class RegexDirectoryIterator

class RegexDirectoryIterator extends \FilterIterator {
    
    /**
     * The regular expression to match.
     *
     * @var string
     */
    protected $regex;
    
    /**
     * RegexDirectoryIterator constructor.
     *
     * @param string $path
     *   The path to scan.
     * @param string $regex
     *   The regular expression to match, including delimiters. For example,
     *   /\.yml$/ would list only files ending in .yml.
     */
    public function __construct($path, $regex) {
        // Use FilesystemIterator to not iterate over the . and .. directories.
        $iterator = new \FilesystemIterator($path);
        parent::__construct($iterator);
        $this->regex = $regex;
    }
    
    /**
     * Implements \FilterIterator::accept().
     */
    public function accept() {
        
        /** @var \SplFileInfo $file_info */
        $file_info = $this->getInnerIterator()
            ->current();
        return $file_info->isFile() && preg_match($this->regex, $file_info->getFilename());
    }

}