Singly Linklist in PHP

singly.php

<?php

/**
 *  Singly LinkList in PHP. For fun!
 *  @author thachp
 **/
 
class Node {
	public $data = null;
	public $next = null;
	
	public function __construct($data)
	{
		$this->data = $data;	
		$this->next= null;		
	}
	
	
	public function clear()
	{
		$this->data = null;
		$this->next = null;		
	}	
}


class Linklist {
	
	private $_head = null;
	private $_tail = null;
	private $_length = 0;	
		
	/**
	* Get node to linklist
	*/
	public function add($data)
	{		
		
		$node = new Node($data);

		// if no head set this node as head		
		// also, set the tail to be the head.
		if($this->_head === null)
		{
				$this->_head = $node; 			
				$this->_tail = $this->_head;
		}			
		
		if($this->_head !== null)
		{			
			//  object  in php is pass by reference id, so this should be okay with the & symbol
			$this->_tail->next = $node;
			$this->_tail = $node;
		}		
		
		// increase length
		$this->_length++;						
	}	
	
	
	/**
	* Search index.
	* Rebuild the linklist by getting the node before it and reconnect to the next.
	*/	
	public function remove($index) {

		if($index === 0)
		{
			$temp = $this->_head;
			$this->_head = $this->_head->next;
			$temp->clear();			
			return;
		}
		
		
		if($index > $this->getLength() - 1)
		{
			throw new Exception('Wow! Buddy!!!');
		}
		
		$previous = false;
		$current = $this->_head;	
		
		for($i=0; $i < $index; $i++)
		{
			$previous = $current;
			$current = $current->next;									
		}
		
		$temp = $previous->next;
		$previous->next = $current->next;		
		$temp->clear();
	}
	
	
	/**
	* Get head of linklist.
	*/
	public function getHead()
	{
		return $this->_head;		
	}
	
	public function getLength()
	{
		return $this->_length;
	}
	
	/**
	 *  Debug purposes.
	 * */
	 
	public function debug($msg = 'print')
	{
		echo $msg . " \n";

		$current_node = $this->getHead();
		while($current_node !== null)
		{
			echo "link1" . $current_node->data . "\n";
			$current_node = $current_node->next;	
		}
	
	}
	
	
} // end link list



// test it out!
$singly = new Linklist();
$singly->add('test0');
$singly->add('test1');
$singly->add('test2');
$singly->add('test3');
$singly->add('test4');


echo('<pre>');
$singly->debug('before');
$singly->remove(0);
$singly->debug('after');
echo('</pre>');

?>