router.hpp

#pragma once

#include "telnetpp/detail/return_default.hpp"
#include <functional>
#include <map>
#include <type_traits>
#include <utility>

namespace telnetpp { namespace detail {

//* =========================================================================
//* =========================================================================
template <
    class Key
  , class Message
  , class Result
  , class KeyFromMessagePolicy
>
class router
{
public :
    typedef Key                                    key_type;
    typedef Message                                message_type;
    typedef Result                                 result_type;
    typedef std::function<Result (Message const&)> function_type;
    typedef std::map
    <
        key_type
      , function_type
    > registered_functions_map_type;

    //* =====================================================================
    //* =====================================================================
    template <typename KeyType, typename Function>
    void register_route(
        KeyType  &&key,
        Function &&function)
    {
        registered_functions_[std::forward<KeyType>(key)] =
            std::forward<Function>(function);
    }

    //* =====================================================================
    //* =====================================================================
    template <typename KeyType>
    void unregister_route(KeyType &&key)
    {
        registered_functions_.erase(std::forward<KeyType>(key));
    }

    //* =====================================================================
    //* =====================================================================
    template <typename Function>
    void set_unregistered_route(Function &&route)
    {
        unregistered_route_ = std::forward<Function>(route);
    }

    //* =====================================================================
    //* =====================================================================
    Result operator()(Message const& message) const
    {
        auto iter = registered_functions_.find(
            KeyFromMessagePolicy::key_from_message(message));

        if (iter != registered_functions_.end())
        {
            return iter->second(message);
        }
        else if (unregistered_route_ != nullptr)
        {
            return unregistered_route_(message);
        }

        // This garbage is just to return either a default-constructed Result,
        // or void if Result is void.
        return detail::return_default_constructed<Result>{}();
    }

private :
    registered_functions_map_type registered_functions_;
    function_type                 unregistered_route_;
};

}}