How to match more than 32766 times in regex?

rsFalse has asked for the wisdom of the Perl Monks concerning the following question:

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Comment on How to match more than 32766 times in regex?

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Match twice by choroba (Cardinal) on Dec 01, 2015 at 18:23 UTC
Update: The whole question is in the title. So does the answer. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l]
Re: How to match more than 32766 times in regex? by BrowserUk (Patriarch) on Dec 01, 2015 at 18:24 UTC
Before I've even read your question; my suggestion is that you take up Python. Going through a bunch of known limitations, and raising questions about them as if you've newly discovered them, is a sad strategy. 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^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
Re^4: How to match more than 32766 times in regex? by rsFalse (Chaplain) on Dec 01, 2015 at 19:49 UTC
Re^5: How to match more than 32766 times in regex? by davido (Cardinal) on Dec 01, 2015 at 21:48 UTC
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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]
Re: How to match more than 32766 times in regex? by Anonymous Monk on Dec 01, 2015 at 18:54 UTC
(shrug) Admittedly at this point BrowserUK's suggestion makes sense to me. But, anyway... use a non-backtracking engine. Or change `REG_INFTY` value in `regcomp.h` and recompile perl (I have no idea whether it will work or not).	[reply] [d/l] [select]
Re^2: How to match more than 32766 times in regex? by FreeBeerReekingMonk (Deacon) on Dec 01, 2015 at 19:48 UTC
`use strict; use warnings; my $X = "a1b2c3d4e5"; # or use File::Slurp my $s = "(\\w\\d)"; # my pattern match $s my $m = qr/$s/; # compiled to a regular expression $m my $counter = 0; while($X=~s/$m//){ ++$counter; next unless $counter > 32766; # wait for it... print "this is the $counter iteration, got $1 \n"; }` [download]	[reply] [d/l]
Re^3: How to match more than 32766 times in regex? by BrowserUk (Patriarch) on Dec 01, 2015 at 20:01 UTC
No need to go to those lengths: `$s = '0123456789' x 100000;; ( $m ) = $s =~ m[((?:(?:0123456789){32000}){3})];; print length $m;; 960000` [download] But for any given application there's almost certainly a better way of tackling the problem. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^3: How to match more than 32766 times in regex? by Anonymous Monk on Dec 01, 2015 at 20:27 UTC
Hmmm, I thought the OP had problems with 'complex regex recursion limit exceeded'. If he just wanted to match something like `(\w\d){32767}`, sure.	[reply] [d/l]
Re^4: How to match more than 32766 times in regex? by FreeBeerReekingMonk (Deacon) on Dec 01, 2015 at 21:25 UTC
Re^5: How to match more than 32766 times in regex? by karlgoethebier (Abbot) on Dec 02, 2015 at 09:55 UTC
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Re^5: How to match more than 32766 times in regex? by rsFalse (Chaplain) on Dec 01, 2015 at 22:26 UTC
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Re: How to match more than 32766 times in regex? by rsFalse (Chaplain) on Nov 01, 2018 at 11:32 UTC
perlre: "This is usually 32766 on the most common platforms" What do you think about the need to expand the perlre section about quantifiers with the suggestion how to handy overcome '+' and '*' limitation and make the equivalent regex which matches {0,infty}? The regex should be readable and not slow in performance.	[reply]
Re^2: How to match more than 32766 times in regex? by choroba (Cardinal) on Nov 06, 2018 at 16:13 UTC
Feel free to send a perlbug with the patch to the documentation. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l]

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