my %escaped = (
               "\n" => '\n',
               "\r" => '\r',
               " "  => '\s',
               # ...
              );

my $string = "1\r\n 2 \n";
while ($string =~ /(.)/sg) {
    my $ch = $1;
    $ch = $escaped{$ch} if exists $escaped{$ch};
    print "Encountered character: $ch\n";
}