74 lines
2.3 KiB
C++
74 lines
2.3 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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#ifndef TRANSPARENT_H
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#define TRANSPARENT_H
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// testing transparent
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#if _LIBCPP_STD_VER > 11
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struct transparent_less
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{
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template <class T, class U>
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constexpr auto operator()(T&& t, U&& u) const
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noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
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-> decltype (std::forward<T>(t) < std::forward<U>(u))
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{ return std::forward<T>(t) < std::forward<U>(u); }
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typedef void is_transparent; // correct
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};
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struct transparent_less_no_type
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{
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template <class T, class U>
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constexpr auto operator()(T&& t, U&& u) const
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noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
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-> decltype (std::forward<T>(t) < std::forward<U>(u))
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{ return std::forward<T>(t) < std::forward<U>(u); }
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private:
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// typedef void is_transparent; // error - should exist
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};
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struct transparent_less_private
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{
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template <class T, class U>
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constexpr auto operator()(T&& t, U&& u) const
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noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
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-> decltype (std::forward<T>(t) < std::forward<U>(u))
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{ return std::forward<T>(t) < std::forward<U>(u); }
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private:
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typedef void is_transparent; // error - should be accessible
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};
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struct transparent_less_not_a_type
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{
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template <class T, class U>
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constexpr auto operator()(T&& t, U&& u) const
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noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
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-> decltype (std::forward<T>(t) < std::forward<U>(u))
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{ return std::forward<T>(t) < std::forward<U>(u); }
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int is_transparent; // error - should be a type
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};
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struct C2Int { // comparable to int
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C2Int() : i_(0) {}
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C2Int(int i): i_(i) {}
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int get () const { return i_; }
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private:
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int i_;
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};
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bool operator <(int rhs, const C2Int& lhs) { return rhs < lhs.get(); }
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bool operator <(const C2Int& rhs, const C2Int& lhs) { return rhs.get() < lhs.get(); }
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bool operator <(const C2Int& rhs, int lhs) { return rhs.get() < lhs; }
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#endif
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#endif // TRANSPARENT_H
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