Horde_Imap_Client_Ids::sort PHP Method

    public function sort()
    {
        if (!$this->_sorted && is_array($this->_ids)) {
            $this->_sort($this->_ids);
            $this->_sorted = true;
        }
    }

 /**
  * Removes messages from the ID mapping.
  *
  * @param Horde_Imap_Client_Ids $ids  IDs to remove.
  */
 public function remove(Horde_Imap_Client_Ids $ids)
 {
     /* For sequence numbers, we need to reindex anytime we have an index
      * that appears equal to or after a previously seen index. If an IMAP
      * server is smart, it will expunge in reverse order instead. */
     if ($ids->sequence) {
         $remove = $ids->ids;
     } else {
         $ids->sort();
         $remove = array_reverse(array_keys($this->lookup($ids)));
     }
     if (empty($remove)) {
         return;
     }
     $this->sort();
     /* Find the minimum sequence number to remove. We know entries before
      * this are untouched so no need to process them multiple times. */
     $first = min($remove);
     $edit = $newids = array();
     foreach (array_keys($this->_ids) as $i => $seq) {
         if ($seq >= $first) {
             $i += $seq == $first ? 0 : 1;
             $newids = array_slice($this->_ids, 0, $i, true);
             $edit = array_slice($this->_ids, $i + ($seq == $first ? 0 : 1), null, true);
             break;
         }
     }
     if (!empty($edit)) {
         foreach ($remove as $val) {
             $found = false;
             $tmp = array();
             foreach (array_keys($edit) as $i => $seq) {
                 if ($found) {
                     $tmp[$seq - 1] = $edit[$seq];
                 } elseif ($seq >= $val) {
                     $tmp = array_slice($edit, 0, $seq == $val ? $i : $i + 1, true);
                     $found = true;
                 }
             }
             $edit = $tmp;
         }
     }
     $this->_ids = $newids + $edit;
 }