-- FileCopyCommand::EXECUTE --

Warning: copy(test) [function.copy]: failed to open stream: No such file or directory in /kunden/145289_55118/code/php/zend/patterns/history.php on line 85
-- FileCopyCommand::UNDO --

Warning: unlink(test.tmp) [function.unlink]: No such file or directory in /kunden/145289_55118/code/php/zend/patterns/history.php on line 73
SUCCESS: Undo, -- FileCopyCommand::REDO --
-- FileCopyCommand::EXECUTE --

Warning: copy(test) [function.copy]: failed to open stream: No such file or directory in /kunden/145289_55118/code/php/zend/patterns/history.php on line 85


<?php

/*

 draft and caseStudy history class 


Alternatives:
http://c2.com/cgi/wiki?MementoPattern
visitor pattern

credit: "do, undo, redo pattern"
http://www.michaelmcgrady.com/do_undo.jsp

*/ 

define ('NEW_LINE', '<br/>');

//------------------------------------------------------------
// Command Pattern 
//------------------------------------------------------------

class Command 
{

  function add($cmd)
  {
    $this->_commands[] = $cmd;
  }
  
  function undo() 
  {
    $this->history->undoCommand();
  }

  function redo() 
  {
    $this->history->redoCommand();
  }
  
  function run() 
  {
    // history executes and adds Command to History
    foreach ($this->_commands as $cmd) {
       $this->history->inVoke($cmd);
    }
  } 

  function Command($history) 
  {
    $this->history = $history;
  }
};

//------------------------------------------------------------

/*
interface ICommand {
  function execute () {}
  function undoCommand () {}
  function redoCommand () {}
};
*/

class FileCopyCommand // implements ICommand
{
  var $src = 'test';
  var $target = 'test.tmp';

  function undoCommand()
  {
    echo '-- FileCopyCommand::UNDO --'.NEW_LINE;
    unlink($this->target);
  }

  function redoCommand()
  {
    echo '-- FileCopyCommand::REDO --'.NEW_LINE;
    $this->execute();
  }
  
  function execute () 
  {
    echo '-- FileCopyCommand::EXECUTE --'.NEW_LINE;
    copy($this->src, $this->target);
  }
};


//------------------------------------------------------------
// History Pattern 
//------------------------------------------------------------

class History 
{

  var $maxHistory = 2;
  var $redoList = array();
  var $undoList = array();


  function inVoke($cmd)
  {
      $cmd->execute();
      $this->addToHistory($cmd);
  }

  function undoCommand()
  {
    if (sizeof($this->undoList) > 0) {
      // echo '--UNDO--';
      $undoCommand = $this->removeFirst($this->undoList);
      $undoCommand->undoCommand();
      $this->addFirst($undoCommand, $this->redoList);
    }
  }

  function redoCommand()
  {
    if (sizeof($this->redoList) > 0) {
      // echo '--REDO--';
      $redoCommand = $this->removeFirst($this->redoList);
      $redoCommand->redoCommand();
      $this->addToHistory($redoCommand);
    }
  }
 
  function addToRedoList($cmd)
  {
    $this->addFirst($cmd, $this->redoList);
    if (sizeof($this->history) > $this->maxHistory) {
      $this->removeLast($this->redoList);
    }
  }

  function addToHistory($cmd)
  {
    $this->addFirst($cmd, $this->undoList);
    if (sizeof($this->undoList) > $this->maxHistory) {
      $this->removeLast($this->undoList);
    }
  }

  function addFirst($cmd, &$history)
  {
    array_unshift($history, $cmd);
    // var_dump($this->undoList);
  }

  function removeLast(&$history)
  {
    array_pop($history);
  }

  function removeFirst(&$history)
  {
    $cmd = array_shift($history);
    return $cmd;
  }
};


//------------------------------------------------------------
// Test
//------------------------------------------------------------

// command need to know history
$history = new History();

$cmd = new Command($history);

$cmd->add(new FileCopyCommand);

//------------------------------------------------------------

$cmd->run();


if (file_exists('test.tmp')) {
echo 'SUCCESS: Command, ';
}

//------------------------------------------------------------

// $history->undoCommand();
$cmd->undo();

if (!file_exists('test.tmp')) {
echo 'SUCCESS: Undo, ';
}

//------------------------------------------------------------

$cmd->redo();

if (file_exists('test.tmp')) {
echo 'SUCCESS: Redo. :-) ';
}

//------------------------------------------------------------

show_source(__FILE__);
?>