Fix Ambiguous Highlights (#275)

### Description

Fixes some bad syntax highlighting caused by overlapping captures
returned from tree-sitter. Previously the last value returned took
precedence, but with the new highlighting system that's not the case.
This filters highlights on duplicate ranges, and prioritizes the best
capture for any range so this is no longer dependent on the highlighting
system's semantics.

### Related Issues

- closes #276 

### Checklist

- [x] I read and understood the [contributing
guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md)
as well as the [code of
conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

Disambiguated highlights:

![Screenshot 2024-11-17 at 2 50
28 PM](https://github.com/user-attachments/assets/e1bde8b3-81b5-481f-80d2-428798374c2b)

Ambiguous highlights:

![Screenshot 2024-11-17 at 2 52
04 PM](https://github.com/user-attachments/assets/90a89ed4-afb6-4d60-a7d7-39ba0a560ee6)

---------

Co-authored-by: Tom Ludwig <[email protected]>

Sources/CodeEditSourceEditor/Highlighting/HighlightRange.swift

@@ -8,7 +8,7 @@
 import Foundation
 
 /// This struct represents a range to highlight, as well as the capture name for syntax coloring.
-public struct HighlightRange: Sendable {
+public struct HighlightRange: Hashable, Sendable {
     public let range: NSRange
     public let capture: CaptureName?
     public let modifiers: CaptureModifierSet
@@ -19,3 +19,13 @@ public struct HighlightRange: Sendable {
         self.modifiers = modifiers
     }
 }
+
+extension HighlightRange: CustomDebugStringConvertible {
+    public var debugDescription: String {
+        if capture == nil && modifiers.isEmpty {
+            "\(range) (empty)"
+        } else {
+            "\(range) (\(capture?.stringValue ?? "No Capture")) \(modifiers.values.map({ $0.stringValue }))"
+        }
+    }
+}

Sources/CodeEditSourceEditor/TreeSitter/TreeSitterClient+Highlight.swift

@@ -87,17 +87,35 @@ extension TreeSitterClient {
         cursor: QueryCursor,
         includedRange: NSRange
     ) -> [HighlightRange] {
+        guard let readCallback else { return [] }
+        var ranges: [NSRange: Int] = [:]
         return cursor
+            .resolve(with: .init(textProvider: readCallback)) // Resolve our cursor against the query
             .flatMap { $0.captures }
-            .compactMap {
-                // Sometimes `cursor.setRange` just doesn't work :( so we have to do a redundant check for a valid range
-                // in the included range
-                let intersectionRange = $0.range.intersection(includedRange) ?? .zero
-                // Check that the capture name is one CESE can parse. If not, ignore it completely.
-                if intersectionRange.length > 0, let captureName = CaptureName.fromString($0.name) {
-                    return HighlightRange(range: intersectionRange, capture: captureName)
+            .reversed() // SwiftTreeSitter returns captures in the reverse order of what we need to filter with.
+            .compactMap { capture in
+                let range = capture.range
+                let index = capture.index
+
+                // Lower indexed captures are favored over higher, this is why we reverse it above
+                if let existingLevel = ranges[range], existingLevel <= index {
+                    return nil
+                }
+
+                guard let captureName = CaptureName.fromString(capture.name) else {
+                    return nil
                 }
-                return nil
+
+                // Update the filter level to the current index since it's lower and a 'valid' capture
+                ranges[range] = index
+
+                // Validate range and capture name
+                let intersectionRange = range.intersection(includedRange) ?? .zero
+                guard intersectionRange.length > 0 else {
+                    return nil
+                }
+
+                return HighlightRange(range: intersectionRange, capture: captureName)
             }
     }
 }

Sources/CodeEditSourceEditor/TreeSitter/TreeSitterClient.swift

@@ -210,7 +210,7 @@ public final class TreeSitterClient: HighlightProviding {
         completion: @escaping @MainActor (Result<[HighlightRange], Error>) -> Void
     ) {
         let operation = { [weak self] in
-            return self?.queryHighlightsForRange(range: range) ?? []
+            return (self?.queryHighlightsForRange(range: range) ?? []).sorted { $0.range.location < $1.range.location }
         }
 
         let longQuery = range.length > Constants.maxSyncQueryLength