Method duplicate_container

src/session/src/session_actor.cpp:2181–2231

// I think the actors themselves need to support a clone atom..

void SessionActor::duplicate_container(
    caf::typed_response_promise<UuidVector> rp,
    const utility::UuidTree<utility::PlaylistItem> &tree,
    caf::actor source_session,
    const utility::Uuid &uuid_before,
    const bool into,
    const bool rename,
    const bool kill_source) {

    // find all actor children.. (Timeline/SUBSET/CONTACTSHEET)
    // quick clone of divider..

    // clone structure
    PlaylistTree new_tree(tree);

    // regenerate uuids..
    new_tree.reset_uuid(true);

    duplicate_tree(new_tree, source_session, rename);

    std::function<void(const PlaylistTree &, std::vector<Uuid> &)> flatten_tree;
    flatten_tree = [&flatten_tree](const PlaylistTree &tree, std::vector<Uuid> &rt) {
        rt.push_back(tree.uuid());
        for (auto i : tree.children_ref()) {
            flatten_tree(i, rt);
        }
    };

    std::vector<Uuid> ordered_uuids;

    // If we clone a session we need to reparent the children of the tree.
    // As they sit under the session item.
    if (new_tree.value().type() == "Session" or new_tree.value().type() == "") {
        // reparent..
        for (auto &i : new_tree.children_) {
            flatten_tree(i, ordered_uuids);
            base_.insert_container(i, uuid_before, into);
        }

    } else {
        flatten_tree(new_tree, ordered_uuids);
        base_.insert_container(new_tree, uuid_before, into);
    }

    base_.send_changed();

    if (kill_source)
        send_exit(source_session, caf::exit_reason::user_shutdown);

    rp.deliver(ordered_uuids);
}

// session actors container groups/dividers and playlists..
void SessionActor::duplicate_tree(