Function flatten_tree

plugins/tile/tree.cpp:514–559

----------------- Generic tree operations implementation ----------------- */

/* ----------------- Generic tree operations implementation ----------------- */
bool flatten_tree(std::unique_ptr<tree_node_t>& root)
{
    /* Cannot flatten a view node */
    if (root->as_view_node())
    {
        return true;
    }

    for (auto it = root->children.begin(); it != root->children.end();)
    {
        if (!flatten_tree(*it))
        {
            it = root->children.erase(it);
        } else
        {
            ++it;
        }
    }

    if (root->children.empty())
    {
        return false;
    }

    /* No flattening required on this level */
    if (root->children.size() >= 2)
    {
        return true;
    }

    nonstd::observer_ptr<tree_node_t> child_ptr = {root->children.front()};

    /* A single view child => cannot make it root */
    if (child_ptr->as_view_node())
    {
        if (!root->parent)
        {
            return true;
        }
    }

    /* Rewire the tree, skipping the current root */
    child_ptr->parent = root->parent;
    root = std::move(root->children.front());
    return true;
}

nonstd::observer_ptr<split_node_t> get_root(
    nonstd::observer_ptr<tree_node_t> node)