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
12// constexpr iterator_t<R> begin();
13// constexpr sentinel_t<R> end();
14// constexpr auto begin() const requires range<const R>;
15// constexpr auto end() const requires range<const R>;
16
17#include <ranges>
18
19#include <array>
20#include <cassert>
21#include <concepts>
22#include <memory>
23
24#include "test_iterators.h"
25#include "test_macros.h"
26
27struct Base {
28 constexpr int *begin() { return nullptr; }
29 constexpr auto end() { return sentinel_wrapper<int*>(nullptr); }
30 constexpr char *begin() const { return nullptr; }
31 constexpr auto end() const { return sentinel_wrapper<char*>(nullptr); }
32};
33static_assert(std::same_as<std::ranges::iterator_t<Base>, int*>);
34static_assert(std::same_as<std::ranges::sentinel_t<Base>, sentinel_wrapper<int*>>);
35static_assert(std::same_as<std::ranges::iterator_t<const Base>, char*>);
36static_assert(std::same_as<std::ranges::sentinel_t<const Base>, sentinel_wrapper<char*>>);
37
38struct NoConst {
39 int* begin();
40 sentinel_wrapper<int*> end();
41};
42
43struct DecayChecker {
44 int*& begin() const;
45 int*& end() const;
46};
47
48template <class T>
49concept HasBegin = requires (T t) {
50 t.begin();
51};
52
53template <class T>
54concept HasEnd = requires (T t) {
55 t.end();
56};
57
58constexpr bool test()
59{
60 {
61 using OwningView = std::ranges::owning_view<Base>;
62 OwningView ov;
63 std::same_as<int*> decltype(auto) b1 = static_cast<OwningView&>(ov).begin();
64 std::same_as<int*> decltype(auto) b2 = static_cast<OwningView&&>(ov).begin();
65 std::same_as<char*> decltype(auto) b3 = static_cast<const OwningView&>(ov).begin();
66 std::same_as<char*> decltype(auto) b4 = static_cast<const OwningView&&>(ov).begin();
67
68 std::same_as<sentinel_wrapper<int*>> decltype(auto) e1 = static_cast<OwningView&>(ov).end();
69 std::same_as<sentinel_wrapper<int*>> decltype(auto) e2 = static_cast<OwningView&&>(ov).end();
70 std::same_as<sentinel_wrapper<char*>> decltype(auto) e3 = static_cast<const OwningView&>(ov).end();
71 std::same_as<sentinel_wrapper<char*>> decltype(auto) e4 = static_cast<const OwningView&&>(ov).end();
72
73 assert(b1 == e1);
74 assert(b2 == e2);
75 assert(b3 == e3);
76 assert(b4 == e4);
77 }
78 {
79 // NoConst has non-const begin() and end(); so does the owning_view.
80 using OwningView = std::ranges::owning_view<NoConst>;
81 static_assert(HasBegin<OwningView&>);
82 static_assert(HasBegin<OwningView&&>);
83 static_assert(!HasBegin<const OwningView&>);
84 static_assert(!HasBegin<const OwningView&&>);
85 static_assert(HasEnd<OwningView&>);
86 static_assert(HasEnd<OwningView&&>);
87 static_assert(!HasEnd<const OwningView&>);
88 static_assert(!HasEnd<const OwningView&&>);
89 }
90 {
91 // DecayChecker's begin() and end() return references; make sure the owning_view decays them.
92 using OwningView = std::ranges::owning_view<DecayChecker>;
93 OwningView ov;
94 ASSERT_SAME_TYPE(decltype(ov.begin()), int*);
95 ASSERT_SAME_TYPE(decltype(ov.end()), int*);
96 }
97 {
98 // Test an empty view.
99 int a[] = {1};
100 auto ov = std::ranges::owning_view(std::ranges::subrange(a, a));
101 assert(ov.begin() == a);
102 assert(std::as_const(ov).begin() == a);
103 assert(ov.end() == a);
104 assert(std::as_const(ov).end() == a);
105 }
106 {
107 // Test a non-empty view.
108 int a[] = {1};
109 auto ov = std::ranges::owning_view(std::ranges::subrange(a, a+1));
110 assert(ov.begin() == a);
111 assert(std::as_const(ov).begin() == a);
112 assert(ov.end() == a+1);
113 assert(std::as_const(ov).end() == a+1);
114 }
115 {
116 // Test a non-view.
117 std::array<int, 2> a = {1, 2};
118 auto ov = std::ranges::owning_view(std::move(a));
119 assert(std::to_address(ov.begin()) != std::to_address(a.begin())); // because it points into the copy
120 assert(std::to_address(std::as_const(ov).begin()) != std::to_address(a.begin()));
121 assert(std::to_address(ov.end()) != std::to_address(a.end()));
122 assert(std::to_address(std::as_const(ov).end()) != std::to_address(a.end()));
123 }
124 return true;
125}
126
127int main(int, char**) {
128 test();
129 static_assert(test());
130
131 return 0;
132}
133

source code of libcxx/test/std/ranges/range.adaptors/range.all/range.owning.view/begin_end.pass.cpp