symfony - Call PHP function from Twig template

Question

I have a function in my controller that returns array of entities so in my twig template I do this to iterate over elements:

{% for groupName, entity in items %}
    <ul>
        <ul>
            {% for element in entity %}
                <li>{{ element.getLabel }}</li>
                <li><input type="text" name="detail[{{ element.getId }}]" id="pd_{{ element.getId }}" /><input type="text" name="price[{{ element.getId }}]" id="pd_price_{{ element.getId }}" /><input type="text" name="stock[{{ element.getId }}]" id="pd_stock_{{ element.getId }}" /></li>
            {% endfor %}
        </ul>
    </ul>
{% endfor %}

In my controller I have also this PHP function:

private function DetailCombination($arr, $level, &$result, $curr = array()) {
    for ($i = 0; $i < count($arr); $i++) {
        $new = array_merge($curr, array($arr[$i]));
        if ($level == 1) {
            sort($new);
            if (!in_array($new, $result)) {
                $result[] = $new;
            }
        } else {
            combinations($arr, $level - 1, $result, $new);
        }
    }
}

I can call it in this way:

for ($i = 0; $i < count($arr); $i++) {
    $this->DetailCombination($arr, $i + 1, $result);
}

// TEST
foreach ($result as $arr) {
    echo join(" ", $arr) . '<br>';
}

It's possible access to the PHP function from Twig template in order to get all the possible combinations of elements in entity? How?

** UPDATE **

This is the function that returns entities processed after by Twig Template:

private function getVariations($category_id) {
    $items = array();

    $em = $this->getDoctrine()->getManager();
    $entityCategory = $em->getRepository('CategoryBundle:Category')->find($category_id);

    foreach ($entityCategory->getProductDetails() as $entity) {
        if ($entity->getToProduct() == 1) {
            foreach ($entity->getDetailGroup() as $group) {
                if (!array_key_exists($group->getName(), $items)) {
                    $items [$group->getName()] = array();
                }

                $items [$group->getName()] [] = $entity;
            }
        } 
    }

    return $items;
} 

Answer 1

Its not possible to access any PHP function inside Twig directly.

What you can do is write a Twig extension. A common structure is, writing a service with some utility functions, write a Twig extension as bridge to access the service from twig. The Twig extension will use the service and your controller can use the service too.

Take a look: http://symfony.com/doc/current/cookbook/templating/twig_extension.html

Cheers.