Add ability to set cursor position (#83)

* Add ability to set cursor position.
* Fix lint issues
* Add default value to initializer

Author: ezraberch

Sources/CodeEditTextView/CodeEditTextView.swift

@@ -25,14 +25,16 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
         theme: Binding<EditorTheme>,
         font: Binding<NSFont>,
         tabWidth: Binding<Int>,
-        lineHeight: Binding<Double>
+        lineHeight: Binding<Double>,
+        cursorPosition: Published<(Int, Int)>.Publisher? = nil
     ) {
         self._text = text
         self.language = language
         self._theme = theme
         self._font = font
         self._tabWidth = tabWidth
         self._lineHeight = lineHeight
+        self.cursorPosition = cursorPosition
     }
 
     @Binding private var text: String
@@ -41,6 +43,7 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
     @Binding private var font: NSFont
     @Binding private var tabWidth: Int
     @Binding private var lineHeight: Double
+    private var cursorPosition: Published<(Int, Int)>.Publisher?
 
     public typealias NSViewControllerType = STTextViewController
 
@@ -50,7 +53,8 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
             language: language,
             font: font,
             theme: theme,
-            tabWidth: tabWidth
+            tabWidth: tabWidth,
+            cursorPosition: cursorPosition
         )
         controller.lineHeightMultiple = lineHeight
         return controller

Sources/CodeEditTextView/STTextViewController.swift

@@ -7,6 +7,7 @@
 
 import AppKit
 import SwiftUI
+import Combine
 import STTextView
 import SwiftTreeSitter
 
@@ -47,13 +48,20 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
 
     // MARK: Init
 
-    public init(text: Binding<String>, language: CodeLanguage, font: NSFont, theme: EditorTheme, tabWidth: Int) {
+    public init(
+        text: Binding<String>,
+        language: CodeLanguage,
+        font: NSFont,
+        theme: EditorTheme,
+        tabWidth: Int,
+        cursorPosition: Published<(Int, Int)>.Publisher? = nil
+    ) {
         self.text = text
         self.language = language
         self.font = font
         self.theme = theme
         self.tabWidth = tabWidth
-
+        self.cursorPosition = cursorPosition
         super.init(nibName: nil, bundle: nil)
     }
 
@@ -124,6 +132,10 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         }
 
         setUpHighlighting()
+
+        self.cursorPositionCancellable = self.cursorPosition?.sink(receiveValue: { value in
+            self.setCursorPosition(value)
+        })
     }
 
     internal func setUpHighlighting() {
@@ -223,6 +235,35 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         keyIsDown = false
     }
 
+    // MARK: Cursor Position
+
+    private var cursorPosition: Published<(Int, Int)>.Publisher?
+    private var cursorPositionCancellable: AnyCancellable?
+
+    private func setCursorPosition(_ position: (Int, Int)) {
+        guard let provider = textView.textLayoutManager.textContentManager else {
+            return
+        }
+
+        var (line, column) = position
+        let string = textView.string
+        if line > 0 {
+            string.enumerateSubstrings(in: string.startIndex..<string.endIndex) { _, lineRange, _, done in
+                line -= 1
+                if line < 1 {
+                    // If `column` exceeds the line length, set cursor to the end of the line.
+                    let index = min(lineRange.upperBound, string.index(lineRange.lowerBound, offsetBy: column - 1))
+                    if let newRange = NSTextRange(NSRange(index..<index, in: string), provider: provider) {
+                        self.textView.setSelectedRange(newRange)
+                    }
+                    done = true
+                } else {
+                    done = false
+                }
+            }
+        }
+    }
+
     deinit {
         textView = nil
         highlighter = nil