Added babel-helper-split-export-declaration (#7313)

packages/babel-helper-module-transforms/package.json

@@ -10,6 +10,7 @@
   "dependencies": {
     "@babel/helper-module-imports": "7.0.0-beta.40",
     "@babel/helper-simple-access": "7.0.0-beta.40",
+    "@babel/helper-split-export-declaration": "7.0.0-beta.40",
     "@babel/template": "7.0.0-beta.40",
     "@babel/types": "7.0.0-beta.40",
     "lodash": "^4.2.0"

packages/babel-helper-module-transforms/src/normalize-and-load-metadata.js

@@ -1,6 +1,6 @@
 import { basename, extname } from "path";
 
-import * as t from "@babel/types";
+import splitExportDeclaration from "@babel/helper-split-export-declaration";
 
 export type ModuleMetadata = {
   exportName: string,
@@ -399,35 +399,7 @@ function nameAnonymousExports(programPath: NodePath) {
   // Name anonymous exported locals.
   programPath.get("body").forEach(child => {
     if (!child.isExportDefaultDeclaration()) return;
-
-    // export default foo;
-    const declaration = child.get("declaration");
-    if (declaration.isFunctionDeclaration()) {
-      if (!declaration.node.id) {
-        declaration.node.id = declaration.scope.generateUidIdentifier(
-          "default",
-        );
-      }
-    } else if (declaration.isClassDeclaration()) {
-      if (!declaration.node.id) {
-        declaration.node.id = declaration.scope.generateUidIdentifier(
-          "default",
-        );
-      }
-    } else {
-      const id = declaration.scope.generateUidIdentifier("default");
-      const namedDecl = t.exportNamedDeclaration(null, [
-        t.exportSpecifier(t.identifier(id.name), t.identifier("default")),
-      ]);
-      namedDecl._blockHoist = child.node._blockHoist;
-
-      const varDecl = t.variableDeclaration("var", [
-        t.variableDeclarator(id, declaration.node),
-      ]);
-      varDecl._blockHoist = child.node._blockHoist;
-
-      child.replaceWithMultiple([namedDecl, varDecl]);
-    }
+    splitExportDeclaration(child);
   });
 }
 

packages/babel-helper-module-transforms/src/rewrite-live-references.js

@@ -112,6 +112,7 @@ const rewriteBindingInitVisitor = {
 
     Object.keys(path.getOuterBindingIdentifiers()).forEach(localName => {
       const exportNames = exported.get(localName) || [];
+
       if (exportNames.length > 0) {
         const statement = t.expressionStatement(
           buildBindingExportAssignmentExpression(

packages/babel-helper-split-export-declaration/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-helper-split-export-declaration/README.md

@@ -0,0 +1,23 @@
+# @babel/helper-split-export-declaration
+
+## API
+
+```js
+declare export default splitExportDeclaration(path: NodePath);
+```
+
+## Usage
+
+```js
+import traverse from "@babel/traverse";
+import splitExportDeclaration from "@babel/helper-split-export-declaration";
+
+// ...
+
+traverse(file, {
+  ExportDefaultDeclaration(path) {
+    if (!path.get("declaration").isClassDeclaration()) return;
+    splitExportDeclaration(path);
+  },
+});
+```

packages/babel-helper-split-export-declaration/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "@babel/helper-split-export-declaration",
+  "version": "7.0.0-beta.40",
+  "description": "",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-helper-split-export-declaration",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "dependencies": {
+    "@babel/types": "7.0.0-beta.40"
+  }
+}

packages/babel-helper-split-export-declaration/src/index.js

@@ -0,0 +1,76 @@
+import * as t from "@babel/types";
+
+export default function splitExportDeclaration(exportDeclaration) {
+  if (!exportDeclaration.isExportDeclaration()) {
+    throw new Error("Only export declarations can be splitted.");
+  }
+
+  // build specifiers that point back to this export declaration
+  const isDefault = exportDeclaration.isExportDefaultDeclaration();
+  const declaration = exportDeclaration.get("declaration");
+  const isClassDeclaration = declaration.isClassDeclaration();
+
+  if (isDefault) {
+    const standaloneDeclaration =
+      declaration.isFunctionDeclaration() || isClassDeclaration;
+
+    const scope = declaration.isScope()
+      ? declaration.scope.parent
+      : declaration.scope;
+
+    let id = declaration.node.id;
+    let needBindingRegistration = false;
+
+    if (!id) {
+      needBindingRegistration = true;
+
+      id = scope.generateUidIdentifier("default");
+
+      if (
+        standaloneDeclaration ||
+        declaration.isFunctionExpression() ||
+        declaration.isClassExpression()
+      ) {
+        declaration.node.id = t.cloneNode(id);
+      }
+    }
+
+    const updatedDeclaration = standaloneDeclaration
+      ? declaration
+      : t.variableDeclaration("var", [
+          t.variableDeclarator(t.cloneNode(id), declaration.node),
+        ]);
+
+    const updatedExportDeclaration = t.exportNamedDeclaration(null, [
+      t.exportSpecifier(t.cloneNode(id), t.identifier("default")),
+    ]);
+
+    exportDeclaration.insertAfter(updatedExportDeclaration);
+    exportDeclaration.replaceWith(updatedDeclaration);
+
+    if (needBindingRegistration) {
+      scope.registerBinding(
+        isClassDeclaration ? "let" : "var",
+        exportDeclaration,
+      );
+    }
+
+    return exportDeclaration;
+  }
+
+  if (exportDeclaration.get("specifiers").length > 0) {
+    throw new Error("It doesn't make sense to split exported specifiers.");
+  }
+
+  const bindingIdentifiers = declaration.getOuterBindingIdentifiers();
+
+  const specifiers = Object.keys(bindingIdentifiers).map(name => {
+    return t.exportSpecifier(t.identifier(name), t.identifier(name));
+  });
+
+  const aliasDeclar = t.exportNamedDeclaration(null, specifiers);
+
+  exportDeclaration.insertAfter(aliasDeclar);
+  exportDeclaration.replaceWith(declaration.node);
+  return exportDeclaration;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/general/regression-T2983/output.js

