Add ability to deduplicate babel helpers.

.eslintrc.js

@@ -26,6 +26,7 @@ module.exports = {
         'blueprints/*/index.js',
         'config/**/*.js',
         'tests/dummy/config/**/*.js',
+        'lib/**/*.js'
       ],
       excludedFiles: [
         'addon/**',

README.md

@@ -94,6 +94,7 @@ interface EmberCLIBabelConfig {
   */
   'ember-cli-babel'?: {
     includePolyfill?: boolean;
+    includeExternalHelpers?: boolean;
     compileModules?: boolean;
     disableDebugTooling?: boolean;
     disablePresetEnv?: boolean;
@@ -159,6 +160,36 @@ let app = new EmberApp(defaults, {
 });
 ```
 
+#### External Helpers
+
+Babel often includes helper functions to handle some of the more complex logic
+in codemods. These functions are inlined by default, so they are duplicated in
+every file that they are used in, which adds some extra weight to final builds.
+
+Enabling `includeExternalHelpers` will cause Babel to import these helpers from
+a shared module, reducing app size overall. This option is available _only_ to
+the root application, because it is a global configuration value due to the fact
+that there can only be one version of helpers included.
+
+Note that there is currently no way to whitelist or blacklist helpers, so all
+helpers will be included, even ones which are not used. If your app is small,
+this could add to overall build size, so be sure to check.
+
+`ember-cli-babel` will attempt to include helpers if it believes that it will
+lower your build size, using a number of heuristics. You can override this to
+force inclusion or exclusion of helpers in your app by passing `true` or `false`
+to `includeExternalHelpers` in your `ember-cli-babel` options.
+
+```js
+// ember-cli-build.js
+
+let app = new EmberApp(defaults, {
+  'ember-cli-babel': {
+    includeExternalHelpers: true
+  }
+});
+```
+
 #### Enabling Source Maps
 
 Babel generated source maps will enable you to debug your original ES6 source

ember-cli-build.js

@@ -19,10 +19,11 @@ module.exports = function(defaults) {
   let app = new EmberAddon(defaults, {
     'ember-cli-babel': {
       includePolyfill: true,
+      includeExternalHelpers: true,
       // ember-cli-babels defaults, should be parallelizable. If they are not,
       // it should fail to build. This flag being enabled ensure that to be the
       // case.
-      throwUnlessParallelizable: true
+      throwUnlessParallelizable: true,
     }
   });
 

index.js

@@ -5,6 +5,11 @@ const clone = require('clone');
 const path = require('path');
 const semver = require('semver');
 
+const defaultShouldIncludeHelpers = require('./lib/default-should-include-helpers');
+const findApp = require('./lib/find-app');
+
+const APP_BABEL_RUNTIME_VERSION = new WeakMap();
+
 let count = 0;
 
 module.exports = {
@@ -84,18 +89,99 @@ module.exports = {
     }
   },
 
+  _shouldIncludeHelpers() {
+    let customAddonOptions = this.parent && this.parent.options && this.parent.options['ember-cli-babel'];
+
+    if (customAddonOptions && 'includeExternalHelpers' in customAddonOptions) {
+      throw new Error('includeExternalHelpers is not supported in addon configurations, it is an app-wide configuration option');
+    }
+
+    let appOptions = this._getAppOptions();
+    let customOptions = appOptions['ember-cli-babel'];
+
+    let shouldIncludeHelpers = false;
+
+    if (customOptions && 'includeExternalHelpers' in customOptions) {
+      shouldIncludeHelpers = customOptions.includeExternalHelpers === true;
+    } else {
+      // Check the project to see if we should include helpers based on heuristics.
+      shouldIncludeHelpers = defaultShouldIncludeHelpers(this.project);
+    }
+
+    let appEmberCliBabelPackage = this.project.addons.find(a => a.name === 'ember-cli-babel').pkg;
+    let appEmberCliBabelVersion = appEmberCliBabelPackage && appEmberCliBabelPackage.version;
+
+    if (appEmberCliBabelVersion && semver.gte(appEmberCliBabelVersion, '7.3.0-beta.1')) {
+      return shouldIncludeHelpers;
+    } else if (shouldIncludeHelpers) {
+      this.project.ui.writeWarnLine(
+        `${this._parentName()} attempted to include external babel helpers to make your build size smaller, but your root app's ember-cli-babel version is not high enough. Please update ember-cli-babel to v7.3.0-beta.1 or later.`
+      );
+    }
+
+    return false;
+  },
+
+  _getHelperVersion() {
+    if (!APP_BABEL_RUNTIME_VERSION.has(this.project)) {
+      let checker = new VersionChecker(this.project);
+      APP_BABEL_RUNTIME_VERSION.set(this.project, checker.for('@babel/runtime', 'npm').version);
+    }
+
+    return APP_BABEL_RUNTIME_VERSION.get(this.project);
+  },
+
+  _getHelpersPlugin() {
+    return [
+      [
+        require.resolve('@babel/plugin-transform-runtime'),
+        {
+          version: this._getHelperVersion(),
+          regenerator: false,
+          useESModules: true
+        }
+      ]
+    ]
+  },
+
+  treeForAddon() {
+    // Helpers are a global config, so only the root application should bother
+    // generating and including the file.
