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 // template<class R>
14 // concept viewable_range;
15 
16 #include <ranges>
17 #include <type_traits>
18 
19 #include "test_iterators.h"
20 #include "test_range.h"
21 
22 // The constraints we have in viewable_range are:
23 //  range<T>
24 //  view<remove_cvref_t<T>>
25 //  constructible_from<remove_cvref_t<T>, T>
26 //  lvalue_reference_t<T> || movable<remove_reference_t<T>>
27 //  is-initializer-list<T>
28 //
29 // We test all the relevant combinations of satisfying/not satisfying those constraints.
30 
31 // viewable_range<T> is not satisfied for (range=false, view=*, constructible_from=*, lvalue-or-movable=*)
32 struct T1 { };
33 static_assert(!std::ranges::range<T1>);
34 
35 static_assert(!std::ranges::viewable_range<T1>);
36 static_assert(!std::ranges::viewable_range<T1&>);
37 static_assert(!std::ranges::viewable_range<T1&&>);
38 static_assert(!std::ranges::viewable_range<T1 const>);
39 static_assert(!std::ranges::viewable_range<T1 const&>);
40 static_assert(!std::ranges::viewable_range<T1 const&&>);
41 
42 // viewable_range<T> is satisfied for (range=true, view=true, constructible_from=true, lvalue-or-movable=true)
43 struct T2 : test_range<cpp20_input_iterator>, std::ranges::view_base {
44   T2(T2 const&) = default;
45 };
46 static_assert(std::ranges::range<T2>);
47 static_assert(std::ranges::view<T2>);
48 static_assert(std::constructible_from<T2, T2>);
49 
50 static_assert(std::ranges::viewable_range<T2>);
51 static_assert(std::ranges::viewable_range<T2&>);
52 static_assert(std::ranges::viewable_range<T2&&>);
53 static_assert(std::ranges::viewable_range<T2 const>);
54 static_assert(std::ranges::viewable_range<T2 const&>);
55 static_assert(std::ranges::viewable_range<T2 const&&>);
56 
57 // viewable_range<T> is satisfied for (range=true, view=true, constructible_from=true, lvalue-or-movable=false)
58 struct T3 : test_range<cpp20_input_iterator>, std::ranges::view_base {
59   T3(T3 const&) = default;
60 };
61 static_assert(std::ranges::range<T3>);
62 static_assert(std::ranges::view<T3>);
63 static_assert(std::constructible_from<T3, T3>);
64 
65 static_assert(std::ranges::viewable_range<T3>);
66 static_assert(std::ranges::viewable_range<T3&>);
67 static_assert(std::ranges::viewable_range<T3&&>);
68 static_assert(std::ranges::viewable_range<T3 const>);
69 static_assert(std::ranges::viewable_range<T3 const&>);
70 static_assert(std::ranges::viewable_range<T3 const&&>);
71 
72 // viewable_range<T> is not satisfied for (range=true, view=true, constructible_from=false, lvalue-or-movable=true)
73 struct T4 : test_range<cpp20_input_iterator>, std::ranges::view_base {
74   T4(T4 const&) = delete;
75   T4(T4&&) = default;             // necessary to model view
76   T4& operator=(T4&&) = default;  // necessary to model view
77 };
78 static_assert(std::ranges::range<T4 const&>);
79 static_assert(std::ranges::view<std::remove_cvref_t<T4 const&>>);
80 static_assert(!std::constructible_from<std::remove_cvref_t<T4 const&>, T4 const&>);
81 
82 static_assert(!std::ranges::viewable_range<T4 const&>);
83 
84 // A type that satisfies (range=true, view=true, constructible_from=false, lvalue-or-movable=false) can't be formed,
85 // because views are movable by definition
86 
87 // viewable_range<T> is satisfied for (range=true, view=false, constructible_from=true, lvalue-or-movable=true)...
88 struct T5 : test_range<cpp20_input_iterator> { };
89 static_assert( std::ranges::range<T5>);
90 static_assert(!std::ranges::view<T5>);
91 static_assert( std::constructible_from<T5, T5>);
92 static_assert( std::movable<T5>);
93 static_assert(!std::movable<const T5>);
94 
95 static_assert( std::ranges::viewable_range<T5>); // movable
96 static_assert( std::ranges::viewable_range<T5&>); // movable
97 static_assert( std::ranges::viewable_range<T5&&>); // movable
98 static_assert(!std::ranges::viewable_range<const T5>);
99 static_assert( std::ranges::viewable_range<const T5&>); // lvalue
100 static_assert(!std::ranges::viewable_range<const T5&&>);
101 
102 // ...but not if the (non-view, lvalue-or-movable) range is an initializer_list.
