22303 2008-11-16 21:27:37 -0800 Optimize /^x/ regexps to fail fast 2011-07-05 14:26:01 -0700 1 1 1 Unclassified WebKit JavaScriptCore 528+ (Nightly build) Mac OS X 10.5 RESOLVED WORKSFORME P2 Normal --- 1 ggaren ggaren barraclough oldest_to_newest 98998 0 ggaren 2008-11-16 21:27:37 -0800 See bug 18086 -- let's do that optimization in WREC. Here's what I think can be a layout test: // Check that an initial ^ will result in a faster match fail. var s = "a"; var i; for (i = 0; i < 20; i++) s = s + s; function test(string, regexp) { var start = new Date; for (i = 0; i < 100; i++) regexp.test(s); return new Date - start; } var result1 = test(s, /b/); var result2 = test(s, /^b/); alert(result1); alert(result2); if ((result1 - result2) / result1 > .75) testPassed("Congrats, your browser didn't hang!"); testFailed("/^b/ did not discover a match failure faster than /b/"); var successfullyParsed = true; 432405 1 barraclough 2011-07-05 14:26:01 -0700 This optimization now exists in YARR.