friendica/library/dddbl2/inc/Queue.class.php

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<?php
namespace DDDBL;
/**
* this class implements a queue of handler, which
* are called in a specified order.
*
* this allows the combiniation of different steps,
* like database-connection management, query execution
* and result parsing in a simple list of actions.
*
* Queue::getClone() returns a clone of the queue,
* which allows modifications of the queue by
* the executed handler.
* in this way different problems, like substituions,
* test-cases, statistics and much more can be solved,
* without destroying the configured order for other queries.
*
**/
class Queue {
/**
* the sorted (!) queue of handler to execute
*
**/
private $arrHandlerQueue = array();
/**
* @see \DDDBL\DataObject
*
* an DataObject, which is used to store the states of the queue
*
**/
private $objState = null;
/**
* @param $intPosition - the position to store the handler at
* @param $cloHandler - the handler to store in the queue
*
* @throws UnexpectedParameterTypeException - if the first parameter is not an integer
* @throws UnexpectedParameterTypeException - if the second parameter is not a callable
* @throws \Exception - if there is already a handler stored under the given position
*
* store the given handler under the given position in the queue.
* if the position is already in use an expection is thrown.
*
**/
public function addHandler($intPosition, $cloHandler) {
if(!is_int($intPosition))
throw new UnexpectedParameterTypeException('integer', $intPosition);
if(!is_callable($cloHandler))
throw new UnexpectedParameterTypeException('callable', $cloHandler);
if(!empty($this->arrHandlerQueue[$intPosition]))
throw new \Exception("there is already a handler stored for position: $intPosition");
$this->arrHandlerQueue[$intPosition] = $cloHandler;
ksort($this->arrHandlerQueue);
}
/**
* @param $intPosition - the position the handler for deletion is stored under
*
* @throws UnexpectedParameterTypeException - if the parameter is not an integer
*
* delete the handler stored under the given position
*
**/
public function deleteHandler($intPosition) {
if(!is_int($intPosition))
throw new UnexpectedParameterTypeException('integer', $intPosition);
if(array_key_exists($intPosition, $this->arrHandlerQueue))
unset($this->arrHandlerQueue[$intPosition]);
}
/**
* @returns (\DDDBL\Queue) - a clone of the queue-instance
*
* return a clone of the acutal queue
*
**/
public function getClone() {
return clone $this;
}
/**
* @param $arrParameter - the parameter to use when executing the queue-handler
*
* @returns (mixed) the state of "result"
*
* execute all handler in the queue, in the given
* order from low to high. after execution return the
* state "result".
*
* handler which generates an output
* are expected to store the result in this state
*
**/
public function execute(array $arrParameter) {
$this->getState()->add(array('result' => null));
foreach($this->arrHandlerQueue AS $cloHandler)
$cloHandler($this, $arrParameter);
return $this->getState()->get('result');
}
/**
* @returns (DataObject) - the DataObject which handles the states of the queue
*
* returns a reference to the DataObject, which
* stores all states of the queue.
*
* if no object exists till now, a new one is created
*
**/
public function getState() {
if(!is_object($this->objState))
$this->objState = new DataObject();
return $this->objState;
}
}