How to use this callback message in this function - symfony

Question

I'm struggeling to select a previous for loop in Twig. I'm trying to display a few category titles in a category if that category has subcategories. If the category has no subcategories then it shhould display the titles from the previous loop. Normally this wouldn't be a problem if any category has the same depth. Unfortunatly the categories have different depths.
So what I try to do is create some sort of function that does this for me.
So for example:
Category A -> Category A.sub -> Category A.subsub
Title1 Title1.1 Title1.2
Title1 Title1.1 Title1.2
Category B -> Category B.sub -> Category A.subsub
Title1 Title1.1 Title1.1
Title1 Title1.1 Title1.1
As you can see Category B.sub.sub hasn't any subcategories. If that's the case it should show the subcategories from Category B.sub. Normally I would do something like this:
{% for category in shop.categories %}
{{ category.title }}
{% if category.subs %}
{% for category in category.subs %}
{{ category.title }}
{% if category.subs %}
{% for category in category.subs %}
{{ category.title }}
{% endfor %}
{% endif %}
{% endfor %}
{% endif %}
{% endfor %}
Is there any way to create somesort of function that checks if a category has subcategories. If that's not the case the access the previous loop and display those category names.
I thought this was as simple as:
{% elseif not category.subs %}
{# Do this #}
But that's not the case :(

Answer 1

My suggestion is to make the structure of the arrays alike within your php code and don't put such kind of logic in the template.
So in php you wold have something like this:
if (!isset($categoryB['sub']['subsub']) {
$categoryB['sub']['subsub'] = $categoryA['sub']['subsub'];
}
and then your template you just iterate:
{% for category in shop.categories %}
{{ category.title }}
{% for category in category.subs %}
{{ category.title }}
{% for category in category.subs.subsub %}
{{ category.title }}
And I would also suggest to make it recursive so you would have something like:
{% itarerateCategoryes categories %}

Answer 2

Agreeing with Fyntasia I wouldn't have lots of logic in the template, I would parse the data in the controller to the form I wanted.
However assuming your data array is something like (couldn't understand your notation);
$categories = [
0 => [
'top' => ['Atop1', 'Atop2'],
'middle' => ['Amiddle1', 'Amiddle2'],
'bottom' => ['Abottom1', 'Abottom2'],
],
1 => [
'top' => ['Btop1', 'Btop2'],
'middle' => ['Bmiddle1', 'Bmiddle2'],
],
];
Something like;
{% for main_index, category in categories %}
{% if category.top is defined and category.top|length > 0 %}
{{ loop.index0 }} has top values
{% endif %}
{% if category.middle is defined and category.middle|length > 0 %}
{{ loop.index0 }} has middle values
{% endif %}
{% if category.bottom is defined and category.bottom|length > 0 %}
{{ loop.index0 }} has bottom values
{% else %}
{{ loop.index0 }} has no value so using {{ categories[loop.index0 - 1].bottom|join(', ') }}
{% endif %}
<br />
{% endfor %}
Outputs something like;
0 has top values 0 has middle values 0 has bottom values
1 has top values 1 has middle values 1 has no value so using Abottom1, Abottom2