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 //   requires (!(simple-view<V> &&
16 //               random_access_range<const V> && sized_range<const V>));
17 // constexpr auto begin() const
18 //   requires random_access_range<const V> && sized_range<const V>;
19 
20 #include <ranges>
21 
22 #include "test_macros.h"
23 #include "types.h"
24 
25 template<class T>
26 concept BeginInvocable = requires(std::ranges::drop_view<T> t) { t.begin(); };
27 
28 constexpr bool test() {
29   // random_access_range<const V> && sized_range<const V>
30   std::ranges::drop_view dropView1(ContiguousView(), 4);
31   assert(dropView1.begin() == globalBuff + 4);
32 
33   // !random_access_range<const V>
34   std::ranges::drop_view dropView2(ForwardView(), 4);
35   assert(dropView2.begin().base() == globalBuff + 4);
36 
37   // !random_access_range<const V>
38   std::ranges::drop_view dropView3(InputView(), 4);
39   assert(dropView3.begin().base() == globalBuff + 4);
40 
41   // random_access_range<const V> && sized_range<const V>
42   std::ranges::drop_view dropView4(ContiguousView(), 8);
43   assert(dropView4.begin() == globalBuff + 8);
44 
45   // random_access_range<const V> && sized_range<const V>
46   std::ranges::drop_view dropView5(ContiguousView(), 0);
47   assert(dropView5.begin() == globalBuff);
48 
49   // random_access_range<const V> && sized_range<const V>
50   const std::ranges::drop_view dropView6(ContiguousView(), 0);
51   assert(dropView6.begin() == globalBuff);
52 
53   // random_access_range<const V> && sized_range<const V>
54   std::ranges::drop_view dropView7(ContiguousView(), 10);
55   assert(dropView7.begin() == globalBuff + 8);
56 
57   CountedView view8;
58   std::ranges::drop_view dropView8(view8, 5);
59   assert(dropView8.begin().base().base() == globalBuff + 5);
60   assert(dropView8.begin().stride_count() == 5);
61   assert(dropView8.begin().base().base() == globalBuff + 5);
62   assert(dropView8.begin().stride_count() == 5);
63 
64   static_assert(!BeginInvocable<const ForwardView>);
65 
66   return true;
67 }
68 
69 int main(int, char**) {
70   test();
71   static_assert(test());
72 
73   return 0;
74 }
75