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 | |
11 | // constexpr auto begin() requires (!simple-view<V>) |
12 | // { return ranges::begin(base_); } |
13 | // |
14 | // constexpr auto begin() const |
15 | // requires range<const V> && |
16 | // indirect_unary_predicate<const Pred, iterator_t<const V>> |
17 | // { return ranges::begin(base_); } |
18 | |
19 | #include <cassert> |
20 | #include <ranges> |
21 | #include <type_traits> |
22 | #include <utility> |
23 | |
24 | #include "types.h" |
25 | |
26 | // Test Constraints |
27 | template <class T> |
28 | concept HasConstBegin = requires(const T& ct) { ct.begin(); }; |
29 | |
30 | template <class T> |
31 | concept HasBegin = requires(T& t) { t.begin(); }; |
32 | |
33 | template <class T> |
34 | concept HasConstAndNonConstBegin = |
35 | HasConstBegin<T> && |
36 | requires(T& t, const T& ct) { requires !std::same_as<decltype(t.begin()), decltype(ct.begin())>; }; |
37 | |
38 | template <class T> |
39 | concept HasOnlyNonConstBegin = HasBegin<T> && !HasConstBegin<T>; |
40 | |
41 | template <class T> |
42 | concept HasOnlyConstBegin = HasConstBegin<T> && !HasConstAndNonConstBegin<T>; |
43 | |
44 | struct Pred { |
45 | constexpr bool operator()(int i) const { return i > 5; } |
46 | }; |
47 | |
48 | static_assert(HasOnlyConstBegin<std::ranges::take_while_view<SimpleView, Pred>>); |
49 | |
50 | static_assert(HasOnlyNonConstBegin<std::ranges::take_while_view<ConstNotRange, Pred>>); |
51 | |
52 | static_assert(HasConstAndNonConstBegin<std::ranges::take_while_view<NonSimple, Pred>>); |
53 | |
54 | struct NotPredForConst { |
55 | constexpr bool operator()(int& i) const { return i > 5; } |
56 | }; |
57 | static_assert(HasOnlyNonConstBegin<std::ranges::take_while_view<NonSimple, NotPredForConst>>); |
58 | |
59 | constexpr bool test() { |
60 | // simple-view |
61 | { |
62 | int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1}; |
63 | SimpleView v{buffer}; |
64 | std::ranges::take_while_view twv(v, Pred{}); |
65 | std::same_as<int*> decltype(auto) it1 = twv.begin(); |
66 | assert(it1 == buffer); |
67 | std::same_as<int*> decltype(auto) it2 = std::as_const(twv).begin(); |
68 | assert(it2 == buffer); |
69 | } |
70 | |
71 | // const not range |
72 | { |
73 | int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1}; |
74 | ConstNotRange v{buffer}; |
75 | std::ranges::take_while_view twv(v, Pred{}); |
76 | std::same_as<int*> decltype(auto) it1 = twv.begin(); |
77 | assert(it1 == buffer); |
78 | } |
79 | |
80 | // NonSimple |
81 | { |
82 | int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1}; |
83 | NonSimple v{buffer}; |
84 | std::ranges::take_while_view twv(v, Pred{}); |
85 | std::same_as<int*> decltype(auto) it1 = twv.begin(); |
86 | assert(it1 == buffer); |
87 | std::same_as<const int*> decltype(auto) it2 = std::as_const(twv).begin(); |
88 | assert(it2 == buffer); |
89 | } |
90 | |
91 | // NotPredForConst |
92 | // LWG 3450: The const overloads of `take_while_view::begin/end` are underconstrained |
93 | { |
94 | int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1}; |
95 | NonSimple v{buffer}; |
96 | std::ranges::take_while_view twv(v, NotPredForConst{}); |
97 | std::same_as<int*> decltype(auto) it1 = twv.begin(); |
98 | assert(it1 == buffer); |
99 | } |
100 | |
101 | return true; |
102 | } |
103 | |
104 | int main(int, char**) { |
105 | test(); |
106 | static_assert(test()); |
107 | return 0; |
108 | } |
109 | |