feat: add Nix syntax highlighting (#3110)

* feat: add Nix syntax highlighting

* fix: update Nix dependency hash

* fix: update Nix dependency hash

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/highlight/package.json

@@ -27,6 +27,7 @@
     "typecheck": "tsgo --noEmit"
   },
   "dependencies": {
+    "@codemirror/autocomplete": "6.20.3",
     "@codemirror/language": "6.12.4",
     "@codemirror/legacy-modes": "^6.5.3",
     "@lezer/common": "^1.5.0",
@@ -45,6 +46,7 @@
     "@lezer/xml": "^1.0.6",
     "@lezer/yaml": "^1.0.4",
     "@replit/codemirror-lang-csharp": "^6.2.0",
+    "@replit/codemirror-lang-nix": "^6.0.1",
     "lezer-elixir": "^1.1.2"
   },
   "devDependencies": {

packages/highlight/src/__tests__/highlighter.test.ts

@@ -75,6 +75,17 @@ describe("highlightCode", () => {
     expect(stringToken?.style).toBe("string");
   });
 
+  it("highlights Nix code", () => {
+    const code = 'let message = "hello"; in message';
+    const result = highlightCode(code, "default.nix");
+
+    const letToken = result[0].find((token) => token.text === "let");
+    expect(letToken?.style).toBe("keyword");
+
+    const stringToken = result[0].find((token) => token.text.includes("hello"));
+    expect(stringToken?.style).toBe("string");
+  });
+
   it("highlights TSX code with correct dialect", () => {
     const code = 'const el = <div className="test">hello</div>;';
     const result = highlightCode(code, "test.tsx");

packages/highlight/src/__tests__/parsers.test.ts

@@ -21,6 +21,7 @@ describe("isLanguageSupported", () => {
     expect(isLanguageSupported("test.swift")).toBe(true);
     expect(isLanguageSupported("test.dart")).toBe(true);
     expect(isLanguageSupported("test.cs")).toBe(true);
+    expect(isLanguageSupported("test.nix")).toBe(true);
     expect(isLanguageSupported("test.ex")).toBe(true);
   });
 
@@ -60,6 +61,7 @@ describe("getSupportedExtensions", () => {
     expect(extensions).toContain("swift");
     expect(extensions).toContain("dart");
     expect(extensions).toContain("cs");
+    expect(extensions).toContain("nix");
     expect(extensions).toContain("json");
   });
 });

packages/highlight/src/parsers.ts

@@ -15,6 +15,7 @@ import { parser as rustParser } from "@lezer/rust";
 import { parser as xmlParser } from "@lezer/xml";
 import { parser as yamlParser } from "@lezer/yaml";
 import { csharpLanguage } from "@replit/codemirror-lang-csharp";
+import { nixLanguage } from "@replit/codemirror-lang-nix";
 import { parser as elixirParser } from "lezer-elixir";
 import type { Parser } from "@lezer/common";
 
@@ -69,6 +70,8 @@ const languagesByExtension: Record<string, Language> = {
   dart: StreamLanguage.define(dart),
   // C#
   cs: csharpLanguage,
+  // Nix
+  nix: nixLanguage,
   // Elixir
   ex: language(elixirParser),
   exs: language(elixirParser),