Subversion-Projekte lars-tiefland.prado

<?php
/**
 * TQueue, TQueueIterator classes
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005-2008 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>
 * @author Knut Urdalen <knut.urdalen@gmail.com>
 * @version $Id$
 * @package System.Collections
 * @since 3.1
 */
class TQueue extends TComponent implements IteratorAggregate,Countable
{
        /**
         * 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;
        }
        
        /**
         * Returns the number of items in the queue.
         * This method is required by Countable interface.
         * @return integer number of items in the queue.
         */
        public function count()
        {
                return $this->getCount();
        }
}

/**
 * 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;
        }
}