72 lines
1.5 KiB
C++
72 lines
1.5 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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// <optional>
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// template <class U> T optional<T>::value_or(U&& v) &&;
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#include <experimental/optional>
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#include <type_traits>
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#include <cassert>
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#if _LIBCPP_STD_VER > 11
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using std::experimental::optional;
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using std::experimental::in_place_t;
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using std::experimental::in_place;
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struct Y
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{
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int i_;
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Y(int i) : i_(i) {}
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};
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struct X
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{
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int i_;
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X(int i) : i_(i) {}
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X(X&& x) : i_(x.i_) {x.i_ = 0;}
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X(const Y& y) : i_(y.i_) {}
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X(Y&& y) : i_(y.i_+1) {}
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friend constexpr bool operator==(const X& x, const X& y)
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{return x.i_ == y.i_;}
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};
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#endif // _LIBCPP_STD_VER > 11
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int main()
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{
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#if _LIBCPP_STD_VER > 11
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{
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optional<X> opt(in_place, 2);
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Y y(3);
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assert(std::move(opt).value_or(y) == 2);
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assert(*opt == 0);
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}
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{
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optional<X> opt(in_place, 2);
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assert(std::move(opt).value_or(Y(3)) == 2);
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assert(*opt == 0);
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}
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{
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optional<X> opt;
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Y y(3);
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assert(std::move(opt).value_or(y) == 3);
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assert(!opt);
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}
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{
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optional<X> opt;
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assert(std::move(opt).value_or(Y(3)) == 4);
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assert(!opt);
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}
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#endif // _LIBCPP_STD_VER > 11
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}
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