Re: When a regexp with /g needs to be run .. twice

$foo = ':{"';
$foo =~ s/([:,{])(.)/$1 $2/g;
print "'$foo'\n";
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If you just want a space after each of those, but not if it's the last char in a string:

1 while $foo =~ s/([:,{])([^ ])/$1 $2/g; # [^ ] is "not space"
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If you want it after the last char in a string, you'll need something like:

1 while $foo =~ s/([:,{])([^ ]|$)/$1 $2/g;
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-QM
--
Quantum Mechanics: The dreams stuff is made of

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Re^2: When a regexp with /g needs to be run .. twice
by AnomalousMonk (Archbishop) on Mar 05, 2018 at 15:52 UTC

But no while-loop at all is needed (and no captures) if lookarounds are used. (I'm substituting '.' rather than a space in the examples below for greater clarity — I hope.)

Inserting something after each character in the class including when it's at the end of the string:

c:\@Work\Perl\monks>perl -wMstrict -le
"my @foos = (':X,{X', ':X,{');
 ;;
 for my $foo (@foos) {
   printf qq{'$foo' -> };
   $foo =~ s( (?<= [:,{]) ){.}xmsg;
   print qq{'$foo'};
   }
"
':X,{X' -> ':.X,.{.X'
':X,{' -> ':.X,.{.'
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except

c:\@Work\Perl\monks>perl -wMstrict -le
"my @foos = (':X,{X', ':X,{');
 ;;
 for my $foo (@foos) {
   printf qq{'$foo' -> };
   $foo =~ s( (?<= [:,{]) (?= .) ){.}xmsg;
   print qq{'$foo'};
   }
"
':X,{X' -> ':.X,.{.X'
':X,{' -> ':.X,.{'
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\K

(?<= [:,{])

[:,{] \K

Update: Note also that in all cases (?! \z) can perhaps better express the "except at the end of the string" requirement than (?= .) — and may even be slightly faster!

Give a man a fish: <%-{-{-{-<

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