Sophiar2/src/utility/tiny_signal.hpp

#ifndef SOPHIAR2_TINY_SIGNAL_HPP
#define SOPHIAR2_TINY_SIGNAL_HPP

#include <boost/intrusive/list.hpp>

#include <cassert>
#include <type_traits>
#include <utility>

namespace sophiar {

    using slot_hook_type = boost::intrusive::list_base_hook<
            boost::intrusive::link_mode<
                    boost::intrusive::auto_unlink>>;

    struct tiny_slot_base : public slot_hook_type {

        bool is_enabled = true;

        virtual ~tiny_slot_base() = default;

        void disconnect() {
            assert(this->is_linked());
            this->unlink();
        }
    };

    struct tiny_signal_base {

        virtual ~tiny_signal_base() = default;

        virtual void add_slot_base(tiny_slot_base *slot_base) = 0;
    };

    template<typename... Args>
    class tiny_signal : public tiny_signal_base {
    public:

        class slot_type : public tiny_slot_base {
        public:

            void signal_received(Args... args) {
                if (!is_enabled) return;
                on_signal_received(std::move(args)...);
            }

        protected:

            virtual void on_signal_received(Args... args) = 0;

        };

        void add_slot_base(tiny_slot_base *slot_base) override {
            auto slot_ptr = dynamic_cast<slot_type *>(slot_base);
            assert(slot_ptr != nullptr);
            slot_list.push_back(*slot_ptr);
        }

        void emit(Args... args) {
            auto iter = slot_list.begin(), iter_end = slot_list.end();
            while (iter != iter_end) {
                auto this_iter = iter++;
                if (iter == iter_end) {
                    this_iter->signal_received(std::move(args)...);
                } else {
                    this_iter->signal_received(args...);
                }
            }
        }

    private:

        using slot_list_type = boost::intrusive::list<
                slot_type, boost::intrusive::constant_time_size<false>>;

        slot_list_type slot_list;

    };

}

#endif //SOPHIAR2_TINY_SIGNAL_HPP