Merge pull request #3421 from loganfsmyth/generate-default-exports

Wrap parens around default exports starting with function/class - fixes T7136

packages/babel-generator/src/node/parentheses.js

@@ -43,12 +43,7 @@ export function UpdateExpression(node: Object, parent: Object): boolean {
 }
 
 export function ObjectExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
-  if (t.isExpressionStatement(parent)) {
+  return isFirstInStatement(printStack, {considerArrow: true});
-    // ({ foo: "bar" });
-    return true;
-  }
-
-  return isFirstInStatement(printStack, true);
 }
 
 export function Binary(node: Object, parent: Object): boolean {
@@ -152,18 +147,8 @@ export function YieldExpression(node: Object, parent: Object): boolean {
 
 export { YieldExpression as AwaitExpression };
 
-export function ClassExpression(node: Object, parent: Object): boolean {
+export function ClassExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
-  // (class {});
+  return isFirstInStatement(printStack, {considerDefaultExports: true});
-  if (t.isExpressionStatement(parent)) {
-    return true;
-  }
-
-  // export default (class () {});
-  if (t.isExportDeclaration(parent)) {
-    return true;
-  }
-
-  return false;
 }
 
 export function UnaryLike(node: Object, parent: Object): boolean {
@@ -179,17 +164,7 @@ export function UnaryLike(node: Object, parent: Object): boolean {
 }
 
 export function FunctionExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
-  // (function () {});
+  return isFirstInStatement(printStack, {considerDefaultExports: true});
-  if (t.isExpressionStatement(parent)) {
-    return true;
-  }
-
-  // export default (function () {});
-  if (t.isExportDeclaration(parent)) {
-    return true;
-  }
-
-  return isFirstInStatement(printStack);
 }
 
 export function ArrowFunctionExpression(node: Object, parent: Object): boolean {
@@ -235,7 +210,10 @@ export function AssignmentExpression(node: Object): boolean {
 
 // Walk up the print stack to deterimine if our node can come first
 // in statement.
-function isFirstInStatement(printStack: Array<Object>, considerArrow: bool = false): boolean {
+function isFirstInStatement(printStack: Array<Object>, {
+    considerArrow = false,
+    considerDefaultExports = false
+  } = {}): boolean {
   let i = printStack.length - 1;
   let node = printStack[i];
   i--;
@@ -245,6 +223,10 @@ function isFirstInStatement(printStack: Array<Object>, considerArrow: bool = fal
       return true;
     }
 
+    if (considerDefaultExports && t.isExportDefaultDeclaration(parent, { declaration: node })) {
+      return true;
+    }
+
     if (considerArrow && t.isArrowFunctionExpression(parent, { body: node })) {
       return true;
     }

packages/babel-generator/test/fixtures/harmony-edgecase/exports/actual.js

@@ -5,5 +5,16 @@ export { a as b, c as d }
 export { }
 export default i = 20
 export function test() { }
+export class test2 { }
 export var i = 20
 export let i = 42
+
+export default (function(){})();
+export default (class {})();
+export default {};
+
+export default function test3(){}
+export default class test4 {}
+
+export default function(){}
+export default class {}

packages/babel-generator/test/fixtures/harmony-edgecase/exports/expected.js

@@ -5,5 +5,16 @@ export { a as b, c as d };
 export {};
 export default i = 20;
 export function test() {}
+export class test2 {}
 export var i = 20;
 export let i = 42;
+
+export default (function () {})();
+export default (class {})();
+export default {};
+
+export default function test3() {}
+export default class test4 {}
+
+export default function () {}
+export default class {}