Use the async version of transform in babel-cli (#6826)

* use the async version of transform in babel-cli

* Modify compile to use async version of transformFile

* Babel-CLI: transform files sequentially

* Remove useless res in callback

packages/babel-cli/src/babel/dir.js

@@ -7,9 +7,13 @@ import fs from "fs";
 import * as util from "./util";
 
 export default function(commander, filenames, opts) {
-  function write(src, relative, base) {
+  function write(src, relative, base, callback) {
+    if (typeof base === "function") {
+      callback = base;
+      base = undefined;
+    }
     if (!util.isCompilableExtension(relative, commander.extensions)) {
-      return false;
+      return callback();
     }
 
     // remove extension and then append back on .js
@@ -17,7 +21,7 @@ export default function(commander, filenames, opts) {
 
     const dest = getDest(commander, relative, base);
 
-    const data = util.compile(
+    util.compile(
       src,
       defaults(
         {
@@ -26,23 +30,28 @@ export default function(commander, filenames, opts) {
         },
         opts,
       ),
-    );
-
-    if (!data) return false;
+      function(err, res) {
+        if (err) return callback(err);
+        if (!res) return callback();
 
         // we've requested explicit sourcemaps to be written to disk
-    if (data.map && commander.sourceMaps && commander.sourceMaps !== "inline") {
+        if (
+          res.map &&
+          commander.sourceMaps &&
+          commander.sourceMaps !== "inline"
+        ) {
           const mapLoc = dest + ".map";
-      data.code = util.addSourceMappingUrl(data.code, mapLoc);
-      outputFileSync(mapLoc, JSON.stringify(data.map));
+          res.code = util.addSourceMappingUrl(res.code, mapLoc);
+          outputFileSync(mapLoc, JSON.stringify(res.map));
         }
 
-    outputFileSync(dest, data.code);
+        outputFileSync(dest, res.code);
         util.chmod(src, dest);
 
         util.log(src + " -> " + dest);
-
-    return true;
+        return callback(null, true);
+      },
+    );
   }
 
   function getDest(commander, filename, base) {
@@ -50,17 +59,45 @@ export default function(commander, filenames, opts) {
     return path.join(commander.outDir, filename);
   }
 
-  function handleFile(src, filename, base) {
-    const didWrite = write(src, filename, base);
+  function handleFile(src, filename, base, callback) {
+    if (typeof base === "function") {
+      callback = base;
+      base = undefined;
+    }
 
-    if (!didWrite && commander.copyFiles) {
+    write(src, filename, base, function(err, res) {
+      if (err) return callback(err);
+      if (!res && commander.copyFiles) {
         const dest = getDest(commander, filename, base);
         outputFileSync(dest, fs.readFileSync(src));
         util.chmod(src, dest);
       }
+
+      return callback();
+    });
   }
 
-  function handle(filename) {
+  function sequentialHandleFile(files, dirname, index, callback) {
+    if (typeof index === "function") {
+      callback = index;
+      index = 0;
+    }
+
+    const filename = files[index];
+    const src = path.join(dirname, filename);
+
+    handleFile(src, filename, dirname, function(err) {
+      if (err) return callback(err);
+      index++;
+      if (index !== files.length) {
+        sequentialHandleFile(files, dirname, index, callback);
+      } else {
+        callback();
+      }
+    });
+  }
+
+  function handle(filename, callback) {
     if (!fs.existsSync(filename)) return;
 
     const stat = fs.statSync(filename);
@@ -72,19 +109,32 @@ export default function(commander, filenames, opts) {
         util.deleteDir(commander.outDir);
       }
 
-      util
-        .readdir(dirname, commander.includeDotfiles)
-        .forEach(function(filename) {
-          const src = path.join(dirname, filename);
-          handleFile(src, filename, dirname);
-        });
+      const files = util.readdir(dirname, commander.includeDotfiles);
+      sequentialHandleFile(files, dirname, callback);
     } else {
-      write(filename, path.basename(filename), path.dirname(filename));
+      write(
+        filename,
+        path.basename(filename),
+        path.dirname(filename),
+        callback,
+      );
     }
   }
 
+  function sequentialHandle(filenames, index = 0) {
+    const filename = filenames[index];
+
+    handle(filename, function(err) {
+      if (err) throw err;
+      index++;
+      if (index !== filenames.length) {
+        sequentialHandle(filenames, index);
+      }
+    });
+  }
+
   if (!commander.skipInitialBuild) {
-    filenames.forEach(handle);
+    sequentialHandle(filenames);
   }
 
   if (commander.watch) {
@@ -104,7 +154,9 @@ export default function(commander, filenames, opts) {
         watcher.on(type, function(filename) {
           const relative = path.relative(dirname, filename) || filename;
           try {
-            handleFile(filename, relative);
+            handleFile(filename, relative, function(err) {
+              if (err) throw err;
+            });
           } catch (err) {
             console.error(err.stack);
           }

packages/babel-cli/src/babel/file.js

@@ -103,7 +103,6 @@ export default function(commander, filenames, opts) {
     });
 
     process.stdin.on("end", function() {
-      results.push(
       util.transform(
         commander.filename,
         code,
@@ -113,9 +112,12 @@ export default function(commander, filenames, opts) {
           },
           opts,
         ),
-        ),
-      );
+        function(err, res) {
+          if (err) throw err;
+          results.push(res);
           output();
+        },
+      );
     });
   };
 
@@ -140,7 +142,9 @@ export default function(commander, filenames, opts) {
       }
     });
 
-    _filenames.forEach(function(filename) {
+    let filesProcessed = 0;
+
+    _filenames.forEach(function(filename, index) {
       let sourceFilename = filename;
       if (commander.outFile) {
         sourceFilename = path.relative(
@@ -150,7 +154,7 @@ export default function(commander, filenames, opts) {
       }
       sourceFilename = slash(sourceFilename);
 
-      const data = util.compile(
+      util.compile(
         filename,
         defaults(
           {
@@ -158,14 +162,18 @@ export default function(commander, filenames, opts) {
           },
           opts,
         ),
-      );
+        function(err, res) {
+          if (err) throw err;
 
-      if (!data) return;
-
-      results.push(data);
-    });
+          filesProcessed++;
+          if (res) results[index] = res;
 
+          if (filesProcessed === _filenames.length) {
             output();
+          }
+        },
+      );
+    });
   };
 
   const files = function() {

packages/babel-cli/src/babel/util.js

@@ -50,25 +50,26 @@ export function log(msg) {
   if (!commander.quiet) console.log(msg);
 }
 
-export function transform(filename, code, opts) {
+export function transform(filename, code, opts, callback) {
   opts = Object.assign({}, opts, {
     filename,
   });
 
-  return babel.transform(code, opts);
+  babel.transform(code, opts, callback);
 }
 
-export function compile(filename, opts) {
-  try {
-    return babel.transformFileSync(filename, opts);
-  } catch (err) {
+export function compile(filename, opts, callback) {
+  babel.transformFile(filename, opts, function(err, res) {
+    if (err) {
       if (commander.watch) {
         console.error(err);
-      return { ignored: true };
+        return callback(null, { ignored: true });
       } else {
-      throw err;
+        return callback(err);
       }
     }
+    return callback(null, res);
+  });
 }
 
 export function deleteDir(path) {