<?php /** * TQueue, TQueueIterator classes * * @author Qiang Xue <qiang.xue@gmail.com> * @link http://www.pradosoft.com/ * @copyright Copyright © 2005 PradoSoft * @license http://www.pradosoft.com/license/ * @version $Id$ * @package System.Collections */ /** * TQueue class * * TQueue implements a queue. * * The typical queue operations are implemented, which include * {@link enqueue()}, {@link dequeue()} and {@link peek()}. In addition, * {@link contains()} can be used to check if an item is contained * in the queue. To obtain the number of the items in the queue, * check the {@link getCount Count} property. * * Items in the queue may be traversed using foreach as follows, * <code> * foreach($queue as $item) ... * </code> * * @author Qiang Xue <qiang.xue@gmail.com> * @version $Id$ * @package System.Collections * @since 3.1 */ class TQueue extends TComponent implements IteratorAggregate { /** * internal data storage * @var array */ private $_d=array(); /** * number of items * @var integer */ private $_c=0; /** * Constructor. * Initializes the queue with an array or an iterable object. * @param array|Iterator the intial data. Default is null, meaning no initialization. * @throws TInvalidDataTypeException If data is not null and neither an array nor an iterator. */ public function __construct($data=null) { if($data!==null) $this->copyFrom($data); } /** * @return array the list of items in queue */ public function toArray() { return $this->_d; } /** * Copies iterable data into the queue. * Note, existing data in the list will be cleared first. * @param mixed the data to be copied from, must be an array or object implementing Traversable * @throws TInvalidDataTypeException If data is neither an array nor a Traversable. */ public function copyFrom($data) { if(is_array($data) || ($data instanceof Traversable)) { $this->clear(); foreach($data as $item) { $this->_d[]=$item; ++$this->_c; } } else if($data!==null) throw new TInvalidDataTypeException('queue_data_not_iterable'); } /** * Removes all items in the queue. */ public function clear() { $this->_c=0; $this->_d=array(); } /** * @param mixed the item * @return boolean whether the queue contains the item */ public function contains($item) { return array_search($item,$this->_d,true)!==false; } /** * Returns the item at the top of the queue. * Unlike {@link pop()}, this method does not remove the item from the queue. * @return mixed item at the top of the queue * @throws TInvalidOperationException if the queue is empty */ public function peek() { if($this->_c===0) throw new TInvalidOperationException('queue_empty'); else return $this->_d[$this->_c-1]; } /** * Removes and returns the object at the beginning of the queue. * @return mixed the item at the beginning of the queue * @throws TInvalidOperationException if the queue is empty */ public function dequeue() { if($this->_c===0) throw new TInvalidOperationException('queue_empty'); else { --$this->_c; return array_shift($this->_d); } } /** * Adds an object to the end of the queue. * @param mixed the item to be appended into the queue */ public function enqueue($item) { ++$this->_c; array_push($this->_d,$item); } /** * Returns an iterator for traversing the items in the queue. * This method is required by the interface IteratorAggregate. * @return Iterator an iterator for traversing the items in the queue. */ public function getIterator() { return new TQueueIterator($this->_d); } /** * @return integer the number of items in the queue */ public function getCount() { return $this->_c; } } /** * TQueueIterator class * * TQueueIterator implements Iterator interface. * * TQueueIterator is used by TQueue. It allows TQueue to return a new iterator * for traversing the items in the queue. * * @author Qiang Xue <qiang.xue@gmail.com> * @version $Id$ * @package System.Collections * @since 3.1 */ class TQueueIterator implements Iterator { /** * @var array the data to be iterated through */ private $_d; /** * @var integer index of the current item */ private $_i; /** * @var integer count of the data items */ private $_c; /** * Constructor. * @param array the data to be iterated through */ public function __construct(&$data) { $this->_d=&$data; $this->_i=0; $this->_c=count($this->_d); } /** * Rewinds internal array pointer. * This method is required by the interface Iterator. */ public function rewind() { $this->_i=0; } /** * Returns the key of the current array item. * This method is required by the interface Iterator. * @return integer the key of the current array item */ public function key() { return $this->_i; } /** * Returns the current array item. * This method is required by the interface Iterator. * @return mixed the current array item */ public function current() { return $this->_d[$this->_i]; } /** * Moves the internal pointer to the next array item. * This method is required by the interface Iterator. */ public function next() { $this->_i++; } /** * Returns whether there is an item at current position. * This method is required by the interface Iterator. * @return boolean */ public function valid() { return $this->_i<$this->_c; } } ?>