1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // <functional>
11
12 // reference_wrapper
13
14 // has weak result type
15
16 #include <functional>
17 #include <type_traits>
18
19 class functor1
20 : public std::unary_function<int, char>
21 {
22 };
23
24 class functor2
25 : public std::binary_function<char, int, double>
26 {
27 };
28
29 class functor3
30 : public std::unary_function<char, int>,
31 public std::binary_function<char, int, double>
32 {
33 public:
34 typedef float result_type;
35 };
36
37 class functor4
38 : public std::unary_function<char, int>,
39 public std::binary_function<char, int, double>
40 {
41 public:
42 };
43
44 class C {};
45
46 template <class T>
47 struct has_result_type
48 {
49 private:
50 struct two {char _; char __;};
51 template <class U> static two test(...);
52 template <class U> static char test(typename U::result_type* = 0);
53 public:
54 static const bool value = sizeof(test<T>(0)) == 1;
55 };
56
main()57 int main()
58 {
59 static_assert((std::is_same<std::reference_wrapper<functor1>::result_type,
60 char>::value), "");
61 static_assert((std::is_same<std::reference_wrapper<functor2>::result_type,
62 double>::value), "");
63 static_assert((std::is_same<std::reference_wrapper<functor3>::result_type,
64 float>::value), "");
65 static_assert((std::is_same<std::reference_wrapper<void()>::result_type,
66 void>::value), "");
67 static_assert((std::is_same<std::reference_wrapper<int*(double*)>::result_type,
68 int*>::value), "");
69 static_assert((std::is_same<std::reference_wrapper<void(*)()>::result_type,
70 void>::value), "");
71 static_assert((std::is_same<std::reference_wrapper<int*(*)(double*)>::result_type,
72 int*>::value), "");
73 static_assert((std::is_same<std::reference_wrapper<int*(C::*)(double*)>::result_type,
74 int*>::value), "");
75 static_assert((std::is_same<std::reference_wrapper<int (C::*)(double*) const volatile>::result_type,
76 int>::value), "");
77 static_assert((std::is_same<std::reference_wrapper<C()>::result_type,
78 C>::value), "");
79 static_assert(has_result_type<std::reference_wrapper<functor3> >::value, "");
80 static_assert(!has_result_type<std::reference_wrapper<functor4> >::value, "");
81 static_assert(!has_result_type<std::reference_wrapper<C> >::value, "");
82 }
83