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November 28, 2018 14:47
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Demonstration of a PHP LinkedList, as well as a LinkedListIterator that implements \Iterator.
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| <?php | |
| class LinkedList { | |
| private $data; | |
| private $next; | |
| private function __construct() {} | |
| public static function fromArray($array) { | |
| $head = new LinkedList(); | |
| $head->data = $array[0]; | |
| $previous = $head; | |
| $array = array_slice($array, 1); | |
| foreach ($array as $item) { | |
| $current = new LinkedList(); | |
| $current->data = $item; | |
| $previous->next = $current; | |
| $previous = $current; | |
| } | |
| return $head; | |
| } | |
| public function data() { return $this->data; } | |
| public function next() { return $this->next; } | |
| public function reverse() { | |
| $current = new LinkedList(); | |
| $current->data = $this->data; | |
| $next = $this->next; | |
| while ($next !== null) { | |
| $prior = new LinkedList(); | |
| $prior->data = $next->data; | |
| $prior->next = $current; | |
| $current = $prior; | |
| $next = $next->next; | |
| } | |
| return $prior; | |
| } | |
| public function iterator() { | |
| return LinkedListIterator::fromLinkedList($this); | |
| } | |
| } | |
| class LinkedListIterator implements \Iterator { | |
| private $head; | |
| private $current; | |
| private $key; | |
| private function __construct() {} | |
| public static function fromLinkedList($linkedList) { | |
| $lli = new LinkedListIterator(); | |
| $lli->head = $linkedList; | |
| $lli->current = $linkedList; | |
| $lli->key = 0; | |
| return $lli; | |
| } | |
| public function current() { | |
| return $this->current->data(); | |
| } | |
| public function key() { | |
| return $this->key; | |
| } | |
| public function next() { | |
| $this->current = $this->current->next(); | |
| $this->key += 1; | |
| } | |
| public function rewind() { | |
| $this->current = $this->head; | |
| $this->key = 0; | |
| } | |
| public function valid() { | |
| return $this->current !== null; | |
| } | |
| } | |
| $ll = LinkedList::fromArray(array(1, 2, 3, 4)); | |
| $lli = $ll->iterator(); | |
| foreach ($lli as $i) { | |
| echo("{$i}\n"); | |
| } | |
| $ll = $ll->reverse(); | |
| $lli = $ll->iterator(); | |
| foreach ($lli as $i) { | |
| echo("{$i}\n"); | |
| } |
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