clean up auxiliaryComment

packages/babel-core/src/transformation/file/options/config.json

@@ -138,10 +138,15 @@
     "description": "",
     "default": "module"
   },
+  
+  "auxiliaryCommentBefore": {
+    "type": "string",
+    "description": "print a comment before any injected non-user code"
+  },
 
-  "auxiliaryComment": {
-    "description": "",
-    "type": "string"
+  "auxiliaryCommentAfter": {
+    "type": "string",
+    "description": "print a comment after any injected non-user code"
   },
 
   "resolveModuleSource": {

packages/babel-core/test/api.js

@@ -47,7 +47,8 @@ suite("api", function () {
 
   test("auxiliaryComment option", function () {
     return transformAsync("class Foo {}", {
-      auxiliaryComment: "yo bro",
+      auxiliaryCommentBefore: "before",
+      auxiliaryCommentAfter: "after",
       plugins: [function (babel) {
         var t = babel.types;
         return {
@@ -60,7 +61,7 @@ suite("api", function () {
         };
       }]
     }).then(function (result) {
-      assert.equal(result.code, "/*yo bro*/start;\nclass Foo {}\n/*yo bro*/end;");
+      assert.equal(result.code, "/*before*/start;\n/*after*/class Foo {}\n/*before*/end;\n/*after*/");
     });
   });
 

packages/babel-generator/src/index.js

@@ -39,7 +39,8 @@ export class CodeGenerator extends Printer {
     shouldPrintComment: boolean;
     retainLines: boolean;
     comments: boolean;
-    auxiliaryComment: string;
+    auxiliaryCommentBefore: string;
+    auxiliaryCommentAfter: string;
     compact: boolean | "auto";
     quotes: "single" | "double";
     concise: boolean;
@@ -50,7 +51,8 @@ export class CodeGenerator extends Printer {
     }
   };
 
-  auxiliaryComment: string;
+  auxiliaryCommentBefore: string;
+  auxiliaryCommentAfter: string;
   whitespace: Whitespace;
   position: Position;
   map: SourceMap;
@@ -64,6 +66,7 @@ export class CodeGenerator extends Printer {
    *
    * - Detects code indentation.
    * - If `opts.compact = "auto"` and the code is over 100KB, `compact` will be set to `true`.
+
    */
 
   static normalizeOptions(code, opts, tokens) {
@@ -74,7 +77,8 @@ export class CodeGenerator extends Printer {
     }
 
     let format = {
-      auxiliaryComment: opts.auxiliaryComment,
+      auxiliaryCommentBefore: opts.auxiliaryCommentBefore,
+      auxiliaryCommentAfter: opts.auxiliaryCommentAfter,
       shouldPrintComment: opts.shouldPrintComment,
       retainLines: opts.retainLines,
       comments: opts.comments == null || opts.comments,
@@ -143,6 +147,7 @@ export class CodeGenerator extends Printer {
 
   generate() {
     this.print(this.ast);
+    this.printAuxAfterComment();
 
     return {
       map:  this.map.get(),

packages/babel-generator/src/printer.js

@@ -9,6 +9,7 @@ export default class Printer extends Buffer {
   constructor(...args) {
     super(...args);
     this.insideAux = false;
+    this.printAuxAfterOnNextUserNode = false;
   }
 
   print(node, parent, opts = {}) {
@@ -31,7 +32,8 @@ export default class Printer extends Buffer {
       throw new ReferenceError(`unknown node of type ${JSON.stringify(node.type)} with constructor ${JSON.stringify(node && node.constructor.name)}`);
     }
 
-    this.printAuxComment(oldInAux);
+    if (node.loc) this.printAuxAfterComment();
+    this.printAuxBeforeComment(oldInAux);
 
     let needsParens = n.needsParens(node, parent);
     if (needsParens) this.push("(");
@@ -62,10 +64,22 @@ export default class Printer extends Buffer {
     this._printNewline(false, node, parent, opts);
   }
 
-  printAuxComment(wasInAux) {
-    let comment = this.format.auxiliaryComment;
-    if (comment && !wasInAux && this.insideAux) {
-      this.printComment({
+  printAuxBeforeComment(wasInAux) {
+    let comment = this.format.auxiliaryCommentBefore;
+    if (!wasInAux && this.insideAux) {
+      this.printAuxAfterOnNextUserNode = true;
+      if (comment) this.printComment({
+        type: "CommentBlock",
+        value: comment
+      });
+    }
+  }
+
+  printAuxAfterComment() {
+    if (this.printAuxAfterOnNextUserNode) {
+      this.printAuxAfterOnNextUserNode = false;
+      let comment = this.format.auxiliaryCommentAfter;
+      if (comment) this.printComment({
         type: "CommentBlock",
         value: comment
       });
@@ -224,7 +238,7 @@ export default class Printer extends Buffer {
 
   printComment(comment) {
     if (!this.shouldPrintComment(comment)) return;
-    
+
     if (comment.ignore) return;
     comment.ignore = true;