<?
$input = '10 20 100 + - 20 * DUP 10 20 + * =';

$t = microtime(1);

for ($i = 0; $i < 10000; $i++) {
    $stack = array();

    foreach (explode(' ', $input) as $chunk) {
        switch ($chunk) {
            case '+':
                array_push($stack, array_pop($stack) + array_pop($stack));
                break;
            case '-':
                array_push($stack, array_pop($stack) - array_pop($stack));
                break;
            case '*':
                array_push($stack, array_pop($stack) * array_pop($stack));
                break;
            case '=':
                array_push($stack, array_pop($stack) === array_pop($stack));
                break;
            case 'DUMP':
                var_dump($stack);
                break;
            case 'DUP':
                array_push($stack, end($stack));
                break;

            default:
                array_push($stack, $chunk);

        }
    }
}

function ap(ArrayObject $arr) {
    $last = $arr->count() - 1;
    $item = $arr[$last];
    $arr->offsetUnset($last);

    return $item;
}


echo 'Array: ', microtime(1) - $t, "\n";

$t = microtime(1);

for ($i = 0; $i < 10000; $i++) {
    $stack = new ArrayObject(array(1,2));

    foreach (explode(' ', $input) as $chunk) {
        switch ($chunk) {
            case '+':
                $stack->append(ap($stack) + ap($stack));
                break;
            case '-':
                $stack->append(ap($stack) - ap($stack));
                break;
            case '*':
                $stack->append(ap($stack) * ap($stack));
                break;
            case '=':
                $stack->append(ap($stack) === ap($stack));
                break;
            case 'DUMP':
                var_dump($stack);
                break;
            case 'DUP':
                $stack->append(end($stack));
                break;

            default:
                $stack->append($chunk);

        }
    }
}

echo 'Array Object: ', microtime(1) - $t, "\n";

$t = microtime(1);

for ($i = 0; $i < 10000; $i++) {
    $stack = new SplStack();

    foreach (explode(' ', $input) as $chunk) {
        switch ($chunk) {
            case '+':
                $stack->push($stack->pop() + $stack->pop());
                break;
            case '-':
                $stack->push($stack->pop() - $stack->pop());
                break;
            case '*':
                $stack->push($stack->pop() * $stack->pop());
                break;
            case '=':
                $stack->push($stack->pop() === $stack->pop());
                break;
            case 'DUMP':
                var_dump($stack);
                break;
            case 'DUP':
                $stack->push($stack->top());
                break;

            default:
                $stack->push($chunk);

        }
    }
}

echo 'SplStack: ', microtime(1) - $t, "\n";