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Extract FunctionReturnType to catch_meta.hpp

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This commit is contained in:
Martin Hořeňovský
2019-10-28 15:06:54 +01:00
parent 5290d4bedc
commit fc320f6b8f
2 changed files with 26 additions and 24 deletions
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36
include/internal/catch_meta.hpp
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@@ -12,22 +12,34 @@
#include <type_traits>
namespace Catch {
template<typename T>
struct always_false : std::false_type {};
template<typename T>
struct always_false : std::false_type {};
template <typename> struct true_given : std::true_type {};
struct is_callable_tester {
template <typename Fun, typename... Args>
true_given<decltype(std::declval<Fun>()(std::declval<Args>()...))> static test(int);
template <typename...>
std::false_type static test(...);
};
template <typename T>
struct is_callable;
template <typename> struct true_given : std::true_type {};
struct is_callable_tester {
template <typename Fun, typename... Args>
true_given<decltype(std::declval<Fun>()(std::declval<Args>()...))> static test(int);
template <typename...>
std::false_type static test(...);
};
struct is_callable<Fun(Args...)> : decltype(is_callable_tester::test<Fun, Args...>(0)) {};
template <typename T>
struct is_callable;
template <typename Fun, typename... Args>
struct is_callable<Fun(Args...)> : decltype(is_callable_tester::test<Fun, Args...>(0)) {};
#if defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable >= 201703
// std::result_of is deprecated in C++17 and removed in C++20. Hence, it is
// replaced with std::invoke_result here. Also *_t format is preferred over
// typename *::type format.
template <typename Func, typename U>
using FunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::invoke_result_t<Func, U>>>;
#else
template <typename Func, typename U>
using FunctionReturnType = typename std::remove_reference<typename std::remove_cv<typename std::result_of<Func(U)>::type>::type>::type;
#endif
} // namespace Catch