BloombergLP::bdlcc::Deque::tryPopFront

Remove up to the specified maxNumItems from the front of this container. Optionally specify a buffer into which the items removed from the container are appended. If buffer is non‐null, the removed items are appended to it as if by repeated application of buffer‐>push_back(popFront()) while the const is not empty and maxNumItems have not yet been removed. Note that *buffer is not cleared ‐‐ the popped items are appended after any pre‐existing contents.