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 // UNSUPPORTED: libcpp-no-concepts
11 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
12 
13 // friend constexpr iterator operator+(iterator i, difference_type n)
14 //   requires advanceable<W>;
15 // friend constexpr iterator operator+(difference_type n, iterator i)
16 //   requires advanceable<W>;
17 
18 #include <ranges>
19 #include <cassert>
20 
21 #include "test_macros.h"
22 #include "../types.h"
23 
24 constexpr bool test() {
25   // When "_Start" is signed integer like.
26   {
27     std::ranges::iota_view<int> io(0);
28     auto iter1 = io.begin();
29     auto iter2 = io.begin();
30     assert(iter1 == iter2);
31     assert(iter1 + 5 != iter2);
32     assert(iter1 + 5 == std::ranges::next(iter2, 5));
33 
34     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
35   }
36 
37   // When "_Start" is not integer like.
38   {
39     std::ranges::iota_view io(SomeInt(0));
40     auto iter1 = io.begin();
41     auto iter2 = io.begin();
42     assert(iter1 == iter2);
43     assert(iter1 + 5 != iter2);
44     assert(iter1 + 5 == std::ranges::next(iter2, 5));
45 
46     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
47   }
48 
49   // When "_Start" is unsigned integer like and n is greater than or equal to zero.
50   {
51     std::ranges::iota_view<unsigned> io(0);
52     auto iter1 = io.begin();
53     auto iter2 = io.begin();
54     assert(iter1 == iter2);
55     assert(iter1 + 5 != iter2);
56     assert(iter1 + 5 == std::ranges::next(iter2, 5));
57 
58     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
59   }
60   {
61     std::ranges::iota_view<unsigned> io(0);
62     auto iter1 = io.begin();
63     auto iter2 = io.begin();
64     assert(iter1 == iter2);
65     assert(iter1 + 0 == iter2);
66   }
67 
68   // When "_Start" is unsigned integer like and n is less than zero.
69   {
70     std::ranges::iota_view<unsigned> io(0);
71     auto iter1 = io.begin();
72     auto iter2 = io.begin();
73     assert(iter1 == iter2);
74     assert(iter1 + 5 != iter2);
75     assert(iter1 + 5 == std::ranges::next(iter2, 5));
76 
77     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
78   }
79 
80   return true;
81 }
82 
83 int main(int, char**) {
84   test();
85   static_assert(test());
86 
87   return 0;
88 }
89