I needed to match in directory tree file name(s) by regular expression. Code is based on Marcus Börger class DirectoryTreeIterator http://cvs.php.net/viewvc.cgi/php-src/ext/spl/examples/ and on examples given in his lecture Introduction to object oriented PHP at PHP Quebec conference 2007 http://talks.somabo.de/
<?php
class KeyFilter extends FilterIterator
{
  private $_rx;
  
  function __construct(Iterator $it, $regex)
  {
    parent::__construct($it);
    $this->_rx= $regex;
  }

  function accept()
  {
    return ereg($this->_rx,$this->getInnerIterator()->key());
  }

  protected function __clone() {
    return false;
  }
}

class DirMach extends KeyFilter
{
  function __construct($path , $regex)
  {
    parent::__construct(
    new DirectoryTreeIterator($path), $regex);
  }

  function current()
  {
    return parent::key();
  }

  function key()
  {
    return parent::key();
  }
}

class DirectoryTreeIterator extends RecursiveIteratorIterator
{
    /** Construct from a path.
     * @param $path directory to iterate
     */
    function __construct($path)
    {
     try {
      parent::__construct(
            new RecursiveCachingIterator(
                new RecursiveDirectoryIterator($path, RecursiveDirectoryIterator::KEY_AS_FILENAME
                ), 
                CachingIterator::CALL_TOSTRING|CachingIterator::CATCH_GET_CHILD
            ), 
            parent::SELF_FIRST
        );
     } catch(Exception $e) {
       echo $e->getMessage();
       exit;
     }
    }

    /** @return the current element prefixed with ASCII graphics
     */    
    function current()
    {
      if ($this->hasChildren())
        $this->next();  
      return $this->key();
    }

    /** Aggregates the inner iterator
     */    
    function __call($func, $params)
    {
      return call_user_func_array(array($this->getSubIterator(), $func), $params);
    }
}
$PathToSearch = 'path_to_search';
$regex = 'regular_expression';
$FileList = new DirMach($PathToSearch, $regex);
foreach ($FileList as $file) {
  $match[] = $file;
}
echo '<pre>';
var_dump($match);
echo '</pre>';
?>