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// constexpr iterator& operator-=(difference_type n)
12// requires advanceable<W>;
13
14#include <cassert>
15#include <ranges>
16#include <type_traits>
17
18#include "test_macros.h"
19#include "../types.h"
20
21constexpr bool test() {
22 // When "_Start" is signed integer like.
23 {
24 std::ranges::iota_view<int> io(0);
25 auto iter1 = std::next(io.begin(), 10);
26 auto iter2 = std::next(io.begin(), 10);
27 assert(iter1 == iter2);
28 iter1 -= 5;
29 assert(iter1 != iter2);
30 assert(iter1 == std::ranges::prev(iter2, 5));
31
32 static_assert(std::is_reference_v<decltype(iter2 -= 5)>);
33 }
34
35 // When "_Start" is not integer like.
36 {
37 std::ranges::iota_view io(SomeInt(0));
38 auto iter1 = std::next(io.begin(), 10);
39 auto iter2 = std::next(io.begin(), 10);
40 assert(iter1 == iter2);
41 iter1 -= 5;
42 assert(iter1 != iter2);
43 assert(iter1 == std::ranges::prev(iter2, 5));
44
45 static_assert(std::is_reference_v<decltype(iter2 -= 5)>);
46 }
47
48 // When "_Start" is unsigned integer like and n is greater than or equal to zero.
49 {
50 std::ranges::iota_view<unsigned> io(0);
51 auto iter1 = std::next(io.begin(), 10);
52 auto iter2 = std::next(io.begin(), 10);
53 assert(iter1 == iter2);
54 iter1 -= 5;
55 assert(iter1 != iter2);
56 assert(iter1 == std::ranges::prev(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 = std::next(io.begin(), 10);
63 auto iter2 = std::next(io.begin(), 10);
64 assert(iter1 == iter2);
65 iter1 -= 0;
66 assert(iter1 == iter2);
67 }
68
69 // When "_Start" is unsigned integer like and n is less than zero.
70 {
71 std::ranges::iota_view<unsigned> io(0);
72 auto iter1 = std::next(io.begin(), 10);
73 auto iter2 = std::next(io.begin(), 10);
74 assert(iter1 == iter2);
75 iter1 -= -5;
76 assert(iter1 != iter2);
77 assert(iter1 == std::ranges::next(iter2, 5));
78
79 static_assert(std::is_reference_v<decltype(iter2 -= -5)>);
80 }
81
82 return true;
83}
84
85int main(int, char**) {
86 test();
87 static_assert(test());
88
89 return 0;
90}
91

source code of libcxx/test/std/ranges/range.factories/range.iota.view/iterator/minus_eq.pass.cpp