xref: /PHP-7.2/ext/spl/internal/splstack.inc (revision 902d39a3)
1<?php
2
3/** @file splstack.inc
4 * @ingroup SPL
5 * @brief class SplStack
6 * @author  Etienne Kneuss
7 * @date    2008 - 2009
8 *
9 * SPL - Standard PHP Library
10 */
11
12/** @ingroup SPL
13 * @brief Implementation of a stack through a DoublyLinkedList. As SplStack
14 *        extends SplDoublyLinkedList, shift() and unshift() are still available even
15 *        though they don't make much sense for a stack.
16 * @since PHP 5.3
17 *
18 * The SplStack class provides the main functionalities of a
19 * stack implemented using a doubly linked list (DLL).
20 */
21class SplStack extends SplDoublyLinkedList
22{
23	protected $_it_mode = parent::IT_MODE_LIFO;
24
25	/** Changes the iteration mode. There are two orthogonal sets of modes that
26	 * can be set:
27	 *
28	 * - The behavior of the iterator (either one or the other)
29	 *  - SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
30	 *  - SplDoublyLnkedList::IT_MODE_KEEP   (Elements are traversed by the iterator)
31	 *
32	 * The default mode is 0 : SplDoublyLnkedList::IT_MODE_LIFO | SplDoublyLnkedList::IT_MODE_KEEP
33	 *
34	 * @note The iteration's direction is not modifiable for stack instances
35	 * @param $mode              New mode of iteration
36	 * @throw RuntimeException   If the new mode affects the iteration's direction.
37	 */
38	public function setIteratorMode($mode)
39	{
40		if ($mode & parent::IT_MODE_LIFO !== parent::IT_MODE_LIFO) {
41			throw new RuntimeException("Iterators' LIFO/FIFO modes for SplStack/SplQueue objects are frozen");
42		}
43
44		$this->_it_mode = $mode;
45	}
46}
47
48?>
49