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diff --git a/tools/eslint/lib/rules/no-empty-class.js b/tools/eslint/lib/rules/no-empty-class.js
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+++ b/tools/eslint/lib/rules/no-empty-class.js
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+/**
+ * @fileoverview Rule to flag the use of empty character classes in regular expressions
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/*
+plain-English description of the following regexp:
+0. `^` fix the match at the beginning of the string
+1. `\/`: the `/` that begins the regexp
+2. `([^\\[]|\\.|\[([^\\\]]|\\.)+\])*`: regexp contents; 0 or more of the following
+  2.0. `[^\\[]`: any character that's not a `\` or a `[` (anything but escape sequences and character classes)
+  2.1. `\\.`: an escape sequence
+  2.2. `\[([^\\\]]|\\.)+\]`: a character class that isn't empty
+3. `\/` the `/` that ends the regexp
+4. `[gimy]*`: optional regexp flags
+5. `$`: fix the match at the end of the string
+*/
+var regex = /^\/([^\\[]|\\.|\[([^\\\]]|\\.)+\])*\/[gimy]*$/;
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    return {
+
+        "Literal": function(node) {
+            var token = context.getFirstToken(node);
+            if (token.type === "RegularExpression" && !regex.test(token.value)) {
+                context.report(node, "Empty class.");
+            }
+        }
+
+    };
+
+};