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 //   requires (!(simple-view<V> &&
15 //               random_access_range<const V> && sized_range<const V>));
16 // constexpr auto begin() const
17 //   requires random_access_range<const V> && sized_range<const V>;
18 
19 #include <ranges>
20 
21 #include "test_macros.h"
22 #include "types.h"
23 
24 template<class T>
25 concept BeginInvocable = requires(std::ranges::drop_view<T> t) { t.begin(); };
26 
27 constexpr bool test() {
28   // random_access_range<const V> && sized_range<const V>
29   std::ranges::drop_view dropView1(MoveOnlyView(), 4);
30   assert(dropView1.begin() == globalBuff + 4);
31 
32   // !random_access_range<const V>
33   std::ranges::drop_view dropView2(ForwardView(), 4);
34   assert(dropView2.begin().base() == globalBuff + 4);
35 
36   // !random_access_range<const V>
37   std::ranges::drop_view dropView3(InputView(), 4);
38   assert(dropView3.begin().base() == globalBuff + 4);
39 
40   // random_access_range<const V> && sized_range<const V>
41   std::ranges::drop_view dropView4(MoveOnlyView(), 8);
42   assert(dropView4.begin() == globalBuff + 8);
43 
44   // random_access_range<const V> && sized_range<const V>
45   std::ranges::drop_view dropView5(MoveOnlyView(), 0);
46   assert(dropView5.begin() == globalBuff);
47 
48   // random_access_range<const V> && sized_range<const V>
49   const std::ranges::drop_view dropView6(MoveOnlyView(), 0);
50   assert(dropView6.begin() == globalBuff);
51 
52   // random_access_range<const V> && sized_range<const V>
53   std::ranges::drop_view dropView7(MoveOnlyView(), 10);
54   assert(dropView7.begin() == globalBuff + 8);
55 
56   CountedView view8;
57   std::ranges::drop_view dropView8(view8, 5);
58   assert(dropView8.begin().base().base() == globalBuff + 5);
59   assert(dropView8.begin().stride_count() == 5);
60   assert(dropView8.begin().base().base() == globalBuff + 5);
61   assert(dropView8.begin().stride_count() == 5);
62 
63   static_assert(!BeginInvocable<const ForwardView>);
64 
65   return true;
66 }
67 
68 int main(int, char**) {
69   test();
70   static_assert(test());
71 
72   return 0;
73 }
74