A simple Swift 4.0 class for syntax highlighting in an NSTextView

SyntaxHighlighter.swift

//
//  SyntaxHighlighter.swift
//  CardsCardsCards
//
//  Created by Martin Pichlmair on 12/10/2018.
//

// Based on https://raw.githubusercontent.com/kuyawa/Macaw/master/Macaw/Macaw.swift

import Cocoa
import Foundation

class SyntaxHighlighter {
	
	struct color {
		static let normal     = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.95, green: 0.95, blue: 0.95, alpha: 1.0)] // light grey
		static let ruleName   = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.40, green: 0.60, blue: 0.90, alpha: 1.0)] // cyan
		static let number     = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.60, green: 0.60, blue: 0.90, alpha: 1.0)] // blue
		static let keyword    = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.75, green: 0.20, blue: 0.75, alpha: 1.0)] // magenta
		static let expression = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.95, green: 0.75, blue: 0.10, alpha: 1.0)] // yellow
		static let modifier   = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.95, green: 0.50, blue: 0.20, alpha: 1.0)] // orange
		static let comment    = [NSAttributedString.Key.foregroundColor: NSColor(red: 0.20, green: 0.60, blue: 0.20, alpha: 1.0)] // green
	}
	
	struct regex {
		static let keywords      = "\\b(origin)\\b"
		static let ruleName 	 = "(\\[.*\\])"
		static let expression 	 = "(\\#[a-zA-Z][a-zA-Z0-9,\\.\\(\\)]*\\#)"
		static let modifier 	 = "\\#.*\\.([a-zA-Z][a-zA-Z0-9,]*\\(.*\\))\\#"
		static let numberLiteral = "\\b([0-9]*(\\.[0-9]*)?)\\b"
		static let symbols       = "(\\+|-|\\*|/|=|\\{|\\}|\\[|\\]|\\(|\\))"
		static let commentLine   = "(^\\\\.*)"
	}
	
	let patterns = [
		regex.commentLine   : color.comment,
		regex.ruleName      : color.keyword,
		regex.numberLiteral : color.number,
		regex.keywords      : color.keyword,
		regex.expression	: color.expression,
		regex.modifier      : color.modifier
	]
	
	init() {
	}
	
	// Colorize all
	func colorize(_ textView: NSTextView) {
		let all = textView.string
		let range = NSString(string: textView.string).range(of: all)
		colorize(textView, range: range)
	}
	
	// Colorize range
	func colorize(_ textView: NSTextView, range: NSRange) {
		var extended = NSUnionRange(range, NSString(string: textView.string).lineRange(for: NSMakeRange(range.location, 0)))
		extended = NSUnionRange(range, NSString(string: textView.string).lineRange(for: NSMakeRange(NSMaxRange(range), 0)))
		
		for (pattern, attribute) in patterns {
			applyStyles(textView, range: extended, pattern: pattern, attribute: attribute)
		}
	}
	
	func applyStyles(_ textView: NSTextView, range: NSRange, pattern: String, attribute: [NSAttributedString.Key: Any]) {
		let regex = try? NSRegularExpression(pattern: pattern, options: [NSRegularExpression.Options.anchorsMatchLines])
		regex?.enumerateMatches(in: textView.string, options: [], range: range) {
			match, flags, stop in
			
			let matchRange = match?.range(at: 1)
			textView.textStorage?.addAttributes(attribute, range: matchRange!)
		}
	}
}