Merge pull request #175 from NullVoxPopuli/add-option-to-preserve-ember-import

Author: Robert Jackson

__tests__/index-test.js

@@ -241,6 +241,52 @@ describe('options', () => {
       expect(actual).toEqual(`var _x = Ember.assert;var _y = Ember.inspect;`);
     });
   });
+
+  describe('useEmberModule', () => {
+    it('does not add Ember import when no Ember related imports are needed', () => {
+      let input = `console.log('hi mom!');`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+
+      expect(actual).toEqual(input);
+    });
+
+    it(`adds the ember import when used in sub-modules`, () => {
+      let input = `import Component from '@ember/component';export default class extends Component {}`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+      let expected = `import _Ember from 'ember';\nexport default class extends _Ember.Component {}`;
+
+      expect(actual).toEqual(expected);
+    });
+
+    it(`keeps the ember import`, () => {
+      let input = `import Ember from 'ember';let x = Ember;`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+
+      expect(actual).toEqual(input);
+    });
+
+    it(`reuses a pre-existing ember import`, () => {
+      let input = `import Ember from 'ember'; import Component from '@ember/component'; export default class extends Component {}`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+      let expected = `import Ember from 'ember';export default class extends Ember.Component {}`;
+
+      expect(actual).toEqual(expected);
+    });
+
+    it(`keeps the ember import when renamed`, () => {
+      let input = `import BestFramework from 'ember';let x = BestFramework;`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+
+      expect(actual).toEqual(input);
+    });
+
+    it(`import then export`, () => {
+      let input = `import mbr from 'ember';export const Ember = mbr;`;
+      let actual = transform(input, [[Plugin, { useEmberModule: true }]]);
+
+      expect(actual).toEqual(input);
+    });
+  });
 });
 
 describe(`import from 'ember'`, () => {

src/index.js

@@ -58,14 +58,17 @@ module.exports = function (babel) {
     reverseMapping[importRoot][importName] = imported;
   });
 
-  function getMemberExpressionFor(global) {
+  function getMemberExpressionFor(global, emberIdentifier) {
     let parts = global.split('.');
 
     let object = parts.shift();
     let property = parts.shift();
 
+    let objectIdentifier =
+      object === 'Ember' ? emberIdentifier : t.identifier(object);
+
     let memberExpression = t.MemberExpression(
-      t.identifier(object),
+      objectIdentifier,
       t.identifier(property)
     );
 
@@ -84,8 +87,49 @@ module.exports = function (babel) {
   return {
     name: 'ember-modules-api-polyfill',
     visitor: {
+      Program(path, state) {
+        let options = state.opts || {};
+        let useEmberModule = Boolean(options.useEmberModule);
+
+        let preexistingEmberImportDeclaration = path
+          .get('body')
+          .filter((n) => n.type === 'ImportDeclaration')
+          .find((n) => n.get('source').get('value').node === 'ember');
+
+        if (
+          // an import was found
+          preexistingEmberImportDeclaration &&
+          // this accounts for `import from 'ember'` without a local identifier
+          preexistingEmberImportDeclaration.node.specifiers.length > 0
+        ) {
+          state.emberIdentifier =
+            preexistingEmberImportDeclaration.node.specifiers[0].local;
+        }
+
+        state.ensureEmberImport = () => {
+          if (!useEmberModule) {
+            // ensures that we can always assume `state.emberIdentifier` is set
+            state.emberIdentifier = t.identifier('Ember');
+            return;
+          }
+
+          if (state.emberIdentifier) return;
+
+          state.emberIdentifier = path.scope.generateUidIdentifier('Ember');
+
+          let emberImport = t.importDeclaration(
+            [t.importDefaultSpecifier(state.emberIdentifier)],
+            t.stringLiteral('ember')
+          );
+
+          path.unshiftContainer('body', emberImport);
+        };
+      },
+
       ImportDeclaration(path, state) {
-        let ignore = (state.opts && state.opts.ignore) || [];
+        let options = state.opts || {};
+        let ignore = options.ignore || [];
+        let useEmberModule = Boolean(options.useEmberModule);
         let node = path.node;
         let declarations = [];
         let removals = [];
@@ -105,10 +149,14 @@ module.exports = function (babel) {
 
           if (specifierPath) {
             let local = specifierPath.node.local;
-            if (local.name !== 'Ember') {
-              path.scope.rename(local.name, 'Ember');
+
+            // when `useEmberModule` is set, we don't need to do anything here
+            if (!useEmberModule) {
+              if (local.name !== 'Ember') {
+                path.scope.rename(local.name, 'Ember');
+              }
+              removals.push(specifierPath);
             }
-            removals.push(specifierPath);
           } else {
             // import 'ember';
             path.remove();
@@ -168,12 +216,15 @@ module.exports = function (babel) {
 
             removals.push(specifierPath);
 
+            // ensure that the Ember global is imported if needed
+            state.ensureEmberImport();
+
             if (
               path.scope.bindings[local.name].referencePaths.find(
                 (rp) => rp.parent.type === 'ExportSpecifier'
               )
             ) {
-              // not safe to use path.scope.rename directly
+              // not safe to use path.scope.rename directly when this identifier is being directly re-exported
               declarations.push(
                 t.variableDeclaration('var', [
                   t.variableDeclarator(
@@ -215,7 +266,10 @@ module.exports = function (babel) {
               // Replace the occurrences of the imported name with the global name.
               referencePaths.forEach((referencePath) => {
                 if (!isTypescriptNode(referencePath.parentPath)) {
-                  const memberExpression = getMemberExpressionFor(global);
+                  const memberExpression = getMemberExpressionFor(
+                    global,
+                    state.emberIdentifier
+                  );
 
                   try {
                     referencePath.replaceWith(memberExpression);