Source for file Head.php

<?php
/**
*  Head class file
*
*  @author        Simon Harris - pointbeing at users.sourceforge.net
*  @package        PHPTuring
*  @version        $Id: Head.php,v 1.4 2005/11/15 10:30:40 pointbeing Exp $
*/
 
/**
*  Head class
*
*  @package        PHPTuring
*/
class Head {
 
    
    /**
    *  @var int 
    */
    private $position = 0;
    
    /**
    *  @var Tape 
    */
    private $tape;
    
    
    /**
    *  @access public
    */
    public function __construct()
    {
        $this->tape = new Tape();
    }
    
    
    /**
    *  Tells the Head which Tape to use
    *
    *  @access public
    *  @param Tape $tape 
    */
    public function setTape(Tape $tape)
    {
        $this->tape = $tape;
    }
    
    
    /**
    *  Shifts the head one cell left
    * 
    *  @access public
    */
    public function shiftLeft()
    {
        $this->position--;
    }
    
    
    /**
    *  Shifts the head one cell right
    * 
    *  @access public
    */
    public function shiftRight()
    {
        $this->position++;        
    }
    
    
    /**
    *  Returns the current symbol
    *
    *  @access public
    *  @return int 
    */
    public function read()
    {
        return $this->tape->read($this->position);
    }    
    
    
    /**
    *  Writes a new value to the current
    *  
    *  @access public
    *  @param int $value 
    */
    public function write($value)
    {
        $this->tape->write($this->position, $value);
    }
        
}
 
 
?>