tools: move eslint from tools to tools/node_modules

This is required because we need to add the babel-eslint dependency
and it has to be able to resolve "eslint".
babel-eslint is required to support future ES features such as async
iterators and import.meta.

Refs: https://github.com/nodejs/node/pull/17755
PR-URL: https://github.com/nodejs/node/pull/17820
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/tools/node_modules/eslint/lib/load-rules.js b/tools/node_modules/eslint/lib/load-rules.js
new file mode 100644
index 0000000000..b74905d65a
--- /dev/null
+++ b/tools/node_modules/eslint/lib/load-rules.js
@@ -0,0 +1,50 @@
+/**
+ * @fileoverview Module for loading rules from files and directories.
+ * @author Michael Ficarra
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const fs = require("fs"),
+    path = require("path");
+
+const rulesDirCache = {};
+
+//------------------------------------------------------------------------------
+// Public Interface
+//------------------------------------------------------------------------------
+
+/**
+ * Load all rule modules from specified directory.
+ * @param {string} [rulesDir] Path to rules directory, may be relative. Defaults to `lib/rules`.
+ * @param {string} cwd Current working directory
+ * @returns {Object} Loaded rule modules by rule ids (file names).
+ */
+module.exports = function(rulesDir, cwd) {
+    if (!rulesDir) {
+        rulesDir = path.join(__dirname, "rules");
+    } else {
+        rulesDir = path.resolve(cwd, rulesDir);
+    }
+
+    // cache will help performance as IO operation are expensive
+    if (rulesDirCache[rulesDir]) {
+        return rulesDirCache[rulesDir];
+    }
+
+    const rules = Object.create(null);
+
+    fs.readdirSync(rulesDir).forEach(file => {
+        if (path.extname(file) !== ".js") {
+            return;
+        }
+        rules[file.slice(0, -3)] = path.join(rulesDir, file);
+    });
+    rulesDirCache[rulesDir] = rules;
+
+    return rules;
+};