Self Modifying PHP

gistfile1.aw

<?php

$var = <<<VAR
1
VAR;

// do stuff here
echo $var;

register_shutdown_function(function() {
    $contents = file_get_contents(__FILE__);
    $pattern = "\$var = <<<VAR\n%s\nVAR;";

    $search_pattern = '@\\'. sprintf($pattern, '(.*)') .'@m';
    preg_match($search_pattern, $contents, $matches);
    $new_contents = preg_replace_callback($search_pattern, function($matches) {
        return str_replace($matches[1], $matches[1] + 1, $matches[0]);
    }, $contents);

    file_put_contents(__FILE__, $new_contents, LOCK_EX);
});