DS implementaions using PHP

Doubly Linked List:

use SplDoublyLinkedList;

$a = new SplDoublyLinkedList;
$arr=[1,2,3,4];
for($i=0;$i<count($arr);$i++){
   $a->add($i,$arr[$i]);
}
$a->push(2);
$a->push(5);
echo $a;

HashMap
Queue
Heap
Stack