103 static_assert( std::ranges::range<std::initializer_list<int>>);
104 static_assert(!std::ranges::view<std::initializer_list<int>>);
105 static_assert( std::constructible_from<std::initializer_list<int>, std::initializer_list<int>>);
106 static_assert( std::movable<std::initializer_list<int>>);
107 
108 static_assert(!std::ranges::viewable_range<std::initializer_list<int>>);
109 static_assert( std::ranges::viewable_range<std::initializer_list<int>&>);
110 static_assert(!std::ranges::viewable_range<std::initializer_list<int>&&>);
111 static_assert(!std::ranges::viewable_range<std::initializer_list<int> const>);
112 static_assert( std::ranges::viewable_range<std::initializer_list<int> const&>);
113 static_assert(!std::ranges::viewable_range<std::initializer_list<int> const&&>);
114 
115 // viewable_range<T> is not satisfied for (range=true, view=false, constructible_from=true, lvalue-or-movable=false)
116 struct T6 : test_range<cpp20_input_iterator> { T6(T6&&); T6& operator=(T6&&) = delete; };
117 static_assert( std::ranges::range<T6>);
118 static_assert(!std::ranges::view<T6>);
119 static_assert( std::constructible_from<T6, T6>);
120 static_assert(!std::movable<T6>);
121 
122 static_assert(!std::ranges::viewable_range<T6>);
123 static_assert( std::ranges::viewable_range<T6&>); // lvalue
124 static_assert(!std::ranges::viewable_range<T6&&>);
125 static_assert(!std::ranges::viewable_range<const T6>);
126 static_assert( std::ranges::viewable_range<const T6&>); // lvalue
127 static_assert(!std::ranges::viewable_range<const T6&&>);
128 
129 // viewable_range<T> is satisfied for (range=true, view=false, constructible_from=false, lvalue-or-movable=true)
130 struct T7 : test_range<cpp20_input_iterator> {
131   T7(T7 const&) = delete;
132 };
133 static_assert(std::ranges::range<T7&>);
134 static_assert(!std::ranges::view<std::remove_cvref_t<T7&>>);
135 static_assert(!std::constructible_from<std::remove_cvref_t<T7&>, T7&>);
136 
137 static_assert(!std::ranges::viewable_range<T7>);
138 static_assert( std::ranges::viewable_range<T7&>);
139 static_assert(!std::ranges::viewable_range<T7&&>);
140 static_assert(!std::ranges::viewable_range<const T7>);
141 static_assert( std::ranges::viewable_range<const T7&>);
142 static_assert(!std::ranges::viewable_range<const T7&&>);
143 
144 // viewable_range<T> is not satisfied for (range=true, view=false, constructible_from=false, lvalue-or-movable=false)
145 struct T8 : test_range<cpp20_input_iterator> {
146   T8(T8 const&) = delete;
147 };
148 static_assert(std::ranges::range<T8>);
149 static_assert(!std::ranges::view<T8>);
150 static_assert(!std::constructible_from<T8, T8>);
151 
152 static_assert(!std::ranges::viewable_range<T8>);
153 static_assert( std::ranges::viewable_range<T8&>);
154 static_assert(!std::ranges::viewable_range<T8&&>);
155 static_assert(!std::ranges::viewable_range<const T8>);
156 static_assert( std::ranges::viewable_range<const T8&>);
157 static_assert(!std::ranges::viewable_range<const T8&&>);
158 
159 // Test with a few degenerate types
160 static_assert(!std::ranges::viewable_range<void>);
161 static_assert(!std::ranges::viewable_range<int>);
162 static_assert(!std::ranges::viewable_range<int (*)(char)>);
163 static_assert(!std::ranges::viewable_range<int[]>);
164 static_assert(!std::ranges::viewable_range<int[10]>);
165 static_assert(!std::ranges::viewable_range<int(&)[]>); // not a range
166 static_assert( std::ranges::viewable_range<int(&)[10]>); // OK, lvalue
167 static_assert(!std::ranges::viewable_range<int(&&)[]>);
168 static_assert(!std::ranges::viewable_range<int(&&)[10]>);
169