xref: /aosp_15_r20/external/libcxx/test/std/containers/sequences/array/array.special/swap.pass.cpp (revision 58b9f456b02922dfdb1fad8a988d5fd8765ecb80)
1  //===----------------------------------------------------------------------===//
2  //
3  //                     The LLVM Compiler Infrastructure
4  //
5  // This file is dual licensed under the MIT and the University of Illinois Open
6  // Source Licenses. See LICENSE.TXT for details.
7  //
8  //===----------------------------------------------------------------------===//
9  
10  // <array>
11  
12  // template <class T, size_t N> void swap(array<T,N>& x, array<T,N>& y);
13  
14  #include <array>
15  #include <cassert>
16  
17  #include "test_macros.h"
18  // std::array is explicitly allowed to be initialized with A a = { init-list };.
19  // Disable the missing braces warning for this reason.
20  #include "disable_missing_braces_warning.h"
21  
22  struct NonSwappable {
NonSwappableNonSwappable23    NonSwappable() {}
24  private:
25    NonSwappable(NonSwappable const&);
26    NonSwappable& operator=(NonSwappable const&);
27  };
28  
29  template <class Tp>
30  decltype(swap(std::declval<Tp>(), std::declval<Tp>()))
31  can_swap_imp(int);
32  
33  template <class Tp>
34  std::false_type can_swap_imp(...);
35  
36  template <class Tp>
37  struct can_swap : std::is_same<decltype(can_swap_imp<Tp>(0)), void> {};
38  
main()39  int main()
40  {
41      {
42          typedef double T;
43          typedef std::array<T, 3> C;
44          C c1 = {1, 2, 3.5};
45          C c2 = {4, 5, 6.5};
46          swap(c1, c2);
47          assert(c1.size() == 3);
48          assert(c1[0] == 4);
49          assert(c1[1] == 5);
50          assert(c1[2] == 6.5);
51          assert(c2.size() == 3);
52          assert(c2[0] == 1);
53          assert(c2[1] == 2);
54          assert(c2[2] == 3.5);
55      }
56      {
57          typedef double T;
58          typedef std::array<T, 0> C;
59          C c1 = {};
60          C c2 = {};
61          swap(c1, c2);
62          assert(c1.size() == 0);
63          assert(c2.size() == 0);
64      }
65      {
66          typedef NonSwappable T;
67          typedef std::array<T, 0> C0;
68          static_assert(can_swap<C0&>::value, "");
69          C0 l = {};
70          C0 r = {};
71          swap(l, r);
72  #if TEST_STD_VER >= 11
73          static_assert(noexcept(swap(l, r)), "");
74  #endif
75      }
76  #if TEST_STD_VER >= 11
77      {
78          // NonSwappable is still considered swappable in C++03 because there
79          // is no access control SFINAE.
80          typedef NonSwappable T;
81          typedef std::array<T, 42> C1;
82          static_assert(!can_swap<C1&>::value, "");
83      }
84  #endif
85  }
86