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I'm trying to find a regex to split a call to a method

boo(a,b), c

so it would return

boo(a,b)

and

c

after splitting by it. Is it possible doing it with regex? Thanks.

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  • 1
    Just find ), and before that is the method and after is the extra stuff? Commented May 3, 2012 at 15:00
  • Are you looking at plaintext, the .class file, or are you reading it in? Commented May 3, 2012 at 15:00
  • the problem is that it has to be recursive. i.e boo(a(a,b),b),c should split by the "," before the c, only find the "highest level" ','s The String is read from a file, manipulated and is in a String object Commented May 3, 2012 at 15:03
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    Instead RegEx you should try parsing it through a Stack. Commented May 3, 2012 at 15:05
  • @Lablabla If that's the case, you should probably edit your post because you did not mention anything of this sort. Also, how would you ever get a method call to look like that in the first place? Commented May 3, 2012 at 15:05

2 Answers 2

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Regular languages cannot express recursion. At the point where you realise that the solution would involve recursion, it is not possible to express this in a "pure" regex engine (in practice, most regex engines have some sort of extension to allow limited violation of this rule).

Since you're writing in a Java context - why not use the nice programming language to perform this fairly simple manipulation of a string, rather than trying to shoehorn a regex into the solution? :)

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3 Comments

+1, for this clear approach. May or may not be it to be done in RegEx is another matter.
it's a about regexes. we could use other methods, however since the homework are all about regexes, if it's possible, I'd rather do it this way
Fair enough (though I think the question would be better if you emphasize that you're specifically thinking about regexes for educational purposes, instead of merely thinking it's a practical way to solve this problem). Though I stand by my answer - strictly you can't do it with regexes, but I'm sure Java's regex engine has something in to cope with this. I leave it to others to point out what that might be! Maybe "no" really is the correct answer in the context of this homework.
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I'm not sure of what you really regarding your question want but with the given case :

"boo(a,b), c".split("(?<=\\)),") //look for a ',' preceeded by ')'

gives you an array containing ["boo(a,b)","c"].

EDIT :

For this case : boo(a(a,b),b),c, use :

"boo(a(a,b),b),c".split("(?<=\\)),(?!(\\w\\p{Punct}?)+\\))")

(?!(\\w\\p{Punct}?)+\\)) means you don't accept match if it's followed by (a word and one or zero punctuation) n times, and a right parenthesis.

The result is an array containing ["boo(a(a,b),b)","c"].

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