PHP에서 연관 배열을 정렬하는 동안 키 순서를 유지할 수 있습니까?

<code class="php">function mergesort(&$array, $cmp_function = 'strcmp') {
    // Handle base cases
    if (count($array) < 2) return;
    
    // Split the array into halves
    $halfway = count($array) / 2;
    $array1 = array_slice($array, 0, $halfway);
    $array2 = array_slice($array, $halfway);
    
    // Recursively sort the halves
    mergesort($array1, $cmp_function);
    mergesort($array2, $cmp_function);
    
    // Merge the sorted halves
    $array = array();
    $ptr1 = $ptr2 = 0;

    while ($ptr1 < count($array1) && $ptr2 < count($array2)) {
        if (call_user_func($cmp_function, $array1[$ptr1], $array2[$ptr2]) < 1) {
            $array[] = $array1[$ptr1++];
        } else {
            $array[] = $array2[$ptr2++];
        }
    }
    
    // Merge the remaining elements
    while ($ptr1 < count($array1)) $array[] = $array1[$ptr1++];
    while ($ptr2 < count($array2)) $array[] = $array2[$ptr2++];
}</code>