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, c++20
10 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11
12 // constexpr iterator& operator--() requires all-bidirectional<Const, Views...>;
13 // constexpr iterator operator--(int) requires all-bidirectional<Const, Views...>;
14
15 #include <array>
16 #include <cassert>
17 #include <ranges>
18 #include <tuple>
19
20 #include "../types.h"
21
22 template <class Iter>
23 concept canDecrement = requires(Iter it) { --it; } || requires(Iter it) { it--; };
24
25 struct NonBidi : IntBufferView {
26 using IntBufferView::IntBufferView;
27 using iterator = forward_iterator<int*>;
beginNonBidi28 constexpr iterator begin() const { return iterator(buffer_); }
endNonBidi29 constexpr sentinel_wrapper<iterator> end() const { return sentinel_wrapper<iterator>(iterator(buffer_ + size_)); }
30 };
31
test()32 constexpr bool test() {
33 std::array a{1, 2, 3, 4};
34 std::array b{4.1, 3.2, 4.3};
35 {
36 // all random access
37 std::ranges::zip_view v(a, b, std::views::iota(0, 5));
38 auto it = v.end();
39 using Iter = decltype(it);
40
41 static_assert(std::is_same_v<decltype(--it), Iter&>);
42 auto& it_ref = --it;
43 assert(&it_ref == &it);
44
45 assert(&(std::get<0>(*it)) == &(a[2]));
46 assert(&(std::get<1>(*it)) == &(b[2]));
47 assert(std::get<2>(*it) == 2);
48
49 static_assert(std::is_same_v<decltype(it--), Iter>);
50 it--;
51 assert(&(std::get<0>(*it)) == &(a[1]));
52 assert(&(std::get<1>(*it)) == &(b[1]));
53 assert(std::get<2>(*it) == 1);
54 }
55
56 {
57 // all bidi+
58 int buffer[2] = {1, 2};
59
60 std::ranges::zip_view v(BidiCommonView{buffer}, std::views::iota(0, 5));
61 auto it = v.begin();
62 using Iter = decltype(it);
63
64 ++it;
65 ++it;
66
67 static_assert(std::is_same_v<decltype(--it), Iter&>);
68 auto& it_ref = --it;
69 assert(&it_ref == &it);
70
71 assert(it == ++v.begin());
72
73 static_assert(std::is_same_v<decltype(it--), Iter>);
74 auto tmp = it--;
75 assert(it == v.begin());
76 assert(tmp == ++v.begin());
77 }
78
79 {
80 // non bidi
81 int buffer[3] = {4, 5, 6};
82 std::ranges::zip_view v(a, NonBidi{buffer});
83 using Iter = std::ranges::iterator_t<decltype(v)>;
84 static_assert(!canDecrement<Iter>);
85 }
86
87 return true;
88 }
89
main(int,char **)90 int main(int, char**) {
91 test();
92 static_assert(test());
93
94 return 0;
95 }
96