Convert Decimal-Number/MIB-Style Strings to Array Indices - php

Question

I'm trying to convert mib-style strings into PHP array indices. The trick is that I have to do this for a variable number of strings. As an example:
$strings = ['1.1.1' => 1, '1.1.2' => 2, '1.2.1' => 1];
# Given the above, generate the below:
$array = [ 1 => [ 1 => [1 => 1, 2 => 2] ], 2 => [1 => 1] ] ] ] ]
I can't think of a way to do it that isn't just a brute-force, inefficient method. Any helpful function/approach/advice is welcome.

Answer 1

You could take a recursive approach since the problem/result you provide seems to be of a recursive nature. (You can achieve the same result with a loop, applying the same logic as the recursive function ofcourse)
So under the assumption that there are no conflicting string inputs/edge cases what so ever, the following could be one approach:
Loop over all the strings and their values, break it up and create a nested structure by passing the result array by its reference.
function createNested($pieces, $currentIndex, &$previous, $value)
{
$index = $pieces[$currentIndex];
// Our base case: when we reached the final/deepest level of nesting.
// Hence when the we reached the final index.
if ($currentIndex == count($pieces) - 1) {
// Can now safely assign the value to index.
$previous[$index] = $value;
} else {
// Have to make sure we do not override the key/index.
if (!key_exists($index, $previous)) {
$previous[$index] = [];
}
// If the key already existed we can just make a new recursive call (note one level deeper as we pass the array that $previous[$index] points to.
createNested($pieces, $currentIndex + 1, $previous[$index], $value);
}
}
$strings = ['1.1.1' => 1, '1.1.2' => 2, '1.2.1' => 1];
$result = [];
foreach ($strings as $string => $value) {
// Break up the string by .
createNested(explode('.', $string), 0, $result, $value);
}
echo '<pre>';
print_r($result);
echo '</pre>';
Will output:
Array
(
[1] => Array
(
[1] => Array
(
[1] => 1
[2] => 2
)
[2] => Array
(
[1] => 1
)
)
)