in reply to Re: Replacement Regex
in thread Replacement Regex

This one will handle nested parens: 

    #!/usr/bin/perl -w
    use strict;
    $_ = '$a ($a (hi) $a) $a (()$a)';
    my  $re;
    $re = qr/(?:[^\(\)]*|\((??{$re})\))+/;
    s/(\($re\))|\$a/$1?$1:'$b'/eg;
    print;

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Update: should've referred to perlre manpage instead of relying on memory, the version there makes it somewhat nicer: 

    my  $re;
    $re = qr/\((?:(?>[^()]*)|(??{$re}))*\)/;
    s/($re)|\$a/$1?$1:'$b'/eg;

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Update: It appears to broken in 5.6.0 (gives output as tachyon shows below), but it works for me with 5.6.1.

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Re: Re: Re: Replacement Regex
by tachyon (Chancellor) on Mar 20, 2002 at 19:29 UTC

    <BEGIN_TEMPT_FATE>This one will handle nested parens:</END_TEMPT_FATE> 

    $_ = '(($a $a hi) $a ($a) $a)';
my  $re;
$re = qr/\((?:(?>[^()]*)|(??{$re}))*\)/;
s/($re)|\$a/$1?$1:'$b'/eg;
print;

__DATA__
(($a $a hi) $b ($a) $b)

    [download]

    Oops!

    cheers

    tachyon

    s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

[reply]
[d/l]
      $_ = '(($a $a hi) $a ($a) $a) $a ($a) $a ';
my $re;
($re=$_) =~ s/((\()|(\))|.)/${['(','']}[!$2]\Q$1\E${[')','']}[!$3]/gs;
$re = join'|',map{quotemeta}eval{/$re/};
die $@ if $@ =~ /unmatched/;
s/($re)|\$a/$1?$1:'$b'/eg;

      [download]
[reply]
[d/l]

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