User defined stream filter sample

stream_filter.php

<?php
/**
* User defined stream filter sample 
* Source: http://php.net/manual/pt_BR/function.stream-filter-register.php
**/

class string_filter extends php_user_filter 
{
 function filter($in, $out, &$consumed, $closing)  
 {
   while ($bucket = stream_bucket_make_writeable($in)) 
   {
     if ($this->mode == 1) 
	 {
       $bucket->data = strtoupper($bucket->data);
		 
     } elseif ($this->mode == 0) 
	 {
       $bucket->data = strtolower($bucket->data);   
	 }
     
	 $consumed += $bucket->datalen;
     stream_bucket_append($out, $bucket);
   }
	 
   return PSFS_PASS_ON;
 }

 function onCreate()  
 {
   if ($this->filtername == 'str.toupper') 
   {
     $this->mode = 1;
	   
   } elseif ($this->filtername == 'str.tolower') 
   {
     $this->mode = 0;  
   } else 
   {  
	   return false;   
   }
   
	 return true;
 }

}

stream_filter_register("str.*", "string_filter") || die("Failed to register filter");	// str.toupper, str.tolower

$fp = fopen("foo-bar.txt", "w");

stream_filter_append($fp, "str.toupper");

fwrite($fp, "Line1, <br />");
fwrite($fp, "Word - 2, <br />");
fwrite($fp, "Easy As 123. <br />");
fclose($fp);

highlight_file("foo-bar.txt");

?>

PhpFiddle.org sample file