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Regex experts should note that \n does not mean "newline," \d does not mean "digit," and so on: In MediaWiki syntax, the only use of \ is to escape metacharacters. / is special because it indicates the end of the regex. For example, insource:/yes/no/ is treated the same as insource:/yes/ no (because the keyword search for no/ ignores
Algebraic laws for regular expressions can be obtained using a method by Gischer which is best explained along an example: In order to check whether (X+Y) * and (X * Y *) * denote the same regular language, for all regular expressions X, Y, it is necessary and sufficient to check whether the particular regular expressions (a+b) * and (a * b ...
Complex regular expressions can often be constructed in several different ways, all with the same outputs but with greatly varying efficiency. If AWB is taking a long time to generate results because of a regex rule: Try constructing the expression a different way. There are several online resources with guidance to creating efficient regex ...
Self-validation: [19] re2c has a special mode in which it ignores all used-defined interface code and generates a self-contained skeleton program. Additionally, re2c generates two files: one with the input strings derived from the regular grammar, and one with compressed match results that are used to verify lexer behavior on all inputs.
For example, instead of supporting POSIX character classes in regex syntax, Ragel implements them as built-in production rules. As with usual parser generators, Ragel allows for handling code for productions to be written with the syntax. [9] The code yielding the above example from the official website is:
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]
Unanswered questions remain about a fatal shooting at a Madison, Wisconsin, private school as new details emerge about the shooter’s family life and possible ties to a California man who ...
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