Google Code Search: Difference between revisions

Revision as of 16:53, 12 March 2021

Revision as of 18:40, 28 October 2021

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== Regular expression engine ==

The site allowed the use of [[regular expression]]s in queries, which at thethat time was not offered by any other search engine for code.{{Citation needed|date=October 2009}} This makes it resemble [[grep]], but over the world's public code. The methodology employed combines a [[trigram]] [[Search engine indexing|index]] with a custom-built, [[ReDoS|denial-of-service]] resistant [[regular expression]] engine.<ref>{{cite web |url = http://swtch.com/~rsc/regexp/regexp4.html |title = Regular Expression Matching with a Trigram Index (or: How Google Code Search Worked) |author = Russ Cox |date = January 2012 |access-date = 2012-01-26 |archive-url = https://web.archive.org/web/20120128183712/http://swtch.com/~rsc/regexp/regexp4.html |archive-date = 2012-01-28 |url-status = live }}</ref>

In March 2010, the code of [[RE2 (software)|RE2]], the regular expression engine used in Google Code Search, was made open source.<ref>{{cite web|url=https://opensource.googleblog.com/2010/03/re2-principled-approach-to-regular.html|title=RE2: a principled approach to regular expression matching|publisher=|access-date=2016-09-24|archive-url=https://web.archive.org/web/20160927023834/https://opensource.googleblog.com/2010/03/re2-principled-approach-to-regular.html|archive-date=2016-09-27|url-status=live}}</ref>