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 Pred const& pred() const;
14
15#include <ranges>
16
17#include <cassert>
18#include <concepts>
19
20struct Range : std::ranges::view_base {
21 int* begin() const;
22 int* end() const;
23};
24
25struct Pred {
26 bool operator()(int, int) const;
27 int value;
28};
29
30constexpr bool test() {
31 {
32 Pred pred{.value: 42};
33 std::ranges::chunk_by_view<Range, Pred> const view(Range{}, pred);
34 std::same_as<Pred const&> decltype(auto) result = view.pred();
35 assert(result.value == 42);
36
37 // Make sure we're really holding a reference to something inside the view
38 assert(&result == &view.pred());
39 }
40
41 // Same, but calling on a non-const view
42 {
43 Pred pred{.value: 42};
44 std::ranges::chunk_by_view<Range, Pred> view(Range{}, pred);
45 std::same_as<Pred const&> decltype(auto) result = view.pred();
46 assert(result.value == 42);
47
48 // Make sure we're really holding a reference to something inside the view
49 assert(&result == &view.pred());
50 }
51
52 return true;
53}
54
55int main(int, char**) {
56 test();
57 static_assert(test());
58
59 return 0;
60}
61

source code of libcxx/test/std/ranges/range.adaptors/range.chunk.by/pred.pass.cpp