libcxx/test/std/utilities/optional/optional.object/optional.object.observe/value_or_const.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14
  10 // <optional>
  11
  12 // template <class U> constexpr T optional<T>::value_or(U&& v) const&;
  13
  14 #include <optional>
  15 #include <type_traits>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 using std::optional;
  21
  22 struct Y
  23 {
  24     int i_;
  25
  26     constexpr Y(int i) : i_(i) {}
  27 };
  28
  29 struct X
  30 {
  31     int i_;
  32
  33     constexpr X(int i) : i_(i) {}
  34     constexpr X(const Y& y) : i_(y.i_) {}
  35     constexpr X(Y&& y) : i_(y.i_+1) {}
  36     friend constexpr bool operator==(const X& x, const X& y)
  37         {return x.i_ == y.i_;}
  38 };
  39
  40 int main(int, char**)
  41 {
  42     {
  43         constexpr optional<X> opt(2);
  44         constexpr Y y(3);
  45         static_assert(opt.value_or(y) == 2, "");
  46     }
  47     {
  48         constexpr optional<X> opt(2);
  49         static_assert(opt.value_or(Y(3)) == 2, "");
  50     }
  51     {
  52         constexpr optional<X> opt;
  53         constexpr Y y(3);
  54         static_assert(opt.value_or(y) == 3, "");
  55     }
  56     {
  57         constexpr optional<X> opt;
  58         static_assert(opt.value_or(Y(3)) == 4, "");
  59     }
  60     {
  61         const optional<X> opt(2);
  62         const Y y(3);
  63         assert(opt.value_or(y) == 2);
  64     }
  65     {
  66         const optional<X> opt(2);
  67         assert(opt.value_or(Y(3)) == 2);
  68     }
  69     {
  70         const optional<X> opt;
  71         const Y y(3);
  72         assert(opt.value_or(y) == 3);
  73     }
  74     {
  75         const optional<X> opt;
  76         assert(opt.value_or(Y(3)) == 4);
  77     }
  78
  79   return 0;
  80 }