router.hpp

#pragma once
 
#include "telnetpp/detail/return_default.hpp"
 
#include <functional>
#include <unordered_map>
#include <utility>
 
namespace telnetpp::detail {
 
//* =========================================================================
//* =========================================================================
template <class Key, class Message, class Function, class KeyFromMessagePolicy>
class router
{
public:
    using key_type = Key;
    using message_type = Message;
    using function_type = std::function<Function>;
    using result_type = typename function_type::result_type;
    using registered_functions_map_type =
        std::unordered_map<key_type, function_type>;
 
    //* =====================================================================
    //* =====================================================================
    template <typename KeyType, typename Continuation>
    void register_route(KeyType &&key, Continuation &&cont)
    {
        registered_functions_[std::forward<KeyType>(key)] =
            std::forward<Continuation>(cont);
    }
 
    //* =====================================================================
    //* =====================================================================
    template <typename KeyType>
    void unregister_route(KeyType &&key)
    {
        registered_functions_.erase(std::forward<KeyType>(key));
    }
 
    //* =====================================================================
    //* =====================================================================
    template <typename Continuation>
    void set_unregistered_route(Continuation &&cont)
    {
        unregistered_route_ = std::forward<Continuation>(cont);
    }
 
    //* =====================================================================
    //* =====================================================================
    template <typename MessageType, typename... Args>
    result_type operator()(MessageType &&message, Args &&...args) const
    {
        if (auto iter = registered_functions_.find(
                KeyFromMessagePolicy::key_from_message(message));
            iter != registered_functions_.end())
        {
            return iter->second(
                std::forward<MessageType>(message),
                std::forward<Args>(args)...);
        }
        else if (unregistered_route_)
        {
            return unregistered_route_(
                std::forward<MessageType>(message),
                std::forward<Args>(args)...);
        }
 
        // This garbage is just to return either a default-constructed Result,
        // or void if Result is void.
        return detail::return_default_constructed<result_type>{}();
    }
 
private:
    registered_functions_map_type registered_functions_;
    function_type unregistered_route_;
};
 
}  // namespace telnetpp::detail