feat: source-map support

Author: pooya parsa

README.md

@@ -46,6 +46,7 @@ function createBundle(bundle: Partial<Bundle> | string, options?: CreateBundleOp
     bundle: Bundle;
     evaluateEntry: (context: object) => any;
     evaluateModule: (filename: string, context: object) => any;
+    rewriteErrorTrace: (err: Error) => Promise<Error>;
 }
 ```
 
@@ -76,6 +77,22 @@ type Bundle = {
 }
 ```
 
+### SourceMap Support
+
+After creating bundle, a `rewriteErrorTrace` utility is exposed which you can use to rewrite traces:
+
+```ts
+const { evaluateEntry, rewriteErrorTrace } = createBundle('path/to/bundle.json')
+
+try {
+  const entry = evaluateEntry(context)
+  const app = await entry({})
+} catch (err) {
+  await rewriteErrorTrace(err)
+  throw err
+}
+```
+
 ## Credits
 
 Inspired by [vue-server-renderer](https://www.npmjs.com/package/vue-server-renderer) made by [Evan You](https://github.com/yyx990803).

package.json

@@ -19,6 +19,9 @@
     "test": "yarn lint && yarn jest",
     "types": "tsc --declarationDir types --declaration --emitDeclarationOnly"
   },
+  "dependencies": {
+    "source-map": "^0.7.3"
+  },
   "devDependencies": {
     "@nuxtjs/eslint-config-typescript": "latest",
     "@rollup/plugin-typescript": "latest",

rollup.config.js

@@ -4,7 +4,10 @@ import typescript from '@rollup/plugin-typescript'
 export default [
   {
     input: './src/index.ts',
-    external: NativeModule.builtinModules,
+    external: [
+      ...NativeModule.builtinModules,
+      'source-map'
+    ],
     output: [
       { file: './dist/bundle-runner.cjs.js', format: 'cjs' },
       { file: './dist/bundle-runner.esm.js', format: 'esm' }

src/bundle.ts

@@ -1,6 +1,7 @@
 import { isAbsolute, dirname } from 'path'
 import fs from 'fs'
 import { CreateEvaluateOptions, createEvaluateModule } from './module'
+import { createSourceMap } from './source-map'
 
 export type Files = { [name: string]: any }
 
@@ -69,6 +70,7 @@ function loadBundle (bundle: Partial<Bundle> | string, basedir?: string): Bundle
 
 export function createBundle (_bundle: Partial<Bundle> | string, options: CreateBundleOptions = {}) {
   const bundle = loadBundle(_bundle, options.basedir)
+  const { rewriteErrorTrace } = createSourceMap(bundle.maps)
 
   const evaluateModule = createEvaluateModule(bundle.files, options)
 
@@ -79,6 +81,7 @@ export function createBundle (_bundle: Partial<Bundle> | string, options: Create
   return {
     bundle,
     evaluateModule,
-    evaluateEntry
+    evaluateEntry,
+    rewriteErrorTrace
   }
 }

src/source-map.ts

@@ -0,0 +1,65 @@
+import { SourceMapConsumer } from 'source-map'
+
+export type RawSourceMaps = {
+  [source: string]: string
+}
+
+type SourceMapConsumers = { [source: string]: Promise<SourceMapConsumer> }
+
+const filenameRE = /\(([^)]+\.js):(\d+):(\d+)\)$/
+const webpackRE = /^webpack:\/\/\//
+
+export function createSourceMap (rawMaps: RawSourceMaps = {}) {
+  const _consumersCache: SourceMapConsumers = {}
+
+  function getConsumer (source: string) {
+    const rawMap = rawMaps[source]
+    if (!rawMap) {
+      return
+    }
+    if (!_consumersCache[source]) {
+      _consumersCache[source] = Promise.resolve(new SourceMapConsumer(rawMap))
+    }
+    return _consumersCache[source]
+  }
+
+  async function rewriteTraceLine (_trace: string) {
+    const m = _trace.match(filenameRE)
+
+    if (!m) {
+      return _trace
+    }
+
+    const consumer = await getConsumer(m[1])
+    if (!consumer) {
+      return _trace
+    }
+
+    const originalPosition = consumer.originalPositionFor({
+      line: Number(m[2]),
+      column: Number(m[3])
+    })
+
+    if (!originalPosition.source) {
+      return _trace
+    }
+
+    const { source, line, column } = originalPosition
+    const mappedPosition = `(${source.replace(webpackRE, '')}:${line}:${column})`
+    const trace = _trace.replace(filenameRE, mappedPosition)
+    return trace
+  }
+
+  async function rewriteErrorTrace (err: Error): Promise<Error> {
+    if (err && typeof err.stack === 'string') {
+      const stack = err.stack.split('\n')
+      const newStack = await Promise.all(stack.map(rewriteTraceLine))
+      err.stack = newStack.join('\n')
+    }
+    return err
+  }
+
+  return {
+    rewriteErrorTrace
+  }
+}