fix: provide file path to dynamic import transform (#33)

BREAKING CHANGE: transformDynamicImport now requires file path

Co-authored-by: Hiroki Osame <hiroki.osame@gmail.com>

Author: mshima

src/transform/apply-transformers.ts

@@ -18,7 +18,10 @@ type TransformerResult = Transformed | undefined;
 
 type Transformer<
 	Result extends MaybePromise<TransformerResult>
-> = (code: string) => Result;
+> = (
+	code: string,
+	filename: string,
+) => Result;
 
 type Results<
 	Array_ extends Transformer<MaybePromise<TransformerResult>>[]
@@ -35,6 +38,7 @@ type AddSourceMap<T> = Omit<T, 'map'> & { map: string };
 export function applyTransformersSync<
 	T extends Readonly<Transformer<TransformerResult>[]>,
 >(
+	filename: string,
 	code: string,
 	transformers: T,
 ) {
@@ -45,7 +49,7 @@ export function applyTransformersSync<
 	};
 
 	for (const transformer of transformers) {
-		const transformed = transformer(result.code);
+		const transformed = transformer(filename, result.code);
 
 		if (transformed) {
 			Object.assign(result, transformed);
@@ -65,6 +69,7 @@ export function applyTransformersSync<
 export async function applyTransformers<
 	T extends Readonly<Transformer<MaybePromise<TransformerResult>>[]>,
 >(
+	filename: string,
 	code: string,
 	transformers: T,
 ) {
@@ -75,7 +80,7 @@ export async function applyTransformers<
 	};
 
 	for (const transformer of transformers) {
-		const transformed = await transformer(result.code);
+		const transformed = await transformer(filename, result.code);
 
 		if (transformed) {
 			Object.assign(result, transformed);

src/transform/index.ts

@@ -45,10 +45,11 @@ export function transformSync(
 	}
 
 	const transformed = applyTransformersSync(
+		filePath,
 		code,
 		[
 			// eslint-disable-next-line @typescript-eslint/no-shadow
-			(code) => {
+			(filePath, code) => {
 				// eslint-disable-next-line @typescript-eslint/no-shadow
 				const transformed = esbuildTransformSync(code, esbuildOptions);
 				if (esbuildOptions.sourcefile !== filePath) {
@@ -90,18 +91,22 @@ export async function transform(
 		return cacheHit;
 	}
 
-	const transformed = await applyTransformers(code, [
-		// eslint-disable-next-line @typescript-eslint/no-shadow
-		async (code) => {
+	const transformed = await applyTransformers(
+		filePath,
+		code,
+		[
 			// eslint-disable-next-line @typescript-eslint/no-shadow
-			const transformed = await esbuildTransform(code, esbuildOptions);
-			if (esbuildOptions.sourcefile !== filePath) {
-				transformed.map = transformed.map.replace(`"${esbuildOptions.sourcefile}"`, `"${filePath}"`);
-			}
-			return transformed;
-		},
-		transformDynamicImport,
-	] as const);
+			async (filePath, code) => {
+				// eslint-disable-next-line @typescript-eslint/no-shadow
+				const transformed = await esbuildTransform(code, esbuildOptions);
+				if (esbuildOptions.sourcefile !== filePath) {
+					transformed.map = transformed.map.replace(`"${esbuildOptions.sourcefile}"`, `"${filePath}"`);
+				}
+				return transformed;
+			},
+			transformDynamicImport,
+		] as const,
+	);
 
 	if (transformed.warnings.length > 0) {
 		const { warnings } = transformed;

src/transform/transform-dynamic-import.ts

@@ -16,29 +16,31 @@ const checkEsModule = `.then((mod)=>{
 })`.replace(/[\n\t]+/g, '');
 
 export function transformDynamicImport(
+	filename: string,
 	code: string,
 ) {
 	// Naive check
 	if (!code.includes('import')) {
 		return;
 	}
 
-	const [imports] = parseEsm(code);
+	const dynamicImports = parseEsm(code)[0].filter(maybeDynamic => maybeDynamic.d > -1);
 
-	if (imports.length === 0) {
+	if (dynamicImports.length === 0) {
 		return;
 	}
 
 	const magicString = new MagicString(code);
 
-	for (const dynamicImport of imports) {
-		if (dynamicImport.d > -1) {
-			magicString.appendRight(dynamicImport.se, checkEsModule);
-		}
+	for (const dynamicImport of dynamicImports) {
+		magicString.appendRight(dynamicImport.se, checkEsModule);
 	}
 
 	return {
 		code: magicString.toString(),
-		map: magicString.generateMap({ hires: true }) as EncodedSourceMap,
+		map: magicString.generateMap({
+			source: filename,
+			hires: true,
+		}) as EncodedSourceMap,
 	};
 }