Swift syntax highlighting

Since: Unreleased

GameEventScriptSyntaxHighlighter is an optional SwiftPM library for GES and GESA editors and terminals. It uses Foundation, with no AppKit, UIKit, Compiler or Runtime dependency. Both CLI highlighting and this library use the canonical TextMate grammars. The public repository-root package exports this product; this directory is its standalone development package.

Highlight an editor document

import GameEventScriptSyntaxHighlighter

let highlighter = try GameEventScriptSyntaxHighlighter() // .ges by default
let result = highlighter.highlight(source)
if result.isComplete {
    for span in result.spans {
        // start/length are UTF-16 offsets; scopes are TextMate scope names.
        applyStyle(span.kind, start: span.start, length: span.length)
    }
}

Create the highlighter once and reuse it. An AppKit adapter can use temporary attributes without changing text or undo history:

import AppKit
import GameEventScriptSyntaxHighlighter

func highlight(_ view: NSTextView, using highlighter: GameEventScriptSyntaxHighlighter) {
    guard let layout = view.layoutManager else { return }
    let source = view.string
    layout.removeTemporaryAttribute(.foregroundColor,
        forCharacterRange: NSRange(location: 0, length: source.utf16.count))
    let result = highlighter.highlight(source)
    guard result.isComplete else { return }
    for span in result.spans {
        let color: NSColor
        switch span.kind {
        case .keyword: color = .systemPurple
        case .builtin, .type, .function: color = .systemTeal
        case .message, .constant: color = .systemOrange
        case .number, .tag: color = .systemBlue
        case .string: color = .systemRed
        case .comment: color = .secondaryLabelColor
        default: color = .textColor
        }
        layout.addTemporaryAttribute(.foregroundColor, value: color,
            forCharacterRange: NSRange(location: span.start, length: span.length))
    }
}

For large documents, cache per-line results from try highlighter.highlightLine(line, state: previousState). Keep line terminators and add each line’s document offset to its spans. After edits, continue until unchanged text and nextState match the cache. An incomplete result has no state; render it plain and do not cache it as a successful result.

Terminal and GESA

let highlighter = try GameEventScriptSyntaxHighlighter(language: .gesa)
let result = highlighter.highlight(dump)
let displayed = result.isComplete
    ? try GameEventScriptAnsiRenderer.render(dump, spans: result.spans)
    : dump

The renderer accepts a custom category-to-SGR-color callback. Terminal detection, NO_COLOR and enabling colors remain application decisions. GESA source blocks retain their embedded GES scopes.

Verification

swift test --package-path implementation/swift/GameEventScriptSyntaxHighlighter \
  --scratch-path artifacts/swift/syntaxhighlighter \
  --disable-build-manifest-caching --configuration release
python3 scripts/sync-highlighter-grammars.py --check

C# and Swift execute the same Markdown cases. See the contract for limits, state semantics and supported TextMate features. The new product is available from the next release, or directly from a checkout containing it.