Re: How to match more than 32766 times in regex?

Replies are listed 'Best First'.
Re^2: How to match more than 32766 times in regex? by rsFalse (Chaplain) on Dec 01, 2015 at 18:45 UTC
I've read about limitation, but is it a way to compose regex without big time penalty? I tried smth like /$regex$regex$regex*/ if I wanted match up to 96000 times, but it takes a lot of time regex to finish.	[reply]
Re^3: How to match more than 32766 times in regex? by FreeBeerReekingMonk (Deacon) on Dec 01, 2015 at 19:15 UTC
To make a regexp faster, search from start or end, using ^ or $ to bind it to that point. But can you explain what you want to do? I am sure there is a better way. As for code, look at the multiplier x 3 that concatenates the string 3 times. Then, we use qr to quote a regular expression, which we then use and capture the results in @R, which we then print. Hope this gets you ideas. (duplicating the expression to capture it 2 times) `$ perl -e '$s="(\\d\\w)" x 3; $X="a1b2c3d4e5"; $m=qr/$s/; @R=$X=~$m; +print join(";",@R)."\n"' 1b;2c;3d` [download] another way could be divide and conquer. Paying a penalty by using $' (the rest of the string that has not matched yet) for the next iteration. another idea is using index	[reply] [d/l]
Re^4: How to match more than 32766 times in regex? by FreeBeerReekingMonk (Deacon) on Dec 01, 2015 at 19:57 UTC
caveat about the multiplier: It assumes you can match that amount, so if you have 10 patterns to find, but matching 3 at a time, you are unable to match the last one.	[reply]
Re^4: How to match more than 32766 times in regex? by rsFalse (Chaplain) on Dec 01, 2015 at 19:49 UTC
I had a input line of 100k characters '0' or '1'. I tried to solve a problem and find length of alternating subsequence. My approach was `() = $line =~ /(.)\1/g` [download] When I got test-case '0' x 100k, I gain answer of 4, not 1. Because (I think) it found three matches of length 32678 and the rest shorter match. When I used `() = $line =~ /(.)\1\1\1\1*/g` [download] - it worked slower on test case '01' x 50k. But I can't say how slower, because it was only a part of program (maybe not hot point).	[reply] [d/l] [select]
Re^5: How to match more than 32766 times in regex? by davido (Cardinal) on Dec 01, 2015 at 21:48 UTC
Re^6: How to match more than 32766 times in regex? by Anonymous Monk on Dec 01, 2015 at 22:38 UTC
Re^5: How to match more than 32766 times in regex? by FreeBeerReekingMonk (Deacon) on Dec 01, 2015 at 21:04 UTC
Re^5: How to match more than 32766 times in regex? by Anonymous Monk on Dec 01, 2015 at 20:32 UTC
Re^3: How to match more than 32766 times in regex? by BrowserUk (Patriarch) on Dec 01, 2015 at 19:07 UTC
if I wanted match up to 96000 times, What's your application? With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^3: How to match more than 32766 times in regex? by Anonymous Monk on Dec 01, 2015 at 18:59 UTC
"... if I wanted match up to 96000 times ..." You're fired.	[reply]