convert nested foreach tree into recursive php function - php

Question

Need to make recursive function from the below code. tried multiple ways but failed. because I don't know how much depth will the tree have. depth may be varying according to the data.
$tot_terms = [];
foreach ($tree as $key => $val) {
$tot_terms[$val->depth][] = $val->tid;
if (!empty($val->children)) {
foreach ($val->children as $key1 => $val1) {
$tot_terms[$val1->depth][] = $val1->tid;
if ($val1->children) {
foreach ($val1->children as $key2 => $val2) {
$tot_terms[$val2->depth][] = $val2->tid;
if ($val2->children) {
foreach ($val2->children as $key3 => $val3) {
$tot_terms[$val3->depth][] = $val3->tid;
if ($val3->children) {
foreach ($val3->children as $key4 => $val4) {
$tot_terms[$val4->depth][] = $val4->tid;
if ($val4->children) {
foreach ($val4->children as $key5 => $val5) {
$tot_terms[$val5->depth][] = $val5->tid;
}
}
}
}
}
}
}
}
}
}
}
and the result should be like this
Array
(
[0] => Array
(
[0] => 20011
[1] => 19991
[2] => 20000
)
[1] => Array
(
[0] => 20010
[1] => 19995
[2] => 19994
[3] => 19990
[4] => 20005
[5] => 19985
[6] => 19999
[7] => 19998
)
[2] => Array
(
[0] => 20012
[1] => 20006
[2] => 19996
[3] => 19993
[4] => 19989
[5] => 19988
[6] => 20004
[7] => 19984
[8] => 20001
)
[3] => Array
(
[0] => 20007
[1] => 20009
[2] => 20008
[3] => 19992
[4] => 19987
[5] => 19986
[6] => 19983
[7] => 19982
[8] => 20003
[9] => 20002
)
[4] => Array
(
[0] => 19997
)
[5] => Array
(
[0] => 19981
)
)
Tried according to other post but it is failing. input $tree is something that is array and an object. will post in next comment if required as total body count is more than its expected

Answer 1

We can use a handler function to store data. Note that we are passing the array by reference.
function func( $item, &$data ) {
if ( is_empty( $item ) ) return;
if ( ! is_object( $item ) ) return;
foreach ($item as $key => $val) {
$data[$val->depth][] = $val->tid;
func( $val->children, $data );
}
}
function func_handler( $item ) {
$data = [];
func( $item, $data );
return $data;
}