| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // <functional> |
| |
| // reference_wrapper |
| |
| // has weak result type |
| |
| // REQUIRES: c++03 || c++11 || c++14 || c++17 |
| |
| #include <functional> |
| #include <type_traits> |
| |
| #include "test_macros.h" |
| |
| template <class Arg, class Result> |
| struct my_unary_function |
| { // std::unary_function was removed in C++17 |
| typedef Arg argument_type; |
| typedef Result result_type; |
| }; |
| |
| template <class Arg1, class Arg2, class Result> |
| struct my_binary_function |
| { // std::binary_function was removed in C++17 |
| typedef Arg1 first_argument_type; |
| typedef Arg2 second_argument_type; |
| typedef Result result_type; |
| }; |
| |
| class functor1 |
| : public my_unary_function<int, char> |
| { |
| }; |
| |
| class functor2 |
| : public my_binary_function<char, int, double> |
| { |
| }; |
| |
| class functor3 |
| : public my_unary_function<char, int>, |
| public my_binary_function<char, int, double> |
| { |
| public: |
| typedef float result_type; |
| }; |
| |
| class functor4 |
| : public my_unary_function<char, int>, |
| public my_binary_function<char, int, double> |
| { |
| public: |
| }; |
| |
| class C {}; |
| |
| template <class T> |
| struct has_result_type |
| { |
| private: |
| struct two {char _; char __;}; |
| template <class U> static two test(...); |
| template <class U> static char test(typename U::result_type* = 0); |
| public: |
| static const bool value = sizeof(test<T>(0)) == 1; |
| }; |
| |
| int main(int, char**) |
| { |
| static_assert((std::is_same<std::reference_wrapper<functor1>::result_type, |
| char>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<functor2>::result_type, |
| double>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<functor3>::result_type, |
| float>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<void()>::result_type, |
| void>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<int*(double*)>::result_type, |
| int*>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<void(*)()>::result_type, |
| void>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<int*(*)(double*)>::result_type, |
| int*>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<int*(C::*)(double*)>::result_type, |
| int*>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<int (C::*)(double*) const volatile>::result_type, |
| int>::value), ""); |
| static_assert((std::is_same<std::reference_wrapper<C()>::result_type, |
| C>::value), ""); |
| static_assert(has_result_type<std::reference_wrapper<functor3> >::value, ""); |
| static_assert(!has_result_type<std::reference_wrapper<functor4> >::value, ""); |
| static_assert(!has_result_type<std::reference_wrapper<C> >::value, ""); |
| |
| return 0; |
| } |