boolean value indicating whether multiple lines are highlighted.
+    func multipleLinesHighlighted() -> Bool {
+        for cursorPosition in self.cursorPositions {
+            if let startLineInfo = textView.layoutManager.textLineForOffset(cursorPosition.range.lowerBound),
+               let endLineInfo = textView.layoutManager.textLineForOffset(cursorPosition.range.upperBound),
+               startLineInfo.index != endLineInfo.index {
+                return true
+            }
+        }
+        return false
+    }
+
     private func getHighlightedLines(for range: NSRange) -> [Int]? {
         guard let startLineInfo = textView.layoutManager.textLineForOffset(range.lowerBound) else {
             return nil

Sources/CodeEditSourceEditor/Controller/TextViewController+LoadView.swift

@@ -120,8 +120,7 @@ extension TextViewController {
             let modifierFlags = event.modifierFlags.intersection(.deviceIndependentFlagsMask).rawValue
 
             if event.keyCode == tabKey {
-                self?.handleTab(modifierFalgs: modifierFlags)
-                return nil
+                return self?.handleTab(event: event, modifierFalgs: modifierFlags)
             } else {
                 return self?.handleCommand(event: event, modifierFlags: modifierFlags)
             }
@@ -145,13 +144,21 @@ extension TextViewController {
         }
     }
 
-    func handleTab(modifierFalgs: UInt) {
+    /// Handles the tab key event.
+    /// If the Shift key is pressed, it handles unindenting. If no modifier key is pressed, it checks if multiple lines
+    /// are highlighted and handles indenting accordingly.
+    ///
+    /// - Returns: The original event if it should be passed on, or `nil` to indicate handling within the method.
+    func handleTab(event: NSEvent, modifierFalgs: UInt) -> NSEvent? {
         let shiftKey = NSEvent.ModifierFlags.shift.rawValue
 
         if modifierFalgs == shiftKey {
             handleIndent(inwards: true)
         } else {
+            // Only allow tab to work if multiple lines are selected
+            guard multipleLinesHighlighted() else { return event }
             handleIndent()
         }
+        return nil
     }
 }

Tests/CodeEditSourceEditorTests/Controller/TextViewController+IndentTests.swift

@@ -0,0 +1,35 @@
+//
+//  TextViewController+IndentTests.swift
+//  CodeEditSourceEditor
+//
+//  Created by Ludwig, Tom on 08.10.24.
+//
+
+import XCTest
+
+final class TextViewController_IndentTests: XCTestCase {
+
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+
+    func testExample() throws {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct results.
+        // Any test you write for XCTest can be annotated as throws and async.
+        // Mark your test throws to produce an unexpected failure when your test encounters an uncaught error.
+        // Mark your test async to allow awaiting for asynchronous code to complete. Check the results with assertions afterwards.
+    }
+
+    func testPerformanceExample() throws {
+        // This is an example of a performance test case.
+        self.measure {
+            // Put the code you want to measure the time of here.
+        }
+    }
+
+}