README.md

<?php

use Sergiors\LinkedList\LinkedList;

$list = new LinkedList();
$list->push(1);
$list->push(2);
$list->push(3);
$list->push(4);

while ($list->count()) {
    var_dump($list->shift());
}

LinkedList.php

<?php

namespace Sergiors\LinkedList;

class LinkedList
{
    private $firstNode;

    private $lastNode;

    private $totalNodes;

    public function isEmpty()
    {
        return null === $this->firstNode
            && null === $this->lastNode;
    }

    public function count()
    {
        return $this->totalNodes;
    }

    public function push($value)
    {
        $this->totalNodes++;

        $node = new Node($value);
        
        if ($this->isEmpty()) {
            $this->firstNode = $node;
        } else {
            $this->lastNode->setNext($node);
        }
        
        $this->lastNode = $node;
    }

    public function shift()
    {
        $this->totalNodes--;

        $tmpNode = $this->firstNode;
        $this->firstNode = $tmpNode->getNext();

        return $tmpNode->getValue();
    }
}

Node.php

<?php

namespace Sergiors\LinkedList;

class Node
{
    private $value;

    private $nextNode;

    public function __construct($value)
    {
        $this->value = $value;
    }

    public function getValue()
    {
        return $this->value;
    }

    public function getNext()
    {
        return $this->nextNode;
    }

    public function setNext(Node $next)
    {
        $this->nextNode = $next;
    }
}