One-pointer Circular Buffer w/o overflow check and FIFO, using SplFixedArray

RingBuffer.class.php

<?php
/**
 * One-pointer Circular Buffer
 *
 * This comes without any overwrite 
 * checks or FIFO functionality. 
 * You'll need SPL. 
 *
 * @author Bernhard Häussner
 * @date 2011-09-07
 */
class RingBuffer {
	
	/**
	 * Next insert index
	 * @var int
	 */
	private $pos=0;
	
	/**
	 * Maximum number of distinct elements
	 * @var int
	 */
	private $size=0;
	
	/**
	 * Tuple of elements
	 * @var SplFixedArray
	 */
	private $data=null;
	
	/**
	 * Initialize with a fixed size
	 * @param int Element count when overwriting starts
	 */
	public function __construct($size) {
		$this->size=$size;
		$this->data=new SplFixedArray($size);
		$this->pos=$size-1;
	}
	
	/**
	 * Append to the buffer
	 * @param mixed elemet
	 * @return self this (chainable)
	 */
	public function add($item) {
		$this->data[$this->pos--]=$item;
		if($this->pos<0) $this->pos=$this->size-1;
		return $this;
	}
	
	/**
	 * Build an array starting with the last inserted element
	 * @return array
	 */
	public function dump() {
		$a=$this->data->toArray(); $p=$this->pos+1;
		return array_merge(array_slice($a,$p),array_slice($a,0,$p));
	}
	
	/**
	 * Last inserted element
	 * @param int optional, return last but [offs] element
	 * @return mixed element
	 */
	public function top($offs=0) {
		return $this->data[($this->pos+1+$offs)%$this->size];
	}
	
}