New: ESLint v4 (#241)

website/package.json

@@ -67,6 +67,7 @@
     "eslint1": "file:packages/eslint1",
     "eslint2": "file:packages/eslint2",
     "eslint3": "file:packages/eslint3",
+    "eslint4": "file:packages/eslint4",
     "espree": "^3.1.0",
     "esprima": "^3.1.3",
     "flow-parser": "^0.47.0",

website/packages/eslint4/eslint4-package.js

@@ -0,0 +1 @@
+module.exports = require('eslint/package.json');

website/packages/eslint4/index.js

@@ -0,0 +1,9 @@
+// Explicitly require just the stuff we care about to avoid loading
+// RuleTester and CLIEngine, which are unnecessary and bloat out the
+// package size.
+const Linter = require('eslint/lib/linter');
+
+module.exports = {
+  eslint: new Linter(),
+  sourceCode: require('eslint/lib/util/source-code')
+};

website/packages/eslint4/package.json

@@ -0,0 +1,9 @@
+{
+  "name": "eslint4",
+  "version": "1.0.0",
+  "description": "Wrapper for ESLint 4",
+  "main": "index.js",
+  "dependencies": {
+    "eslint": "^4.0.0"
+  }
+}

website/src/parsers/js/transformers/eslint4/codeExample.txt

@@ -0,0 +1,7 @@
+export default function(context) {
+  return {
+    TemplateLiteral(node) {
+      context.report(node, 'Do not use template literals');
+    }
+  };
+};

website/src/parsers/js/transformers/eslint4/index.js

@@ -0,0 +1,25 @@
+import pkg from 'eslint4/eslint4-package';
+
+const ID = 'eslint-v4';
+const name = 'ESLint v4';
+
+export default {
+  id: ID,
+  displayName: name,
+  version: pkg.version,
+  homepage: pkg.homepage,
+
+  defaultParserID: 'babel-eslint',
+
+  loadTransformer(callback) {
+    require(
+      ['eslint4', '../../utils/eslint4Utils'],
+      (eslint, utils) => callback({...eslint, utils})
+    );
+  },
+
+  transform({ eslint, sourceCode, utils }, transformCode, code) {
+    utils.defineRule(eslint, transformCode);
+    return utils.runRule(code, eslint, sourceCode);
+  },
+};

website/src/parsers/js/utils/eslint4Utils.js

@@ -0,0 +1,44 @@
+import compileModule from '../../utils/compileModule';
+import {parseNoPatch} from 'babel-eslint';
+
+export function formatResults(results) {
+  return results.length === 0
+    ? 'Lint rule not fired.'
+    : results.map(formatResult).join('').trim();
+}
+
+export function formatResult(result) {
+  var pointer = '-'.repeat(result.column - 1) + '^';
+  return `
+// ${result.message} (at ${result.line}:${result.column})
+   ${result.source}
+// ${pointer}
+`;
+}
+
+export function defineRule(eslint, code) {
+  // Compile the transform code and install it as an ESLint rule. The rule
+  // name doesn't really matter here, so we'll just use a hard-coded name.
+  const rule = compileModule(code);
+    eslint.defineRule('astExplorerRule', rule.default || rule);
+}
+
+export function runRule(code, eslint, sourceCode) {
+  // Run the ESLint rule on the AST of the provided code.
+  // Reference: http://eslint.org/docs/developer-guide/nodejs-api
+  const ast = parseNoPatch(code, {
+    sourceType: 'module',
+  });
+  const results = eslint.verify(new sourceCode(code, ast), {
+    env: {es6: true},
+    parserOptions: {
+      ecmaVersion: 8,
+      sourceType: 'module',
+      ecmaFeatures: {experimentalObjectRestSpread: true},
+    },
+    rules: {
+      astExplorerRule: 2,
+    },
+  });
+  return formatResults(results);
+}