Ruby: add RegExpPatterns module

ruby/ql/lib/codeql/ruby/security/performance/RegExpTreeView.qll

@@ -59,6 +59,19 @@ module RegExpFlags {
   }
 }
 
+/**
+ * Provides regular expression patterns.
+ */
+module RegExpPatterns {
+  /**
+   * Gets a pattern that matches common top-level domain names in lower case.
+   */
+  string commonTLD() {
+    // according to ranking by http://google.com/search?q=site:.<<TLD>>
+    result = "(?:com|org|edu|gov|uk|net|io)(?![a-z0-9])"
+  }
+}
+
 /**
  * An element containing a regular expression term, that is, either
  * a string literal (parsed as a regular expression)