function my_handler($filename) {
  echo $filename . "\n";
}
find_files('c:/', '/php$/', 'my_handler');

function find_files($path, $pattern, $callback) {
  $path = rtrim(str_replace("\\", "/", $path), '/') . '/';
  $matches = Array();
  $entries = Array();
  $dir = dir($path);
  while (false !== ($entry = $dir->read())) {
    $entries[] = $entry;
  }
  $dir->close();
  foreach ($entries as $entry) {
    $fullname = $path . $entry;
    if ($entry != '.' && $entry != '..' && is_dir($fullname)) {
      find_files($fullname, $pattern, $callback);
    } else if (is_file($fullname) && preg_match($pattern, $entry)) {
      call_user_func($callback, $fullname);
    }
  }
}

combine([1,2]) == [[1], [2], [1,2]];

var combine = function(a) {
  var fn = function(n, src, got, all) {
    if (n == 0) {
      if (got.length > 0) {
        all[all.length] = got;
      }
      return;
    }
    for (var j = 0; j < src.length; j++) {
      fn(n - 1, src.slice(j + 1), got.concat([src[j]]), all);
    }
    return;
  }
  var all = [];
  for (var i=0; i < a.length; i++) {
    fn(i, a, [], all);
  }
  all.push(a);
  return all;
}