<?php
-
/** @file spldoublylinkedlist.inc
* @ingroup SPL
* @brief class SplDoublyLinkedList
* @brief Doubly Linked List
* @since PHP 5.3
*
- * The SplDoublyLinkedList class provides the main functionnalities of a
+ * The SplDoublyLinkedList class provides the main functionalities of a
* doubly linked list (DLL).
+ * @note The following userland implementation of Iterator is a bit different
+ * from the internal one. Internally, iterators generated by nested
+ * foreachs are independant, while they share the same traverse pointer
+ * in userland.
*/
-class SplDoublyLinkedList implements Traversable, ArrayAccess, Countable
+class SplDoublyLinkedList implements Iterator, ArrayAccess, Countable
{
+ protected $_llist = array();
+ protected $_it_mode = 0;
+ protected $_it_pos = 0;
/** Iterator mode
* @see setIteratorMode
*/
- const IT_MODE_LIFO = 0x00000001;
+ const IT_MODE_LIFO = 0x00000002;
/** Iterator mode
* @see setIteratorMode
*/
const IT_MODE_FIFO = 0x00000000;
-
/** Iterator mode
* @see setIteratorMode
*/
/** Iterator mode
* @see setIteratorMode
*/
- const IT_MODE_DELETE = 0x00000002;
+ const IT_MODE_DELETE = 0x00000001;
/** @return the element popped from the end of the DLL.
+ * @throw RuntimeException If the datastructure is empty.
*/
- function pop() {/**/}
+ public function pop()
+ {
+ if (count($this->_llist) == 0) {
+ throw new RuntimeException("Can't pop from an empty datastructure");
+ }
+ return array_pop($this->_llist);
+ }
/** @return the element shifted from the beginning of the DLL.
+ * @throw RuntimeException If the datastructure is empty.
*/
- function shift() {/**/}
+ public function shift()
+ {
+ if (count($this->_llist) == 0) {
+ throw new RuntimeException("Can't shift from an empty datastructure");
+ }
+ return array_shift($this->_llist);
+ }
/** Pushes an element to the end of the DLL.
* @param $data variable to add to the DLL.
*/
- function push($data) {/**/}
+ public function push($data)
+ {
+ array_push($this->_llist, $data);
+ return true;
+ }
/** Adds an element to the beginning of the DLL.
* @param $data variable to add to the DLL.
*/
- function unshift($data) {/**/}
+ public function unshift($data)
+ {
+ array_unshift($this->_llist, $data);
+ return true;
+ }
/** @return the element at the beginning of the DLL.
*/
- function top() {/**/}
+ public function top()
+ {
+ return end($this->_llist);
+ }
/** @return the element at the end of the DLL.
*/
- function bottom() {/**/}
+ public function bottom()
+ {
+ return reset($this->_llist);
+ }
/** @return number elements in the DLL.
*/
- function count() {/**/}
+ public function count()
+ {
+ return count($this->_llist);
+ }
/** @return whether the DLL is empty.
*/
- function isEmpty() {/**/}
+ public function isEmpty()
+ {
+ return ($this->count() == 0);
+ }
/** Changes the iteration mode. There are two orthogonal sets of modes that
* can be set:
*
* @param $mode new mode of iteration
*/
- function setIteratorMode($mode) {/**/}
+ public function setIteratorMode($mode)
+ {
+ $this->_it_mode = $mode;
+ }
/** @return the current iteration mode
* @see setIteratorMode
*/
- function getIteratorMode() {/**/}
+ public function getIteratorMode()
+ {
+ return $this->_it_mode;
+ }
+
+ /** Rewind to top iterator as set in constructor
+ */
+ public function rewind()
+ {
+ if ($this->_it_mode & self::IT_MODE_LIFO) {
+ $this->_it_pos = count($this->_llist)-1;
+ } else {
+ $this->_it_pos = 0;
+ }
+ }
+
+ /** @return whether iterator is valid
+ */
+ public function valid()
+ {
+ return array_key_exists($this->_it_pos, $this->_llist);
+ }
+
+ /** @return current key
+ */
+ public function key()
+ {
+ return $this->_it_pos;
+ }
+
+ /** @return current object
+ */
+ public function current()
+ {
+ return $this->_llist[$this->_it_pos];
+ }
+
+ /** Forward to next element
+ */
+ public function next()
+ {
+ if ($this->_it_mode & self::IT_MODE_LIFO) {
+ if ($this->_it_mode & self::IT_MODE_DELETE) {
+ $this->pop();
+ }
+ $this->_it_pos--;
+ } else {
+ if ($this->_it_mode & self::IT_MODE_DELETE) {
+ $this->shift();
+ } else {
+ $this->_it_pos++;
+ }
+ }
+ }
+
+ /** @return whether a certain offset exists in the DLL
+ *
+ * @param $offset The offset
+ * @throw OutOfRangeException If the offset is either invalid or out of
+ * range.
