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  1.     #include <iostream>
  2.     struct lua_State {};
  3.     template<typename T>
  4.     T CheckLuaValue( int n, lua_State* l)
  5.     {
  6.         std::cout << "arg[" << n << "] gotten\n";
  7.         return T(n);
  8.     }
  9.  
  10.     template<int ...>
  11.     struct seq { };
  12.  
  13.     template<int First, int Last>
  14.     struct gen_seq
  15.     {
  16.       template<int N, int... S>
  17.       struct helper : helper<N-1, N-1, S...> {};
  18.       template<int... S>
  19.       struct helper<First, S...> {
  20.         typedef seq<S...> type;
  21.       };
  22.       typedef typename helper<Last>::type type;
  23.     };
  24.  
  25.     template< typename X >
  26.     struct MemberFunctionWrapper;
  27.  
  28.     template< typename F >
  29.     struct MemberFunctionHelper
  30.     {
  31.         typedef F MethodPtr;
  32.     };
  33.     template<class InstanceType, typename ReturnType, typename... Params>
  34.     struct MemberFunctionWrapper< ReturnType(InstanceType::*)(Params...) >
  35.     {
  36.       typedef MemberFunctionHelper<ReturnType(InstanceType::*)(Params...)> Helper;
  37.       typedef typename Helper::MethodPtr MethodPtr;
  38.       static MethodPtr& GetFunctionPointer() {static MethodPtr pFunc; return pFunc;}
  39.       static InstanceType*& GetMemberPointer() {static InstanceType* pThis;return pThis;}
  40.       template<int n, typename Param>
  41.       static auto GetLuaValue( lua_State* luaState )->decltype(CheckLuaValue<Param>(n,luaState))
  42.       {
  43.         return CheckLuaValue<Param>(n,luaState);
  44.       }
  45.  
  46.       template< typename sequence >
  47.       struct call;
  48.  
  49.       template< int... I >
  50.       struct call<seq<I...>>
  51.       {
  52.         ReturnType operator()( lua_State* luaState, InstanceType* instance, MethodPtr method ) const
  53.         {
  54.           return (instance->*method)( GetLuaValue<I,Params>( luaState )... );
  55.         }
  56.       };
  57.       static int CFunctionWrapper( lua_State* luaState)
  58.       {
  59.         MethodPtr func = GetFunctionPointer();
  60.         InstanceType* instance = GetMemberPointer();
  61.         ReturnType retval = call< typename gen_seq< 1, sizeof...(Params)+1 >::type >()( luaState, instance, func );
  62.         return 0;
  63.       }
  64.     };
  65.  
  66.     struct test{ int foo(int x, double d){std::cout << "x:" << x << " d:" << d << "\n";}};
  67.     int main(){
  68.         typedef MemberFunctionWrapper< int(test::*)(int, double) > wrapper;
  69.         test bar;
  70.         wrapper::GetFunctionPointer() = &test::foo;
  71.         wrapper::GetMemberPointer() = &bar;
  72.         wrapper::CFunctionWrapper(0);
  73.     }
Success #stdin #stdout 0s 2884KB
comments (?)
stdin
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Standard input is empty
stdout
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arg[2] gotten
arg[1] gotten
x:1 d:2
https://ideone.com/XVmQQ6
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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