AAA class functions.

  /**
  * @deprecated Ambiguously abominable atrocity.
  * @see \tool::setFilterTarget()
  * @see \tool::startFilter()
  * @see \tool::stopFilter()
  * @see \tool::breakpoint()
  */ // FIX: Deprecated.
  static function debugFilter($mode, $param = NULL)
  {
    switch(strtoupper($mode))
    {
      case 'SET':
        if(self::$_filterEnabled)
          throw new ErrorException('Unable to configure running filter.');

        if(empty($param))
          self::$_filterTarget = NULL;
        else
          self::$_filterTarget = $param;
        break;
      case 'START':
        if(self::$_filterEnabled)
          break;

        ob_start(array('tool', 'ob_debugfilter'), version_compare(PHP_VERSION, '5.4.0', '<') ? 2 : 1);
        self::$_filterEnabled = true;
        print 'Debug output started.';
        break;
      case 'STOP':
        if(self::$_filterEnabled)
        {
          print 'Debug output stopped.';
          ob_end_flush();
          self::$_filterEnabled = false;
        }
        break;
      default:
        if(self::$_filterEnabled)
          print new toolBreakpoint($mode);
    }
  }