From c1d3b6222ee853b42c000e7d0f6c12b90cf5fa63 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Thu, 5 Apr 2018 09:45:11 -0400
Subject: [PATCH] code review: use regex to speed up CSS selector validation

---
 src/js/static-ext-filtering.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/js/static-ext-filtering.js b/src/js/static-ext-filtering.js
index c4da31bd7..59fc173ed 100644
--- a/src/js/static-ext-filtering.js
+++ b/src/js/static-ext-filtering.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
     uBlock Origin - a browser extension to block requests.
-    Copyright (C) 2017 Raymond Hill
+    Copyright (C) 2017-2018 Raymond Hill
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -94,7 +94,11 @@
         } catch (ex) {
             matchesFn = div.querySelector.bind(div);
         }
+        // Quick regex-based validation -- most cosmetic filters are of the
+        // simple form and in such case a regex is much faster.
+        var reSimple = /^[#.][\w-]+$/;
         return function(s) {
+            if ( reSimple.test(s) ) { return true; }
             try {
                 matchesFn(s + ', ' + s + ':not(#foo)');
             } catch (ex) {