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in reply to Re^2: Faster regex to split a string into runs of similar characters?
in thread Faster regex to split a string into runs of similar characters?

No. That won't match a single character 'run'.

Right. /((.)\2*)/g does though, and this time it is faster (by 12% on my computer).

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Re^4: Faster regex to split a string into runs of similar characters?
by BrowserUk (Patriarch) on Nov 21, 2016 at 11:31 UTC
    /((.)\2*)/g does though,

    Huh:) How did I missed that?!

    ... faster (by 12% on my computer).

    Only 4% difference on mine under 5.10 or 5.22:

    ## this 5.10 [0]{} Perl> cmpthese -1,{a=>q[ 1 while $s =~ m[((?=(.))\2+)]sg;],b=>q[ +1 while $s =~ m[((.)\2*)]sg;] };; Rate a b a 204/s -- -4% b 212/s 4% -- [0]{} Perl> cmpthese -1,{a=>q[ 1 while $s =~ m[((?=(.))\2+)]sg;],b=>q[ +1 while $s =~ m[((.)\2*)]sg;] };; Rate a b a 204/s -- -4% b 212/s 4% -- [0]{} Perl> C:\test>\Perl22\bin\perl.exe \Perl22\bin\p1.pl [0]{} Perl> $s = join'', map{ chr( 65+rand(26) ) x rand( 100 ) } 1 .. +1000;; [0]{} Perl> cmpthese -1,{a=>q[ 1 while $s =~ m[((?=(.))\2+)]sg;],b=>q[ +1 while $s =~ m[((.)\2*)]sg;] };; Rate a b a 229/s -- -3% b 235/s 3% -- [0]{} Perl> cmpthese -1,{a=>q[ 1 while $s =~ m[((?=(.))\2+)]sg;],b=>q[ +1 while $s =~ m[((.)\2*)]sg;] };; Rate a b a 229/s -- -4% b 238/s 4% --

    A small, but consistent gain. Thanks.


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