Regular Expression Matching with a Trigram IndexRegular Expression Matching with a Trigram Index or How Google Code Search Worked Russ Cox rsc@swtch.com January 2012 Introduction In the summer of 2006, I was lucky enough to be an intern at Google. At the time, Google had an internal tool called gsearch that acted as if it ran grep over all the files in the Google source tree and printed the results. Of course, that implementation would be fairl
