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我试图用模板元编程技术开发一个有限状态机,但是我得到一个必须在编译时填充的映射,这个代码(GCC 4.8 C++ 11):C++ 11模板元编程在编译时构造一个std :: unorderer_map
#include <functional>
#include <type_traits>
#include <iostream>
#include <unordered_map>
namespace NSStateMachine {
//Definicion de estado unidad
template<class FSM, class From, class Event, class TO, bool(FSM::* transicion_fn)(const Event &)>
struct Transition
{
using FSM_TYPE=FSM;
using FROM_STATE= From;
using EVENT_TYPE= Event;
using TO_STATE_TYPE=TO;
using EVENT_BASE_TYPE = typename Event::BASE_TYPE;
static bool do_transition(FSM_TYPE& currenState, EVENT_BASE_TYPE const& aEvent)
{
return (currenState.*transicion_fn)(static_cast<EVENT_TYPE const&>(aEvent));
}
};
//States
template<class Transition, const Transition * const TransitionPtr, class ... Args>
class StateMachine
{
public:
StateMachine():transitionMap{{static_cast<typename Transition::TransitionID>(*TransitionPtr::TransitionID_Value),nullptr}}
{}
template<class Event>
bool evalEvent(const Event & aEvent)
{
std::cout<<"evento recibido"<<std::endl;
}
std::unordered_map<typename Transition::TransitionID, const Transition * const > transitionMap ;
};
}
int main()
{
//it doesnt compile, i canoot create the state machine
return 0;
}
编译错误:
error: 'TransitionPtr' is not a class, namespace, or enumeration
StateMachine():transitionMap{{static_cast<typename Transition::TransitionID>(*TransitionPtr::TransitionID_Value),nullptr}}
^
的问题似乎是在线路
transitionMap{{static_cast<typename Transition::TransitionID>(*TransitionPtr::TransitionID_Value),nullptr}}
我会尝试用自动构造函数初始化unorderer_map。 我已经将此Transition :: TransitionID定义为由模板参数表示的类中定义的类变量
我非常感谢任何帮助。 Thx !!!!
我已经默认类型的测试,它编译并运行此