Move class properties transformation logic to enanced-classes

packages/babel-plugin-class-features/.npmignore

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+src
+test
+*.log

packages/babel-plugin-class-features/README.md

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+# @babel/plugin-class-features
+
+> Compile class public and private fields, private methods and decorators to ES6
+
+See our website [@babel/plugin-class-features](https://babeljs.io/docs/en/next/babel-plugin-class-features.html) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-class-features
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-class-features --dev
+```

packages/babel-plugin-class-features/package.json

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+{
+  "name": "@babel/plugin-class-features",
+  "version": "7.1.4",
+  "author": "The Babel Team (https://babeljs.io/team)",
+  "license": "MIT",
+  "description": "Compile class public and private fields, private methods and decorators to ES6",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-class-features",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel",
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-function-name": "^7.1.0",
+    "@babel/helper-member-expression-to-functions": "^7.0.0",
+    "@babel/helper-optimise-call-expression": "^7.0.0",
+    "@babel/helper-plugin-utils": "^7.0.0",
+    "@babel/helper-replace-supers": "^7.1.0"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.1.0",
+    "@babel/helper-plugin-test-runner": "^7.0.0"
+  }
+}

packages/babel-plugin-class-features/src/decorators.js

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+export function hasDecorators(path) {
+  return !!(path.node.decorators && path.node.decorators.length);
+}

packages/babel-plugin-class-features/src/features.js

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+import { hasDecorators } from "./decorators";
+
+export const FEATURES = Object.freeze({
+  //classes: 1 << 0,
+  fields: 1 << 1,
+  privateMethods: 1 << 2,
+  decorators: 1 << 3,
+});
+
+// We can't use a symbol because this needs to always be the same, even if
+// this package isn't deduped by npm. e.g.
+//  - node_modules/
+//    - @babel/plugin-class-features
+//    - @babel/plugin-proposal-decorators
+//      - node_modules
+//        - @babel-plugin-class-features
+const featuresKey = "@babel/plugin-class-features/featuresKey";
+const looseKey = "@babel/plugin-class-features/looseKey";
+
+export function enableFeature(file, feature, loose) {
+  // We can't blindly enable the feature because, if it was already set,
+  // "loose" can't be changed, so that
+  //   @babel/plugin-class-properties { loose: true }
+  //   @babel/plugin-class-properties { loose: false }
+  // is transformed in loose mode.
+  // We only enabled the feature if it was previously disabled.
+  if (!hasFeature(file, feature)) {
+    file.set(featuresKey, file.get(featuresKey) | feature);
+    if (loose) file.set(looseKey, file.get(looseKey) | feature);
+  }
+}
+
+function hasFeature(file, feature) {
+  return !!(file.get(featuresKey) & feature);
+}
+
+export function isLoose(file, feature) {
+  return !!(file.get(looseKey) & feature);
+}
+
+export function verifyUsedFeatures(path, file) {
+  if (hasFeature(file, FEATURES.decorators)) {
+    throw new Error(
+      "@babel/plugin-class-features doesn't support decorators yet.",
+    );
+  }
+  if (hasFeature(file, FEATURES.privateMethods)) {
+    throw new Error(
+      "@babel/plugin-class-features doesn't support private methods yet.",
+    );
+  }
+
+  if (hasDecorators(path) && !hasFeature(file, FEATURES.decorators)) {
+    throw path.buildCodeFrameError("Decorators are not enabled.");
+  }
+
+  if (path.isProperty()) {
+    if (!hasFeature(file, FEATURES.fields)) {
+      throw path.buildCodeFrameError("Class fields are not enabled.");
+    }
+  }
+}