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: gcc-10
12 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
13 
14 // constexpr auto begin();
15 // constexpr auto begin() const requires range<const V>;
16 
17 #include <ranges>
18 #include <cassert>
19 
20 #include "test_macros.h"
21 #include "test_iterators.h"
22 #include "test_range.h"
23 
24 struct ContiguousView : std::ranges::view_base {
25   int *ptr_;
26   constexpr ContiguousView(int* ptr) : ptr_(ptr) {}
27   constexpr ContiguousView(ContiguousView&&) = default;
28   constexpr ContiguousView& operator=(ContiguousView&&) = default;
29   friend constexpr int* begin(ContiguousView& view) { return view.ptr_; }
30   friend constexpr int* begin(ContiguousView const& view) { return view.ptr_; }
31   friend constexpr sentinel_wrapper<int*> end(ContiguousView& view) {
32     return sentinel_wrapper<int*>{view.ptr_ + 8};
33   }
34   friend constexpr sentinel_wrapper<int*> end(ContiguousView const& view) {
35     return sentinel_wrapper<int*>{view.ptr_ + 8};
36   }
37 };
38 
39 struct CopyableView : std::ranges::view_base {
40   int *ptr_;
41   constexpr CopyableView(int* ptr) : ptr_(ptr) {}
42   friend constexpr int* begin(CopyableView& view) { return view.ptr_; }
43   friend constexpr int* begin(CopyableView const& view) { return view.ptr_; }
44   friend constexpr sentinel_wrapper<int*> end(CopyableView& view) {
45     return sentinel_wrapper<int*>{view.ptr_ + 8};
46   }
47   friend constexpr sentinel_wrapper<int*> end(CopyableView const& view) {
48     return sentinel_wrapper<int*>{view.ptr_ + 8};
49   }
50 };
51 
52 struct MutableView : std::ranges::view_base {
53   int *ptr_;
54   constexpr MutableView(int* ptr) : ptr_(ptr) {}
55   constexpr int* begin() { return ptr_; }
56   constexpr sentinel_wrapper<int*> end() { return sentinel_wrapper<int*>{ptr_ + 8}; }
57 };
58 
59 using ForwardIter = forward_iterator<int*>;
60 struct SizedForwardView : std::ranges::view_base {
61   int *ptr_;
62   constexpr SizedForwardView(int* ptr) : ptr_(ptr) {}
63   friend constexpr ForwardIter begin(SizedForwardView& view) { return ForwardIter(view.ptr_); }
64   friend constexpr ForwardIter begin(SizedForwardView const& view) { return ForwardIter(view.ptr_); }
65   friend constexpr sentinel_wrapper<ForwardIter> end(SizedForwardView& view) {
66     return sentinel_wrapper<ForwardIter>{ForwardIter(view.ptr_ + 8)};
67   }
68   friend constexpr sentinel_wrapper<ForwardIter> end(SizedForwardView const& view) {
69     return sentinel_wrapper<ForwardIter>{ForwardIter(view.ptr_ + 8)};
70   }
71 };
72 // Required to make SizedForwardView a sized view.
73 constexpr auto operator-(sentinel_wrapper<ForwardIter> sent, ForwardIter iter) {
74   return sent.base().base() - iter.base();
75 }
76 constexpr auto operator-(ForwardIter iter, sentinel_wrapper<ForwardIter> sent) {
77   return iter.base() - sent.base().base();
78 }
79 
80 using RandomAccessIter = random_access_iterator<int*>;
81 struct SizedRandomAccessView : std::ranges::view_base {
82   int *ptr_;
83   constexpr SizedRandomAccessView(int* ptr) : ptr_(ptr) {}
84   friend constexpr RandomAccessIter begin(SizedRandomAccessView& view) { return RandomAccessIter(view.ptr_); }
85   friend constexpr RandomAccessIter begin(SizedRandomAccessView const& view) { return RandomAccessIter(view.ptr_); }
86   friend constexpr sentinel_wrapper<RandomAccessIter> end(SizedRandomAccessView& view) {
87     return sentinel_wrapper<RandomAccessIter>{RandomAccessIter(view.ptr_ + 8)};
88   }
89   friend constexpr sentinel_wrapper<RandomAccessIter> end(SizedRandomAccessView const& view) {
90     return sentinel_wrapper<RandomAccessIter>{RandomAccessIter(view.ptr_ + 8)};
91   }
92 };
93 // Required to make SizedRandomAccessView a sized view.
94 constexpr auto operator-(sentinel_wrapper<RandomAccessIter> sent, RandomAccessIter iter) {
95   return sent.base().base() - iter.base();
96 }
97 constexpr auto operator-(RandomAccessIter iter, sentinel_wrapper<RandomAccessIter> sent) {
98   return iter.base() - sent.base().base();
99 }
100 
101 template<class T>
102 concept BeginEnabled = requires(const std::ranges::common_view<T>& comm) {
103   comm.begin();
104 };
105 
106 constexpr bool test() {
107   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
108 
109   {
110     static_assert( BeginEnabled<CopyableView>);
111     static_assert(!BeginEnabled<MutableView>);
112   }
113 
114   {
115     std::ranges::common_view<SizedRandomAccessView> comm(SizedRandomAccessView{buffer});
116     assert(comm.begin() == begin(SizedRandomAccessView(buffer)));
117     ASSERT_SAME_TYPE(decltype(comm.begin()), RandomAccessIter);
118   }
119 
120   {
121     const std::ranges::common_view<SizedRandomAccessView> comm(SizedRandomAccessView{buffer});
122     assert(comm.begin() == begin(SizedRandomAccessView(buffer)));
123     ASSERT_SAME_TYPE(decltype(comm.begin()), RandomAccessIter);
124   }
125 
126   return true;
127 }
128 
129 int main(int, char**) {
130   test();
131   static_assert(test());
132 
133   // The non-constexpr tests:
134   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
135 
136   {
137     std::ranges::common_view<SizedForwardView> comm(SizedForwardView{buffer});
138     assert(comm.begin() == begin(SizedForwardView(buffer)));
139     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<ForwardIter, sentinel_wrapper<ForwardIter>>);
140   }
141 
142   {
143     std::ranges::common_view<ContiguousView> comm(ContiguousView{buffer});
144     assert(comm.begin() == begin(ContiguousView(buffer)));
145     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<int*, sentinel_wrapper<int*>>);
146   }
147 
148   {
149     const std::ranges::common_view<SizedForwardView> comm(SizedForwardView{buffer});
150     assert(comm.begin() == begin(SizedForwardView(buffer)));
151     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<ForwardIter, sentinel_wrapper<ForwardIter>>);
152   }
153 
154   {
155     const std::ranges::common_view<CopyableView> comm(CopyableView{buffer});
156     assert(comm.begin() == begin(CopyableView(buffer)));
157     ASSERT_SAME_TYPE(decltype(comm.begin()), std::common_iterator<int*, sentinel_wrapper<int*>>);
158   }
159 
160   return 0;
161 }
162