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-no-concepts
11 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
12 
13 // constexpr auto begin();
14 // constexpr auto begin() const requires range<const V>;
15 
16 #include <ranges>
17 #include <cassert>
18 
19 #include "test_macros.h"
20 #include "test_iterators.h"
21 #include "test_range.h"
22 
23 struct ContiguousView : std::ranges::view_base {
24   int *ptr_;
25   constexpr ContiguousView(int* ptr) : ptr_(ptr) {}
26   constexpr ContiguousView(ContiguousView&&) = default;
27   constexpr ContiguousView& operator=(ContiguousView&&) = default;
28   friend constexpr int* begin(ContiguousView& view) { return view.ptr_; }
29   friend constexpr int* begin(ContiguousView const& view) { return view.ptr_; }
30   friend constexpr sentinel_wrapper<int*> end(ContiguousView& view) {
31     return sentinel_wrapper<int*>{view.ptr_ + 8};
32   }
33   friend constexpr sentinel_wrapper<int*> end(ContiguousView const& view) {
34     return sentinel_wrapper<int*>{view.ptr_ + 8};
35   }
36 };
37 
38 struct CopyableView : std::ranges::view_base {
39   int *ptr_;
40   constexpr CopyableView(int* ptr) : ptr_(ptr) {}
41   friend constexpr int* begin(CopyableView& view) { return view.ptr_; }
42   friend constexpr int* begin(CopyableView const& view) { return view.ptr_; }
43   friend constexpr sentinel_wrapper<int*> end(CopyableView& view) {
44     return sentinel_wrapper<int*>{view.ptr_ + 8};
45   }
46   friend constexpr sentinel_wrapper<int*> end(CopyableView const& view) {
47     return sentinel_wrapper<int*>{view.ptr_ + 8};
48   }
49 };
50 
51 struct MutableView : std::ranges::view_base {
52   int *ptr_;
53   constexpr MutableView(int* ptr) : ptr_(ptr) {}
54   constexpr int* begin() { return ptr_; }
55   constexpr sentinel_wrapper<int*> end() { return sentinel_wrapper<int*>{ptr_ + 8}; }
56 };
57 
58 using ForwardIter = forward_iterator<int*>;
59 struct SizedForwardView : std::ranges::view_base {
60   int *ptr_;
61   constexpr SizedForwardView(int* ptr) : ptr_(ptr) {}
62   friend constexpr ForwardIter begin(SizedForwardView& view) { return ForwardIter(view.ptr_); }
63   friend constexpr ForwardIter begin(SizedForwardView const& view) { return ForwardIter(view.ptr_); }
64   friend constexpr sentinel_wrapper<ForwardIter> end(SizedForwardView& view) {
65     return sentinel_wrapper<ForwardIter>{ForwardIter(view.ptr_ + 8)};
66   }
67   friend constexpr sentinel_wrapper<ForwardIter> end(SizedForwardView const& view) {
68     return sentinel_wrapper<ForwardIter>{ForwardIter(view.ptr_ + 8)};
69   }
70 };
71 // Required to make SizedForwardView a sized view.
72 constexpr auto operator-(sentinel_wrapper<ForwardIter> sent, ForwardIter iter) {
73   return sent.base().base() - iter.base();
74 }
75 constexpr auto operator-(ForwardIter iter, sentinel_wrapper<ForwardIter> sent) {
76   return iter.base() - sent.base().base();
77 }
78 
79 using RandomAccessIter = random_access_iterator<int*>;
80 struct SizedRandomAccessView : std::ranges::view_base {
81   int *ptr_;
82   constexpr SizedRandomAccessView(int* ptr) : ptr_(ptr) {}
83   friend constexpr RandomAccessIter begin(SizedRandomAccessView& view) { return RandomAccessIter(view.ptr_); }
84   friend constexpr RandomAccessIter begin(SizedRandomAccessView const& view) { return RandomAccessIter(view.ptr_); }
85   friend constexpr sentinel_wrapper<RandomAccessIter> end(SizedRandomAccessView& view) {
86     return sentinel_wrapper<RandomAccessIter>{RandomAccessIter(view.ptr_ + 8)};
87   }
88   friend constexpr sentinel_wrapper<RandomAccessIter> end(SizedRandomAccessView const& view) {
89     return sentinel_wrapper<RandomAccessIter>{RandomAccessIter(view.ptr_ + 8)};
90   }
91 };
92 // Required to make SizedRandomAccessView a sized view.
93 constexpr auto operator-(sentinel_wrapper<RandomAccessIter> sent, RandomAccessIter iter) {
94   return sent.base().base() - iter.base();
95 }
96 constexpr auto operator-(RandomAccessIter iter, sentinel_wrapper<RandomAccessIter> sent) {
97   return iter.base() - sent.base().base();
98 }
99 
100 template<class T>
101 concept BeginEnabled = requires(const std::ranges::common_view<T>& comm) {
102   comm.begin();
103 };
104 
105 constexpr bool test() {
106   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
107 
108   {
109     static_assert( BeginEnabled<CopyableView>);
110     static_assert(!BeginEnabled<MutableView>);
111   }
112 
113   {
114     std::ranges::common_view<SizedRandomAccessView> comm(SizedRandomAccessView{buffer});
115     assert(comm.begin() == begin(SizedRandomAccessView(buffer)));
116     ASSERT_SAME_TYPE(decltype(comm.begin()), RandomAccessIter);
117   }
118 
119   {
120     const std::ranges::common_view<SizedRandomAccessView> comm(SizedRandomAccessView{buffer});
121     assert(comm.begin() == begin(SizedRandomAccessView(buffer)));
122     ASSERT_SAME_TYPE(decltype(comm.begin()), RandomAccessIter);
123   }
124 
125   return true;
126 }
127 
128 int main(int, char**) {
129   test();
130   static_assert(test());
131 
132   // The non-constexpr tests:
133   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
134 
135   {
136     std::ranges::common_view<SizedForwardView> comm(SizedForwardView{buffer});
137     assert(comm.begin() == begin(SizedForwardView(buffer)));
138     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<ForwardIter, sentinel_wrapper<ForwardIter>>);
139   }
140 
141   {
142     std::ranges::common_view<ContiguousView> comm(ContiguousView{buffer});
143     assert(comm.begin() == begin(ContiguousView(buffer)));
144     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<int*, sentinel_wrapper<int*>>);
145   }
146 
147   {
148     const std::ranges::common_view<SizedForwardView> comm(SizedForwardView{buffer});
149     assert(comm.begin() == begin(SizedForwardView(buffer)));
150     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<ForwardIter, sentinel_wrapper<ForwardIter>>);
151   }
152 
153   {
154     const std::ranges::common_view<CopyableView> comm(CopyableView{buffer});
155     assert(comm.begin() == begin(CopyableView(buffer)));
156     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<int*, sentinel_wrapper<int*>>);
157   }
158 
159   return 0;
160 }
161