add AdGuard syntax highlighting to custom filter rule editor

[0xCUB3]

Syntax highlighting for the custom filter rule editor. Tokenizer handles all AdGuard rule types (comments, element hiding, URL blocking, exceptions, modifiers, extended CSS, scriptlets, HTML filtering, regex). Wired into EditUserListView on both macOS and iOS via native NSTextView/UITextView wrappers.

Closes #263

Test plan:

• Open Edit User List, paste AdGuard rules, verify colors appear
• Type rules character by character, confirm cursor doesn't jump
• Check both macOS and iOS
• Check light and dark mode contrast

[gemini-code-assist]

Summary of Changes

Hello @0xCUB3, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the user experience in the custom filter rule editor by integrating real-time AdGuard syntax highlighting. This visual aid improves the readability and maintainability of filter rules, making it easier for users to author and manage their custom AdGuard configurations on both macOS and iOS. The implementation leverages native text views for optimal performance and user interaction.

Highlights

• Real-time AdGuard Syntax Highlighting: Introduced real-time AdGuard syntax highlighting to the custom filter rule editor (EditUserListView) for both macOS and iOS platforms.
• New AdGuardSyntaxHighlighter: Developed a new AdGuardSyntaxHighlighter tokenizer capable of coloring various AdGuard rule components, including comments, element hiding rules, URL blocking, exceptions, modifiers, extended CSS, scriptlets, HTML filtering, and regex patterns.
• New SyntaxHighlightingTextView: Created a SyntaxHighlightingTextView SwiftUI representable that wraps native NSTextView (macOS) and UITextView (iOS), providing highlighting, preserving cursor position during updates, and guarding against update loops.

Changelog

• docs/plans/2026-02-23-adguard-syntax-highlighting-design.md
  • Added a detailed design document outlining the implementation plan for AdGuard syntax highlighting.
• wBlock/AdGuardSyntaxHighlighter.swift
  • Introduced a new AdGuardSyntaxHighlighter struct responsible for tokenizing and applying syntax coloring to AdGuard filter rules.
  • Defined a Theme struct for platform-adaptive colors.
  • Implemented regex-based pattern matching for various AdGuard rule types (comments, exceptions, element hiding, URL blocking, modifiers, etc.).
  • Provided methods to highlight a given string and apply colors/fonts based on detected patterns.
• wBlock/ContentView.swift
  • Replaced existing TextEditor instances in EditUserListView with the new SyntaxHighlightingTextView for both iOS and macOS targets.
  • Removed redundant font and background styling as these are now handled by SyntaxHighlightingTextView.
• wBlock/SyntaxHighlightingTextView.swift
  • Created a new SwiftUI NSViewRepresentable (macOS) and UIViewRepresentable (iOS) to wrap native NSTextView and UITextView.
  • Integrated the AdGuardSyntaxHighlighter to apply real-time syntax highlighting.
  • Implemented logic to preserve the cursor position during text updates and re-highlighting.
  • Configured native text view properties for a monospaced font and disabled automatic text features.

Activity

• A detailed implementation plan was created and followed, breaking down the feature into logical tasks.
• The AdGuardSyntaxHighlighter tokenizer was developed and compiled.
• The SyntaxHighlightingTextView representable was created and compiled for both macOS and iOS.
• The new syntax highlighting view was integrated into EditUserListView for both platforms.
• Platform-specific color API differences were addressed to ensure correct rendering on both macOS and iOS.
• Manual testing was planned to verify correct syntax coloring for various rule types and to ensure cursor stability during typing.

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[gemini-code-assist]

Code Review

This pull request introduces AdGuard syntax highlighting to the custom filter rule editor on both macOS and iOS. The changes involve creating a new AdGuardSyntaxHighlighter class responsible for tokenizing and applying NSAttributedString colors to AdGuard rules using regular expressions, and a SyntaxHighlightingTextView SwiftUI representable that wraps native NSTextView/UITextView to display the highlighted text while preserving cursor position. The existing TextEditor in EditUserListView is replaced with this new custom view. A review comment highlights that the htmlFiltering color is defined using a magic number and suggests using a named constant or system color for better maintainability.

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: e1df5f4515

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[0xCUB3]

Fixed both in b233375.

Gemini: extracted the amber color to private static let amberColor on Theme. We use custom amber instead of systemYellow because yellow washes out on light backgrounds.

Codex: good catch. UITextView.selectedRange is in UTF-16 units but the bounds check compared against String.count (grapheme clusters). Fixed both spots to use (text as NSString).length.

The two comments on the design doc are about the plan file, not the actual code.