PHP Create breadcrumb list of every value in nested array - php

Question

I have an array that looks like the following:
[
'applicant' => [
'user' => [
'username' => true,
'password' => true,
'data' => [
'value' => true,
'anotherValue' => true
]
]
]
]
What I want to be able to do is convert that array into an array that looks like:
[
'applicant.user.username',
'applicant.user.password',
'applicant.user.data.value',
'applicant.user.data.anotherValue'
]
Basically, I need to somehow loop through the nested array and every time a leaf node is reached, save the entire path to that node as a dot separated string.
Only keys with true as a value are leaf nodes, every other node will always be an array. How would I go about accomplishing this?
edit
This is what I have tried so far, but doesnt give the intended results:
$tree = $this->getTree(); // Returns the above nested array
$crumbs = [];
$recurse = function ($tree, &$currentTree = []) use (&$recurse, &$crumbs)
{
foreach ($tree as $branch => $value)
{
if (is_array($value))
{
$currentTree[] = $branch;
$recurse($value, $currentTree);
}
else
{
$crumbs[] = implode('.', $currentTree);
}
}
};
$recurse($tree);

Answer 1

This function does what you want:
function flattenArray($arr) {
$output = [];
foreach ($arr as $key => $value) {
if (is_array($value)) {
foreach(flattenArray($value) as $flattenKey => $flattenValue) {
$output["${key}.${flattenKey}"] = $flattenValue;
}
} else {
$output[$key] = $value;
}
}
return $output;
}
You can see it running here.