+ */
+ public function offsetExists($offset)
+ {
+ if (!is_numeric($offset)) {
+ throw new OutOfRangeException("Offset invalid or out of range");
+ } else {
+ return array_key_exists($offset, $this->_llist);
+ }
+ }
+
+ /** @return the data at a certain offset in the DLL
+ *
+ * @param $offset The offset
+ * @throw OutOfRangeException If the offset is either invalid or out of
+ * range.
+ */
+ public function offsetGet($offset)
+ {
+ if ($this->_it_mode & self::IT_MODE_LIFO) {
+ $realOffset = count($this->_llist)-$offset;
+ } else {
+ $realOffset = $offset;
+ }
+
+ if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
+ throw new OutOfRangeException("Offset invalid or out of range");
+ } else {
+ return $this->_llist[$realOffset];
+ }
+ }
+
+ /** Defines the data at a certain offset in the DLL
+ *
+ * @param $offset The offset
+ * @param $value New value
+ * @throw OutOfRangeException If the offset is either invalid or out of
+ * range.
+ */
+ public function offsetSet($offset, $value)
+ {
+ if ($offset === null) {
+ return $this->push($value);
+ }
+
+ if ($this->_it_mode & self::IT_MODE_LIFO) {
+ $realOffset = count($this->_llist)-$offset;
+ } else {
+ $realOffset = $offset;
+ }
+
+ if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
+ throw new OutOfRangeException("Offset invalid or out of range");
+ } else {
+ $this->_llist[$realOffset] = $value;
+ }
+ }
+
+ /** Unsets the element at a certain offset in the DLL
+ *
+ * @param $offset The offset
+ * @throw OutOfRangeException If the offset is either invalid or out of
+ * range.
+ */
+ public function offsetUnset($offset)
+ {
+ if ($this->_it_mode & self::IT_MODE_LIFO) {
+ $realOffset = count($this->_llist)-$offset;
+ } else {
+ $realOffset = $offset;
+ }
+ if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
+ throw new OutOfRangeException("Offset invalid or out of range");
+ } else {
+ array_splice($this->_llist, $realOffset, 1);
+ }
+ }
}
?>
*/
/** @ingroup SPL
- * @brief Implementation of a Queue through a DoublyLinkedList. As SplQueue
- * extends SplDoublyLinkedList, unshift() and pop() are still available even
- * though they don't make much sense for a queue. For convenience, two aliases
- * are available:
- * - enqueue() is an alias of push()
- * - dequeue() is an alias of shift()
+ * @brief Implementation of a Queue through a DoublyLinkedList. As SplQueue
+ * extends SplDoublyLinkedList, unshift() and pop() are still available
+ * even though they don't make much sense for a queue. For convenience,
+ * two aliases are available:
+ * - enqueue() is an alias of push()
+ * - dequeue() is an alias of shift()
*
* @since PHP 5.3
*
- * The SplQueue class provides the main functionnalities of a
- * queue implemented by a doubly linked list.
+ * The SplQueue class provides the main functionalities of a
+ * queue implemented using a doubly linked list (DLL).
