Traverser.h

#pragma once
 
namespace spark::patterns::details
{
    template <typename NodeType, typename... FnArgsTypes>
    class TreeTraverserCaller
    {
    public:
        template <typename Traverser>
        static void exec(NodeType* container, Traverser& traverser, FnArgsTypes&&... args)
        {
            for (auto* child : container->children())
            {
                if (!child->children().empty())
                {
                    auto* sub_container = static_cast<std::conditional_t<std::is_const_v<NodeType>, const NodeType, NodeType>*>(child);
                    traverser.pre(child, std::forward<FnArgsTypes>(args)...);
                    traverser.apply(child, std::forward<FnArgsTypes>(args)...);
                    exec(sub_container, traverser, std::forward<FnArgsTypes>(args)...);
                    traverser.post(child, std::forward<FnArgsTypes>(args)...);
                } else
                    traverser.apply(child, std::forward<FnArgsTypes>(args)...);
            }
        }
    };
}