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| #include <iostream> | |
| #if defined(__clang__) | |
| enum { max_depth = 256}; | |
| #else | |
| enum { max_depth = 100}; | |
| #endif | |
| #define INIT_REGISTER(REG) \ | |
| template<typename T, int N> \ | |
| struct REG:REG<T, N-1>{ \ | |
| enum {value = N}; \ | |
| }; \ | |
| template<typename T> \ | |
| struct REG<T, 0>{ \ | |
| enum {value = 0}; \ | |
| }; \ | |
| template <typename T> \ | |
| REG<T, 0> get(REG<T, 0>){ \ | |
| return {}; \ | |
| } | |
| #define GET_REGISTERED_TIMES(REG, T) \ | |
| decltype(get(REG<T, max_depth>()))::value | |
| #define REGISTER(REG, T) \ | |
| REG<T, GET_REGISTERED_TIMES(REG, T) + 1> get(REG<T, GET_REGISTERED_TIMES(REG, T) + 1>){ \ | |
| return {}; \ | |
| }\ | |
| static_assert(true, "") | |
| #define IF_REGISTED(REG, T) \ | |
| (GET_REGISTERED_TIMES(REG, T) > 0) | |
| using namespace std; | |
| INIT_REGISTER(Int); | |
| REGISTER(Int, int); | |
| REGISTER(Int, int); | |
| INIT_REGISTER(Float); | |
| REGISTER(Float, float); | |
| REGISTER(Float, float); | |
| REGISTER(Float, double); | |
| REGISTER(Float, double); | |
| REGISTER(Float, double); | |
| int main() | |
| { | |
| cout << "Int:int times: " << GET_REGISTERED_TIMES(Int, int) << "\n"; | |
| cout << "if int is Int: " << IF_REGISTED(Int, int) << "\n"; | |
| cout << "if long is Int: " << IF_REGISTED(Int, long) << "\n"; | |
| cout << "if float is Int: " << IF_REGISTED(Int, float) << "\n\n"; | |
| cout << "Float:double times: " << GET_REGISTERED_TIMES(Float, double) << "\n"; | |
| cout << "if int is Float: " << IF_REGISTED(Float, int) << "\n"; | |
| cout << "if double is Float: " << IF_REGISTED(Float, double) << "\n"; | |
| return 0; | |
| } | |
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Int:int times: 2
if int is Int: 1
if long is Int: 0
if float is Int: 0
Float:double times: 3
if int is Float: 0
if double is Float: 1