Variant type list helper for node spawning

.cpp

template <typename... NodeTypes>
struct ViewportNodes
{
    using NodeSpawner = std::function<std::shared_ptr<ImFlow::BaseNode>( ImFlow::ImNodeFlow & )>;
    using NodeTypeVariants = std::variant<NodeTypes...>;

    struct NodeMeta
    {
        NodeMeta( std::string_view name, NodeSpawner spawner )
            : name( name ), spawner( spawner )
        {}

        std::string_view name;
        NodeSpawner spawner;
    };

    template<std::size_t N>
    using AllowedNode = std::variant_alternative_t<N, NodeTypeVariants>;

    template<std::size_t... Is>
    static auto generateNodeMeta( std::index_sequence<Is...> )
    {
        return std::array<NodeMeta, sizeof...( Is )>
        {
            NodeMeta
            {
                typeid( AllowedNode<Is> ).name(),
                []( ImFlow::ImNodeFlow & graph ) -> std::shared_ptr<ImFlow::BaseNode>
                {
                    return graph.placeNode<AllowedNode<Is>>();
                }
            }...
        };
    }

    static const std::array<NodeMeta, std::variant_size_v<NodeTypeVariants>> nodeMetas;

    static std::shared_ptr<ImFlow::BaseNode> CreateNode( uint32_t index, ImFlow::ImNodeFlow & graph )
    {
        if ( index >= nodeMetas.size() )
            return nullptr;

        return nodeMetas[ index ].spawner( graph );
    }

    static std::string_view GetNodeName( uint32_t index )
    {
        // TODO: not throw, maybe an error code and expected?
        if ( index >= nodeMetas.size() )
            throw std::out_of_range("Invalid node index");


        return nodeMetas[ index ].name;
    }
};

template <typename... NodeTypes>
const std::array<typename ViewportNodes<NodeTypes...>::NodeMeta, std::variant_size_v<typename ViewportNodes<NodeTypes...>::NodeTypeVariants>>
ViewportNodes<NodeTypes...>::nodeMetas = ViewportNodes<NodeTypes...>::generateNodeMeta( std::make_index_sequence<std::variant_size_v<typename ViewportNodes<NodeTypes...>::NodeTypeVariants>>() );