#!/usr/bin/perl -w
#By Ørjan Johansen, June 2009-Jan 2012.  This file is in the public domain.

my $debug =
    ($#ARGV >= 0 and $ARGV[0] =~ m/^-d([1-2]?)$/ and shift and ($1 || 2));
$| = 1;

$_ = join '', <>;
while (1) {
        print "\n[", $_, "]" if $debug >= 2;
        if (s!^GG((?:[^/\\]|\\.)*?)GG!!s) {
            my $s = $1;
            $s =~ s/\\(.)/$1/gs;
            $d = getc();
            no warnings;
            while (s/(?:\Q$s\E)/$d/) { 
            }
        }
        elsif (s!^([^/\\][^/\\G]*)!! or s!^\\(.)!!s) { 
                print($1);
                print "\n[", $_, "]" if $debug == 1;
        }
        elsif (s!^/((?:[^/\\]|\\.)*)/((?:[^/\\]|\\.)*)/!!s) {
            my ($s,$d) = ($1,$2);
            $s =~ s/\\(.)/$1/gs;
            $d =~ s/\\(.)/$1/gs;
            while (s/(?:\Q$s\E)/$d/) { 
            }
        }
        else { last; }
}