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
11 // <ranges>
12
13 // constexpr View base() const& requires copy_constructible<View>;
14 // constexpr View base() &&;
15
16 #include <ranges>
17
18 #include <cassert>
19 #include <concepts>
20 #include <utility>
21
22 struct Range : std::ranges::view_base {
RangeRange23 constexpr explicit Range(int* b, int* e) : begin_(b), end_(e) {}
RangeRange24 constexpr Range(Range const& other) : begin_(other.begin_), end_(other.end_), wasCopyInitialized(true) {}
RangeRange25 constexpr Range(Range&& other) : begin_(other.begin_), end_(other.end_), wasMoveInitialized(true) {}
26 Range& operator=(Range const&) = default;
27 Range& operator=(Range&&) = default;
beginRange28 constexpr int* begin() const { return begin_; }
endRange29 constexpr int* end() const { return end_; }
30
31 int* begin_;
32 int* end_;
33 bool wasCopyInitialized = false;
34 bool wasMoveInitialized = false;
35 };
36
37 static_assert(std::ranges::view<Range>);
38 static_assert(std::ranges::forward_range<Range>);
39
40 struct Pred {
41 bool operator()(int, int) const;
42 };
43
44 struct NonCopyableRange : std::ranges::view_base {
45 explicit NonCopyableRange(int*, int*);
46 NonCopyableRange(NonCopyableRange const&) = delete;
47 NonCopyableRange(NonCopyableRange&&) = default;
48 NonCopyableRange& operator=(NonCopyableRange const&) = default;
49 NonCopyableRange& operator=(NonCopyableRange&&) = default;
50 int* begin() const;
51 int* end() const;
52 };
53
54 static_assert(!std::copy_constructible<NonCopyableRange>);
55
56 template <typename T>
57 concept CanCallBaseOn = requires(T t) { std::forward<T>(t).base(); };
58
test()59 constexpr bool test() {
60 int buff[] = {1, 2, 3, 4};
61
62 // Check the const& overload
63 {
64 Range range(buff, buff + 4);
65 std::ranges::chunk_by_view<Range, Pred> const view(range, Pred{});
66 std::same_as<Range> decltype(auto) result = view.base();
67 assert(result.wasCopyInitialized);
68 assert(result.begin() == buff);
69 assert(result.end() == buff + 4);
70 }
71
72 // Check the && overload
73 {
74 Range range(buff, buff + 4);
75 std::ranges::chunk_by_view<Range, Pred> view(range, Pred{});
76 std::same_as<Range> decltype(auto) result = std::move(view).base();
77 assert(result.wasMoveInitialized);
78 assert(result.begin() == buff);
79 assert(result.end() == buff + 4);
80 }
81
82 // Ensure the const& overload is not considered when the base is not copy-constructible
83 {
84 static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred> const&>);
85 static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>&>);
86 static_assert(!CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred> const&&>);
87 static_assert(CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>&&>);
88 static_assert(CanCallBaseOn<std::ranges::chunk_by_view<NonCopyableRange, Pred>>);
89 }
90
91 return true;
92 }
93
main(int,char **)94 int main(int, char**) {
95 test();
96 static_assert(test());
97
98 return 0;
99 }
100