+    if (!(this.parent === this.project && this._shouldIncludeHelpers())) return;
+
+    const path = require('path');
+    const Funnel = require('broccoli-funnel');
+    const UnwatchedDir = require('broccoli-source').UnwatchedDir;
+
+    const babelHelpersPath = path.dirname(require.resolve('@babel/runtime/package.json'));
+
+    let babelHelpersTree = new Funnel(new UnwatchedDir(babelHelpersPath), {
+      srcDir: 'helpers/esm',
+      destDir: '@babel/runtime/helpers/esm'
+    });
+
+    return this.transpileTree(babelHelpersTree, {
+      'ember-cli-babel': {
+        // prevents the helpers from being double transpiled, and including themselves
+        disablePresetEnv: true
+      }
+    });
+  },
+
   treeForVendor() {
-    if (!this._shouldIncludePolyfill()) { return; }
+    if (!this._shouldIncludePolyfill()) return;
 
     const Funnel = require('broccoli-funnel');
     const UnwatchedDir = require('broccoli-source').UnwatchedDir;
 
     // Find babel-core's browser polyfill and use its directory as our vendor tree
     let polyfillDir = path.dirname(require.resolve('@babel/polyfill/dist/polyfill'));
 
-    return new Funnel(new UnwatchedDir(polyfillDir), {
+    let polyfillTree = new Funnel(new UnwatchedDir(polyfillDir), {
       destDir: 'babel-polyfill'
     });
+
+    return polyfillTree;
   },
 
   included: function(app) {
@@ -123,6 +209,12 @@ module.exports = {
     return (this.parent && this.parent.options) || (this.app && this.app.options) || {};
   },
 
+  _getAppOptions() {
+    let app = findApp(this);
+
+    return (app && app.options) || {};
+  },
+
   _parentName() {
     let parentName;
 
@@ -158,6 +250,7 @@ module.exports = {
   _getBabelOptions(config) {
     let addonProvidedConfig = this._getAddonProvidedConfig(config);
     let shouldCompileModules = this._shouldCompileModules(config);
+    let shouldIncludeHelpers = this._shouldIncludeHelpers();
 
     let emberCLIBabelConfig = config['ember-cli-babel'];
     let shouldRunPresetEnv = true;
@@ -188,6 +281,7 @@ module.exports = {
     let userPostTransformPlugins = addonProvidedConfig.postTransformPlugins;
 
     options.plugins = [].concat(
+      shouldIncludeHelpers && this._getHelpersPlugin(),
       userPlugins,
       this._getDebugMacroPlugins(config),
       this._getEmberModulesAPIPolyfill(config),

lib/default-should-include-helpers.js

@@ -0,0 +1,34 @@
+const SHOULD_INCLUDE_HELPERS = new WeakMap();
+
+function shouldIncludeHelpers(addonOrProject) {
+  // Currently we check for @ember-decorators transforms specifically, but we
+  // could check for any number of heuristics in this function. What we want is
+  // to default to on if we reasonably believe that users will incur massive
+  // cost for inlining helpers. Stage 2+ decorators are a very clear indicator
+  // that helpers should be included, at 12kb for the helpers, it pays for
+  // itself after usage in 5 files. With stage 1 decorators, it pays for itself
+  // after 25 files.
+  if (addonOrProject.pkg && addonOrProject.pkg.name === '@ember-decorators/babel-transforms') {
+    return true;
+  }
+
+  if (addonOrProject.addons) {
+    return addonOrProject.addons.some(shouldIncludeHelpers);
+  }
+
+  return false;
+}
+
+
+module.exports = function defaultShouldIncludeHelpers(project) {
+  if (SHOULD_INCLUDE_HELPERS.has(project)) {
+    return SHOULD_INCLUDE_HELPERS.get(project);
+  }
+
+  let shouldInclude = shouldIncludeHelpers(project);
+
+  SHOULD_INCLUDE_HELPERS.set(project, shouldInclude);
+
+  return shouldInclude;
+}
+

lib/find-app.js

@@ -0,0 +1,14 @@
+'use strict';
+
+module.exports = function findApp(addon) {
+  let current = addon;
+  let app;
+
+  // Keep iterating upward until we don't have a grandparent.
+  // Has to do this grandparent check because at some point we hit the project.
