Self written array_column of function less compatible than PHP version 5.5

array_column is used to fetch elements from a 2-D array (PHP 5.5 new function), but we sometimes need to use it in a lower version of PHP

if( ! function_exists('array_column'))
{
  function array_column($input, $columnKey, $indexKey = NULL)
  {
    $columnKeyIsNumber = (is_numeric($columnKey)) ? TRUE : FALSE;
    $indexKeyIsNull = (is_null($indexKey)) ? TRUE : FALSE;
    $indexKeyIsNumber = (is_numeric($indexKey)) ? TRUE : FALSE;
    $result = array();

    foreach ((array)$input AS $key => $row)
    { 
      if ($columnKeyIsNumber)
      {
        $tmp = array_slice($row, $columnKey, 1);
        $tmp = (is_array($tmp) && !empty($tmp)) ? current($tmp) : NULL;
      }
      else
      {
        $tmp = isset($row[$columnKey]) ? $row[$columnKey] : NULL;
      }
      if ( ! $indexKeyIsNull)
      {
        if ($indexKeyIsNumber)
        {
          $key = array_slice($row, $indexKey, 1);
          $key = (is_array($key) && ! empty($key)) ? current($key) : NULL;
          $key = is_null($key) ? 0 : $key;
        }
        else
        {
          $key = isset($row[$indexKey]) ? $row[$indexKey] : 0;
        }
      }

      $result[$key] = $tmp;
    }

    return $result;
  }
}