super-light templating system in PHP that doesn't allow php code inside templates or use eval

I'm searching for a very basic PHP templating system. Right now I'm using:

/**
 * Renders a single line. Looks for {{ var }}
 *
 * @param string $string
 * @param array $parameters
 *
 * @return string
 */
function renderString($string, array $parameters)
{
    $replacer = function ($match) use ($parameters)
    {
        return isset($parameters[$match[1]]) ? $parameters[$match[1]] : $match[0];
    };

    return preg_replace_callback('/{{\s*(.+?)\s*}}/', $replacer, $string);
}

(from here: PHP - Extremely light templating system)

but I can only assign and display variables. I also need a way to use conditions like IF and loop arrays.

I found Rain TPL - http://www.raintpl.com/Quick-Start/#if - which is very close to what I'm looking for, but there are a few things that I don't like it it:

• it allows the dude who is writing the template to run PHP functions (inside the IF condition).
• it writes cache and php files, which I don't want

So, is there anything out there similar to this, but even more "basic", strict, and more secure?