+  do {
+    app = current.app || app;
+  } while (current.parent.parent && (current = current.parent));
+
+  return app;
+}

lib/relative-module-paths.js

@@ -1,4 +1,3 @@
-/* eslint-env node */
 'use strict';
 
 const path = require('path');

node-tests/addon-test.js

@@ -21,12 +21,19 @@ describe('ember-cli-babel', function() {
 
   beforeEach(function() {
     this.ui = new MockUI();
-    let project = { root: __dirname, emberCLIVersion: () => '2.16.2' };
+    let project = {
+      root: __dirname,
+      emberCLIVersion: () => '2.16.2',
+      addons: []
+    };
+
     this.addon = new Addon({
       project,
       parent: project,
       ui: this.ui,
     });
+
+    project.addons.push(this.addon);
   });
 
   afterEach(function() {
@@ -283,12 +290,19 @@ describe('ember-cli-babel', function() {
 
     describe('@ember/string detection', function() {
       beforeEach(function() {
-        let project = { root: input.path(), emberCLIVersion: () => '2.16.2' };
+        let project = {
+          root: input.path(),
+          emberCLIVersion: () => '2.16.2',
+          addons: []
+        };
+
         this.addon = new Addon({
           project,
           parent: project,
           ui: this.ui,
         });
+
+        project.addons.push(this.addon);
       });
 
       it('does not transpile the @ember/string imports when addon is present', co.wrap(function* () {
@@ -456,6 +470,81 @@ describe('ember-cli-babel', function() {
     });
   });
 
+  describe('_shouldIncludeHelpers()', function() {
+    beforeEach(function() {
+      this.addon.app = {
+        options: {}
+      };
+    });
+
+    it('should return false without any includeExternalHelpers option set', function() {
+      expect(this.addon._shouldIncludeHelpers()).to.be.false;
+    });
+
+    it('should throw an error with ember-cli-babel.includeExternalHelpers = true in parent', function() {
+      this.addon.parent.options = { 'ember-cli-babel': { includeExternalHelpers: true } };
+
+      expect(this.addon._shouldIncludeHelpers).to.throw;
+    });
+
+    it('should return true with ember-cli-babel.includeExternalHelpers = true in app and ember-cli-version is high enough', function() {
+      this.addon.pkg = { version: '7.3.0-beta.1' };
+
+      this.addon.app.options = { 'ember-cli-babel': { includeExternalHelpers: true } };
+
+      expect(this.addon._shouldIncludeHelpers()).to.be.true;
+    });
+
+    it('should return false with ember-cli-babel.includeExternalHelpers = true in app and write warn line if ember-cli-version is not high enough', function() {
+      this.addon.project.name = 'dummy';
+      this.addon.project.ui = {
+        writeWarnLine(message) {
+          expect(message).to.match(/dummy attempted to include external babel helpers/);
+        }
+      };
+
+      this.addon.app.options = { 'ember-cli-babel': { includeExternalHelpers: true } };
+
+      expect(this.addon._shouldIncludeHelpers()).to.be.false;
+    });
+
+    it('should return false with ember-cli-babel.includeExternalHelpers = false in host', function() {
+      this.addon.app.options = { 'ember-cli-babel': { includeExternalHelpers: false } };
+
+      expect(this.addon._shouldIncludeHelpers()).to.be.false;
+    });
+
+    describe('autodetection', function() {
+      it('should return true if @ember-decorators/babel-transforms exists and ember-cli-babel version is high enough', function() {
+        this.addon.pkg = { version: '7.3.0-beta.1' };
+        this.addon.project.addons.push({
+          pkg: {
+            name: '@ember-decorators/babel-transforms'
+          }
+        });
+
+        expect(this.addon._shouldIncludeHelpers()).to.be.true;
+      });
+
+      it('should return false if @ember-decorators/babel-transforms exists and write warn line if ember-cli-version is not high enough', function() {
+        this.addon.project.name = 'dummy';
+        this.addon.project.ui = {
+          writeWarnLine(message) {
+            expect(message).to.match(/dummy attempted to include external babel helpers/);
+          }
+        };
+
+        this.addon.project.addons.push({
+          pkg: {
+            name: '@ember-decorators/babel-transforms'
+          }
+        });
+
+        expect(this.addon._shouldIncludeHelpers()).to.be.false;
+      });
+    })
+  });
+
   describe('_shouldCompileModules()', function() {
     beforeEach(function() {
       this.addon.parent = {

package.json

@@ -40,8 +40,10 @@
   "dependencies": {
     "@babel/core": "^7.0.0",
     "@babel/plugin-transform-modules-amd": "^7.0.0",
+    "@babel/plugin-transform-runtime": "^7.2.0",
     "@babel/polyfill": "^7.0.0",
     "@babel/preset-env": "^7.0.0",
+    "@babel/runtime": "^7.2.0",
     "amd-name-resolver": "^1.2.1",
     "babel-plugin-debug-macros": "^0.2.0-beta.6",
     "babel-plugin-ember-modules-api-polyfill": "^2.6.0",