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Regular Expression Flavor Comparison – Detailed comparison of the most popular regular expression flavors; Regexp Syntax Summary; Online Regular Expression Testing – with support for Java, JavaScript, .Net, PHP, Python and Ruby; Implementing Regular Expressions – series of articles by Russ Cox, author of RE2; Regular Expression Engines
A regular expression (shortened as regex or regexp), [1] sometimes referred to as rational expression, [2] [3] is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings , or for input validation .
In the case of a web application, the programmer may use the same regular expression to validate input on both the client and the server side of the system. An attacker could inspect the client code, looking for evil regular expressions, and send crafted input directly to the web server in order to hang it. [9]
A snippet of JavaScript code with keywords highlighted in different colors The syntax of JavaScript is the set of rules that define a correctly structured JavaScript program. The examples below make use of the log function of the console object present in most browsers for standard text output .
re2c is a free and open-source lexer generator for C, C++, D, Go, Haskell, Java, JavaScript, OCaml, Python, Rust, V and Zig. It compiles declarative regular expression specifications to deterministic finite automata.
Regex searches that take too long will "time out" and return only partial results. Overuse of slow regex searches might cause temporary throttling of the feature for yourself and/or everyone on Wikipedia. (However, you cannot affect the site performance of Wikipedia as a whole simply by abusing regex search.) Remember that a single regex search ...
Pages in category "Regular expressions" The following 12 pages are in this category, out of 12 total. ... Code of Conduct; Developers; Statistics; Cookie statement;
The RE2 algorithm has been rewritten in Rust as the package "regex". CloudFlare's web application firewall uses this package because the RE2 algorithm is immune to ReDoS. [8] Russ Cox also wrote RE1, an earlier regular expression based on a bytecode interpreter. [9] OpenResty uses a RE1 fork called "sregex". [10]