force generateSourceMaps, compose source maps manually

Author: David Sheldrick

__specs__/__snapshots__/transformer.test.js.snap

@@ -12,30 +12,11 @@ exports.default = Cheese;"
 
 exports[`the transformer works 2`] = `
 Object {
-  "mappings": "AAAA;;AACAA,OAAOC,cAAP,CAAsBC,OAAtB,EAA+B,YAA/B,EAA6C,EAAEC,OAAO,IAAT,EAA7C;AACA,SAASC,MAAT,GAAkB;AACd,WAAO,EAAEC,QAAQ,SAAV,EAAP;AACH;AACDH,QAAQI,OAAR,GAAkBF,MAAlB",
-  "names": Array [
-    "Object",
-    "defineProperty",
-    "exports",
-    "value",
-    "Cheese",
-    "cheese",
-    "default",
-  ],
+  "mappings": ";;;AAKA,SAAA,MAAA,GAAA;AACE,WAAO,EAAC,QAAQ,SAAT,EAAP;AACD;AAFD,QAAA,OAAA,GAAA,MAAA",
+  "names": Array [],
   "sources": Array [
     "blah.tsx",
   ],
-  "sourcesContent": Array [
-    "
-type Cheese = {
-  readonly cheese: string
-}
-
-export default function Cheese(): Cheese {
-  return {cheese: 'stilton'};
-}
-",
-  ],
   "version": 3,
 }
 `;

index.js

@@ -9,9 +9,38 @@ const TSCONFIG_PATH = process.env.TSCONFIG_PATH
 
 const { SourceMapConsumer, SourceMapGenerator } = require('source-map')
 
-function composeSourceMaps(tsMap, babelMap) {
-  const map = SourceMapGenerator.fromSourceMap(new SourceMapConsumer(babelMap))
-  map.applySourceMap(new SourceMapConsumer(tsMap))
+function composeSourceMaps(tsMap, babelMap, fileName) {
+  // applySourceMap wasn't working for me, so doing it manually
+  const map = new SourceMapGenerator()
+  const tsConsumer = new SourceMapConsumer(tsMap)
+  const babelConsumer = new SourceMapConsumer(babelMap)
+
+  babelConsumer.eachMapping(
+    ({
+      source,
+      generatedLine,
+      generatedColumn,
+      originalLine,
+      originalColumn,
+      name,
+    }) => {
+      if (originalLine) {
+        const original = tsConsumer.originalPositionFor({
+          line: originalLine,
+          column: originalColumn,
+        })
+        if (original.line) {
+          map.addMapping({
+            generated: { line: generatedLine, column: generatedColumn },
+            original: { line: original.line, column: original.column },
+            source: fileName,
+            name: null,
+          })
+        }
+      }
+    }
+  )
+
   return map.toJSON()
 }
 
@@ -41,21 +70,25 @@ const compilerOptions = Object.assign(tsConfig.compilerOptions, {
 })
 
 module.exports.transform = function(sourceCode, fileName, options) {
+  options = Object.assign({}, options, { generateSourceMaps: true })
+
   if (fileName.endsWith('.ts') || fileName.endsWith('.tsx')) {
     const tsCompileResult = ts.transpileModule(sourceCode, {
       compilerOptions,
       fileName,
     })
+
     const babelCompileResult = upstreamTransformer.transform(
       tsCompileResult.outputText,
       fileName,
-      Object.assign({}, options, { generateSourceMaps: true })
+      options
     )
 
     return Object.assign({}, babelCompileResult, {
       map: composeSourceMaps(
         tsCompileResult.sourceMapText,
-        babelCompileResult.map
+        babelCompileResult.map,
+        fileName
       ),
     })
   } else {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-native-typescript-transformer",
-  "version": "1.0.0",
+  "version": "1.0.3",
   "description": "TypeScript transformer for react-native",
   "main": "index.js",
   "repository": "https://github.com/ds300/react-native-typescript-transformer",