Convert an array of strings, each string has dot separated values, to a multidimensional array

I have the following array:

Array
(
    [0] => INBOX.Trash
    [1] => INBOX.Sent
    [2] => INBOX.Drafts
    [3] => INBOX.Test.sub folder
    [4] => INBOX.Test.sub folder.test 2
)

How can I convert this array to a multidimensional array like this:

Array
(
    [Inbox] => Array
        (
            [Trash] => Array
                (
                )

            [Sent] => Array
                (
                )

            [Drafts] => Array
                (
                )

            [Test] => Array
                (
                    [sub folder] => Array
                        (
                            [test 2] => Array
                                (
                                )

                        )

                )

        )

)

This code uses a function from this answer to do what you're looking for.

<?php
$test = Array
(
    0 => 'INBOX.Trash',
    1 => 'INBOX.Sent',
    2 => 'INBOX.Drafts',
    3 => 'INBOX.Test.sub folder',
    4 => 'INBOX.Test.sub folder.test 2',
);

$output = array();
foreach($test as $element){
    assignArrayByPath($output, $element);   
}
debug($output);

function assignArrayByPath(&$arr, $path) {
    $keys = explode('.', $path);
    
    while ($key = array_shift($keys)) {
        $arr = &$arr[$key];
    }
}

function debug($arr){
    echo "<pre>";
    print_r($arr);
    echo "</pre>";
}