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<?php
/**
* @version $Id$
* @package Koowa_Command
* @copyright Copyright (C) 2007 - 2012 Johan Janssens. All rights reserved.
* @license GNU GPLv3 <http://www.gnu.org/licenses/gpl.html>
* @link http://www.nooku.org
*/
/**
* Command Chain
*
* The command queue implements a double linked list. The command handle is used
* as the key. Each command can have a priority, default priority is 3 The queue
* is ordered by priority, commands with a higher priority are called first.
*
* @author Johan Janssens <johan@nooku.org>
* @package Koowa_Command
*/
class KCommandChain extends KObjectQueue
{
/**
* Enabled status of the chain
*
* @var boolean
*/
protected $_enabled = true;
/**
* The chain's break condition
*
* @see run()
* @var boolean
*/
protected $_break_condition = false;
/**
* The command context object
*
* @var KCommandContext
*/
protected $_context = null;
/**
* Constructor
*
* @return void
*/
public function __construct(KConfig $config = null)
{
//If no config is passed create it
if(!isset($config)) $config = new KConfig();
parent::__construct($config);
$this->_break_condition = (boolean) $config->break_condition;
$this->_enabled = (boolean) $config->enabled;
$this->_context = $config->context;
}
/**
* Initializes the default configuration for the object
*
* Called from {@link __construct()} as a first step of object instantiation.
*
* @param object An optional KConfig object with configuration options.
* @return void
*/
protected function _initialize(KConfig $config)
{
$config->append(array(
'context' => new KCommandContext(),
'enabled' => true,
'break_condition' => false,
));
parent::_initialize($config);
}
/**
* Attach a command to the chain
*
* The priority parameter can be used to override the command priority with
* enqueing the command.
*
* @param object A KCommand object
* @param integer The command priority, usually between 1 (high priority) and 5 (lowest),
* default is 3. If no priority is set, the command priority will be used
* instead.
* @return KCommandChain
* @throws InvalidArgumentException if the object doesn't implement KCommandInterface
*/
public function enqueue(KObjectHandlable $cmd, $priority = null)
{
if (!$cmd instanceof KCommandInterface) {
throw new InvalidArgumentException('Command needs to implement KCommandInterface');
}
$priority = is_int($priority) ? $priority : $cmd->getPriority();
return parent::enqueue($cmd, $priority);
}
/**
* Run the commands in the chain
*
* If a command returns the 'break condition' the executing is halted.
*
* @param string The command name
* @param mixed The command context
* @return void|boolean If the chain is broken, returns the break condition. Default returns void.
*/
public function run( $name, KCommandContext $context )
{
if($this->_enabled)
{
foreach($this as $command)
{
if ( $command->execute( $name, $context ) === $this->_break_condition) {
return $this->_break_condition;
}
}
}
}
/**
* Enable the chain
*
* @return void
*/
public function enable()
{
$this->_enabled = true;
return $this;
}
/**
* Disable the chain
*
* If the chain is disabled running the chain will always return TRUE
*
* @return void
*/
public function disable()
{
$this->_enabled = false;
return $this;
}
/**
* Set the priority of a command
*
* @param object A KCommand object
* @param integer The command priority
* @return KCommandChain
*/
public function setPriority(KObjectHandlable $cmd, $priority)
{
if (!$cmd instanceof KCommandInterface) {
throw new InvalidArgumentException('Command needs to implement KCommandInterface');
}
return parent::setPriority($cmd, $priority);
}
/**
* Get the priority of a command
*
* @param object A KCommand object
* @param integer The command priority
* @return integer The command priority
*/
public function getPriority(KObjectHandlable $cmd)
{
if (!$cmd instanceof KCommandInterface) {
throw new InvalidArgumentException('Command needs to implement KCommandInterface');
}
return parent::getPriority($cmd);
}
/**
* Factory method for a command context.
*
* @return KCommandContext
*/
public function getContext()
{
return clone $this->_context;
}
}
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