@@ -9,15 +9,15 @@ call((_temp = _class = function _class() {
   value: true
 }), _temp));
 
-var _class2 = function _class2() {
-  babelHelpers.classCallCheck(this, _class2);
+var _default = function _default() {
+  babelHelpers.classCallCheck(this, _default);
 };
 
-Object.defineProperty(_class2, "test", {
+Object.defineProperty(_default, "test", {
   configurable: true,
   enumerable: true,
   writable: true,
   value: true
 });
-export { _class2 as default };
+export { _default as default };
 ;

packages/babel-plugin-proposal-class-properties/test/fixtures/regression/T2983/output.js

@@ -4,10 +4,10 @@ call((_temp = _class = function _class() {
   babelHelpers.classCallCheck(this, _class);
 }, _class.test = true, _temp));
 
-var _class2 = function _class2() {
-  babelHelpers.classCallCheck(this, _class2);
+var _default = function _default() {
+  babelHelpers.classCallCheck(this, _default);
 };
 
-_class2.test = true;
-export { _class2 as default };
+_default.test = true;
+export { _default as default };
 ;

packages/babel-plugin-transform-classes/package.json

@@ -11,6 +11,7 @@
     "@babel/helper-function-name": "7.0.0-beta.40",
     "@babel/helper-optimise-call-expression": "7.0.0-beta.40",
     "@babel/helper-replace-supers": "7.0.0-beta.40",
+    "@babel/helper-split-export-declaration": "7.0.0-beta.40",
     "globals": "^11.1.0"
   },
   "keywords": [

packages/babel-plugin-transform-classes/src/index.js

@@ -2,6 +2,7 @@ import LooseTransformer from "./loose";
 import VanillaTransformer from "./vanilla";
 import annotateAsPure from "@babel/helper-annotate-as-pure";
 import nameFunction from "@babel/helper-function-name";
+import splitExportDeclaration from "@babel/helper-split-export-declaration";
 import { types as t } from "@babel/core";
 import globals from "globals";
 
@@ -24,19 +25,7 @@ export default function(api, options) {
     visitor: {
       ExportDefaultDeclaration(path) {
         if (!path.get("declaration").isClassDeclaration()) return;
-
-        const { node } = path;
-        const ref =
-          node.declaration.id || path.scope.generateUidIdentifier("class");
-        node.declaration.id = ref;
-
-        // Split the class declaration and the export into two separate statements.
-        path.replaceWith(node.declaration);
-        path.insertAfter(
-          t.exportNamedDeclaration(null, [
-            t.exportSpecifier(t.cloneNode(ref), t.identifier("default")),
-          ]),
-        );
+        splitExportDeclaration(path);
       },
 
       ClassDeclaration(path) {

packages/babel-plugin-transform-classes/test/fixtures/regression/2941/output.js

@@ -5,8 +5,8 @@ Object.defineProperty(exports, "__esModule", {
 });
 exports.default = void 0;
 
-var _class = function _class() {
-  babelHelpers.classCallCheck(this, _class);
+var _default = function _default() {
+  babelHelpers.classCallCheck(this, _default);
 };
 
-exports.default = _class;
+exports.default = _default;

packages/babel-plugin-transform-classes/test/fixtures/spec/export-super-class/output.js

@@ -1,14 +1,14 @@
-var _class =
+var _default =
 /*#__PURE__*/
 function (_A) {
-  babelHelpers.inherits(_class, _A);
+  babelHelpers.inherits(_default, _A);
 
-  function _class() {
-    babelHelpers.classCallCheck(this, _class);
-    return babelHelpers.possibleConstructorReturn(this, (_class.__proto__ || Object.getPrototypeOf(_class)).apply(this, arguments));
+  function _default() {
+    babelHelpers.classCallCheck(this, _default);
+    return babelHelpers.possibleConstructorReturn(this, (_default.__proto__ || Object.getPrototypeOf(_default)).apply(this, arguments));
   }
 
