libcxx/test/std/containers/sequences/array/array.special/swap.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 // <array>
  10
  11 // template <class T, size_t N> void swap(array<T,N>& x, array<T,N>& y);
  12
  13 #include <array>
  14 #include <cassert>
  15 #include <utility>
  16
  17 #include "test_macros.h"
  18
  19 struct NonSwappable {
  20     TEST_CONSTEXPR NonSwappable() { }
  21 private:
  22     NonSwappable(NonSwappable const&);
  23     NonSwappable& operator=(NonSwappable const&);
  24 };
  25
  26 template <class Tp>
  27 decltype(swap(std::declval<Tp>(), std::declval<Tp>()))
  28 can_swap_imp(int);
  29
  30 template <class Tp>
  31 std::false_type can_swap_imp(...);
  32
  33 template <class Tp>
  34 struct can_swap : std::is_same<decltype(can_swap_imp<Tp>(0)), void> { };
  35
  36 TEST_CONSTEXPR_CXX20 bool tests()
  37 {
  38     {
  39         typedef double T;
  40         typedef std::array<T, 3> C;
  41         C c1 = {1, 2, 3.5};
  42         C c2 = {4, 5, 6.5};
  43         swap(c1, c2);
  44         assert(c1.size() == 3);
  45         assert(c1[0] == 4);
  46         assert(c1[1] == 5);
  47         assert(c1[2] == 6.5);
  48         assert(c2.size() == 3);
  49         assert(c2[0] == 1);
  50         assert(c2[1] == 2);
  51         assert(c2[2] == 3.5);
  52     }
  53     {
  54         typedef double T;
  55         typedef std::array<T, 0> C;
  56         C c1 = {};
  57         C c2 = {};
  58         swap(c1, c2);
  59         assert(c1.size() == 0);
  60         assert(c2.size() == 0);
  61     }
  62     {
  63         typedef NonSwappable T;
  64         typedef std::array<T, 0> C0;
  65         static_assert(can_swap<C0&>::value, "");
  66         C0 l = {};
  67         C0 r = {};
  68         swap(l, r);
  69 #if TEST_STD_VER >= 11
  70         static_assert(noexcept(swap(l, r)), "");
  71 #endif
  72     }
  73 #if TEST_STD_VER >= 11
  74     {
  75         // NonSwappable is still considered swappable in C++03 because there
  76         // is no access control SFINAE.
  77         typedef NonSwappable T;
  78         typedef std::array<T, 42> C1;
  79         static_assert(!can_swap<C1&>::value, "");
  80     }
  81 #endif
  82
  83     return true;
  84 }
  85
  86 int main(int, char**)
  87 {
  88     tests();
  89 #if TEST_STD_VER >= 20
  90     static_assert(tests(), "");
  91 #endif
  92     return 0;
  93 }