forked from OSchip/llvm-project
83 lines
2.7 KiB
C++
83 lines
2.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <functional>
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// reference_wrapper
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// has weak result type
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#include <functional>
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#include <type_traits>
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class functor1
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: public std::unary_function<int, char>
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{
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};
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class functor2
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: public std::binary_function<char, int, double>
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{
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};
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class functor3
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: public std::unary_function<char, int>,
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public std::binary_function<char, int, double>
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{
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public:
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typedef float result_type;
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};
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class functor4
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: public std::unary_function<char, int>,
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public std::binary_function<char, int, double>
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{
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public:
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};
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class C {};
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template <class T>
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struct has_result_type
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{
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private:
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struct two {char _; char __;};
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template <class U> static two test(...);
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template <class U> static char test(typename U::result_type* = 0);
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public:
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static const bool value = sizeof(test<T>(0)) == 1;
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};
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int main()
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{
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static_assert((std::is_same<std::reference_wrapper<functor1>::result_type,
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char>::value), "");
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static_assert((std::is_same<std::reference_wrapper<functor2>::result_type,
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double>::value), "");
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static_assert((std::is_same<std::reference_wrapper<functor3>::result_type,
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float>::value), "");
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static_assert((std::is_same<std::reference_wrapper<void()>::result_type,
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void>::value), "");
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static_assert((std::is_same<std::reference_wrapper<int*(double*)>::result_type,
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int*>::value), "");
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static_assert((std::is_same<std::reference_wrapper<void(*)()>::result_type,
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void>::value), "");
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static_assert((std::is_same<std::reference_wrapper<int*(*)(double*)>::result_type,
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int*>::value), "");
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static_assert((std::is_same<std::reference_wrapper<int*(C::*)(double*)>::result_type,
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int*>::value), "");
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static_assert((std::is_same<std::reference_wrapper<int (C::*)(double*) const volatile>::result_type,
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int>::value), "");
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static_assert((std::is_same<std::reference_wrapper<C()>::result_type,
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C>::value), "");
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static_assert(has_result_type<std::reference_wrapper<functor3> >::value, "");
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static_assert(!has_result_type<std::reference_wrapper<functor4> >::value, "");
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static_assert(!has_result_type<std::reference_wrapper<C> >::value, "");
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}
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