Created
January 3, 2016 12:09
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#include <utility> | |
#include <initializer_list> | |
#include <stddef.h> | |
using namespace std; | |
#define USE_RECURSION 0 | |
#if USE_RECURSION | |
template <typename...> | |
struct count; | |
template <typename T> | |
struct count<T> { | |
constexpr static size_t value = 0; | |
}; | |
template <typename T, typename Head, typename... Tail> | |
struct count<T, Head, Tail...> { | |
constexpr static size_t value = | |
(std::is_same<T, Head>::value ? 1 : 0) + count<T, Tail...>::value; | |
}; | |
#else | |
template<typename T, typename... Ts> | |
constexpr size_t count_impl() | |
{ | |
size_t count = 0; | |
auto x = {(count += std::is_same<T, Ts>::value)...}; | |
(void)x; | |
return count; | |
} | |
template<typename T, typename... Ts> | |
struct count | |
{ | |
static constexpr size_t value = count_impl<T, Ts...> (); | |
}; | |
#endif | |
template<typename... Ts> struct void_t {}; | |
template<typename T, typename... Ts> | |
constexpr size_t count_func (void_t<Ts...>) { return count<T, Ts...>::value; } | |
template<typename... Ts> | |
auto create_void_impl (Ts... t) { return void_t<Ts...> ();} | |
template<size_t...s> | |
auto create_void1 (index_sequence<s...>) { return create_void_impl ((s, 1)...); } | |
template<size_t s> | |
auto create_void () { return create_void1 (make_index_sequence<s> ()); } | |
int main () | |
{ | |
return count_func<int> (create_void<1200>()); | |
} |
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