How to check if a variable is a Magic Constant?

I don't find any way online or scratching through the PHP docs to do this.

Is there a friendly or light way check if a variable is a Magic Constant like __FILE__ or __DIR__? Similar to is_callable()?

I want to check against the $var passed and run some if/else conditions on it.

Small example.

function test($var) {

    if ($var == 'string_value') {

        // Do this...

    }

    elseif (is_magic_constant($var)) {

        // Do this...

    }

    else {

        // Do this...

    }

}

test('string_value');
test(__FILE__);