PHP FileSystem using Composite Pattern

ls.php

<?php
 # ············································································
 # Filename: ls.php
 # Syntax: php ls.php -d=directory -s  
 # Options:
 #   -d=directory (required)       input directory to show (default=current)
 #   -s                            displays size in bytes (default=disabled)
 # Description: Builds a hierarchical representation of the filesystem using   
 # a composite design pattern http://en.wikipedia.org/wiki/Composite_pattern
 # ············································································
 # Examples:
 #
 #  fer@local:~/Documents$ php ls.php 
 #  Projects
 #  Source
 #  Repos
 #  README.md
 #
 #  fer@local:~/Documents$ php ls.php -s
 #  22911 bytes                   Projects
 #  4110 bytes                    Source
 #  3288 bytes                    Repos
 #  1091 bytes                    README.md
 #
 #  fer@local:~/Documents$ php ls.php -s -d=../Desktop/Muse\ 2nd\ Law/
 #  208 bytes                     Tracklist.txt
 #  200 bytes                     Muse 2nd Law 2012 320kbps Mp3.zip.xml
 #  104092497 bytes               Muse 2nd Law 2012 320kbps Mp3.zip
 #  43613 bytes                   Muse 2nd Law Cover.jpeg
 #  49 bytes                      ReadMe.txt
 #  
 #  fer@local:~$ php -v
 #  PHP 5.3.10-1ubuntu3.4 with Suhosin-Patch (cli) (built: Sep 12 2012 19:00:43) 


 ###
 ### Composite Class Definitions (component, leaf & composite classes)
 ###  

 # Component class: FileSystem 
 # Description: declares interfaces for constructor and output methods
 class FileSystem {  
  protected $_name, $_size;
  
  function __construct($name=null, $size=null){
   $this->_size = $size;
   $this->_name = $name;
  }

  function __toString(){
   if ($this->_size) 
    return str_pad($this->_size, 30) . $this->_name."\n"; 
   else 
    return $this->_name . "\n";
  }
 }

 # Leaf class: File
 class File extends FileSystem { }

 # Composite class: Folder
 class Folder extends FileSystem { 
  protected $_children = array();

  function addChild(FileSystem $element){
   $this->_children[] = $element;
  }

  function __toString(){
   if ($this->_size) 
    $str = str_pad($this->_size, 30) . $this->_name."\n";
   elseif ($this->_name) 
    $str = $this->_name . "\n";
   else 
    $str = "";

   foreach ($this->_children as $child) 
    $str .= (string) $child;

   return $str;
  }
 } 

 ###
 ### Helper functions (filesize_r & init_structure)
 ###

 # Returns filesize in bytes 
 function filesize_r($path){
  if (!file_exists($path)) return 0;
  if (is_file($path)) return filesize($path) . " bytes";
  $ret = 0;
  foreach(glob($path."/*") as $fn) $ret += filesize_r($fn);
  return $ret . " bytes";
 }

 # Maps files and dirs in the "composite pattern" structure  
 function init_structure($directory, $show_size=false){
  
  # Create main container
  $initial_folder = new Folder();   

  # Read system folder
  if ($handle = opendir($directory)) {

   while (false !== ($entry = readdir($handle))) {

     # Skip parent directories
     if ($entry != "." && $entry != "..") {

      # Build path & show size check
      $route = $directory."/".$entry;  
      ($show_size) ? $size = filesize_r($route) : $size = null;

      # Directory check & instantiation
      if (is_dir($route."/")) 
       $initial_folder->addChild(new Folder($entry, $size));

      # File check & instantiation
      if (is_file($route)) 
       $initial_folder->addChild(new File($entry, $size));
     }
   }
   closedir($handle);  
   return $initial_folder;   
  }
 }

 ###
 ### Main Flow (check params, execute init_structure)
 ###

 $options = getopt("d::s");
 (isset($options["d"])) ? $dir = $options["d"] : $dir = ".";
 echo init_structure($dir, isset($options["s"])); 

?>