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 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11
12 // constexpr auto begin()
13 // requires (!(simple-view<V> &&
14 // random_access_range<const V> && sized_range<const V>));
15 // constexpr auto begin() const
16 // requires random_access_range<const V> && sized_range<const V>;
17
18 #include <ranges>
19
20 #include "test_macros.h"
21 #include "test_iterators.h"
22 #include "types.h"
23
24 template<class T>
25 concept BeginInvocable = requires(std::ranges::drop_view<T> t) { t.begin(); };
26
27 template <bool IsSimple>
28 struct MaybeSimpleView : std::ranges::view_base {
29 int* num_of_non_const_begin_calls;
30 int* num_of_const_begin_calls;
31
beginMaybeSimpleView32 constexpr int* begin() {
33 ++(*num_of_non_const_begin_calls);
34 return nullptr;
35 }
beginMaybeSimpleView36 constexpr std::conditional_t<IsSimple, int*, const int*> begin() const {
37 ++(*num_of_const_begin_calls);
38 return nullptr;
39 }
endMaybeSimpleView40 constexpr int* end() const { return nullptr; }
sizeMaybeSimpleView41 constexpr size_t size() const { return 0; }
42 };
43
44 using SimpleView = MaybeSimpleView<true>;
45 using NonSimpleView = MaybeSimpleView<false>;
46
test()47 constexpr bool test() {
48 // random_access_range<const V> && sized_range<const V>
49 std::ranges::drop_view dropView1(MoveOnlyView(), 4);
50 assert(dropView1.begin() == globalBuff + 4);
51
52 // !random_access_range<const V>
53 std::ranges::drop_view dropView2(ForwardView(), 4);
54 assert(base(dropView2.begin()) == globalBuff + 4);
55
56 // !random_access_range<const V>
57 std::ranges::drop_view dropView3(InputView(), 4);
58 assert(base(dropView3.begin()) == globalBuff + 4);
59
60 // random_access_range<const V> && sized_range<const V>
61 std::ranges::drop_view dropView4(MoveOnlyView(), 8);
62 assert(dropView4.begin() == globalBuff + 8);
63
64 // random_access_range<const V> && sized_range<const V>
65 std::ranges::drop_view dropView5(MoveOnlyView(), 0);
66 assert(dropView5.begin() == globalBuff);
67
68 // random_access_range<const V> && sized_range<const V>
69 const std::ranges::drop_view dropView6(MoveOnlyView(), 0);
70 assert(dropView6.begin() == globalBuff);
71
72 // random_access_range<const V> && sized_range<const V>
73 std::ranges::drop_view dropView7(MoveOnlyView(), 10);
74 assert(dropView7.begin() == globalBuff + 8);
75
76 CountedView view8;
77 std::ranges::drop_view dropView8(view8, 5);
78 assert(base(base(dropView8.begin())) == globalBuff + 5);
79 assert(dropView8.begin().stride_count() == 5);
80 assert(base(base(dropView8.begin())) == globalBuff + 5);
81 assert(dropView8.begin().stride_count() == 5);
82
83 static_assert(!BeginInvocable<const ForwardView>);
84
85 {
86 static_assert(std::ranges::random_access_range<const SimpleView>);
87 static_assert(std::ranges::sized_range<const SimpleView>);
88 LIBCPP_STATIC_ASSERT(std::ranges::__simple_view<SimpleView>);
89 int non_const_calls = 0;
90 int const_calls = 0;
91 std::ranges::drop_view dropView(SimpleView{{}, &non_const_calls, &const_calls}, 4);
92 assert(dropView.begin() == nullptr);
93 assert(non_const_calls == 0);
94 assert(const_calls == 1);
95 assert(std::as_const(dropView).begin() == nullptr);
96 assert(non_const_calls == 0);
97 assert(const_calls == 2);
98 }
99
100 {
101 static_assert(std::ranges::random_access_range<const NonSimpleView>);
102 static_assert(std::ranges::sized_range<const NonSimpleView>);
103 LIBCPP_STATIC_ASSERT(!std::ranges::__simple_view<NonSimpleView>);
104 int non_const_calls = 0;
105 int const_calls = 0;
106 std::ranges::drop_view dropView(NonSimpleView{{}, &non_const_calls, &const_calls}, 4);
107 assert(dropView.begin() == nullptr);
108 assert(non_const_calls == 1);
109 assert(const_calls == 0);
110 assert(std::as_const(dropView).begin() == nullptr);
111 assert(non_const_calls == 1);
112 assert(const_calls == 1);
113 }
114
115 return true;
116 }
117
main(int,char **)118 int main(int, char**) {
119 test();
120 static_assert(test());
121
122 return 0;
123 }
124