Refactor syntax parser initialization

Author: 1024jp

CotEditor/Sources/Document Window/Content View/DocumentViewController.swift

@@ -134,6 +134,9 @@ final class DocumentViewController: NSSplitViewController, ThemeChanging, NSTool
             }
         }
 
+        // start parsing
+        self.document.syntaxController.setupParser()
+        
         NotificationCenter.default.addObserver(self, selector: #selector(textStorageDidProcessEditing),
                                                name: NSTextStorage.didProcessEditingNotification,
                                                object: self.document.textStorage)

CotEditor/Sources/Models/Syntax/NSLayoutManager+SyntaxHighlight.swift

@@ -39,6 +39,8 @@ extension NSTextStorage {
     ///   - range: The range to update syntax highlight. 
     @MainActor func apply(highlights: [Highlight], theme: Theme?, in range: NSRange) {
 
+        guard self.length > 0 else { return }
+        
         for layoutManager in self.layoutManagers {
             layoutManager.apply(highlights: highlights, theme: theme, in: range)
         }

CotEditor/Sources/Models/Syntax/SyntaxController.swift

@@ -42,6 +42,7 @@ extension NSAttributedString.Key {
     // MARK: Public Properties
 
     private(set) var syntax: Syntax
+    private(set) var syntaxName: String
 
     var theme: Theme?
 
@@ -57,6 +58,7 @@ extension NSAttributedString.Key {
     private var highlightParseTask: Task<Void, any Error>?
     private var outlineParseTask: Task<Void, any Error>?
     private var invalidRanges: EditedRangeSet
+    private var isReady = false
 
 
     // MARK: Lifecycle
@@ -70,11 +72,10 @@ extension NSAttributedString.Key {
     init(textStorage: NSTextStorage, syntax: Syntax, name: String) {
 
         self.textStorage = textStorage
-        self.invalidRanges = EditedRangeSet(range: textStorage.range)
-        
         self.syntax = syntax
-        self.highlightParser = try? LanguageRegistry.shared.highlightParser(name: name) ?? syntax.highlightParser
-        self.outlineParser = syntax.outlineParser
+        self.syntaxName = name
+        
+        self.invalidRanges = EditedRangeSet(range: textStorage.range)
     }
 
 
@@ -85,6 +86,19 @@ extension NSAttributedString.Key {
 
     // MARK: Public Methods
 
+    /// Sets up parsers and starts the initial parse.
+    func setupParser() {
+        
+        self.cancel()
+        
+        self.highlightParser = try? LanguageRegistry.shared.highlightParser(name: self.syntaxName) ?? self.syntax.highlightParser
+        self.outlineParser = self.syntax.outlineParser
+        self.isReady = true
+        
+        self.parseAll()
+    }
+    
+    
     /// Cancels all remaining parsing tasks.
     func cancel() {
 
@@ -104,16 +118,17 @@ extension NSAttributedString.Key {
 
         self.cancel()
 
+        self.syntax = syntax
+        self.syntaxName = name
+        
+        guard self.isReady else { return }
+        
         // clear current highlight
         if self.highlightParser != nil {
             self.textStorage.apply(highlights: [], theme: nil, in: self.textStorage.range)
         }
 
-        self.syntax = syntax
-        self.highlightParser = try? LanguageRegistry.shared.highlightParser(name: name) ?? syntax.highlightParser
-        self.outlineParser = syntax.outlineParser
-        
-        self.parseAll()
+        self.setupParser()
     }
 
 
@@ -124,6 +139,8 @@ extension NSAttributedString.Key {
     ///   - delta: The change in length.
     func invalidate(in editedRange: NSRange, changeInLength delta: Int) {
 
+        assert(self.isReady)
+        
         self.highlightParseTask?.cancel()
         self.highlightParseTask = nil
 
@@ -136,6 +153,8 @@ extension NSAttributedString.Key {
     /// Applies a short debounce before parsing to allow the text system to settle.
     func parseIfNeeded() {
 
+        assert(self.isReady)
+        
         self.updateOutline(withDelay: true)
         self.highlightIfNeeded(withDelay: true)
     }
@@ -144,6 +163,8 @@ extension NSAttributedString.Key {
     /// Re-parses the entire document immediately.
     func parseAll() {
 
+        assert(self.isReady)
+        
         self.invalidRanges.update(editedRange: self.textStorage.range)
 
         self.updateOutline(withDelay: false)