Add params to array request - php

Question

I have a pretty large array that I would need to parse, but the request changes depending on enabled/disabled parameters.
For example:
$array['a'][1]['b'][1]['c'][1] = 'asd';
$str = $array['a'][1];
dd($str);
This would give me:
Array
(
[b] => Array
(
[1] => Array
(
[c] => Array
(
[1] => asd
)
)
)
)
Which, of course, is correct. But now, if I know, that I need also the next parameter, I would need to add that like $str = $array['a'][1]['b'];.
But since there are way too many combinations, I wondered, if I can construct the call manually, something like this":
$str = $array['a'][1];
if ($b) {
$str .= ['b'][1];
}
if ($c) {
$str .= ['c'][1];
}
dd($str);
Any hints will be appreciated.
PS: I know I can do this with eval, but was really looking for a better solution:
eval("\$str = \$array$str;");
dd($str);

Answer 1

It can be done with Reference
$string = "['a'][1]['b'][1]";
// Maybe, not optimal, but it's not the point of the code
preg_match_all('/\[\'?([^\]\']+)\'?\]/', $string, $steps);
// "Root" of the array
$p = &$array;
foreach($steps[1] as $s) {
// Next step with current key
if (isset($p[$s]) && is_array($p)) $p = &$p[$s];
else throw new Exception("No such item");
}
// Target value
$str = $p;
demo