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72 lines
2.0 KiB
PHP
72 lines
2.0 KiB
PHP
<?php
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/** @file splqueue.inc
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* @ingroup SPL
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* @brief class SplQueue
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* @author Etienne Kneuss
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* @date 2008 - 2009
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*
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* SPL - Standard PHP Library
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*/
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/** @ingroup SPL
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* @brief Implementation of a Queue through a DoublyLinkedList. As SplQueue
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* extends SplDoublyLinkedList, unshift() and pop() are still available
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* even though they don't make much sense for a queue. For convenience,
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* two aliases are available:
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* - enqueue() is an alias of push()
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* - dequeue() is an alias of shift()
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*
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* @since PHP 5.3
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*
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* The SplQueue class provides the main functionalities of a
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* queue implemented using a doubly linked list (DLL).
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*/
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class SplQueue extends SplDoublyLinkedList
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{
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protected $_it_mode = parent::IT_MODE_FIFO;
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/** Changes the iteration mode. There are two orthogonal sets of modes that
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* can be set:
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*
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* - The behavior of the iterator (either one or the other)
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* - SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
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* - SplDoublyLnkedList::IT_MODE_KEEP (Elements are traversed by the iterator)
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*
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* The default mode is 0 : SplDoublyLnkedList::IT_MODE_LIFO | SplDoublyLnkedList::IT_MODE_KEEP
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*
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* @note The iteration's direction is not modifiable for queue instances
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* @param $mode New mode of iteration
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* @throw RuntimeException If the new mode affects the iteration's direction.
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*/
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public function setIteratorMode($mode)
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{
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if ($mode & parent::IT_MODE_LIFO === parent::IT_MODE_LIFO) {
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throw new RuntimeException("Iterators' LIFO/FIFO modes for SplStack/SplQueue objects are frozen");
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}
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$this->_it_mode = $mode;
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}
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/** @return the first element of the queue.
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* @note dequeue is an alias of push()
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* @see splDoublyLinkedList::push()
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*/
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public function dequeue()
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{
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return parent::shift();
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}
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/** Pushes an element at the end of the queue.
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* @param $data variable to add to the queue.
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* @note enqueue is an alias of shift()
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* @see splDoublyLinkedList::shift()
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*/
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public function enqueue($data)
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{
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return parent::push($data);
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}
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}
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?>
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