*/
class SplQueue extends SplDoublyLinkedList
{
- /** Changes the iteration mode. For queues, the direction mode
- * is frozen. Attempting to modify it will result in an RuntimeException.
+ protected $_it_mode = parent::IT_MODE_FIFO;
+
+ /** Changes the iteration mode. There are two orthogonal sets of modes that
+ * can be set:
+ *
+ * - The behavior of the iterator (either one or the other)
+ * - SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
+ * - SplDoublyLnkedList::IT_MODE_KEEP (Elements are traversed by the iterator)
*
- * @throws RuntimeException
- * @param $mode new mode of iteration
- * @see SplDoublyLinkedList::setIteratorMode
+ * The default mode is 0 : SplDoublyLnkedList::IT_MODE_LIFO | SplDoublyLnkedList::IT_MODE_KEEP
+ *
+ * @note The iteration's direction is not modifiable for queue instances
+ * @param $mode New mode of iteration
+ * @throw RuntimeException If the new mode affects the iteration's direction.
*/
- function setIteratorMode($mode) {/**/}
+ public function setIteratorMode($mode)
+ {
+ if ($mode & parent::IT_MODE_LIFO === parent::IT_MODE_LIFO) {
+ throw new RuntimeException("Iterators' LIFO/FIFO modes for SplStack/SplQueue objects are frozen");
+ }
+
+ $this->_it_mode = $mode;
+ }
/** @return the first element of the queue.
* @note dequeue is an alias of push()
* @see splDoublyLinkedList::push()
*/
- function dequeue() {/**/}
+ public function dequeue()
+ {
+ return parent::shift();
+ }
/** Pushes an element at the end of the queue.
* @param $data variable to add to the queue.
* @note enqueue is an alias of shift()
* @see splDoublyLinkedList::shift()
*/
- function enqueue($data) {/**/}
+ public function enqueue($data)
+ {
+ return parent::push($data);
+ }
}
?>
* SPL - Standard PHP Library
*/
-
/** @ingroup SPL
* @brief Implementation of a stack through a DoublyLinkedList. As SplStack
- * extends SplDoublyLinkedList, shift() and unshift() are still available even
- * though they don't make much sense for a stack.
- *
+ * extends SplDoublyLinkedList, shift() and unshift() are still available even
+ * though they don't make much sense for a stack.
* @since PHP 5.3
*
- * The SplStack class provides the main functionnalities of a
- * stack implemented by a doubly linked list.
+ * The SplStack class provides the main functionalities of a
+ * stack implemented using a doubly linked list (DLL).
*/
class SplStack extends SplDoublyLinkedList
{
- /** Changes the iteration mode. For stacks, the direction mode
- * is frozen. Attempting to modify it will result in an RuntimeException.
+ protected $_it_mode = parent::IT_MODE_LIFO;
+
+ /** Changes the iteration mode. There are two orthogonal sets of modes that
+ * can be set:
*
- * @throws RuntimeException
- * @param $mode new mode of iteration
- * @see SplDoublyLinkedList::setIteratorMode
+ * - The behavior of the iterator (either one or the other)
+ * - SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
+ * - SplDoublyLnkedList::IT_MODE_KEEP (Elements are traversed by the iterator)
+ *
+ * The default mode is 0 : SplDoublyLnkedList::IT_MODE_LIFO | SplDoublyLnkedList::IT_MODE_KEEP
+ *
+ * @note The iteration's direction is not modifiable for stack instances
+ * @param $mode New mode of iteration
+ * @throw RuntimeException If the new mode affects the iteration's direction.
*/
- function setIteratorMode($mode) {/**/}
+ public function setIteratorMode($mode)
+ {
+ if ($mode & parent::IT_MODE_LIFO !== parent::IT_MODE_LIFO) {
+ throw new RuntimeException("Iterators' LIFO/FIFO modes for SplStack/SplQueue objects are frozen");
+ }
+
+ $this->_it_mode = $mode;
+ }
}
?>
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