class DiffElem

class DiffElem {
    public const TYPE_KEEP = 0;
    public const TYPE_REMOVE = 1;
    public const TYPE_ADD = 2;
    public const TYPE_REPLACE = 3;
    
    /** @var self::TYPE_* */
    public $type;
    
    /** @var mixed Is null for add operations */
    public $old;
    
    /** @var mixed Is null for remove operations */
    public $new;
    
    /**
     * @param self::TYPE_* $type
     * @param mixed $old Is null for add operations
     * @param mixed $new Is null for remove operations
     */
    public function __construct(int $type, $old, $new) {
        $this->type = $type;
        $this->old = $old;
        $this->new = $new;
    }

}