-  return _class;
+  return _default;
 }(A);
 
-export { _class as default };
+export { _default as default };

packages/babel-plugin-transform-function-name/test/fixtures/function-name/export/output.js

@@ -1,13 +1,14 @@
-export { _whatever as whatever };
-export { _wowzers as default };
 var _foo = "yes",
     foob = "no";
 export { _foo as foo, foob };
 
 function _whatever() {}
 
+export { _whatever as whatever };
+
 function _wowzers() {}
 
+export { _wowzers as default };
 var bar = {
   foo: function foo() {
     _foo;

packages/babel-plugin-transform-function-name/test/fixtures/function-name/modules-4/output.js

@@ -1,7 +1,6 @@
-export { _foo as foo };
-
 function _foo(bar) {}
 
+export { _foo as foo };
 var bar = {
   foo: function foo() {
     _foo;

packages/babel-traverse/package.json

@@ -11,6 +11,7 @@
     "@babel/code-frame": "7.0.0-beta.40",
     "@babel/generator": "7.0.0-beta.40",
     "@babel/helper-function-name": "7.0.0-beta.40",
+    "@babel/helper-split-export-declaration": "7.0.0-beta.40",
     "@babel/types": "7.0.0-beta.40",
     "babylon": "7.0.0-beta.40",
     "debug": "^3.0.1",

packages/babel-traverse/src/scope/index.js

@@ -210,7 +210,7 @@ export default class Scope {
    * Generate a unique identifier and add it to the current scope.
    */
 
-  generateDeclaredUidIdentifier(name: string = "temp") {
+  generateDeclaredUidIdentifier(name?: string) {
     const id = this.generateUidIdentifier(name);
     this.push({ id });
     return t.cloneNode(id);
@@ -220,7 +220,7 @@ export default class Scope {
    * Generate a unique identifier.
    */
 
-  generateUidIdentifier(name: string = "temp") {
+  generateUidIdentifier(name?: string) {
     return t.identifier(this.generateUid(name));
   }
 

packages/babel-traverse/src/scope/lib/renamer.js

@@ -1,4 +1,5 @@
 import Binding from "../binding";
+import splitExportDeclaration from "@babel/helper-split-export-declaration";
 import * as t from "@babel/types";
 
 const renameVisitor = {
@@ -40,48 +41,20 @@ export default class Renamer {
   binding: Binding;
 
   maybeConvertFromExportDeclaration(parentDeclar) {
-    const exportDeclar =
-      parentDeclar.parentPath.isExportDeclaration() && parentDeclar.parentPath;
-    if (!exportDeclar) return;
+    const maybeExportDeclar = parentDeclar.parentPath;
 
-    // build specifiers that point back to this export declaration
-    const isDefault = exportDeclar.isExportDefaultDeclaration();
+    if (!maybeExportDeclar.isExportDeclaration()) {
+      return;
+    }
 
     if (
-      isDefault &&
-      (parentDeclar.isFunctionDeclaration() ||
-        parentDeclar.isClassDeclaration()) &&
-      !parentDeclar.node.id
+      maybeExportDeclar.isExportDefaultDeclaration() &&
+      !maybeExportDeclar.get("declaration").node.id
     ) {
-      // Ensure that default class and function exports have a name so they have a identifier to
-      // reference from the export specifier list.
-      parentDeclar.node.id = parentDeclar.scope.generateUidIdentifier(
-        "default",
-      );
+      return;
     }
 
-    const bindingIdentifiers = parentDeclar.getOuterBindingIdentifiers();
-    const specifiers = [];
-
-    for (const name in bindingIdentifiers) {
-      const localName = name === this.oldName ? this.newName : name;
-      const exportedName = isDefault ? "default" : name;
-      specifiers.push(
-        t.exportSpecifier(t.identifier(localName), t.identifier(exportedName)),
-      );
-    }
-
-    if (specifiers.length) {
-      const aliasDeclar = t.exportNamedDeclaration(null, specifiers);
-
-      // hoist to the top if it's a function
-      if (parentDeclar.isFunctionDeclaration()) {
-        aliasDeclar._blockHoist = 3;
-      }
-
-      exportDeclar.insertAfter(aliasDeclar);
-      exportDeclar.replaceWith(parentDeclar.node);
-    }
+    splitExportDeclaration(maybeExportDeclar);
   }
 
   maybeConvertFromClassFunctionDeclaration(path) {
@@ -129,7 +102,10 @@ export default class Renamer {
     const { scope, path } = binding;
 
     const parentDeclar = path.find(
-      path => path.isDeclaration() || path.isFunctionExpression(),
+      path =>
+        path.isDeclaration() ||
+        path.isFunctionExpression() ||
+        path.isClassExpression(),
     );
     if (parentDeclar) {
       this.maybeConvertFromExportDeclaration(parentDeclar);