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C++ typedef args to typeid list
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| #include <iostream> | |
| #include <typeinfo> | |
| #include <typeindex> | |
| #include <span> | |
| typedef int (*tExample) (int a, bool b, char* c, long long d); | |
| template<typename T> | |
| struct arg_types {}; | |
| template<typename R, typename... A> | |
| struct arg_types<R(*)(A...)> { | |
| inline static const std::type_index value[] = {typeid(A)...}; | |
| }; | |
| template<typename T> | |
| static constexpr std::span<const std::type_index> arg_types_v = arg_types<T>::value; | |
| int main() | |
| { | |
| auto vec = arg_types_v<tExample>; | |
| for (const auto& t : vec) | |
| { | |
| std::cout << t.hash_code() << std::endl; | |
| } | |
| } | |
| // ALTERNATIVE (free standing, no typeid). Also fixes bug with function types with 0 args by using std::array | |
| using hash_t = std::uint64_t; | |
| // FNV-1a 64 bit hash | |
| consteval hash_t fnv1a_hash(std::size_t n, const char* str, hash_t hash = 14695981039346656037ull) | |
| { | |
| return n > 0 ? fnv1a_hash(n - 1, str + 1, (hash ^ *str) * 1099511628211ull) : hash; | |
| } | |
| template<std::size_t N> | |
| consteval hash_t fnv1a_hash(const char(&array)[N]) | |
| { | |
| return fnv1a_hash(N - 1, &array[0]); | |
| } | |
| struct string_view | |
| { | |
| char const* data; | |
| std::size_t size; | |
| consteval uint64_t hash() { | |
| return fnv1a_hash(size, data); | |
| } | |
| }; | |
| template<size_t N> | |
| consteval size_t length(char const (&)[N]) | |
| { | |
| return N - 1; | |
| } | |
| template<class T> | |
| consteval string_view get_unique_name_for_type() | |
| { | |
| return { __FUNCSIG__, length(__FUNCSIG__)}; | |
| } | |
| template<typename T> | |
| consteval uint64_t get_type_id() { | |
| return get_unique_name_for_type<T>().hash(); | |
| } | |
| template<typename T> | |
| struct arg_types {}; | |
| template<typename R, typename... A> | |
| struct arg_types<R(*)(A...)> { | |
| static constexpr std::array<uint64_t, sizeof...(A)> value = {get_type_id<A>()...}; | |
| }; |
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