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 auto begin() requires (!(simple-view<Views> && ...));
13 // constexpr auto begin() const requires (range<const Views> && ...);
14
15 #include <ranges>
16
17 #include <cassert>
18 #include <concepts>
19 #include <tuple>
20 #include <utility>
21
22 #include "types.h"
23
24 template <class T>
25 concept HasConstBegin = requires(const T& ct) { ct.begin(); };
26
27 template <class T>
28 concept HasBegin = requires(T& t) { t.begin(); };
29
30 template <class T>
31 concept HasConstAndNonConstBegin =
32 HasConstBegin<T> &&
33 requires(T& t, const T& ct) { requires !std::same_as<decltype(t.begin()), decltype(ct.begin())>; };
34
35 template <class T>
36 concept HasOnlyNonConstBegin = HasBegin<T> && !
37 HasConstBegin<T>;
38
39 template <class T>
40 concept HasOnlyConstBegin = HasConstBegin<T> && !
41 HasConstAndNonConstBegin<T>;
42
43 struct NoConstBeginView : std::ranges::view_base {
44 int* begin();
45 int* end();
46 };
47
test()48 constexpr bool test() {
49 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
50 {
51 // all underlying iterators should be at the begin position
52 std::ranges::zip_view v(SizedRandomAccessView{buffer}, std::views::iota(0), std::ranges::single_view(2.));
53 std::same_as<std::tuple<int&, int, double&>> decltype(auto) val = *v.begin();
54 assert(val == std::make_tuple(1, 0, 2.0));
55 assert(&(std::get<0>(val)) == &buffer[0]);
56 }
57
58 {
59 // with empty range
60 std::ranges::zip_view v(SizedRandomAccessView{buffer}, std::ranges::empty_view<int>());
61 assert(v.begin() == v.end());
62 }
63
64 {
65 // underlying ranges all model simple-view
66 std::ranges::zip_view v(SimpleCommon{buffer}, SimpleCommon{buffer});
67 static_assert(std::is_same_v<decltype(v.begin()), decltype(std::as_const(v).begin())>);
68 assert(v.begin() == std::as_const(v).begin());
69 auto [x, y] = *std::as_const(v).begin();
70 assert(&x == &buffer[0]);
71 assert(&y == &buffer[0]);
72
73 using View = decltype(v);
74 static_assert(HasOnlyConstBegin<View>);
75 static_assert(!HasOnlyNonConstBegin<View>);
76 static_assert(!HasConstAndNonConstBegin<View>);
77 }
78
79 {
80 // not all underlying ranges model simple-view
81 std::ranges::zip_view v(SimpleCommon{buffer}, NonSimpleNonCommon{buffer});
82 static_assert(!std::is_same_v<decltype(v.begin()), decltype(std::as_const(v).begin())>);
83 assert(v.begin() == std::as_const(v).begin());
84 auto [x, y] = *std::as_const(v).begin();
85 assert(&x == &buffer[0]);
86 assert(&y == &buffer[0]);
87
88 using View = decltype(v);
89 static_assert(!HasOnlyConstBegin<View>);
90 static_assert(!HasOnlyNonConstBegin<View>);
91 static_assert(HasConstAndNonConstBegin<View>);
92 }
93
94 {
95 // underlying const R is not a range
96 using View = std::ranges::zip_view<SimpleCommon, NoConstBeginView>;
97 static_assert(!HasOnlyConstBegin<View>);
98 static_assert(HasOnlyNonConstBegin<View>);
99 static_assert(!HasConstAndNonConstBegin<View>);
100 }
101 return true;
102 }
103
main(int,char **)104 int main(int, char**) {
105 test();
106 static_assert(test());
107
108 return 0;
109 }
110