The following should do what you want if the input is in the format you specify, i.e. nested function with single arguments.

my $example1 = 'this(is(a(test)))';

foreach (0..4) {
    print "level $_: '", peel($example1, $_), "'\n";
}
print "level -1: '", peel($example1, -1), "'\n";

sub peel {
    my ($str, $level) = @_;
    if ($level < 0) {
        $str =~ /([^\(\)]+)\)+\Z/;
        return $1;
    }
    my $opening = '(?:[^\(]+\(){' . $level . '}';
    my $closing = '\){' . $level . '}';
    $str =~ /\A$opening(.+?)$closing\Z/;
    return $1;
}

[download]

Hope this helps, -gjb-

In reply to Re: Peeling the Peelings by gjb
in thread Peeling the Peelings by PetaMem

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