Debug function extracted from Nette framework (http://nette.org/)

function dump($var, $return = FALSE)
{
   $output = "<pre class=\"dump\">" . _dump($var, 0) . "</pre>\n";

   if (!$return)
   {
      $trace = debug_backtrace();
      $i = isset($trace[1]['class']) && $trace[1]['class'] === __CLASS__ ? 1 : 0;
      if (isset($trace[$i]['file'], $trace[$i]['line']))
      {
     $output = substr_replace($output, ' <small>' . htmlspecialchars("in file {$trace[$i]['file']} on line {$trace[$i]['line']}", ENT_NOQUOTES) . '</small>', -8, 0);
      }
   }

   if ($return)
   {
      return $output;
   }
   else
   {
      echo $output;
      return $var;
   }
}

function _dump(&$var, $level)
{
   $maxDepth = 4;
   $maxLen = 250;

   $tableUtf = $tableBin = array();
   $reBinary = '#[^\x09\x0A\x0D\x20-\x7E\xA0-\x{10FFFF}]#u';
   if ($tableUtf === NULL)
   {
      foreach (range("\x00", "\xFF") as $ch)
      {
     if (ord($ch) < 32 && strpos("\r\n\t", $ch) === FALSE)
        $tableUtf[$ch] = $tableBin[$ch] = '\\x' . str_pad(dechex(ord($ch)), 2, '0', STR_PAD_LEFT);
     elseif (ord($ch) < 127)
        $tableUtf[$ch] = $tableBin[$ch] = $ch;
     else
     {
        $tableUtf[$ch] = $ch;
        $tableBin[$ch] = '\\x' . dechex(ord($ch));
     }
      }
      $tableBin["\\"] = '\\\\';
      $tableBin["\r"] = '\\r';
      $tableBin["\n"] = '\\n';
      $tableBin["\t"] = '\\t';
      $tableUtf['\\x'] = $tableBin['\\x'] = '\\\\x';
   }

   if (is_bool($var))
   {
      return ($var ? 'TRUE' : 'FALSE') . "\n";
   }
   elseif ($var === NULL)
   {
      return "NULL\n";
   }
   elseif (is_int($var))
   {
      return "$var\n";
   }
   elseif (is_float($var))
   {
      $var = (string) $var;
      if (strpos($var, '.') === FALSE)
     $var .= '.0';
      return "$var\n";
   } elseif (is_string($var))
   {
      if ($maxLen && strlen($var) > $maxLen)
      {
     $s = htmlSpecialChars(substr($var, 0, $maxLen), ENT_NOQUOTES) . ' ... ';
      }
      else
      {
     $s = htmlSpecialChars($var, ENT_NOQUOTES);
      }
      $s = strtr($s, preg_match($reBinary, $s) || preg_last_error() ? $tableBin : $tableUtf);
      $len = strlen($var);
      return "\"$s\"" . ($len > 1 ? " ($len)" : "") . "\n";
   }
   elseif (is_array($var))
   {
      $s = "<span>array</span>(" . count($var) . ") ";
      $space = str_repeat($space1 = '   ', $level);
      $brackets = range(0, count($var) - 1) === array_keys($var) ? "[]" : "{}";

      static $marker;
      if ($marker === NULL)
     $marker = uniqid("\x00", TRUE);
      if (empty($var))
      {

      }
      elseif (isset($var[$marker]))
      {
     $brackets = $var[$marker];
     $s .= "$brackets[0] *RECURSION* $brackets[1]";
      }
      elseif ($level < $maxDepth || !$maxDepth)
      {
     $s .= "<code>$brackets[0]\n";
     $var[$marker] = $brackets;
     foreach ($var as $k => &$v)
     {
        if ($k === $marker)
           continue;
        $k = is_int($k) ? $k : '"' . strtr($k, preg_match($reBinary, $k) || preg_last_error() ? $tableBin : $tableUtf) . '"';
        $s .= "$space$space1$k => " . _dump($v, $level + 1);
     }
     unset($var[$marker]);
     $s .= "$space$brackets[1]</code>";
      } else
      {
     $s .= "$brackets[0] ... $brackets[1]";
      }
      return $s . "\n";
   }
   elseif (is_object($var))
   {
      $arr = (array) $var;
      $s = "<span>" . get_class($var) . "</span>(" . count($arr) . ") ";
      $space = str_repeat($space1 = '   ', $level);

      static $list = array();
      if (empty($arr))
      {

      }
      elseif (in_array($var, $list, TRUE))
      {
     $s .= "{ *RECURSION* }";
      }
      elseif ($level < $maxDepth || !$maxDepth)
      {
     $s .= "<code>{\n";
     $list[] = $var;
     foreach ($arr as $k => &$v)
     {
        $m = '';
        if ($k[0] === "\x00")
        {
           $m = $k[1] === '*' ? ' <span>protected</span>' : ' <span>private</span>';
           $k = substr($k, strrpos($k, "\x00") + 1);
        }
        $k = strtr($k, preg_match($reBinary, $k) || preg_last_error() ? $tableBin : $tableUtf);
        $s .= "$space$space1\"$k\"$m => " . _dump($v, $level + 1);
     }
     array_pop($list);
     $s .= "$space}</code>";
      }
      else
      {
     $s .= "{ ... }";
      }
      return $s . "\n";
   }
   elseif (is_resource($var))
   {
      return "<span>" . get_resource_type($var) . " resource</span>\n";
   }
   else
   {
      return "<span>unknown type</span>\n";
   }
}