class Command {
	public function add()  {
		$command = new Read();
		$this->_commands []= $command;
	}
 
	public funtion run()
	{
		foreach($this->_commands as $cmd)  {
			$cmd->execute();
		}
	}
}
 
$command = new Command();
$command->add();
$command->add();
$command->add();
$command->add();
$command->run(); // dedigimizde tum komutları çalıştırır

interface ICommand  {
	public function execute();
	public function undo();
        public function redo();
        public function cevir();
}
 
class Read implements ICommand {
 
    private $obj;
    public $act;
    public $count;
    public $_page;
 
    public function __construct($act, $count, $obj) {
        $this->obj = $obj;
        $this->act = $act;
        $this->count = $count;
    }
 
    public function execute() {
        $this->_page = $this->obj->Read($this->act, $this->count);
 
        echo $this->count.' sayfa ('.$this->act.') yönde değişti.<br>';
        return true;
 
    }
 
    public function undo() {
        echo 'undo : ';
        $this->cevir();
        $this->execute();
    }
 
    public function redo() {
 
        echo 'redo : ';
        $this->cevir();
        $this->execute();
    }
 
    public function cevir() {
        $this->act = ($this->act == '+') ? '-' : '+';
    }
 
}
class Book  {
	private $_commands = array();
        private $_redo = array();
	private $_undo = array();
        private $pager;
 
	public function __construct($obj)  {
            $this->pager = new Pager();
	}
 
	public function addCommand($act, $count)  {
 
            $command = new Read($act, $count, $this->pager);
            $this->_commands []= $command;
	}
 
	public function activate()  {
            foreach($this->_commands as $cmd)  {
                if($cmd->execute())  {
			array_push($this->_undo, $cmd);
		}
            }
 
	}
 
	public function undo()  {
            $cmd = array_pop($this->_undo);
            array_push($this->_redo, $cmd);
            $cmd->undo();
	}
 
        public function redo()
        {
            $cmd = array_pop($this->_redo);
            array_push($this->_undo, $cmd);
            $cmd->redo();
        }
 
        public function display()
        {
            $count = count($this->_undo);
 
            echo 'şu an '.$this->_undo[$count - 1]->_page.'. sayfadasınız';
        }
 
}

echo '<pre>';
$Book = new Book($page);
$Book->addCommand('+', 5);
$Book->addCommand('+', 1);
$Book->addCommand('-', 3);
$Book->addCommand('+', 4);
$Book->addCommand('-', 6);
$Book->activate();
$Book->undo();
$Book->undo();
$Book->redo();
$Book->display();