Listing all patterns that a regex matches

Question

I am looking for a way to list all possible patterns from a finite regex (with no duplicates). Is there any source available?

@Artha Any language preference? – moinudin Jan 05 '11 at 14:51 — moinudin, Jan 05 '11 at 14:51
Can you give an example of input and expected output? – Gumbo Jan 05 '11 at 15:07 — Gumbo, Jan 05 '11 at 15:07
Do you mean all possible matches from a regex? – Jan 05 '11 at 19:01 — , Jan 05 '11 at 19:01

score 3 · Accepted Answer · edited May 23 '17 at 09:58

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Although it won't cover some advanced features, and has its own share of other caveats, Regexp::Genex seems to be close to what you are looking for.

There's also this thread of PerlMonks which is relevant enough (as well as explaining how Regexp::Genex might not do for you, and some roll-yourself alternatives).

Otherwise, as per Jeffrey Friedl's Mastering Regular Expressions, you could use the /g modifier, coupled with the (?{CODE}) extension and a pattern that will never match, ala:

perl -E '$_ = 'Mastering Regular Expressions'; /(\p{L}*)(?{ say qq![$^N]! })(?!)/g;'

edited May 23 '17 at 09:58

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answered Jan 06 '11 at 03:31

Hugmeir

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Is there any fully developed code -- Regex::Genex was alpha and does not support ^ $ \G... – Artha Jan 06 '11 at 15:03
Not that I know, unfortunately - Maybe a combination of that example from Mastering Regular Expressions (if you really, really needed it, you could even use $& and friends instead of capturing groups.. I don't know whenever $^{MATCH} works inside (?{CODE}) blocks) plus String::Random could do the trick? – Hugmeir Jan 06 '11 at 15:09

score 0 · Answer 2 · answered May 15 '13 at 05:15

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A Haskell program based on Perl's Regexp::Genex can be found on Github and on Hackage.

According to the author, it was inspired by Regexp::Genex, but "uses a random-walk approach for character classes, instead of enumerating all possibilities."

answered May 15 '13 at 05:15

waldyrious

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Listing all patterns that a regex matches

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