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
10 
11 // friend constexpr bool operator==(const outer-iterator& x, const outer-iterator& y)
12 //   requires forward_range<Base>;
13 //
14 // friend constexpr bool operator==(const outer-iterator& x, default_sentinel_t);
15 
16 #include <ranges>
17 
18 #include <concepts>
19 #include <string_view>
20 #include "../types.h"
21 
22 template <class Iter>
23 concept CanCallEquals = requires(const Iter& i) {
24   i == i;
25   i != i;
26 };
27 
28 constexpr bool test() {
29   // Forward range supports both overloads of `operator==`.
30   {
31     // outer-iterator == outer-iterator
32     {
33       SplitViewForward v("abc def", " ");
34       auto b = v.begin(), e = v.end();
35 
36       assert(b == b);
37       assert(!(b != b));
38 
39       assert(e == e);
40       assert(!(e != e));
41 
42       assert(!(b == e));
43       assert(b != e);
44     }
45 
46     // outer-iterator == default_sentinel
47     {
48       SplitViewForward v("abc def", " ");
49       auto b = v.begin(), e = v.end();
50 
51       assert(!(b == std::default_sentinel));
52       assert(b != std::default_sentinel);
53       assert(e == std::default_sentinel);
54       assert(!(e != std::default_sentinel));
55     }
56 
57       // Default-constructed `outer-iterator`s compare equal.
58       {
59         OuterIterForward i1, i2;
60         assert(i1 == i2);
61         assert(!(i1 != i2));
62       }
63   }
64 
65   // Input range only supports comparing an `outer-iterator` to the default sentinel.
66   {
67     using namespace std::string_view_literals;
68     SplitViewInput v("abc def"sv, ' ');
69     auto b = v.begin();
70     std::same_as<std::default_sentinel_t> decltype(auto) e = v.end();
71 
72     static_assert(!CanCallEquals<decltype(b)>);
73 
74     assert(!(b == std::default_sentinel));
75     assert(b != std::default_sentinel);
76     assert(!(b == e));
77     assert(b != e);
78   }
79 
80   return true;
81 }
82 
83 int main(int, char**) {
84   test();
85   static_assert(test());
86 
87   return 0;
88 }
89