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It wasn't just regex search that I loved Code Search for; it allowed search over functions, classes, etc. It also listed the functions defined in a file in a pane on the left. I wonder if they used a regex for that? It would be nice if they opensource that component as well.

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> I wonder if they used a regex for that?

Not possible. You have to parse the file fully to extract that information; regular expressions aren't powerful enough.

It depends on what you mean by regex. Modern engines go beyond the capabilities of regular expression grammars, describing things that are not possible with a finite-state machine.

And for example, the regex engine from Perl 5.10 and up has had support for recursive patterns. See the faq: http://perldoc.perl.org/perlfaq6.html#Can-I-use-Perl-regular...

And once you have recursion support, you can parse context-free languages.

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