libcxx/test/std/algorithms/algorithms.results/in_value_result.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, c++17, c++20
  10
  11 // template <class I, class T>
  12 // struct in_value_result;
  13
  14 #include <algorithm>
  15 #include <cassert>
  16 #include <type_traits>
  17 #include <utility>
  18
  19 #include "MoveOnly.h"
  20
  21 struct A {
  22   explicit A(int);
  23 };
  24 // no implicit conversion
  25 static_assert(!std::is_constructible_v<std::ranges::in_value_result<A, A>, std::ranges::in_value_result<int, int>>);
  26
  27 struct B {
  28   B(int);
  29 };
  30 // implicit conversion
  31 static_assert(std::is_constructible_v<std::ranges::in_value_result<B, B>, std::ranges::in_value_result<int, int>>);
  32 static_assert(std::is_constructible_v<std::ranges::in_value_result<B, B>, std::ranges::in_value_result<int, int>&>);
  33 static_assert(
  34     std::is_constructible_v<std::ranges::in_value_result<B, B>, const std::ranges::in_value_result<int, int>>);
  35 static_assert(
  36     std::is_constructible_v<std::ranges::in_value_result<B, B>, const std::ranges::in_value_result<int, int>&>);
  37
  38 struct C {
  39   C(int&);
  40 };
  41 static_assert(!std::is_constructible_v<std::ranges::in_value_result<C, C>, std::ranges::in_value_result<int, int>&>);
  42
  43 // has to be convertible via const&
  44 static_assert(std::is_convertible_v<std::ranges::in_value_result<int, int>&, std::ranges::in_value_result<long, long>>);
  45 static_assert(
  46     std::is_convertible_v<const std::ranges::in_value_result<int, int>&, std::ranges::in_value_result<long, long>>);
  47 static_assert(
  48     std::is_convertible_v<std::ranges::in_value_result<int, int>&&, std::ranges::in_value_result<long, long>>);
  49 static_assert(
  50     std::is_convertible_v<const std::ranges::in_value_result<int, int>&&, std::ranges::in_value_result<long, long>>);
  51
  52 // should be move constructible
  53 static_assert(std::is_move_constructible_v<std::ranges::in_value_result<MoveOnly, int>>);
  54 static_assert(std::is_move_constructible_v<std::ranges::in_value_result<int, MoveOnly>>);
  55
  56 // should not be copy constructible with move-only type
  57 static_assert(!std::is_copy_constructible_v<std::ranges::in_value_result<MoveOnly, int>>);
  58 static_assert(!std::is_copy_constructible_v<std::ranges::in_value_result<int, MoveOnly>>);
  59
  60 struct NotConvertible {};
  61 // conversions should not work if there is no conversion
  62 static_assert(
  63     !std::is_convertible_v<std::ranges::in_value_result<NotConvertible, int>, std::ranges::in_value_result<int, int>>);
  64 static_assert(
  65     !std::is_convertible_v<std::ranges::in_value_result<int, NotConvertible>, std::ranges::in_value_result<int, int>>);
  66
  67 template <class T>
  68 struct ConvertibleFrom {
  69   constexpr ConvertibleFrom(T c) : content{c} {}
  70   T content;
  71 };
  72
  73 constexpr bool test() {
  74   // Checks that conversion operations are correct.
  75   {
  76     std::ranges::in_value_result<int, double> res{10, 0.};
  77     assert(res.in == 10);
  78     assert(res.value == 0.);
  79     std::ranges::in_value_result<ConvertibleFrom<int>, ConvertibleFrom<double>> res2 = res;
  80     assert(res2.in.content == 10);
  81     assert(res2.value.content == 0.);
  82   }
  83
  84   // Checks that conversions are possible when one of the types is move-only.
  85   {
  86     std::ranges::in_value_result<MoveOnly, int> res{MoveOnly{}, 2};
  87     assert(res.in.get() == 1);
  88     assert(res.value == 2);
  89     auto res2 = static_cast<std::ranges::in_value_result<MoveOnly, int>>(std::move(res));
  90     assert(res.in.get() == 0);
  91     assert(res2.in.get() == 1);
  92     assert(res2.value == 2);
  93   }
  94
  95   // Checks that structured bindings get the correct values.
  96   {
  97     auto [in, value] = std::ranges::in_value_result<int, int>{1, 2};
  98     assert(in == 1);
  99     assert(value == 2);
 100   }
 101   return true;
 102 }
 103
 104 int main(int, char**) {
 105   test();
 106   static_assert(test());
 107
 108   return 0;
 109 }