如何通过在分层键的循环数组中访问它来取消设置对象键 (php)

Question

I have a XML Object

$xml = SimpleXMLElement Object
    (
        [a] => SimpleXMLElement Object
                    (
                        [b] => SimpleXMLElement Object
                                   (
                                       [c] => 'hey',
                                   ),
                     ),
    )

Now, I put all keys in array and I want to unset the last key ie 'c' from the object

$temp = $xml;
$keys_arr = ['a', 'b', 'c'];
foreach($keys_arr => $key){
    $temp = $temp->$key;
}
unset($temp) // I want this to work like when we use this 'unset($xml->a->b->c);'

And when we print $temp:

print_r($temp);

the output should be:

SimpleXMLElement Object
        (
            [a] => SimpleXMLElement Object
                        (
                            [b] => SimpleXMLElement Object
                                       (
                                           // without '[c]' key
                                       ),
                         ),
        )

Answer 1

This is a recursive approach (as opposed to stacking):

Code: ( Demo )

function recurse(&$object,$keys){  // modify the input by reference
    $key=array_shift($keys);
    if(isset($object->$key)){  // avoid trouble
        if(empty($keys)){
            unset($object->$key);  // remove at last key
        }else{
            recurse($object->$key,$keys);  // continue recursion
        }
    }
}

$xmlstring=<<<XML
    <root>
        <a>
            <b>
                <c>hey</c>
            </b>
        </a>
    </root>
XML;
$keys=['a','b','c'];

$xml=new SimpleXMLElement($xmlstring);
echo "Before: \n";
var_export($xml);
echo "\n----\nAfter:\n";

recurse($xml,$keys);  // modify input
var_export($xml);

Output:

Before: 
SimpleXMLElement::__set_state(array(
   'a' => 
  SimpleXMLElement::__set_state(array(
     'b' => 
    SimpleXMLElement::__set_state(array(
       'c' => 'hey',
    )),
  )),
))
----
After:
SimpleXMLElement::__set_state(array(
   'a' => 
  SimpleXMLElement::__set_state(array(
     'b' => 
    SimpleXMLElement::__set_state(array(
    )),
  )),
))

---

And here is how I'd stack it to achieve the same result: Demo

$mod=&$xml;               // modify $xml by reference
$keys=['a','b','c'];
$last=array_pop($keys);   // assuming the array will not be empty, the array will contain valid/existing object keys
foreach($keys as $key){   // iterate/traverse all remaining keys (e.g. 'a','b' because 'c' was popped off)
    $mod=&$mod->$key;     // overwrite $mod by reference while traversing
}
unset($mod->$last);       // unset the last object
var_export($xml);         // print modified $xml to screen

Answer 2

Walk the keys array except last item, and finally do the unset. But assign to $temp by reference!!

$temp = &$xml;
$keys_arr = ['a', 'b', 'c'];
for($i,$size=count($keys_arr); $i<$size-1; $i++){
    $temp = &$temp->$keys_arr[$i];
}
unset($temp->$keys_arr[$i]);