4 files changed, 133 insertions, 7 deletions
diff --git a/packages/iku/src/checker.test.ts b/packages/iku/src/checker.test.ts
index 58a861c..457d956 100644
--- a/packages/iku/src/checker.test.ts
+++ b/packages/iku/src/checker.test.ts
@@ -280,4 +280,61 @@ console.log(a);
 			expect(errors).toHaveLength(3);
 		});
 	});
+	describe("comments", () => {
+		it("detects single-line comments by default", () => {
+			const content = `const a = 1;
+// this is a comment
+const b = 2;
+`;
+			const filePath = createTempFile(content);
+			const errors = checkFile(filePath);
+
+			cleanupTempFile(filePath);
+			expect(errors.some((error) => error.includes("Comment detected"))).toBe(true);
+		});
+		it("detects multi-line comments by default", () => {
+			const content = `const a = 1;
+/* this is a
+   multi-line comment */
+const b = 2;
+`;
+			const filePath = createTempFile(content);
+			const errors = checkFile(filePath);
+
+			cleanupTempFile(filePath);
+			expect(errors.some((error) => error.includes("Comment detected"))).toBe(true);
+		});
+		it("detects trailing comments by default", () => {
+			const content = `const a = 1; // trailing comment
+`;
+			const filePath = createTempFile(content);
+			const errors = checkFile(filePath);
+
+			cleanupTempFile(filePath);
+			expect(errors.some((error) => error.includes("Comment detected"))).toBe(true);
+		});
+		it("allows comments when noComments is false", () => {
+			const content = `const a = 1;
+// this is a comment
+const b = 2;
+`;
+			const filePath = createTempFile(content);
+			const errors = checkFile(filePath, { noComments: false });
+
+			cleanupTempFile(filePath);
+			expect(errors.some((error) => error.includes("Comment detected"))).toBe(false);
+		});
+		it("detects JSDoc comments by default", () => {
+			const content = `/**
+ * This is a JSDoc comment
+ */
+function test() {}
+`;
+			const filePath = createTempFile(content);
+			const errors = checkFile(filePath);
+
+			cleanupTempFile(filePath);
+			expect(errors.some((error) => error.includes("Comment detected"))).toBe(true);
+		});
+	});
 });
diff --git a/packages/iku/src/checker.ts b/packages/iku/src/checker.ts
index d541028..93781ec 100644
--- a/packages/iku/src/checker.ts
+++ b/packages/iku/src/checker.ts
@@ -2,6 +2,14 @@ import { readdirSync, statSync } from "node:fs";
 import { extname, join } from "node:path";
 import * as typescript from "typescript";
 
+export interface CheckerOptions {
+	noComments?: boolean;
+}
+
+const defaultOptions: CheckerOptions = {
+	noComments: true,
+};
+
 type StatementCategory =
 	| "import"
 	| "variableDeclaration"
@@ -188,7 +196,41 @@ function visitBlocks(
 	});
 }
 
-export function checkFile(filePath: string): string[] {
+function checkForComments(sourceFile: typescript.SourceFile, filePath: string): string[] {
+	const errors: string[] = [];
+	const text = sourceFile.getFullText();
+
+	function visit(node: typescript.Node): void {
+		const leadingComments = typescript.getLeadingCommentRanges(text, node.getFullStart());
+		const trailingComments = typescript.getTrailingCommentRanges(text, node.getEnd());
+
+		if (leadingComments) {
+			for (const comment of leadingComments) {
+				const line = sourceFile.getLineAndCharacterOfPosition(comment.pos).line + 1;
+
+				errors.push(`${filePath}:${line}: Comment detected`);
+			}
+		}
+
+		if (trailingComments) {
+			for (const comment of trailingComments) {
+				const line = sourceFile.getLineAndCharacterOfPosition(comment.pos).line + 1;
+
+				errors.push(`${filePath}:${line}: Comment detected`);
+			}
+		}
+
+		typescript.forEachChild(node, visit);
+	}
+
+	visit(sourceFile);
+
+	const uniqueErrors = [...new Set(errors)];
+
+	return uniqueErrors;
+}
+
+export function checkFile(filePath: string, options: CheckerOptions = defaultOptions): string[] {
 	const program = typescript.createProgram([filePath], {
 		target: typescript.ScriptTarget.ESNext,
 		module: typescript.ModuleKind.ESNext,
@@ -210,6 +252,12 @@ export function checkFile(filePath: string): string[] {
 	errors.push(...topLevelErrors);
 	visitBlocks(sourceFile, sourceFile, filePath, errors);
 
+	if (options.noComments) {
+		const commentErrors = checkForComments(sourceFile, filePath);
+
+		errors.push(...commentErrors);
+	}
+
 	return errors;
 }
 
@@ -232,12 +280,15 @@ export function walkDirectory(directory: string): string[] {
 	return files;
 }
 
-export function checkDirectory(directory: string): { errors: string[]; hasErrors: boolean } {
+export function checkDirectory(
+	directory: string,
+	options: CheckerOptions = defaultOptions,
+): { errors: string[]; hasErrors: boolean } {
 	const files = walkDirectory(directory);
 	const allErrors: string[] = [];
 
 	for (const file of files) {
-		const errors = checkFile(file);
+		const errors = checkFile(file, options);
 
 		allErrors.push(...errors);
 	}
diff --git a/packages/iku/src/cli.ts b/packages/iku/src/cli.ts
index c0a85fc..8ea07a4 100644
--- a/packages/iku/src/cli.ts
+++ b/packages/iku/src/cli.ts
@@ -2,7 +2,7 @@
 
 import { existsSync } from "node:fs";
 import { dirname, join } from "node:path";
-import { checkDirectory } from "./checker.js";
+import { checkDirectory, type CheckerOptions } from "./checker.js";
 
 function findMonorepoRoot(startDirectory: string): string | null {
 	let current = startDirectory;
@@ -21,6 +21,23 @@ function findMonorepoRoot(startDirectory: string): string | null {
 	return null;
 }
 
+function parseArguments(arguments_: string[]): { directory?: string; options: CheckerOptions } {
+	const options: CheckerOptions = {
+		noComments: true,
+	};
+	let directory: string | undefined;
+
+	for (const argument of arguments_) {
+		if (argument === "--allow-comments") {
+			options.noComments = false;
+		} else if (!argument.startsWith("-")) {
+			directory = argument;
+		}
+	}
+
+	return { directory, options };
+}
+
 const monorepoRoot = findMonorepoRoot(process.cwd());
 
 if (!monorepoRoot) {
@@ -28,8 +45,9 @@ if (!monorepoRoot) {
 	process.exit(1);
 }
 
-const targetDirectory = process.argv[2] ?? join(monorepoRoot, "packages");
-const { errors, hasErrors } = checkDirectory(targetDirectory);
+const { directory, options } = parseArguments(process.argv.slice(2));
+const targetDirectory = directory ?? join(monorepoRoot, "packages");
+const { errors, hasErrors } = checkDirectory(targetDirectory, options);
 
 for (const error of errors) {
 	console.error(error);
diff --git a/packages/iku/src/index.ts b/packages/iku/src/index.ts
index dc64d12..d3d29ae 100644
--- a/packages/iku/src/index.ts
+++ b/packages/iku/src/index.ts
@@ -1 +1 @@
-export { checkFile, walkDirectory, checkDirectory } from "./checker.js";
+export { checkFile, walkDirectory, checkDirectory, type CheckerOptions } from "./checker.js";