Scripted_state_machine.hpp

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#ifndef HRK_SCRIPTED_STATE_MACHINE_HPP
#define HRK_SCRIPTED_STATE_MACHINE_HPP

#include <iostream>
#include <luabind/luabind.hpp>


namespace hrk
{
    template <class T>
    class Scripted_state_machine
    {
    public:
        Scripted_state_machine(T* owner, lua_State* lua)
            : owner_(owner), lua_(lua)
        {
        }


        void set_current_state(const std::string& state_name)
        {
            luabind::object global = luabind::globals(lua_);
            luabind::object state = global[state_name];

            check_state_is_table(state, state_name);
            previous_state_ = current_state_;
            current_state_ = state;
            current_state_name_ = state_name;
        }


        luabind::object change_to_previous(void) const
        {
            return previous_state_;
        }


        bool update(void)
        {
            if (!current_state_.is_valid()) {
                return false;
            }

            if (luabind::type(current_state_["Execute"]) != LUA_TFUNCTION) {
                std::string state_name = current_state_name_ + "['Execute']";
                std::cerr << "Not found function: " << state_name << std::endl;
                return false;
            }
            current_state_["Execute"](owner_);

            return true;
        }


        bool change_to(const std::string& next_state_name)
        {
            if (current_state_.is_valid()) {
                if (luabind::type(current_state_["Exit"]) != LUA_TFUNCTION) {
                    std::cerr << "Not found function: "
                              << current_state_name_ << "['Exit']"
                              << std::endl;
                    return false;
                }
                current_state_["Exit"](owner_);
            }

            // 直前の状態を保持しておく
            previous_state_ = current_state_;
            current_state_name_ = next_state_name;

            luabind::object global = luabind::globals(lua_);
            luabind::object next_state = global[next_state_name];
            check_state_is_table(next_state, next_state_name);
            current_state_ = next_state;
            if (luabind::type(current_state_["Enter"]) != LUA_TFUNCTION) {
                std::cerr << "Not found function: "
                          << next_state_name << "['Enter']" << std::endl;
                return false;
            }
            current_state_["Enter"](owner_);

            return true;
        }


    private:
        void check_state_is_table(const luabind::object& state,
                                  const std::string& state_name)
        {
            if (luabind::type(state) != LUA_TTABLE) {
                std::cerr << "'" << state_name
                          << "' variable is not table." << std::endl;
                if (luabind::type(state) == LUA_TNIL) {
                    std::cerr << "'" << state_name << "' is nil." << std::endl;
                }
            }
        }


        T* owner_;
        lua_State* lua_;
        luabind::object current_state_;
        luabind::object previous_state_;
        std::string current_state_name_;
    };
}

#endif