I need to replace some metachars ? => # and * => ? but only if they are unescaped and at the same time unescape all escaped chars.
I first tried many variations with a couple of substitutions but none of them worked. At last I found something that works but looks somewhat odd: 
my $string = 't?e\\\\xt\\\\* with escapes\\*';

my $result = '';
while (not $string =~ m/\G\z/gc) {
    if ($string =~ /\G([^\\*?]+)/gc) { # normal chars
        $result .= $1;
    }
    elsif ($string =~ /\G\\(.)/gc) {   # escaped
        $result .= $1;
    }
    elsif ($string =~ /\G\*/gc) {      # unescaped *
        $result .= '?';
    }
    elsif ($string =~ /\G\?/gc) {      # unescaped ?
        $result .= '#';
    }
}
$string = $result; 
print $string;     # prints 't#e\xt\? with escapes*'

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As I said I can live with it but I wonder if there is also a solution based on a couple of s///g; It is somewhat embarrassing not to find a solution for such a seemingly simple problem. So I hope for your wisdom to learn and improve my regex arsenal.

Thanks
Michael

In reply to Replace only unescaped metachars by Anonymous Monk

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